fix(ui): split message header into two rows

Move assistant meta below speaker label and bump speaker label size.

AGENTS.md

@@ -15,6 +15,35 @@
 - Prefer composable primitives (signals, hooks, utilities) over deep inheritance or implicit global state.
 - When adding platform integrations (SSE, IPC, SDK), isolate them in thin adapters that surface typed events/actions.
 
+## Multi-Language Support (i18n)
+
+The UI uses a small custom i18n layer (no ICU/messageformat). When building features, never hardcode user-visible strings.
+
+- **Runtime API:** use `useI18n()` in components (`const { t } = useI18n();`) and `tGlobal(...)` in stores/non-component code.
+  - Implementation: `packages/ui/src/lib/i18n/index.tsx`
+- **Where messages live:** `packages/ui/src/lib/i18n/messages/<locale>/` as TypeScript objects (`"flat.dot.keys": "string"`).
+  - Each locale has an `index.ts` that merges message parts; duplicate keys throw at build time.
+  - Merge helper: `packages/ui/src/lib/i18n/messages/merge.ts`
+- **Adding a new string:** add it to the appropriate `.../messages/en/*.ts` part file, then add the same key to each other locale’s corresponding file.
+  - Missing translations fall back to English (and finally to the key), so gaps can be easy to miss.
+- **Interpolation:** placeholders are simple `{name}` replacements (word characters only). Avoid placeholders like `{file-name}`.
+- **Pluralization:** handle manually via separate keys like `something.one` / `something.other` and choose in code.
+- **Adding a new language:** add a new `messages/<locale>/` folder + `index.ts`, register it in `packages/ui/src/lib/i18n/index.tsx`, and add it to the language picker in `packages/ui/src/components/folder-selection-view.tsx`.
+- **Locale persistence:** the selected locale is stored in app preferences (`locale`) and persisted via the server config (default `~/.config/codenomad/config.json`).
+- **Avoid English-only paths:** do not import `enMessages` directly in feature code; always go through `t(...)` so locale changes apply.
+
+## File Length Guidelines (Highlight Only)
+
+We track file size as a refactoring signal. When you touch or create files, highlight oversized files so the team can plan refactors when time permits.
+
+- Source files: warn after ~500 lines; target limit ~800 lines
+- Test files: highlight after ~1000 lines
+
+Behavior for agents:
+- Do not refactor solely to satisfy these thresholds.
+- When a change touches a file that exceeds the warning/limit, mention it in your final response and include the file path and approximate line count.
+- When creating new files, aim to stay under the thresholds unless there's a clear reason.
+
 ## Tooling Preferences
 - Use the `edit` tool for modifying existing files; prefer it over other editing methods.
 - Use the `write` tool only when creating new files from scratch.

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "codenomad-workspace",
-  "version": "0.10.2",
+  "version": "0.10.3",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "codenomad-workspace",
-      "version": "0.10.2",
+      "version": "0.10.3",
       "license": "MIT",
       "dependencies": {
         "7zip-bin": "^5.2.0",
@@ -8008,6 +8008,12 @@
         "obliterator": "^2.0.1"
       }
     },
+    "node_modules/monaco-editor": {
+      "version": "0.52.2",
+      "resolved": "https://registry.npmjs.org/monaco-editor/-/monaco-editor-0.52.2.tgz",
+      "integrity": "sha512-GEQWEZmfkOGLdd3XK8ryrfWz3AIP8YymVXiPHEdewrUq7mh0qrKrfHLNCXcbB6sTnMLnOZ3ztSiKcciFUkIJwQ==",
+      "license": "MIT"
+    },
     "node_modules/ms": {
       "version": "2.1.3",
       "license": "MIT"
@@ -11964,7 +11970,7 @@
     },
     "packages/electron-app": {
       "name": "@neuralnomads/codenomad-electron-app",
-      "version": "0.10.2",
+      "version": "0.10.3",
       "license": "MIT",
       "dependencies": {
         "@codenomad/ui": "file:../ui",
@@ -11999,7 +12005,7 @@
     },
     "packages/server": {
       "name": "@neuralnomads/codenomad",
-      "version": "0.10.2",
+      "version": "0.10.3",
       "license": "MIT",
       "dependencies": {
         "@fastify/cors": "^8.5.0",
@@ -12039,7 +12045,7 @@
     },
     "packages/tauri-app": {
       "name": "@codenomad/tauri-app",
-      "version": "0.10.2",
+      "version": "0.10.3",
       "license": "MIT",
       "devDependencies": {
         "@tauri-apps/cli": "^2.9.4"
@@ -12047,7 +12053,7 @@
     },
     "packages/ui": {
       "name": "@codenomad/ui",
-      "version": "0.10.2",
+      "version": "0.10.3",
       "license": "MIT",
       "dependencies": {
         "@git-diff-view/solid": "^0.0.8",
@@ -12064,6 +12070,7 @@
         "github-markdown-css": "^5.8.1",
         "lucide-solid": "^0.300.0",
         "marked": "^12.0.0",
+        "monaco-editor": "^0.52.2",
         "qrcode": "^1.5.3",
         "shiki": "^3.13.0",
         "solid-js": "^1.8.0",

package.json

@@ -1,6 +1,6 @@
 {
   "name": "codenomad-workspace",
-  "version": "0.10.2",
+  "version": "0.10.3",
   "private": true,
   "description": "CodeNomad monorepo workspace",
   "license": "MIT",

packages/cloudflare/release-config.json

@@ -1,4 +1,4 @@
 {
-  "minServerVersion": "0.10.2",
+  "minServerVersion": "0.10.3",
   "latestServerUrl": "https://github.com/NeuralNomadsAI/CodeNomad/releases/latest"
 }

packages/electron-app/electron.vite.config.ts

@@ -1,6 +1,7 @@
 import { defineConfig, externalizeDepsPlugin } from "electron-vite"
 import solid from "vite-plugin-solid"
 import { resolve } from "path"
+import { copyMonacoPublicAssets } from "../ui/scripts/monaco-public-assets.js"
 
 const uiRoot = resolve(__dirname, "../ui")
 const uiSrc = resolve(uiRoot, "src")
@@ -8,6 +9,32 @@ const uiRendererRoot = resolve(uiRoot, "src/renderer")
 const uiRendererEntry = resolve(uiRendererRoot, "index.html")
 const uiRendererLoadingEntry = resolve(uiRendererRoot, "loading.html")
 
+function prepareMonacoPublicAssets() {
+  return {
+    name: "prepare-monaco-public-assets",
+    configureServer(server: any) {
+      copyMonacoPublicAssets({
+        uiRendererRoot: uiRendererRoot,
+        warn: (msg: string) => server.config.logger.warn(msg),
+        sourceRoots: [
+          resolve(__dirname, "../../node_modules/monaco-editor/min/vs"),
+          resolve(uiRoot, "node_modules/monaco-editor/min/vs"),
+        ],
+      })
+    },
+    buildStart(this: any) {
+      copyMonacoPublicAssets({
+        uiRendererRoot: uiRendererRoot,
+        warn: (msg: string) => this.warn(msg),
+        sourceRoots: [
+          resolve(__dirname, "../../node_modules/monaco-editor/min/vs"),
+          resolve(uiRoot, "node_modules/monaco-editor/min/vs"),
+        ],
+      })
+    },
+  }
+}
+
 export default defineConfig({
   main: {
     plugins: [externalizeDepsPlugin()],
@@ -40,7 +67,7 @@ export default defineConfig({
   },
   renderer: {
     root: uiRendererRoot,
-    plugins: [solid()],
+    plugins: [solid(), prepareMonacoPublicAssets()],
     css: {
       postcss: resolve(uiRoot, "postcss.config.js"),
     },

packages/electron-app/electron/main/main.ts

@@ -399,7 +399,11 @@ async function exchangeBootstrapToken(baseUrl: string, token: string): Promise<b
 
 async function startCli() {
   try {
-    const devMode = process.env.NODE_ENV === "development"
+    // In desktop dev workflows we always want the CLI to run in dev mode so it:
+    // - uses plain HTTP
+    // - proxies UI requests to the renderer dev server
+    // Monaco's AMD assets are served from that dev server.
+    const devMode = !app.isPackaged
     console.info("[cli] start requested (dev mode:", devMode, ")")
     await cliManager.start({ dev: devMode })
   } catch (error) {

packages/electron-app/electron/main/process-manager.ts

@@ -390,7 +390,8 @@ export class CliProcessManager extends EventEmitter {
     }
 
     if (options.dev) {
-      args.push("--ui-dev-server", "http://localhost:3000", "--log-level", "debug")
+      const devServer = process.env.VITE_DEV_SERVER_URL || process.env.ELECTRON_RENDERER_URL || "http://localhost:3000"
+      args.push("--ui-dev-server", devServer, "--log-level", "debug")
     }
 
     return args

packages/electron-app/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@neuralnomads/codenomad-electron-app",
-  "version": "0.10.2",
+  "version": "0.10.3",
   "description": "CodeNomad - AI coding assistant",
   "license": "MIT",
   "author": {

packages/server/package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "@neuralnomads/codenomad",
-  "version": "0.10.2",
+  "version": "0.10.3",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "@neuralnomads/codenomad",
-      "version": "0.10.2",
+      "version": "0.10.3",
       "dependencies": {
         "@fastify/cors": "^8.5.0",
         "@fastify/reply-from": "^9.8.0",

packages/server/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@neuralnomads/codenomad",
-  "version": "0.10.2",
+  "version": "0.10.3",
   "description": "CodeNomad Server",
   "license": "MIT",
   "author": {

packages/server/src/workspaces/runtime.ts

@@ -116,12 +116,26 @@ export class WorkspaceRuntime {
           folder: options.folder,
           binary: options.binaryPath,
           spawnCommand: spec.command,
-          spawnArgs: spec.args,
           commandLine,
-          env: redactEnvironment(env),
         },
         "Launching OpenCode process",
       )
+
+      this.logger.debug(
+        {
+          workspaceId: options.workspaceId,
+          spawnArgs: spec.args,
+        },
+        "OpenCode spawn args",
+      )
+
+      this.logger.trace(
+        {
+          workspaceId: options.workspaceId,
+          env: redactEnvironment(env),
+        },
+        "OpenCode spawn environment",
+      )
       const detached = process.platform !== "win32"
       const child = spawn(spec.command, spec.args, {
         cwd: options.folder,

packages/tauri-app/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@codenomad/tauri-app",
-  "version": "0.10.2",
+  "version": "0.10.3",
   "private": true,
   "license": "MIT",
   "scripts": {

packages/tauri-app/scripts/dev-prep.js

@@ -3,6 +3,7 @@
 const fs = require("fs")
 const path = require("path")
 const { execSync } = require("child_process")
+const { pathToFileURL } = require("url")
 
 const root = path.resolve(__dirname, "..")
 const workspaceRoot = path.resolve(root, "..", "..")
@@ -10,6 +11,20 @@ const uiRoot = path.resolve(root, "..", "ui")
 const uiDist = path.resolve(uiRoot, "src", "renderer", "dist")
 const uiLoadingDest = path.resolve(root, "src-tauri", "resources", "ui-loading")
 
+async function ensureMonacoAssets() {
+  const helperPath = path.join(uiRoot, "scripts", "monaco-public-assets.js")
+  const helperUrl = pathToFileURL(helperPath).href
+  const { copyMonacoPublicAssets } = await import(helperUrl)
+  copyMonacoPublicAssets({
+    uiRendererRoot: path.join(uiRoot, "src", "renderer"),
+    warn: (msg) => console.warn(`[dev-prep] ${msg}`),
+    sourceRoots: [
+      path.resolve(workspaceRoot, "node_modules", "monaco-editor", "min", "vs"),
+      path.resolve(uiRoot, "node_modules", "monaco-editor", "min", "vs"),
+    ],
+  })
+}
+
 function ensureUiBuild() {
   const loadingHtml = path.join(uiDist, "loading.html")
   if (fs.existsSync(loadingHtml)) {
@@ -42,5 +57,11 @@ function copyUiLoadingAssets() {
   console.log(`[dev-prep] copied loader bundle from ${uiDist}`)
 }
 
-ensureUiBuild()
-copyUiLoadingAssets()
+;(async () => {
+  await ensureMonacoAssets()
+  ensureUiBuild()
+  copyUiLoadingAssets()
+})().catch((err) => {
+  console.error("[dev-prep] failed:", err)
+  process.exit(1)
+})

packages/tauri-app/scripts/prebuild.js

@@ -2,6 +2,7 @@
 const fs = require("fs")
 const path = require("path")
 const { execSync } = require("child_process")
+const { pathToFileURL } = require("url")
 
 const root = path.resolve(__dirname, "..")
 const workspaceRoot = path.resolve(root, "..", "..")
@@ -37,6 +38,20 @@ const braceExpansionPath = path.join(
 
 const viteBinPath = path.join(uiRoot, "node_modules", ".bin", "vite")
 
+async function ensureMonacoAssets() {
+  const helperPath = path.join(uiRoot, "scripts", "monaco-public-assets.js")
+  const helperUrl = pathToFileURL(helperPath).href
+  const { copyMonacoPublicAssets } = await import(helperUrl)
+  copyMonacoPublicAssets({
+    uiRendererRoot: path.join(uiRoot, "src", "renderer"),
+    warn: (msg) => console.warn(`[prebuild] ${msg}`),
+    sourceRoots: [
+      path.resolve(workspaceRoot, "node_modules", "monaco-editor", "min", "vs"),
+      path.resolve(uiRoot, "node_modules", "monaco-editor", "min", "vs"),
+    ],
+  })
+}
+
 function ensureServerBuild() {
   const distPath = path.join(serverRoot, "dist")
   const publicPath = path.join(serverRoot, "public")
@@ -223,12 +238,18 @@ function copyUiLoadingAssets() {
   console.log(`[prebuild] prepared UI loading assets from ${uiDist}`)
 }
 
-ensureServerDevDependencies()
-ensureUiDevDependencies()
-ensureRollupPlatformBinary()
-ensureServerDependencies()
-ensureServerBuild()
-ensureUiBuild()
-copyServerArtifacts()
-stripNodeModuleBins()
-copyUiLoadingAssets()
+;(async () => {
+  ensureServerDevDependencies()
+  ensureUiDevDependencies()
+  await ensureMonacoAssets()
+  ensureRollupPlatformBinary()
+  ensureServerDependencies()
+  ensureServerBuild()
+  ensureUiBuild()
+  copyServerArtifacts()
+  stripNodeModuleBins()
+  copyUiLoadingAssets()
+})().catch((err) => {
+  console.error("[prebuild] failed:", err)
+  process.exit(1)
+})

packages/ui/.gitignore

@@ -2,3 +2,4 @@ node_modules/
 dist/
 .vite/
 src/renderer/public/logo.png
+src/renderer/public/monaco/

packages/ui/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@codenomad/ui",
-  "version": "0.10.2",
+  "version": "0.10.3",
   "private": true,
   "license": "MIT",
   "type": "module",
@@ -25,6 +25,7 @@
     "github-markdown-css": "^5.8.1",
     "lucide-solid": "^0.300.0",
     "marked": "^12.0.0",
+    "monaco-editor": "^0.52.2",
     "qrcode": "^1.5.3",
     "shiki": "^3.13.0",
     "solid-js": "^1.8.0",

packages/ui/scripts/monaco-public-assets.d.ts

@@ -0,0 +1,7 @@
+export type CopyMonacoPublicAssetsParams = {
+  uiRendererRoot: string
+  warn?: (message: string) => void
+  sourceRoots?: string[]
+}
+
+export function copyMonacoPublicAssets(params: CopyMonacoPublicAssetsParams): void

packages/ui/scripts/monaco-public-assets.js

@@ -0,0 +1,97 @@
+import fs from "fs"
+import { resolve } from "path"
+
+/**
+ * Copy Monaco's AMD `min/vs` assets into the UI renderer public folder.
+ *
+ * Monaco is loaded at runtime via `/monaco/vs/loader.js`. These assets are gitignored
+ * and generated on demand in dev/build so the repo stays clean.
+ *
+ * @param {object} params
+ * @param {string} params.uiRendererRoot Absolute path to `packages/ui/src/renderer`.
+ * @param {(message: string) => void} [params.warn] Warning logger.
+ * @param {string[]} [params.sourceRoots] Optional override list of `.../monaco-editor/min/vs` roots.
+ */
+export function copyMonacoPublicAssets(params) {
+  const uiRendererRoot = params?.uiRendererRoot
+  if (!uiRendererRoot) {
+    throw new Error("copyMonacoPublicAssets: uiRendererRoot is required")
+  }
+
+  const warn = params?.warn ?? ((message) => console.warn(message))
+  const publicDir = resolve(uiRendererRoot, "public")
+  const destRoot = resolve(publicDir, "monaco/vs")
+
+  const candidates =
+    params?.sourceRoots?.length > 0
+      ? params.sourceRoots
+      : [
+          // Workspace root hoisted deps.
+          resolve(process.cwd(), "node_modules/monaco-editor/min/vs"),
+          // UI package local deps (covers non-hoisted installs).
+          resolve(process.cwd(), "packages/ui/node_modules/monaco-editor/min/vs"),
+        ]
+
+  const sourceRoot = candidates.find((p) => fs.existsSync(resolve(p, "loader.js")))
+  if (!sourceRoot) {
+    warn("Monaco source directory not found; skipping copy")
+    return
+  }
+
+  const copyRecursive = (src, dest) => {
+    const stat = fs.statSync(src)
+    if (stat.isDirectory()) {
+      fs.mkdirSync(dest, { recursive: true })
+      for (const entry of fs.readdirSync(src)) {
+        copyRecursive(resolve(src, entry), resolve(dest, entry))
+      }
+      return
+    }
+    fs.copyFileSync(src, dest)
+  }
+
+  // Keep the working tree clean; these assets are generated.
+  try {
+    fs.rmSync(destRoot, { recursive: true, force: true })
+  } catch {
+    // ignore
+  }
+  fs.mkdirSync(destRoot, { recursive: true })
+
+  // Copy core Monaco runtime.
+  for (const dir of ["base", "editor", "platform"]) {
+    const src = resolve(sourceRoot, dir)
+    if (fs.existsSync(src)) {
+      copyRecursive(src, resolve(destRoot, dir))
+    }
+  }
+
+  // loader.js is required.
+  copyRecursive(resolve(sourceRoot, "loader.js"), resolve(destRoot, "loader.js"))
+
+  // Copy baseline rich language packages + workers.
+  for (const lang of ["typescript", "html", "json", "css"]) {
+    const src = resolve(sourceRoot, "language", lang)
+    if (fs.existsSync(src)) {
+      copyRecursive(src, resolve(destRoot, "language", lang))
+    }
+  }
+
+  // Copy baseline basic tokenizers.
+  for (const lang of ["python", "markdown", "cpp", "kotlin"]) {
+    const src = resolve(sourceRoot, "basic-languages", lang)
+    if (fs.existsSync(src)) {
+      copyRecursive(src, resolve(destRoot, "basic-languages", lang))
+    }
+  }
+
+  // Copy monaco.contribution.js entrypoints (needed by some loads).
+  const monacoContribution = resolve(sourceRoot, "basic-languages", "monaco.contribution.js")
+  if (fs.existsSync(monacoContribution)) {
+    copyRecursive(monacoContribution, resolve(destRoot, "basic-languages", "monaco.contribution.js"))
+  }
+  const underscoreContribution = resolve(sourceRoot, "basic-languages", "_.contribution.js")
+  if (fs.existsSync(underscoreContribution)) {
+    copyRecursive(underscoreContribution, resolve(destRoot, "basic-languages", "_.contribution.js"))
+  }
+}

packages/ui/src/components/file-viewer/monaco-diff-viewer.tsx

@@ -0,0 +1,116 @@
+import { createEffect, createSignal, onCleanup, onMount } from "solid-js"
+import { loadMonaco } from "../../lib/monaco/setup"
+import { getOrCreateTextModel } from "../../lib/monaco/model-cache"
+import { inferMonacoLanguageId } from "../../lib/monaco/language"
+import { ensureMonacoLanguageLoaded } from "../../lib/monaco/setup"
+import { useTheme } from "../../lib/theme"
+
+interface MonacoDiffViewerProps {
+  scopeKey: string
+  path: string
+  before: string
+  after: string
+  viewMode?: "split" | "unified"
+  contextMode?: "expanded" | "collapsed"
+}
+
+export function MonacoDiffViewer(props: MonacoDiffViewerProps) {
+  const { isDark } = useTheme()
+  let host: HTMLDivElement | undefined
+
+  let diffEditor: any = null
+  let monaco: any = null
+  const [ready, setReady] = createSignal(false)
+
+  const disposeEditor = () => {
+    try {
+      diffEditor?.setModel(null as any)
+    } catch {
+      // ignore
+    }
+    try {
+      diffEditor?.dispose()
+    } catch {
+      // ignore
+    }
+    diffEditor = null
+  }
+
+  onMount(() => {
+    let cancelled = false
+    void (async () => {
+      monaco = await loadMonaco()
+      if (cancelled) return
+      if (!host || !monaco) return
+
+      monaco.editor.setTheme(isDark() ? "vs-dark" : "vs")
+      diffEditor = monaco.editor.createDiffEditor(host, {
+        readOnly: true,
+        automaticLayout: true,
+        renderSideBySide: true,
+        renderSideBySideInlineBreakpoint: 0,
+        renderMarginRevertIcon: false,
+        minimap: { enabled: false },
+        scrollBeyondLastLine: false,
+        renderWhitespace: "selection",
+        fontSize: 13,
+        wordWrap: "off",
+        glyphMargin: false,
+        folding: false,
+        // Keep enough gutter space so unified diffs don't overlap `+`/`-` markers.
+        lineNumbersMinChars: 4,
+        lineDecorationsWidth: 12,
+      })
+
+      setReady(true)
+    })()
+
+    onCleanup(() => {
+      cancelled = true
+      setReady(false)
+      disposeEditor()
+    })
+  })
+
+  createEffect(() => {
+    if (!ready() || !monaco || !diffEditor) return
+    monaco.editor.setTheme(isDark() ? "vs-dark" : "vs")
+  })
+
+  createEffect(() => {
+    if (!ready() || !monaco || !diffEditor) return
+    const viewMode = props.viewMode === "unified" ? "unified" : "split"
+    const contextMode = props.contextMode === "collapsed" ? "collapsed" : "expanded"
+
+    diffEditor.updateOptions({
+      renderSideBySide: viewMode === "split",
+      renderSideBySideInlineBreakpoint: 0,
+      hideUnchangedRegions:
+        contextMode === "collapsed"
+          ? { enabled: true }
+          : { enabled: false },
+    })
+  })
+
+  createEffect(() => {
+    if (!ready() || !monaco || !diffEditor) return
+    const languageId = inferMonacoLanguageId(monaco, props.path)
+    const beforeKey = `${props.scopeKey}:diff:${props.path}:before`
+    const afterKey = `${props.scopeKey}:diff:${props.path}:after`
+
+    const original = getOrCreateTextModel({ monaco, cacheKey: beforeKey, value: props.before, languageId })
+    const modified = getOrCreateTextModel({ monaco, cacheKey: afterKey, value: props.after, languageId })
+    diffEditor.setModel({ original, modified })
+
+    void ensureMonacoLanguageLoaded(languageId).then(() => {
+      try {
+        monaco.editor.setModelLanguage(original, languageId)
+        monaco.editor.setModelLanguage(modified, languageId)
+      } catch {
+        // ignore
+      }
+    })
+  })
+
+  return <div class="monaco-viewer" ref={host} />
+}

packages/ui/src/components/file-viewer/monaco-file-viewer.tsx

@@ -0,0 +1,89 @@
+import { createEffect, createSignal, onCleanup, onMount } from "solid-js"
+import { loadMonaco } from "../../lib/monaco/setup"
+import { getOrCreateTextModel } from "../../lib/monaco/model-cache"
+import { inferMonacoLanguageId } from "../../lib/monaco/language"
+import { ensureMonacoLanguageLoaded } from "../../lib/monaco/setup"
+import { useTheme } from "../../lib/theme"
+
+interface MonacoFileViewerProps {
+  scopeKey: string
+  path: string
+  content: string
+}
+
+export function MonacoFileViewer(props: MonacoFileViewerProps) {
+  const { isDark } = useTheme()
+  let host: HTMLDivElement | undefined
+
+  let editor: any = null
+  let monaco: any = null
+  const [ready, setReady] = createSignal(false)
+
+  const disposeEditor = () => {
+    try {
+      editor?.setModel(null)
+    } catch {
+      // ignore
+    }
+    try {
+      editor?.dispose()
+    } catch {
+      // ignore
+    }
+    editor = null
+  }
+
+  onMount(() => {
+    let cancelled = false
+    void (async () => {
+      monaco = await loadMonaco()
+      if (cancelled) return
+      if (!host || !monaco) return
+
+      monaco.editor.setTheme(isDark() ? "vs-dark" : "vs")
+      editor = monaco.editor.create(host, {
+        value: "",
+        language: "plaintext",
+        readOnly: true,
+        automaticLayout: true,
+        lineNumbers: "on",
+        minimap: { enabled: false },
+        scrollBeyondLastLine: false,
+        wordWrap: "off",
+        renderWhitespace: "selection",
+        fontSize: 13,
+      })
+
+      setReady(true)
+    })()
+
+    onCleanup(() => {
+      cancelled = true
+      setReady(false)
+      disposeEditor()
+    })
+  })
+
+  createEffect(() => {
+    if (!ready() || !monaco || !editor) return
+    monaco.editor.setTheme(isDark() ? "vs-dark" : "vs")
+  })
+
+  createEffect(() => {
+    if (!ready() || !monaco || !editor) return
+    const languageId = inferMonacoLanguageId(monaco, props.path)
+    const cacheKey = `${props.scopeKey}:file:${props.path}`
+    const model = getOrCreateTextModel({ monaco, cacheKey, value: props.content, languageId })
+    editor.setModel(model)
+
+    void ensureMonacoLanguageLoaded(languageId).then(() => {
+      try {
+        monaco.editor.setModelLanguage(model, languageId)
+      } catch {
+        // ignore
+      }
+    })
+  })
+
+  return <div class="monaco-viewer" ref={host} />
+}

packages/ui/src/components/folder-selection-view.tsx

@@ -254,12 +254,63 @@ const FolderSelectionView: Component<FolderSelectionViewProps> = (props) => {
 
 
   function getDisplayPath(path: string): string {
+    if (!path) return path
+
+    // macOS: /Users/<name>/...
     if (path.startsWith("/Users/")) {
       return path.replace(/^\/Users\/[^/]+/, "~")
     }
+
+    // Linux: /home/<name>/...
+    if (path.startsWith("/home/")) {
+      return path.replace(/^\/home\/[^/]+/, "~")
+    }
+
+    // Windows: C:\Users\<name>\... (and the forward-slash variant)
+    if (/^[A-Za-z]:\\Users\\/.test(path)) {
+      return path.replace(/^[A-Za-z]:\\Users\\[^\\]+/, "~")
+    }
+    if (/^[A-Za-z]:\/Users\//.test(path)) {
+      return path.replace(/^[A-Za-z]:\/Users\/[^/]+/, "~")
+    }
+
     return path
   }
 
+  function looksLikeWindowsPath(value: string): boolean {
+    if (!value) return false
+    // Drive letter (C:\...) or UNC (\\server\share\...)
+    return /^[A-Za-z]:[\\/]/.test(value) || /^\\\\[^\\]+\\[^\\]+/.test(value)
+  }
+
+  function splitFolderPath(rawPath: string): { baseName: string; dirName: string } {
+    if (!rawPath) return { baseName: "", dirName: "" }
+
+    const isWindows = looksLikeWindowsPath(rawPath)
+    const trimmed = rawPath.replace(/[\\/]+$/, "")
+
+    // Root edge-cases ("/", "C:\\", "\\\\server\\share\\")
+    if (!trimmed) {
+      return { baseName: rawPath, dirName: "" }
+    }
+
+    if (isWindows && /^[A-Za-z]:$/.test(trimmed)) {
+      return { baseName: `${trimmed}\\`, dirName: "" }
+    }
+
+    const lastSlash = trimmed.lastIndexOf("/")
+    const lastBackslash = isWindows ? trimmed.lastIndexOf("\\") : -1
+    const lastSep = Math.max(lastSlash, lastBackslash)
+
+    if (lastSep < 0) {
+      return { baseName: trimmed, dirName: "" }
+    }
+
+    const baseName = trimmed.slice(lastSep + 1) || trimmed
+    const dirName = trimmed.slice(0, lastSep)
+    return { baseName, dirName }
+  }
+
   return (
     <>
       <div
@@ -441,14 +492,14 @@ const FolderSelectionView: Component<FolderSelectionViewProps> = (props) => {
                                   <div class="flex items-center gap-2 mb-1">
                                     <Folder class="w-4 h-4 flex-shrink-0 icon-muted" />
                                     <span class="text-sm font-medium truncate text-primary">
-                                      {folder.path.split("/").pop()}
+                                      {splitFolderPath(folder.path).baseName}
                                     </span>
                                   </div>
-                                  <div class="text-xs font-mono truncate pl-6 text-muted">
-                                    {getDisplayPath(folder.path)}
-                                  </div>
-                                  <div class="text-xs mt-1 pl-6 text-muted">
-                                    {formatRelativeTime(folder.lastAccessed)}
+                                  <div class="flex items-center gap-2 pl-6 text-xs text-muted min-w-0">
+                                    <span class="font-mono truncate-start flex-1 min-w-0">
+                                      {getDisplayPath(folder.path)}
+                                    </span>
+                                    <span class="flex-shrink-0">{formatRelativeTime(folder.lastAccessed)}</span>
                                   </div>
                                 </div>
                                 <Show when={focusMode() === "recent" && selectedIndex() === index()}>

packages/ui/src/components/instance/shell/SessionSidebar.tsx

@@ -0,0 +1,168 @@
+import { Show, type Accessor, type Component } from "solid-js"
+import type { SessionThread } from "../../../stores/session-state"
+import type { Session } from "../../../types/session"
+import type { KeyboardShortcut } from "../../../lib/keyboard-registry"
+import type { DrawerViewState } from "./types"
+
+import { Search } from "lucide-solid"
+import IconButton from "@suid/material/IconButton"
+import MenuOpenIcon from "@suid/icons-material/MenuOpen"
+import PushPinIcon from "@suid/icons-material/PushPin"
+import PushPinOutlinedIcon from "@suid/icons-material/PushPinOutlined"
+import InfoOutlinedIcon from "@suid/icons-material/InfoOutlined"
+
+import SessionList from "../../session-list"
+import KeyboardHint from "../../keyboard-hint"
+import Kbd from "../../kbd"
+import WorktreeSelector from "../../worktree-selector"
+import AgentSelector from "../../agent-selector"
+import ModelSelector from "../../model-selector"
+import ThinkingSelector from "../../thinking-selector"
+import { getLogger } from "../../../lib/logger"
+
+const log = getLogger("session")
+
+interface SessionSidebarProps {
+  t: (key: string) => string
+  instanceId: string
+  threads: Accessor<SessionThread[]>
+  activeSessionId: Accessor<string | null>
+  activeSession: Accessor<Session | null>
+
+  showSearch: Accessor<boolean>
+  onToggleSearch: () => void
+
+  keyboardShortcuts: Accessor<KeyboardShortcut[]>
+  isPhoneLayout: Accessor<boolean>
+  drawerState: Accessor<DrawerViewState>
+  leftPinned: Accessor<boolean>
+
+  onSelectSession: (sessionId: string) => void
+  onNewSession: () => Promise<void> | void
+  onSidebarAgentChange: (sessionId: string, agent: string) => Promise<void>
+  onSidebarModelChange: (sessionId: string, model: { providerId: string; modelId: string }) => Promise<void>
+  onPinLeftDrawer: () => void
+  onUnpinLeftDrawer: () => void
+  onCloseLeftDrawer: () => void
+
+  setContentEl: (el: HTMLElement | null) => void
+}
+
+const SessionSidebar: Component<SessionSidebarProps> = (props) => (
+  <div class="flex flex-col h-full min-h-0" ref={props.setContentEl}>
+    <div class="flex flex-col gap-2 px-4 py-3 border-b border-base">
+      <div class="flex items-center justify-between gap-2">
+        <span class="session-sidebar-title text-sm font-semibold uppercase text-primary">
+          {props.t("instanceShell.leftPanel.sessionsTitle")}
+        </span>
+        <div class="flex items-center gap-2 text-primary">
+          <IconButton
+            size="small"
+            color="inherit"
+            aria-label={props.t("sessionList.filter.ariaLabel")}
+            title={props.t("sessionList.filter.ariaLabel")}
+            aria-pressed={props.showSearch()}
+            onClick={props.onToggleSearch}
+            sx={{
+              color: props.showSearch() ? "var(--text-primary)" : "inherit",
+              backgroundColor: props.showSearch() ? "var(--surface-hover)" : "transparent",
+              "&:hover": {
+                backgroundColor: "var(--surface-hover)",
+              },
+            }}
+          >
+            <Search class={props.showSearch() ? "w-4 h-4" : "w-4 h-4 opacity-70"} />
+          </IconButton>
+          <IconButton
+            size="small"
+            color="inherit"
+            aria-label={props.t("instanceShell.leftPanel.instanceInfo")}
+            title={props.t("instanceShell.leftPanel.instanceInfo")}
+            onClick={() => props.onSelectSession("info")}
+          >
+            <InfoOutlinedIcon fontSize="small" />
+          </IconButton>
+          <Show when={!props.isPhoneLayout()}>
+            <IconButton
+              size="small"
+              color="inherit"
+              aria-label={props.leftPinned() ? props.t("instanceShell.leftDrawer.unpin") : props.t("instanceShell.leftDrawer.pin")}
+              onClick={() => (props.leftPinned() ? props.onUnpinLeftDrawer() : props.onPinLeftDrawer())}
+            >
+              {props.leftPinned() ? <PushPinIcon fontSize="small" /> : <PushPinOutlinedIcon fontSize="small" />}
+            </IconButton>
+          </Show>
+          <Show when={props.drawerState() === "floating-open"}>
+            <IconButton
+              size="small"
+              color="inherit"
+              aria-label={props.t("instanceShell.leftDrawer.toggle.close")}
+              title={props.t("instanceShell.leftDrawer.toggle.close")}
+              onClick={props.onCloseLeftDrawer}
+            >
+              <MenuOpenIcon fontSize="small" />
+            </IconButton>
+          </Show>
+        </div>
+      </div>
+      <div class="session-sidebar-shortcuts">
+        <Show when={props.keyboardShortcuts().length}>
+          <KeyboardHint shortcuts={props.keyboardShortcuts()} separator=" " showDescription={false} />
+        </Show>
+      </div>
+    </div>
+
+    <div class="session-sidebar flex flex-col flex-1 min-h-0">
+      <SessionList
+        instanceId={props.instanceId}
+        threads={props.threads()}
+        activeSessionId={props.activeSessionId()}
+        onSelect={props.onSelectSession}
+        onNew={() => {
+          const result = props.onNewSession()
+          if (result instanceof Promise) {
+            void result.catch((error) => log.error("Failed to create session:", error))
+          }
+        }}
+        enableFilterBar={props.showSearch()}
+        showHeader={false}
+        showFooter={false}
+      />
+
+      <div class="session-sidebar-separator" />
+      <Show when={props.activeSession()}>
+        {(activeSession) => (
+          <>
+            <div class="session-sidebar-controls px-4 py-4 border-t border-base flex flex-col gap-3">
+              <WorktreeSelector instanceId={props.instanceId} sessionId={activeSession().id} />
+
+              <AgentSelector
+                instanceId={props.instanceId}
+                sessionId={activeSession().id}
+                currentAgent={activeSession().agent}
+                onAgentChange={(agent) => props.onSidebarAgentChange(activeSession().id, agent)}
+              />
+
+              <ModelSelector
+                instanceId={props.instanceId}
+                sessionId={activeSession().id}
+                currentModel={activeSession().model}
+                onModelChange={(model) => props.onSidebarModelChange(activeSession().id, model)}
+              />
+
+              <ThinkingSelector instanceId={props.instanceId} currentModel={activeSession().model} />
+
+              <div class="session-sidebar-selector-hints" aria-hidden="true">
+                <Kbd shortcut="cmd+shift+a" />
+                <Kbd shortcut="cmd+shift+m" />
+                <Kbd shortcut="cmd+shift+t" />
+              </div>
+            </div>
+          </>
+        )}
+      </Show>
+    </div>
+  </div>
+)
+
+export default SessionSidebar

packages/ui/src/components/instance/shell/right-panel/RightPanel.tsx

@@ -0,0 +1,829 @@
+import {
+  Show,
+  createEffect,
+  createMemo,
+  createSignal,
+  onCleanup,
+  type Accessor,
+  type Component,
+} from "solid-js"
+import type { ToolState } from "@opencode-ai/sdk"
+import type { FileContent, FileNode, File as GitFileStatus } from "@opencode-ai/sdk/v2/client"
+import IconButton from "@suid/material/IconButton"
+import MenuOpenIcon from "@suid/icons-material/MenuOpen"
+import PushPinIcon from "@suid/icons-material/PushPin"
+import PushPinOutlinedIcon from "@suid/icons-material/PushPinOutlined"
+
+import type { Instance } from "../../../../types/instance"
+import type { BackgroundProcess } from "../../../../../../server/src/api-types"
+import type { Session } from "../../../../types/session"
+import type { DrawerViewState } from "../types"
+import type { DiffContextMode, DiffViewMode, RightPanelTab } from "./types"
+
+import ChangesTab from "./tabs/ChangesTab"
+import FilesTab from "./tabs/FilesTab"
+import GitChangesTab from "./tabs/GitChangesTab"
+import StatusTab from "./tabs/StatusTab"
+
+import { getDefaultWorktreeSlug, getOrCreateWorktreeClient, getWorktreeSlugForSession } from "../../../../stores/worktrees"
+import { requestData } from "../../../../lib/opencode-api"
+import { buildUnifiedDiffFromSdkPatch, tryReverseApplyUnifiedDiff } from "../../../../lib/unified-diff-reverse"
+import { useGlobalPointerDrag } from "../useGlobalPointerDrag"
+import {
+  RIGHT_PANEL_CHANGES_DIFF_CONTEXT_MODE_KEY,
+  RIGHT_PANEL_CHANGES_DIFF_VIEW_MODE_KEY,
+  RIGHT_PANEL_CHANGES_LIST_OPEN_NONPHONE_KEY,
+  RIGHT_PANEL_CHANGES_LIST_OPEN_PHONE_KEY,
+  RIGHT_PANEL_CHANGES_SPLIT_WIDTH_KEY,
+  RIGHT_PANEL_FILES_LIST_OPEN_NONPHONE_KEY,
+  RIGHT_PANEL_FILES_LIST_OPEN_PHONE_KEY,
+  RIGHT_PANEL_FILES_SPLIT_WIDTH_KEY,
+  RIGHT_PANEL_GIT_CHANGES_LIST_OPEN_NONPHONE_KEY,
+  RIGHT_PANEL_GIT_CHANGES_LIST_OPEN_PHONE_KEY,
+  RIGHT_PANEL_GIT_CHANGES_SPLIT_WIDTH_KEY,
+  RIGHT_PANEL_TAB_STORAGE_KEY,
+  readStoredBool,
+  readStoredEnum,
+  readStoredPanelWidth,
+  readStoredRightPanelTab,
+} from "../storage"
+
+interface RightPanelProps {
+  t: (key: string, vars?: Record<string, any>) => string
+
+  instanceId: string
+  instance: Instance
+
+  activeSessionId: Accessor<string | null>
+  activeSession: Accessor<Session | null>
+  activeSessionDiffs: Accessor<any[] | undefined>
+
+  latestTodoState: Accessor<ToolState | null>
+  backgroundProcessList: Accessor<BackgroundProcess[]>
+  onOpenBackgroundOutput: (process: BackgroundProcess) => void
+  onStopBackgroundProcess: (processId: string) => Promise<void> | void
+  onTerminateBackgroundProcess: (processId: string) => Promise<void> | void
+
+  isPhoneLayout: Accessor<boolean>
+  rightDrawerWidth: Accessor<number>
+  rightDrawerWidthInitialized: Accessor<boolean>
+  rightDrawerState: Accessor<DrawerViewState>
+  rightPinned: Accessor<boolean>
+  onCloseRightDrawer: () => void
+  onPinRightDrawer: () => void
+  onUnpinRightDrawer: () => void
+
+  setContentEl: (el: HTMLElement | null) => void
+}
+
+const RightPanel: Component<RightPanelProps> = (props) => {
+  const [rightPanelTab, setRightPanelTab] = createSignal<RightPanelTab>(readStoredRightPanelTab("changes"))
+  const [rightPanelExpandedItems, setRightPanelExpandedItems] = createSignal<string[]>([
+    "plan",
+    "background-processes",
+    "mcp",
+    "lsp",
+    "plugins",
+  ])
+  const [selectedFile, setSelectedFile] = createSignal<string | null>(null)
+
+  const [browserPath, setBrowserPath] = createSignal(".")
+  const [browserEntries, setBrowserEntries] = createSignal<FileNode[] | null>(null)
+  const [browserLoading, setBrowserLoading] = createSignal(false)
+  const [browserError, setBrowserError] = createSignal<string | null>(null)
+  const [browserSelectedPath, setBrowserSelectedPath] = createSignal<string | null>(null)
+  const [browserSelectedContent, setBrowserSelectedContent] = createSignal<string | null>(null)
+  const [browserSelectedLoading, setBrowserSelectedLoading] = createSignal(false)
+  const [browserSelectedError, setBrowserSelectedError] = createSignal<string | null>(null)
+
+  const [diffViewMode, setDiffViewMode] = createSignal<DiffViewMode>(
+    readStoredEnum(RIGHT_PANEL_CHANGES_DIFF_VIEW_MODE_KEY, ["split", "unified"] as const) ?? "unified",
+  )
+  const [diffContextMode, setDiffContextMode] = createSignal<DiffContextMode>(
+    readStoredEnum(RIGHT_PANEL_CHANGES_DIFF_CONTEXT_MODE_KEY, ["expanded", "collapsed"] as const) ?? "collapsed",
+  )
+
+  const [changesSplitWidth, setChangesSplitWidth] = createSignal(320)
+  const [filesSplitWidth, setFilesSplitWidth] = createSignal(320)
+  const [gitChangesSplitWidth, setGitChangesSplitWidth] = createSignal(320)
+  const [activeSplitResize, setActiveSplitResize] = createSignal<"changes" | "git-changes" | "files" | null>(null)
+  const [splitResizeStartX, setSplitResizeStartX] = createSignal(0)
+  const [splitResizeStartWidth, setSplitResizeStartWidth] = createSignal(0)
+
+  const [filesListOpen, setFilesListOpen] = createSignal(true)
+  const [filesListTouched, setFilesListTouched] = createSignal(false)
+  const [changesListOpen, setChangesListOpen] = createSignal(true)
+  const [changesListTouched, setChangesListTouched] = createSignal(false)
+  const [gitChangesListOpen, setGitChangesListOpen] = createSignal(true)
+  const [gitChangesListTouched, setGitChangesListTouched] = createSignal(false)
+
+  const listLayoutKey = createMemo(() => (props.isPhoneLayout() ? "phone" : "nonphone"))
+
+  const listOpenStorageKey = (tab: "changes" | "git-changes" | "files") => {
+    const layout = listLayoutKey()
+    if (tab === "changes") {
+      return layout === "phone" ? RIGHT_PANEL_CHANGES_LIST_OPEN_PHONE_KEY : RIGHT_PANEL_CHANGES_LIST_OPEN_NONPHONE_KEY
+    }
+    if (tab === "git-changes") {
+      return layout === "phone"
+        ? RIGHT_PANEL_GIT_CHANGES_LIST_OPEN_PHONE_KEY
+        : RIGHT_PANEL_GIT_CHANGES_LIST_OPEN_NONPHONE_KEY
+    }
+    return layout === "phone" ? RIGHT_PANEL_FILES_LIST_OPEN_PHONE_KEY : RIGHT_PANEL_FILES_LIST_OPEN_NONPHONE_KEY
+  }
+
+  const persistListOpen = (tab: "changes" | "git-changes" | "files", value: boolean) => {
+    if (typeof window === "undefined") return
+    window.localStorage.setItem(listOpenStorageKey(tab), value ? "true" : "false")
+  }
+
+  createEffect(() => {
+    // Refresh persisted visibility when layout changes (phone vs non-phone).
+    const layout = listLayoutKey()
+    layout
+
+    const filesPersisted = readStoredBool(listOpenStorageKey("files"))
+    if (filesPersisted !== null) {
+      setFilesListOpen(filesPersisted)
+      setFilesListTouched(true)
+    } else {
+      setFilesListOpen(true)
+      setFilesListTouched(false)
+    }
+
+    const changesPersisted = readStoredBool(listOpenStorageKey("changes"))
+    if (changesPersisted !== null) {
+      setChangesListOpen(changesPersisted)
+      setChangesListTouched(true)
+    } else {
+      setChangesListOpen(true)
+      setChangesListTouched(false)
+    }
+
+    const gitPersisted = readStoredBool(listOpenStorageKey("git-changes"))
+    if (gitPersisted !== null) {
+      setGitChangesListOpen(gitPersisted)
+      setGitChangesListTouched(true)
+    } else {
+      setGitChangesListOpen(true)
+      setGitChangesListTouched(false)
+    }
+  })
+
+  createEffect(() => {
+    // Default behavior: when nothing is selected, keep the file list open.
+    // Once the user explicitly toggles it, we stop auto-opening.
+    if (rightPanelTab() !== "files") return
+    if (filesListTouched()) return
+    if (!browserSelectedPath()) {
+      setFilesListOpen(true)
+    }
+  })
+
+  createEffect(() => {
+    if (typeof window === "undefined") return
+    window.localStorage.setItem(RIGHT_PANEL_TAB_STORAGE_KEY, rightPanelTab())
+  })
+
+  createEffect(() => {
+    if (typeof window === "undefined") return
+    window.localStorage.setItem(RIGHT_PANEL_CHANGES_DIFF_VIEW_MODE_KEY, diffViewMode())
+  })
+
+  createEffect(() => {
+    if (typeof window === "undefined") return
+    window.localStorage.setItem(RIGHT_PANEL_CHANGES_DIFF_CONTEXT_MODE_KEY, diffContextMode())
+  })
+
+  const clampSplitWidth = (value: number) => {
+    const min = 200
+    const maxByDrawer = Math.max(min, Math.floor(props.rightDrawerWidth() * 0.65))
+    const max = Math.min(560, maxByDrawer)
+    return Math.min(max, Math.max(min, Math.floor(value)))
+  }
+
+  const [splitWidthsInitialized, setSplitWidthsInitialized] = createSignal(false)
+
+  createEffect(() => {
+    if (splitWidthsInitialized()) return
+    if (!props.rightDrawerWidthInitialized()) return
+    setSplitWidthsInitialized(true)
+    setChangesSplitWidth(clampSplitWidth(readStoredPanelWidth(RIGHT_PANEL_CHANGES_SPLIT_WIDTH_KEY, 320)))
+    setFilesSplitWidth(clampSplitWidth(readStoredPanelWidth(RIGHT_PANEL_FILES_SPLIT_WIDTH_KEY, 320)))
+    setGitChangesSplitWidth(clampSplitWidth(readStoredPanelWidth(RIGHT_PANEL_GIT_CHANGES_SPLIT_WIDTH_KEY, 320)))
+  })
+
+  const persistSplitWidth = (mode: "changes" | "git-changes" | "files", width: number) => {
+    if (typeof window === "undefined") return
+    const key =
+      mode === "changes"
+        ? RIGHT_PANEL_CHANGES_SPLIT_WIDTH_KEY
+        : mode === "git-changes"
+          ? RIGHT_PANEL_GIT_CHANGES_SPLIT_WIDTH_KEY
+          : RIGHT_PANEL_FILES_SPLIT_WIDTH_KEY
+    window.localStorage.setItem(key, String(width))
+  }
+
+  function stopSplitResize() {
+    setActiveSplitResize(null)
+    if (typeof document === "undefined") return
+    splitPointerDrag.stop()
+  }
+
+  function splitMouseMove(event: MouseEvent) {
+    const mode = activeSplitResize()
+    if (!mode) return
+    event.preventDefault()
+    const delta = event.clientX - splitResizeStartX()
+    const next = clampSplitWidth(splitResizeStartWidth() + delta)
+    if (mode === "changes") setChangesSplitWidth(next)
+    else if (mode === "git-changes") setGitChangesSplitWidth(next)
+    else setFilesSplitWidth(next)
+  }
+
+  function splitMouseUp() {
+    const mode = activeSplitResize()
+    if (mode) {
+      const width =
+        mode === "changes" ? changesSplitWidth() : mode === "git-changes" ? gitChangesSplitWidth() : filesSplitWidth()
+      persistSplitWidth(mode, width)
+    }
+    stopSplitResize()
+  }
+
+  function splitTouchMove(event: TouchEvent) {
+    const mode = activeSplitResize()
+    if (!mode) return
+    const touch = event.touches[0]
+    if (!touch) return
+    event.preventDefault()
+    const delta = touch.clientX - splitResizeStartX()
+    const next = clampSplitWidth(splitResizeStartWidth() + delta)
+    if (mode === "changes") setChangesSplitWidth(next)
+    else if (mode === "git-changes") setGitChangesSplitWidth(next)
+    else setFilesSplitWidth(next)
+  }
+
+  function splitTouchEnd() {
+    const mode = activeSplitResize()
+    if (mode) {
+      const width =
+        mode === "changes" ? changesSplitWidth() : mode === "git-changes" ? gitChangesSplitWidth() : filesSplitWidth()
+      persistSplitWidth(mode, width)
+    }
+    stopSplitResize()
+  }
+
+  const splitPointerDrag = useGlobalPointerDrag({
+    onMouseMove: splitMouseMove,
+    onMouseUp: splitMouseUp,
+    onTouchMove: splitTouchMove,
+    onTouchEnd: splitTouchEnd,
+  })
+
+  const startSplitResize = (mode: "changes" | "git-changes" | "files", clientX: number) => {
+    if (typeof document === "undefined") return
+    setActiveSplitResize(mode)
+    setSplitResizeStartX(clientX)
+    setSplitResizeStartWidth(
+      mode === "changes" ? changesSplitWidth() : mode === "git-changes" ? gitChangesSplitWidth() : filesSplitWidth(),
+    )
+    splitPointerDrag.start()
+  }
+
+  const handleSplitResizeMouseDown = (mode: "changes" | "git-changes" | "files") => (event: MouseEvent) => {
+    event.preventDefault()
+    startSplitResize(mode, event.clientX)
+  }
+
+  const handleSplitResizeTouchStart = (mode: "changes" | "git-changes" | "files") => (event: TouchEvent) => {
+    const touch = event.touches[0]
+    if (!touch) return
+    event.preventDefault()
+    startSplitResize(mode, touch.clientX)
+  }
+
+  onCleanup(() => {
+    stopSplitResize()
+  })
+
+  const worktreeSlugForViewer = createMemo(() => {
+    const sessionId = props.activeSessionId()
+    if (sessionId && sessionId !== "info") {
+      return getWorktreeSlugForSession(props.instanceId, sessionId)
+    }
+    return getDefaultWorktreeSlug(props.instanceId)
+  })
+
+  const browserClient = createMemo(() => getOrCreateWorktreeClient(props.instanceId, worktreeSlugForViewer()))
+
+  const [gitStatusEntries, setGitStatusEntries] = createSignal<GitFileStatus[] | null>(null)
+  const [gitStatusLoading, setGitStatusLoading] = createSignal(false)
+  const [gitStatusError, setGitStatusError] = createSignal<string | null>(null)
+  const [gitSelectedPath, setGitSelectedPath] = createSignal<string | null>(null)
+  const [gitSelectedLoading, setGitSelectedLoading] = createSignal(false)
+  const [gitSelectedError, setGitSelectedError] = createSignal<string | null>(null)
+  const [gitSelectedBefore, setGitSelectedBefore] = createSignal<string | null>(null)
+  const [gitSelectedAfter, setGitSelectedAfter] = createSignal<string | null>(null)
+
+  const gitMostChangedPath = createMemo<string | null>(() => {
+    const entries = gitStatusEntries()
+    if (!Array.isArray(entries) || entries.length === 0) return null
+    const candidates = entries.filter((item) => item && item.status !== "deleted")
+    if (candidates.length === 0) return null
+    const best = candidates.reduce((currentBest, item) => {
+      const bestScore = (currentBest?.added ?? 0) + (currentBest?.removed ?? 0)
+      const score = (item?.added ?? 0) + (item?.removed ?? 0)
+      if (score > bestScore) return item
+      if (score < bestScore) return currentBest
+      return String(item.path || "").localeCompare(String(currentBest?.path || "")) < 0 ? item : currentBest
+    }, candidates[0])
+    return typeof best?.path === "string" ? best.path : null
+  })
+
+  createEffect(() => {
+    // Reset tab state when worktree context changes.
+    worktreeSlugForViewer()
+    setBrowserPath(".")
+    setBrowserEntries(null)
+    setBrowserError(null)
+    setBrowserSelectedPath(null)
+    setBrowserSelectedContent(null)
+    setBrowserSelectedError(null)
+    setBrowserSelectedLoading(false)
+
+    setGitStatusEntries(null)
+    setGitStatusError(null)
+    setGitStatusLoading(false)
+    setGitSelectedPath(null)
+    setGitSelectedLoading(false)
+    setGitSelectedError(null)
+    setGitSelectedBefore(null)
+    setGitSelectedAfter(null)
+  })
+
+  const loadGitStatus = async (force = false) => {
+    if (!force && gitStatusEntries() !== null) return
+    setGitStatusLoading(true)
+    setGitStatusError(null)
+    try {
+      const list = await requestData<GitFileStatus[]>(browserClient().file.status(), "file.status")
+      setGitStatusEntries(Array.isArray(list) ? list : [])
+    } catch (error) {
+      setGitStatusError(error instanceof Error ? error.message : "Failed to load git status")
+      setGitStatusEntries([])
+    } finally {
+      setGitStatusLoading(false)
+    }
+  }
+
+  async function openGitFile(path: string) {
+    setGitSelectedPath(path)
+    setGitSelectedLoading(true)
+    setGitSelectedError(null)
+    setGitSelectedBefore(null)
+    setGitSelectedAfter(null)
+
+    const list = gitStatusEntries() || []
+    const entry = list.find((item) => item.path === path) || null
+    if (entry?.status === "deleted") {
+      setGitSelectedError("Deleted file diff is not available yet")
+      setGitSelectedLoading(false)
+      return
+    }
+
+    // Phone: treat file selection as a commit action and close the overlay.
+    if (props.isPhoneLayout()) {
+      setGitChangesListOpen(false)
+    }
+
+    try {
+      const content = await requestData<FileContent>(browserClient().file.read({ path }), "file.read")
+      const type = (content as any)?.type
+      const encoding = (content as any)?.encoding
+      if (type && type !== "text") {
+        throw new Error("Binary file cannot be displayed")
+      }
+      if (encoding === "base64") {
+        throw new Error("Binary file cannot be displayed")
+      }
+      const afterText = typeof (content as any)?.content === "string" ? ((content as any).content as string) : null
+      if (afterText === null) {
+        throw new Error("Unsupported file type")
+      }
+
+      setGitSelectedAfter(afterText)
+
+      if (entry?.status === "added") {
+        setGitSelectedBefore("")
+        return
+      }
+
+      const diffText =
+        typeof (content as any)?.diff === "string" && String((content as any).diff).trim().length > 0
+          ? String((content as any).diff)
+          : (content as any)?.patch
+            ? buildUnifiedDiffFromSdkPatch((content as any).patch)
+            : ""
+
+      const beforeText = tryReverseApplyUnifiedDiff(afterText, diffText)
+      if (beforeText === null) {
+        throw new Error("Unable to calculate diff for this file")
+      }
+      setGitSelectedBefore(beforeText)
+    } catch (error) {
+      setGitSelectedError(error instanceof Error ? error.message : "Failed to load file changes")
+    } finally {
+      setGitSelectedLoading(false)
+    }
+  }
+
+  createEffect(() => {
+    if (rightPanelTab() !== "git-changes") return
+    const entries = gitStatusEntries()
+    if (entries === null) return
+    if (gitSelectedPath()) return
+    const next = gitMostChangedPath()
+    if (!next) return
+    void openGitFile(next)
+  })
+
+  const refreshGitStatus = async () => {
+    await loadGitStatus(true)
+    const selected = gitSelectedPath()
+    if (selected) {
+      void openGitFile(selected)
+    }
+  }
+
+  const bestDiffFile = createMemo<string | null>(() => {
+    const diffs = props.activeSessionDiffs()
+    if (!Array.isArray(diffs) || diffs.length === 0) return null
+    const best = diffs.reduce((currentBest, item) => {
+      const bestAdd = typeof (currentBest as any)?.additions === "number" ? (currentBest as any).additions : 0
+      const bestDel = typeof (currentBest as any)?.deletions === "number" ? (currentBest as any).deletions : 0
+      const bestScore = bestAdd + bestDel
+
+      const add = typeof (item as any)?.additions === "number" ? (item as any).additions : 0
+      const del = typeof (item as any)?.deletions === "number" ? (item as any).deletions : 0
+      const score = add + del
+
+      if (score > bestScore) return item
+      if (score < bestScore) return currentBest
+      return String(item.file || "").localeCompare(String((currentBest as any)?.file || "")) < 0 ? item : currentBest
+    }, diffs[0])
+    return typeof (best as any)?.file === "string" ? (best as any).file : null
+  })
+
+  createEffect(() => {
+    const next = bestDiffFile()
+    if (!next) return
+    const diffs = props.activeSessionDiffs()
+    if (!Array.isArray(diffs) || diffs.length === 0) return
+
+    const current = selectedFile()
+    if (current && diffs.some((d) => d.file === current)) return
+    setSelectedFile(next)
+  })
+
+  const normalizeBrowserPath = (input: string) => {
+    const raw = String(input || ".").trim()
+    if (!raw || raw === "./") return "."
+    const cleaned = raw.replace(/\\/g, "/").replace(/\/+$/, "")
+    return cleaned === "" ? "." : cleaned
+  }
+
+  const getParentPath = (path: string): string | null => {
+    const current = normalizeBrowserPath(path)
+    if (current === ".") return null
+    const parts = current.split("/").filter(Boolean)
+    parts.pop()
+    return parts.length ? parts.join("/") : "."
+  }
+
+  const loadBrowserEntries = async (path: string) => {
+    const normalized = normalizeBrowserPath(path)
+    setBrowserLoading(true)
+    setBrowserError(null)
+    try {
+      const nodes = await requestData<FileNode[]>(browserClient().file.list({ path: normalized }), "file.list")
+      setBrowserPath(normalized)
+      setBrowserEntries(Array.isArray(nodes) ? nodes : [])
+    } catch (error) {
+      setBrowserError(error instanceof Error ? error.message : "Failed to load files")
+      setBrowserEntries([])
+    } finally {
+      setBrowserLoading(false)
+    }
+  }
+
+  const openBrowserFile = async (path: string) => {
+    setBrowserSelectedPath(path)
+    setBrowserSelectedLoading(true)
+    setBrowserSelectedError(null)
+    setBrowserSelectedContent(null)
+
+    // Phone: treat file selection as a commit action and close the overlay.
+    if (props.isPhoneLayout()) {
+      setFilesListOpen(false)
+    }
+    try {
+      const content = await requestData<FileContent>(browserClient().file.read({ path }), "file.read")
+      const type = (content as any)?.type
+      const encoding = (content as any)?.encoding
+      if (type && type !== "text") {
+        throw new Error("Binary file cannot be displayed")
+      }
+      if (encoding === "base64") {
+        throw new Error("Binary file cannot be displayed")
+      }
+      const text = (content as any)?.content
+      if (typeof text !== "string") {
+        throw new Error("Unsupported file type")
+      }
+      setBrowserSelectedContent(text)
+    } catch (error) {
+      setBrowserSelectedError(error instanceof Error ? error.message : "Failed to read file")
+    } finally {
+      setBrowserSelectedLoading(false)
+    }
+  }
+
+  createEffect(() => {
+    if (rightPanelTab() !== "files") return
+    if (browserLoading()) return
+    if (browserEntries() !== null) return
+    void loadBrowserEntries(browserPath())
+  })
+
+  createEffect(() => {
+    if (rightPanelTab() !== "git-changes") return
+    if (gitStatusLoading()) return
+    if (gitStatusEntries() !== null) return
+    void loadGitStatus()
+  })
+
+  const handleSelectChangesFile = (file: string, closeList: boolean) => {
+    setSelectedFile(file)
+    if (closeList) {
+      setChangesListOpen(false)
+    }
+  }
+
+  const toggleChangesList = () => {
+    setChangesListTouched(true)
+    setChangesListOpen((current) => {
+      const next = !current
+      persistListOpen("changes", next)
+      return next
+    })
+  }
+
+  const toggleFilesList = () => {
+    setFilesListTouched(true)
+    setFilesListOpen((current) => {
+      const next = !current
+      persistListOpen("files", next)
+      return next
+    })
+  }
+
+  const toggleGitList = () => {
+    setGitChangesListTouched(true)
+    setGitChangesListOpen((current) => {
+      const next = !current
+      persistListOpen("git-changes", next)
+      return next
+    })
+  }
+
+  const refreshFilesTab = async () => {
+    void loadBrowserEntries(browserPath())
+    const selected = browserSelectedPath()
+    if (selected) {
+      // Refresh file content without altering overlay state.
+      setBrowserSelectedLoading(true)
+      setBrowserSelectedError(null)
+      try {
+        const content = await requestData<FileContent>(browserClient().file.read({ path: selected }), "file.read")
+        const type = (content as any)?.type
+        const encoding = (content as any)?.encoding
+        if (type && type !== "text") {
+          throw new Error("Binary file cannot be displayed")
+        }
+        if (encoding === "base64") {
+          throw new Error("Binary file cannot be displayed")
+        }
+        const text = (content as any)?.content
+        if (typeof text !== "string") {
+          throw new Error("Unsupported file type")
+        }
+        setBrowserSelectedContent(text)
+      } catch (error) {
+        setBrowserSelectedError(error instanceof Error ? error.message : "Failed to read file")
+      } finally {
+        setBrowserSelectedLoading(false)
+      }
+    }
+  }
+
+  const browserParentPath = createMemo(() => getParentPath(browserPath()))
+  const browserScopeKey = createMemo(() => `${props.instanceId}:${worktreeSlugForViewer()}`)
+  const gitScopeKey = createMemo(() => `${props.instanceId}:git:${worktreeSlugForViewer()}`)
+
+  const openChangesTabFromStatus = (file?: string) => {
+    if (file) {
+      setSelectedFile(file)
+    }
+    setRightPanelTab("changes")
+  }
+
+  const statusSectionIds = ["session-changes", "plan", "background-processes", "mcp", "lsp", "plugins"]
+
+  createEffect(() => {
+    const currentExpanded = new Set(rightPanelExpandedItems())
+    if (statusSectionIds.every((id) => currentExpanded.has(id))) return
+    setRightPanelExpandedItems(statusSectionIds)
+  })
+
+  const handleAccordionChange = (values: string[]) => {
+    setRightPanelExpandedItems(values)
+  }
+
+  const tabClass = (tab: RightPanelTab) =>
+    `right-panel-tab ${rightPanelTab() === tab ? "right-panel-tab-active" : "right-panel-tab-inactive"}`
+
+  return (
+    <div class="flex flex-col h-full" ref={props.setContentEl}>
+      <div class="right-panel-tab-bar">
+        <div class="tab-container">
+          <div class="tab-strip-shortcuts text-primary">
+            <Show when={props.rightDrawerState() === "floating-open"}>
+              <IconButton
+                size="small"
+                color="inherit"
+                aria-label={props.t("instanceShell.rightDrawer.toggle.close")}
+                title={props.t("instanceShell.rightDrawer.toggle.close")}
+                onClick={props.onCloseRightDrawer}
+              >
+                <MenuOpenIcon fontSize="small" sx={{ transform: "scaleX(-1)" }} />
+              </IconButton>
+            </Show>
+            <Show when={!props.isPhoneLayout()}>
+              <IconButton
+                size="small"
+                color="inherit"
+                aria-label={props.rightPinned() ? props.t("instanceShell.rightDrawer.unpin") : props.t("instanceShell.rightDrawer.pin")}
+                onClick={() => (props.rightPinned() ? props.onUnpinRightDrawer() : props.onPinRightDrawer())}
+              >
+                {props.rightPinned() ? <PushPinIcon fontSize="small" /> : <PushPinOutlinedIcon fontSize="small" />}
+              </IconButton>
+            </Show>
+          </div>
+          <div class="tab-scroll">
+            <div class="tab-strip">
+              <div class="tab-strip-tabs" role="tablist" aria-label={props.t("instanceShell.rightPanel.tabs.ariaLabel")}> 
+                <button
+                  type="button"
+                  role="tab"
+                  class={tabClass("changes")}
+                  aria-selected={rightPanelTab() === "changes"}
+                  onClick={() => setRightPanelTab("changes")}
+                >
+                  <span class="tab-label">{props.t("instanceShell.rightPanel.tabs.changes")}</span>
+                </button>
+                <button
+                  type="button"
+                  role="tab"
+                  class={tabClass("git-changes")}
+                  aria-selected={rightPanelTab() === "git-changes"}
+                  onClick={() => setRightPanelTab("git-changes")}
+                >
+                  <span class="tab-label">{props.t("instanceShell.rightPanel.tabs.gitChanges")}</span>
+                </button>
+                <button
+                  type="button"
+                  role="tab"
+                  class={tabClass("files")}
+                  aria-selected={rightPanelTab() === "files"}
+                  onClick={() => setRightPanelTab("files")}
+                >
+                  <span class="tab-label">{props.t("instanceShell.rightPanel.tabs.files")}</span>
+                </button>
+                <button
+                  type="button"
+                  role="tab"
+                  class={tabClass("status")}
+                  aria-selected={rightPanelTab() === "status"}
+                  onClick={() => setRightPanelTab("status")}
+                >
+                  <span class="tab-label">{props.t("instanceShell.rightPanel.tabs.status")}</span>
+                </button>
+              </div>
+
+              <div class="tab-strip-spacer" />
+            </div>
+          </div>
+        </div>
+      </div>
+
+      <div class="flex-1 overflow-y-auto">
+        <Show when={rightPanelTab() === "changes"}>
+          <ChangesTab
+            t={props.t}
+            instanceId={props.instanceId}
+            activeSessionId={props.activeSessionId}
+            activeSessionDiffs={props.activeSessionDiffs}
+            selectedFile={selectedFile}
+            onSelectFile={handleSelectChangesFile}
+            diffViewMode={diffViewMode}
+            diffContextMode={diffContextMode}
+            onViewModeChange={setDiffViewMode}
+            onContextModeChange={setDiffContextMode}
+            listOpen={changesListOpen}
+            onToggleList={toggleChangesList}
+            splitWidth={changesSplitWidth}
+            onResizeMouseDown={handleSplitResizeMouseDown("changes")}
+            onResizeTouchStart={handleSplitResizeTouchStart("changes")}
+            isPhoneLayout={props.isPhoneLayout}
+          />
+        </Show>
+
+        <Show when={rightPanelTab() === "git-changes"}>
+          <GitChangesTab
+            t={props.t}
+            activeSessionId={props.activeSessionId}
+            entries={gitStatusEntries}
+            statusLoading={gitStatusLoading}
+            statusError={gitStatusError}
+            selectedPath={gitSelectedPath}
+            selectedLoading={gitSelectedLoading}
+            selectedError={gitSelectedError}
+            selectedBefore={gitSelectedBefore}
+            selectedAfter={gitSelectedAfter}
+            mostChangedPath={gitMostChangedPath}
+            scopeKey={gitScopeKey}
+            diffViewMode={diffViewMode}
+            diffContextMode={diffContextMode}
+            onViewModeChange={setDiffViewMode}
+            onContextModeChange={setDiffContextMode}
+            onOpenFile={(path) => void openGitFile(path)}
+            onRefresh={() => void refreshGitStatus()}
+            listOpen={gitChangesListOpen}
+            onToggleList={toggleGitList}
+            splitWidth={gitChangesSplitWidth}
+            onResizeMouseDown={handleSplitResizeMouseDown("git-changes")}
+            onResizeTouchStart={handleSplitResizeTouchStart("git-changes")}
+            isPhoneLayout={props.isPhoneLayout}
+          />
+        </Show>
+
+        <Show when={rightPanelTab() === "files"}>
+          <FilesTab
+            t={props.t}
+            browserPath={browserPath}
+            browserEntries={browserEntries}
+            browserLoading={browserLoading}
+            browserError={browserError}
+            browserSelectedPath={browserSelectedPath}
+            browserSelectedContent={browserSelectedContent}
+            browserSelectedLoading={browserSelectedLoading}
+            browserSelectedError={browserSelectedError}
+            parentPath={browserParentPath}
+            scopeKey={browserScopeKey}
+            onLoadEntries={(path) => void loadBrowserEntries(path)}
+            onOpenFile={(path) => void openBrowserFile(path)}
+            onRefresh={() => void refreshFilesTab()}
+            listOpen={filesListOpen}
+            onToggleList={toggleFilesList}
+            splitWidth={filesSplitWidth}
+            onResizeMouseDown={handleSplitResizeMouseDown("files")}
+            onResizeTouchStart={handleSplitResizeTouchStart("files")}
+            isPhoneLayout={props.isPhoneLayout}
+          />
+        </Show>
+
+        <Show when={rightPanelTab() === "status"}>
+          <StatusTab
+            t={props.t}
+            instanceId={props.instanceId}
+            instance={props.instance}
+            activeSessionId={props.activeSessionId}
+            activeSession={props.activeSession}
+            activeSessionDiffs={props.activeSessionDiffs}
+            latestTodoState={props.latestTodoState}
+            backgroundProcessList={props.backgroundProcessList}
+            onOpenBackgroundOutput={props.onOpenBackgroundOutput}
+            onStopBackgroundProcess={props.onStopBackgroundProcess}
+            onTerminateBackgroundProcess={props.onTerminateBackgroundProcess}
+            expandedItems={rightPanelExpandedItems}
+            onExpandedItemsChange={handleAccordionChange}
+            onOpenChangesTab={openChangesTabFromStatus}
+          />
+        </Show>
+      </div>
+    </div>
+  )
+}
+
+export default RightPanel

packages/ui/src/components/instance/shell/right-panel/components/DiffToolbar.tsx

@@ -0,0 +1,53 @@
+import type { Component } from "solid-js"
+
+import type { DiffContextMode, DiffViewMode } from "../types"
+
+interface DiffToolbarProps {
+  viewMode: DiffViewMode
+  contextMode: DiffContextMode
+  onViewModeChange: (mode: DiffViewMode) => void
+  onContextModeChange: (mode: DiffContextMode) => void
+}
+
+const DiffToolbar: Component<DiffToolbarProps> = (props) => {
+  return (
+    <div class="file-viewer-toolbar">
+      <button
+        type="button"
+        class={`file-viewer-toolbar-button${props.viewMode === "split" ? " active" : ""}`}
+        aria-pressed={props.viewMode === "split"}
+        onClick={() => props.onViewModeChange("split")}
+      >
+        Split
+      </button>
+      <button
+        type="button"
+        class={`file-viewer-toolbar-button${props.viewMode === "unified" ? " active" : ""}`}
+        aria-pressed={props.viewMode === "unified"}
+        onClick={() => props.onViewModeChange("unified")}
+      >
+        Unified
+      </button>
+      <button
+        type="button"
+        class={`file-viewer-toolbar-button${props.contextMode === "collapsed" ? " active" : ""}`}
+        aria-pressed={props.contextMode === "collapsed"}
+        onClick={() => props.onContextModeChange("collapsed")}
+        title="Hide unchanged regions"
+      >
+        Collapsed
+      </button>
+      <button
+        type="button"
+        class={`file-viewer-toolbar-button${props.contextMode === "expanded" ? " active" : ""}`}
+        aria-pressed={props.contextMode === "expanded"}
+        onClick={() => props.onContextModeChange("expanded")}
+        title="Show full file"
+      >
+        Expanded
+      </button>
+    </div>
+  )
+}
+
+export default DiffToolbar

packages/ui/src/components/instance/shell/right-panel/components/OverlayList.tsx

@@ -0,0 +1,16 @@
+import type { Component, JSX } from "solid-js"
+
+interface OverlayListProps {
+  ariaLabel: string
+  children: JSX.Element
+}
+
+const OverlayList: Component<OverlayListProps> = (props) => {
+  return (
+    <div class="file-list-overlay" role="dialog" aria-label={props.ariaLabel}>
+      <div class="file-list-scroll">{props.children}</div>
+    </div>
+  )
+}
+
+export default OverlayList

packages/ui/src/components/instance/shell/right-panel/components/SplitFilePanel.tsx

@@ -0,0 +1,70 @@
+import { Show, type Component, type JSX } from "solid-js"
+
+import OverlayList from "./OverlayList"
+
+type SplitFilePanelList = {
+  panel: () => JSX.Element
+  overlay: () => JSX.Element
+}
+
+interface SplitFilePanelProps {
+  header: JSX.Element
+  list: SplitFilePanelList
+  viewer: JSX.Element
+
+  listOpen: boolean
+  onToggleList: () => void
+
+  splitWidth: number
+  onResizeMouseDown: (event: MouseEvent) => void
+  onResizeTouchStart: (event: TouchEvent) => void
+
+  isPhoneLayout: boolean
+  overlayAriaLabel: string
+}
+
+const SplitFilePanel: Component<SplitFilePanelProps> = (props) => {
+  return (
+    <div class="files-tab-container">
+      <div class="files-tab-header">
+        <div class="files-tab-header-row">
+          <button type="button" class="files-toggle-button" onClick={props.onToggleList}>
+            {props.listOpen ? "Hide files" : "Show files"}
+          </button>
+
+          {props.header}
+        </div>
+      </div>
+
+      <div class="files-tab-body">
+        <Show
+          when={!props.isPhoneLayout && props.listOpen}
+          fallback={props.viewer}
+        >
+          <div class="files-split" style={{ "--files-pane-width": `${props.splitWidth}px` }}>
+            <div class="file-list-panel">
+              <div class="file-list-scroll">{props.list.panel()}</div>
+            </div>
+            <div
+              class="file-split-handle"
+              role="separator"
+              aria-orientation="vertical"
+              aria-label="Resize file list"
+              onMouseDown={props.onResizeMouseDown}
+              onTouchStart={props.onResizeTouchStart}
+            />
+            {props.viewer}
+          </div>
+        </Show>
+
+        <Show when={props.isPhoneLayout}>
+          <Show when={props.listOpen}>
+            <OverlayList ariaLabel={props.overlayAriaLabel}>{props.list.overlay()}</OverlayList>
+          </Show>
+        </Show>
+      </div>
+    </div>
+  )
+}
+
+export default SplitFilePanel

packages/ui/src/components/instance/shell/right-panel/tabs/ChangesTab.tsx

@@ -0,0 +1,203 @@
+import { For, Show, type Accessor, type Component, type JSX } from "solid-js"
+
+import { MonacoDiffViewer } from "../../../../file-viewer/monaco-diff-viewer"
+
+import DiffToolbar from "../components/DiffToolbar"
+import SplitFilePanel from "../components/SplitFilePanel"
+import type { DiffContextMode, DiffViewMode } from "../types"
+
+interface ChangesTabProps {
+  t: (key: string, vars?: Record<string, any>) => string
+
+  instanceId: string
+  activeSessionId: Accessor<string | null>
+  activeSessionDiffs: Accessor<any[] | undefined>
+
+  selectedFile: Accessor<string | null>
+  onSelectFile: (file: string, closeList: boolean) => void
+
+  diffViewMode: Accessor<DiffViewMode>
+  diffContextMode: Accessor<DiffContextMode>
+  onViewModeChange: (mode: DiffViewMode) => void
+  onContextModeChange: (mode: DiffContextMode) => void
+
+  listOpen: Accessor<boolean>
+  onToggleList: () => void
+  splitWidth: Accessor<number>
+  onResizeMouseDown: (event: MouseEvent) => void
+  onResizeTouchStart: (event: TouchEvent) => void
+  isPhoneLayout: Accessor<boolean>
+}
+
+const ChangesTab: Component<ChangesTabProps> = (props) => {
+  const renderContent = (): JSX.Element => {
+    const sessionId = props.activeSessionId()
+
+    const hasSession = Boolean(sessionId && sessionId !== "info")
+    const diffs = hasSession ? props.activeSessionDiffs() : null
+
+    const sorted = Array.isArray(diffs) ? [...diffs].sort((a, b) => String(a.file || "").localeCompare(String(b.file || ""))) : []
+    const totals = sorted.reduce(
+      (acc, item) => {
+        acc.additions += typeof item.additions === "number" ? item.additions : 0
+        acc.deletions += typeof item.deletions === "number" ? item.deletions : 0
+        return acc
+      },
+      { additions: 0, deletions: 0 },
+    )
+
+    const mostChanged = sorted.length
+      ? sorted.reduce((best, item) => {
+          const bestAdd = typeof (best as any)?.additions === "number" ? (best as any).additions : 0
+          const bestDel = typeof (best as any)?.deletions === "number" ? (best as any).deletions : 0
+          const bestScore = bestAdd + bestDel
+
+          const add = typeof (item as any)?.additions === "number" ? (item as any).additions : 0
+          const del = typeof (item as any)?.deletions === "number" ? (item as any).deletions : 0
+          const score = add + del
+
+          if (score > bestScore) return item
+          if (score < bestScore) return best
+          return String(item.file || "").localeCompare(String((best as any)?.file || "")) < 0 ? item : best
+        }, sorted[0])
+      : null
+
+    // Auto-select the most-changed file if none selected.
+    const currentSelected = props.selectedFile()
+    const selectedFileData = sorted.find((f) => f.file === currentSelected) || mostChanged
+
+    const scopeKey = `${props.instanceId}:${hasSession ? sessionId : "no-session"}`
+
+    const emptyViewerMessage = () => {
+      if (!hasSession) return props.t("instanceShell.sessionChanges.noSessionSelected")
+      if (diffs === undefined) return props.t("instanceShell.sessionChanges.loading")
+      if (!Array.isArray(diffs) || diffs.length === 0) return props.t("instanceShell.sessionChanges.empty")
+      return props.t("instanceShell.filesShell.viewerEmpty")
+    }
+
+    const renderViewer = () => (
+      <div class="file-viewer-panel flex-1">
+        <div class="file-viewer-header">
+          <DiffToolbar
+            viewMode={props.diffViewMode()}
+            contextMode={props.diffContextMode()}
+            onViewModeChange={props.onViewModeChange}
+            onContextModeChange={props.onContextModeChange}
+          />
+        </div>
+        <div class="file-viewer-content file-viewer-content--monaco">
+          <Show
+            when={selectedFileData && hasSession && Array.isArray(diffs) && diffs.length > 0 ? selectedFileData : null}
+            fallback={
+              <div class="file-viewer-empty">
+                <span class="file-viewer-empty-text">{emptyViewerMessage()}</span>
+              </div>
+            }
+          >
+            {(file) => (
+              <MonacoDiffViewer
+                scopeKey={scopeKey}
+                path={String(file().file || "")}
+                before={String((file() as any).before || "")}
+                after={String((file() as any).after || "")}
+                viewMode={props.diffViewMode()}
+                contextMode={props.diffContextMode()}
+              />
+            )}
+          </Show>
+        </div>
+      </div>
+    )
+
+    const renderEmptyList = () => (
+      <div class="p-3 text-xs text-secondary">{emptyViewerMessage()}</div>
+    )
+
+    const renderListPanel = () => (
+      <Show when={sorted.length > 0} fallback={renderEmptyList()}>
+        <For each={sorted}>
+          {(item) => (
+            <div
+              class={`file-list-item ${selectedFileData?.file === item.file ? "file-list-item-active" : ""}`}
+              onClick={() => {
+                props.onSelectFile(item.file, props.isPhoneLayout())
+              }}
+            >
+              <div class="file-list-item-content">
+                <div class="file-list-item-path" title={item.file}>
+                  <span class="file-path-text">{item.file}</span>
+                </div>
+                <div class="file-list-item-stats">
+                  <span class="file-list-item-additions">+{item.additions}</span>
+                  <span class="file-list-item-deletions">-{item.deletions}</span>
+                </div>
+              </div>
+            </div>
+          )}
+        </For>
+      </Show>
+    )
+
+    const renderListOverlay = () => (
+      <Show when={sorted.length > 0} fallback={renderEmptyList()}>
+        <For each={sorted}>
+          {(item) => (
+            <div
+              class={`file-list-item ${selectedFileData?.file === item.file ? "file-list-item-active" : ""}`}
+              onClick={() => {
+                props.onSelectFile(item.file, true)
+              }}
+              title={item.file}
+            >
+              <div class="file-list-item-content">
+                <div class="file-list-item-path" title={item.file}>
+                  <span class="file-path-text">{item.file}</span>
+                </div>
+                <div class="file-list-item-stats">
+                  <span class="file-list-item-additions">+{item.additions}</span>
+                  <span class="file-list-item-deletions">-{item.deletions}</span>
+                </div>
+              </div>
+            </div>
+          )}
+        </For>
+      </Show>
+    )
+
+    const headerPath = () => (selectedFileData?.file ? selectedFileData.file : props.t("instanceShell.rightPanel.tabs.changes"))
+
+    return (
+      <SplitFilePanel
+        header={
+          <>
+            <span class="files-tab-selected-path" title={headerPath()}>
+              <span class="file-path-text">{headerPath()}</span>
+            </span>
+
+            <div class="files-tab-stats" style={{ flex: "0 0 auto" }}>
+              <span class="files-tab-stat files-tab-stat-additions">
+                <span class="files-tab-stat-value">+{totals.additions}</span>
+              </span>
+              <span class="files-tab-stat files-tab-stat-deletions">
+                <span class="files-tab-stat-value">-{totals.deletions}</span>
+              </span>
+            </div>
+          </>
+        }
+        list={{ panel: renderListPanel, overlay: renderListOverlay }}
+        viewer={renderViewer()}
+        listOpen={props.listOpen()}
+        onToggleList={props.onToggleList}
+        splitWidth={props.splitWidth()}
+        onResizeMouseDown={props.onResizeMouseDown}
+        onResizeTouchStart={props.onResizeTouchStart}
+        isPhoneLayout={props.isPhoneLayout()}
+        overlayAriaLabel="Changes"
+      />
+    )
+  }
+
+  return <>{renderContent()}</>
+}
+
+export default ChangesTab

packages/ui/src/components/instance/shell/right-panel/tabs/FilesTab.tsx

@@ -0,0 +1,191 @@
+import { For, Show, type Accessor, type Component, type JSX } from "solid-js"
+import type { FileNode } from "@opencode-ai/sdk/v2/client"
+
+import { RefreshCw } from "lucide-solid"
+
+import { MonacoFileViewer } from "../../../../file-viewer/monaco-file-viewer"
+
+import SplitFilePanel from "../components/SplitFilePanel"
+
+interface FilesTabProps {
+  t: (key: string, vars?: Record<string, any>) => string
+
+  browserPath: Accessor<string>
+  browserEntries: Accessor<FileNode[] | null>
+  browserLoading: Accessor<boolean>
+  browserError: Accessor<string | null>
+
+  browserSelectedPath: Accessor<string | null>
+  browserSelectedContent: Accessor<string | null>
+  browserSelectedLoading: Accessor<boolean>
+  browserSelectedError: Accessor<string | null>
+
+  parentPath: Accessor<string | null>
+  scopeKey: Accessor<string>
+
+  onLoadEntries: (path: string) => void
+  onOpenFile: (path: string) => void
+  onRefresh: () => void
+
+  listOpen: Accessor<boolean>
+  onToggleList: () => void
+  splitWidth: Accessor<number>
+  onResizeMouseDown: (event: MouseEvent) => void
+  onResizeTouchStart: (event: TouchEvent) => void
+  isPhoneLayout: Accessor<boolean>
+}
+
+const FilesTab: Component<FilesTabProps> = (props) => {
+  const renderContent = (): JSX.Element => {
+    const entriesValue = props.browserEntries()
+    const entries = entriesValue || []
+    const sorted = [...entries].sort((a, b) => {
+      const aDir = a.type === "directory" ? 0 : 1
+      const bDir = b.type === "directory" ? 0 : 1
+      if (aDir !== bDir) return aDir - bDir
+      return String(a.name || "").localeCompare(String(b.name || ""))
+    })
+
+    const parent = props.parentPath()
+
+    const headerDisplayedPath = () => props.browserSelectedPath() || props.browserPath()
+
+    const emptyViewerMessage = () => {
+      if (props.browserLoading() && entriesValue === null) return "Loading files..."
+      return "Select a file to preview"
+    }
+
+    const renderViewer = () => (
+      <div class="file-viewer-panel flex-1">
+        <div class="file-viewer-content file-viewer-content--monaco">
+          <Show
+            when={props.browserSelectedLoading()}
+            fallback={
+              <Show
+                when={props.browserSelectedError()}
+                fallback={
+                  <Show
+                    when={
+                      props.browserSelectedPath() && props.browserSelectedContent() !== null
+                        ? { path: props.browserSelectedPath() as string, content: props.browserSelectedContent() as string }
+                        : null
+                    }
+                    fallback={
+                      <div class="file-viewer-empty">
+                        <span class="file-viewer-empty-text">{emptyViewerMessage()}</span>
+                      </div>
+                    }
+                  >
+                    {(payload) => (
+                      <MonacoFileViewer scopeKey={props.scopeKey()} path={payload().path} content={payload().content} />
+                    )}
+                  </Show>
+                }
+              >
+                {(err) => (
+                  <div class="file-viewer-empty">
+                    <span class="file-viewer-empty-text">{err()}</span>
+                  </div>
+                )}
+              </Show>
+            }
+          >
+            <div class="file-viewer-empty">
+              <span class="file-viewer-empty-text">Loading…</span>
+            </div>
+          </Show>
+        </div>
+      </div>
+    )
+
+    const renderList = () => (
+      <>
+        <Show when={parent}>
+          {(p) => (
+            <div class="file-list-item" onClick={() => props.onLoadEntries(p())}>
+              <div class="file-list-item-content">
+                <div class="file-list-item-path" title={p()}>
+                  <span class="file-path-text">..</span>
+                </div>
+              </div>
+            </div>
+          )}
+        </Show>
+
+        <Show when={props.browserLoading() && entriesValue === null}>
+          <div class="p-3 text-xs text-secondary">Loading files...</div>
+        </Show>
+
+        <For each={sorted}>
+          {(item) => (
+            <div
+              class={`file-list-item ${props.browserSelectedPath() === item.path ? "file-list-item-active" : ""}`}
+              onClick={() => {
+                if (item.type === "directory") {
+                  props.onLoadEntries(item.path)
+                  return
+                }
+                props.onOpenFile(item.path)
+              }}
+              title={item.path}
+            >
+              <div class="file-list-item-content">
+                <div class="file-list-item-path" title={item.path}>
+                  <span class="file-path-text">{item.name}</span>
+                </div>
+                <div class="file-list-item-stats">
+                  <span class="text-[10px] text-secondary">{item.type}</span>
+                </div>
+              </div>
+            </div>
+          )}
+        </For>
+      </>
+    )
+
+    return (
+      <SplitFilePanel
+        header={
+          <>
+            <div class="files-tab-stats">
+              <span class="files-tab-stat">
+                <span class="files-tab-selected-path" title={headerDisplayedPath()}>
+                  <span class="file-path-text">{headerDisplayedPath()}</span>
+                </span>
+              </span>
+              <Show when={props.browserLoading()}>
+                <span>Loading…</span>
+              </Show>
+              <Show when={props.browserError()}>{(err) => <span class="text-error">{err()}</span>}</Show>
+            </div>
+
+            <button
+              type="button"
+              class="files-header-icon-button"
+              title={props.t("instanceShell.rightPanel.actions.refresh")}
+              aria-label={props.t("instanceShell.rightPanel.actions.refresh")}
+              disabled={props.browserLoading()}
+              style={{ "margin-left": "auto" }}
+              onClick={() => props.onRefresh()}
+            >
+              <RefreshCw class={`h-4 w-4${props.browserLoading() ? " animate-spin" : ""}`} />
+            </button>
+          </>
+        }
+        list={{ panel: renderList, overlay: renderList }}
+        viewer={renderViewer()}
+        listOpen={props.listOpen()}
+        onToggleList={props.onToggleList}
+        splitWidth={props.splitWidth()}
+        onResizeMouseDown={props.onResizeMouseDown}
+        onResizeTouchStart={props.onResizeTouchStart}
+        isPhoneLayout={props.isPhoneLayout()}
+        overlayAriaLabel="Files"
+      />
+    )
+  }
+
+  return <>{renderContent()}</>
+}
+
+export default FilesTab

packages/ui/src/components/instance/shell/right-panel/tabs/GitChangesTab.tsx

@@ -0,0 +1,258 @@
+import { For, Show, type Accessor, type Component, type JSX } from "solid-js"
+import type { File as GitFileStatus } from "@opencode-ai/sdk/v2/client"
+
+import { RefreshCw } from "lucide-solid"
+
+import { MonacoDiffViewer } from "../../../../file-viewer/monaco-diff-viewer"
+
+import DiffToolbar from "../components/DiffToolbar"
+import SplitFilePanel from "../components/SplitFilePanel"
+import type { DiffContextMode, DiffViewMode } from "../types"
+
+interface GitChangesTabProps {
+  t: (key: string, vars?: Record<string, any>) => string
+
+  activeSessionId: Accessor<string | null>
+
+  entries: Accessor<GitFileStatus[] | null>
+  statusLoading: Accessor<boolean>
+  statusError: Accessor<string | null>
+
+  selectedPath: Accessor<string | null>
+  selectedLoading: Accessor<boolean>
+  selectedError: Accessor<string | null>
+  selectedBefore: Accessor<string | null>
+  selectedAfter: Accessor<string | null>
+  mostChangedPath: Accessor<string | null>
+
+  scopeKey: Accessor<string>
+
+  diffViewMode: Accessor<DiffViewMode>
+  diffContextMode: Accessor<DiffContextMode>
+  onViewModeChange: (mode: DiffViewMode) => void
+  onContextModeChange: (mode: DiffContextMode) => void
+
+  onOpenFile: (path: string) => void
+  onRefresh: () => void
+
+  listOpen: Accessor<boolean>
+  onToggleList: () => void
+  splitWidth: Accessor<number>
+  onResizeMouseDown: (event: MouseEvent) => void
+  onResizeTouchStart: (event: TouchEvent) => void
+  isPhoneLayout: Accessor<boolean>
+}
+
+const GitChangesTab: Component<GitChangesTabProps> = (props) => {
+  const renderContent = (): JSX.Element => {
+    const sessionId = props.activeSessionId()
+
+    const hasSession = Boolean(sessionId && sessionId !== "info")
+    const entries = hasSession ? props.entries() : null
+
+    const sorted = Array.isArray(entries)
+      ? [...entries].sort((a, b) => String(a.path || "").localeCompare(String(b.path || "")))
+      : []
+
+    const totals = sorted.reduce(
+      (acc, item) => {
+        acc.additions += typeof item.added === "number" ? item.added : 0
+        acc.deletions += typeof item.removed === "number" ? item.removed : 0
+        return acc
+      },
+      { additions: 0, deletions: 0 },
+    )
+
+    const nonDeleted = sorted.filter((item) => item && item.status !== "deleted")
+
+    const emptyViewerMessage = () => {
+      if (!hasSession) return "Select a session to view changes."
+      if (entries === null) return "Loading git changes…"
+      if (nonDeleted.length === 0) return "No git changes yet."
+      return "No file selected."
+    }
+
+    const selectedPath = props.selectedPath()
+    const fallbackPath = props.mostChangedPath()
+    const selectedEntry =
+      sorted.find((item) => item.path === selectedPath) ||
+      (fallbackPath ? sorted.find((item) => item.path === fallbackPath) : null)
+
+    const renderViewer = () => (
+      <div class="file-viewer-panel flex-1">
+        <div class="file-viewer-header">
+          <DiffToolbar
+            viewMode={props.diffViewMode()}
+            contextMode={props.diffContextMode()}
+            onViewModeChange={props.onViewModeChange}
+            onContextModeChange={props.onContextModeChange}
+          />
+        </div>
+        <div class="file-viewer-content file-viewer-content--monaco">
+          <Show
+            when={props.selectedLoading()}
+            fallback={
+              <Show
+                when={props.selectedError()}
+                fallback={
+                  <Show
+                    when={
+                      selectedEntry &&
+                      props.selectedBefore() !== null &&
+                      props.selectedAfter() !== null &&
+                      selectedEntry.status !== "deleted"
+                        ? {
+                            path: selectedEntry.path,
+                            before: props.selectedBefore() as string,
+                            after: props.selectedAfter() as string,
+                          }
+                        : null
+                    }
+                    fallback={
+                      <div class="file-viewer-empty">
+                        <span class="file-viewer-empty-text">{emptyViewerMessage()}</span>
+                      </div>
+                    }
+                  >
+                    {(file) => (
+                      <MonacoDiffViewer
+                        scopeKey={props.scopeKey()}
+                        path={String(file().path || "")}
+                        before={String((file() as any).before || "")}
+                        after={String((file() as any).after || "")}
+                        viewMode={props.diffViewMode()}
+                        contextMode={props.diffContextMode()}
+                      />
+                    )}
+                  </Show>
+                }
+              >
+                {(err) => (
+                  <div class="file-viewer-empty">
+                    <span class="file-viewer-empty-text">{err()}</span>
+                  </div>
+                )}
+              </Show>
+            }
+          >
+            <div class="file-viewer-empty">
+              <span class="file-viewer-empty-text">Loading…</span>
+            </div>
+          </Show>
+        </div>
+      </div>
+    )
+
+    const renderEmptyList = () => <div class="p-3 text-xs text-secondary">{emptyViewerMessage()}</div>
+
+    const renderListPanel = () => (
+      <Show when={nonDeleted.length > 0} fallback={renderEmptyList()}>
+        <For each={sorted}>
+          {(item) => (
+            <div
+              class={`file-list-item ${props.selectedPath() === item.path ? "file-list-item-active" : ""}`}
+              onClick={() => {
+                props.onOpenFile(item.path)
+              }}
+            >
+              <div class="file-list-item-content">
+                <div class="file-list-item-path" title={item.path}>
+                  <span class="file-path-text">{item.path}</span>
+                </div>
+                <div class="file-list-item-stats">
+                  <Show when={item.status === "deleted"}>
+                    <span class="text-[10px] text-secondary">deleted</span>
+                  </Show>
+                  <Show when={item.status !== "deleted"}>
+                    <>
+                      <span class="file-list-item-additions">+{item.added}</span>
+                      <span class="file-list-item-deletions">-{item.removed}</span>
+                    </>
+                  </Show>
+                </div>
+              </div>
+            </div>
+          )}
+        </For>
+      </Show>
+    )
+
+    const renderListOverlay = () => (
+      <Show when={nonDeleted.length > 0} fallback={renderEmptyList()}>
+        <For each={sorted}>
+          {(item) => (
+            <div
+              class={`file-list-item ${props.selectedPath() === item.path ? "file-list-item-active" : ""}`}
+              onClick={() => props.onOpenFile(item.path)}
+              title={item.path}
+            >
+              <div class="file-list-item-content">
+                <div class="file-list-item-path" title={item.path}>
+                  <span class="file-path-text">{item.path}</span>
+                </div>
+                <div class="file-list-item-stats">
+                  <Show when={item.status === "deleted"}>
+                    <span class="text-[10px] text-secondary">deleted</span>
+                  </Show>
+                  <Show when={item.status !== "deleted"}>
+                    <>
+                      <span class="file-list-item-additions">+{item.added}</span>
+                      <span class="file-list-item-deletions">-{item.removed}</span>
+                    </>
+                  </Show>
+                </div>
+              </div>
+            </div>
+          )}
+        </For>
+      </Show>
+    )
+
+    return (
+      <SplitFilePanel
+        header={
+          <>
+            <span class="files-tab-selected-path" title={selectedEntry?.path || "Git Changes"}>
+              <span class="file-path-text">{selectedEntry?.path || "Git Changes"}</span>
+            </span>
+
+            <div class="files-tab-stats" style={{ flex: "0 0 auto" }}>
+              <span class="files-tab-stat files-tab-stat-additions">
+                <span class="files-tab-stat-value">+{totals.additions}</span>
+              </span>
+              <span class="files-tab-stat files-tab-stat-deletions">
+                <span class="files-tab-stat-value">-{totals.deletions}</span>
+              </span>
+              <Show when={props.statusError()}>{(err) => <span class="text-error">{err()}</span>}</Show>
+            </div>
+
+            <button
+              type="button"
+              class="files-header-icon-button"
+              title={props.t("instanceShell.rightPanel.actions.refresh")}
+              aria-label={props.t("instanceShell.rightPanel.actions.refresh")}
+              disabled={!hasSession || props.statusLoading() || entries === null}
+              style={{ "margin-left": "auto" }}
+              onClick={() => props.onRefresh()}
+            >
+              <RefreshCw class={`h-4 w-4${props.statusLoading() ? " animate-spin" : ""}`} />
+            </button>
+          </>
+        }
+        list={{ panel: renderListPanel, overlay: renderListOverlay }}
+        viewer={renderViewer()}
+        listOpen={props.listOpen()}
+        onToggleList={props.onToggleList}
+        splitWidth={props.splitWidth()}
+        onResizeMouseDown={props.onResizeMouseDown}
+        onResizeTouchStart={props.onResizeTouchStart}
+        isPhoneLayout={props.isPhoneLayout()}
+        overlayAriaLabel="Git Changes"
+      />
+    )
+  }
+
+  return <>{renderContent()}</>
+}
+
+export default GitChangesTab

packages/ui/src/components/instance/shell/right-panel/tabs/StatusTab.tsx

@@ -0,0 +1,294 @@
+import { For, Show, type Accessor, type Component } from "solid-js"
+import type { ToolState } from "@opencode-ai/sdk"
+import { Accordion } from "@kobalte/core"
+
+import { ChevronDown, TerminalSquare, Trash2, XOctagon } from "lucide-solid"
+
+import type { Instance } from "../../../../../types/instance"
+import type { BackgroundProcess } from "../../../../../../../server/src/api-types"
+import type { Session } from "../../../../../types/session"
+
+import ContextUsagePanel from "../../../../session/context-usage-panel"
+import { TodoListView } from "../../../../tool-call/renderers/todo"
+import InstanceServiceStatus from "../../../../instance-service-status"
+
+interface StatusTabProps {
+  t: (key: string, vars?: Record<string, any>) => string
+
+  instanceId: string
+  instance: Instance
+
+  activeSessionId: Accessor<string | null>
+  activeSession: Accessor<Session | null>
+  activeSessionDiffs: Accessor<any[] | undefined>
+
+  latestTodoState: Accessor<ToolState | null>
+
+  backgroundProcessList: Accessor<BackgroundProcess[]>
+  onOpenBackgroundOutput: (process: BackgroundProcess) => void
+  onStopBackgroundProcess: (processId: string) => Promise<void> | void
+  onTerminateBackgroundProcess: (processId: string) => Promise<void> | void
+
+  expandedItems: Accessor<string[]>
+  onExpandedItemsChange: (values: string[]) => void
+
+  onOpenChangesTab: (file?: string) => void
+}
+
+const StatusTab: Component<StatusTabProps> = (props) => {
+  const isSectionExpanded = (id: string) => props.expandedItems().includes(id)
+
+  const renderStatusSessionChanges = () => {
+    const sessionId = props.activeSessionId()
+    if (!sessionId || sessionId === "info") {
+      return (
+        <div class="right-panel-empty right-panel-empty--left">
+          <span class="text-xs">{props.t("instanceShell.sessionChanges.noSessionSelected")}</span>
+        </div>
+      )
+    }
+
+    const diffs = props.activeSessionDiffs()
+    if (diffs === undefined) {
+      return (
+        <div class="right-panel-empty right-panel-empty--left">
+          <span class="text-xs">{props.t("instanceShell.sessionChanges.loading")}</span>
+        </div>
+      )
+    }
+
+    if (!Array.isArray(diffs) || diffs.length === 0) {
+      return (
+        <div class="right-panel-empty right-panel-empty--left">
+          <span class="text-xs">{props.t("instanceShell.sessionChanges.empty")}</span>
+        </div>
+      )
+    }
+
+    const sorted = [...diffs].sort((a, b) => String(a.file || "").localeCompare(String(b.file || "")))
+    const totals = sorted.reduce(
+      (acc, item) => {
+        acc.additions += typeof item.additions === "number" ? item.additions : 0
+        acc.deletions += typeof item.deletions === "number" ? item.deletions : 0
+        return acc
+      },
+      { additions: 0, deletions: 0 },
+    )
+
+    return (
+      <div class="flex flex-col gap-3 min-h-0">
+        <div class="flex items-center justify-between gap-2 text-[11px] text-secondary">
+          <span>{props.t("instanceShell.sessionChanges.filesChanged", { count: sorted.length })}</span>
+          <span class="flex items-center gap-2">
+            <span style={{ color: "var(--session-status-idle-fg)" }}>{`+${totals.additions}`}</span>
+            <span style={{ color: "var(--session-status-working-fg)" }}>{`-${totals.deletions}`}</span>
+          </span>
+        </div>
+
+        <div class="rounded-md border border-base bg-surface-secondary p-2 max-h-[40vh] overflow-y-auto">
+          <div class="flex flex-col">
+            <For each={sorted}>
+              {(item) => (
+                <button
+                  type="button"
+                  class="border-b border-base last:border-b-0 text-left hover:bg-surface-muted rounded-sm"
+                  onClick={() => props.onOpenChangesTab(item.file)}
+                  title={props.t("instanceShell.sessionChanges.actions.show")}
+                >
+                  <div class="flex items-center justify-between gap-3">
+                    <div
+                      class="text-xs font-mono text-primary min-w-0 flex-1 overflow-hidden whitespace-nowrap"
+                      title={item.file}
+                      style="text-overflow: ellipsis; direction: rtl; text-align: left; unicode-bidi: plaintext;"
+                    >
+                      {item.file}
+                    </div>
+                    <div class="flex items-center gap-2 text-[11px] flex-shrink-0">
+                      <span style={{ color: "var(--session-status-idle-fg)" }}>{`+${item.additions}`}</span>
+                      <span style={{ color: "var(--session-status-working-fg)" }}>{`-${item.deletions}`}</span>
+                    </div>
+                  </div>
+                </button>
+              )}
+            </For>
+          </div>
+        </div>
+      </div>
+    )
+  }
+
+  const renderPlanSectionContent = () => {
+    const sessionId = props.activeSessionId()
+    if (!sessionId || sessionId === "info") {
+      return (
+        <div class="right-panel-empty right-panel-empty--left">
+          <span class="text-xs">{props.t("instanceShell.plan.noSessionSelected")}</span>
+        </div>
+      )
+    }
+    const todoState = props.latestTodoState()
+    if (!todoState) {
+      return (
+        <div class="right-panel-empty right-panel-empty--left">
+          <span class="text-xs">{props.t("instanceShell.plan.empty")}</span>
+        </div>
+      )
+    }
+    return <TodoListView state={todoState} emptyLabel={props.t("instanceShell.plan.empty")} showStatusLabel={false} />
+  }
+
+  const renderBackgroundProcesses = () => {
+    const processes = props.backgroundProcessList()
+    if (processes.length === 0) {
+      return (
+        <div class="right-panel-empty right-panel-empty--left">
+          <span class="text-xs">{props.t("instanceShell.backgroundProcesses.empty")}</span>
+        </div>
+      )
+    }
+
+    return (
+      <div class="flex flex-col gap-2">
+        <For each={processes}>
+          {(process) => (
+            <div class="status-process-card">
+              <div class="status-process-header">
+                <span class="status-process-title">{process.title}</span>
+                <div class="status-process-meta">
+                  <span>{props.t("instanceShell.backgroundProcesses.status", { status: process.status })}</span>
+                  <Show when={typeof process.outputSizeBytes === "number"}>
+                    <span>
+                      {props.t("instanceShell.backgroundProcesses.output", {
+                        sizeKb: Math.round((process.outputSizeBytes ?? 0) / 1024),
+                      })}
+                    </span>
+                  </Show>
+                </div>
+              </div>
+              <div class="status-process-actions">
+                <button
+                  type="button"
+                  class="button-tertiary w-full p-1 inline-flex items-center justify-center"
+                  onClick={() => props.onOpenBackgroundOutput(process)}
+                  aria-label={props.t("instanceShell.backgroundProcesses.actions.output")}
+                  title={props.t("instanceShell.backgroundProcesses.actions.output")}
+                >
+                  <TerminalSquare class="h-4 w-4" />
+                </button>
+                <button
+                  type="button"
+                  class="button-tertiary w-full p-1 inline-flex items-center justify-center"
+                  disabled={process.status !== "running"}
+                  onClick={() => props.onStopBackgroundProcess(process.id)}
+                  aria-label={props.t("instanceShell.backgroundProcesses.actions.stop")}
+                  title={props.t("instanceShell.backgroundProcesses.actions.stop")}
+                >
+                  <XOctagon class="h-4 w-4" />
+                </button>
+                <button
+                  type="button"
+                  class="button-tertiary w-full p-1 inline-flex items-center justify-center"
+                  onClick={() => props.onTerminateBackgroundProcess(process.id)}
+                  aria-label={props.t("instanceShell.backgroundProcesses.actions.terminate")}
+                  title={props.t("instanceShell.backgroundProcesses.actions.terminate")}
+                >
+                  <Trash2 class="h-4 w-4" />
+                </button>
+              </div>
+            </div>
+          )}
+        </For>
+      </div>
+    )
+  }
+
+  const statusSections = [
+    {
+      id: "session-changes",
+      labelKey: "instanceShell.rightPanel.sections.sessionChanges",
+      render: renderStatusSessionChanges,
+    },
+    {
+      id: "plan",
+      labelKey: "instanceShell.rightPanel.sections.plan",
+      render: renderPlanSectionContent,
+    },
+    {
+      id: "background-processes",
+      labelKey: "instanceShell.rightPanel.sections.backgroundProcesses",
+      render: renderBackgroundProcesses,
+    },
+    {
+      id: "mcp",
+      labelKey: "instanceShell.rightPanel.sections.mcp",
+      render: () => (
+        <InstanceServiceStatus
+          initialInstance={props.instance}
+          sections={["mcp"]}
+          showSectionHeadings={false}
+          class="space-y-2"
+        />
+      ),
+    },
+    {
+      id: "lsp",
+      labelKey: "instanceShell.rightPanel.sections.lsp",
+      render: () => (
+        <InstanceServiceStatus
+          initialInstance={props.instance}
+          sections={["lsp"]}
+          showSectionHeadings={false}
+          class="space-y-2"
+        />
+      ),
+    },
+    {
+      id: "plugins",
+      labelKey: "instanceShell.rightPanel.sections.plugins",
+      render: () => (
+        <InstanceServiceStatus
+          initialInstance={props.instance}
+          sections={["plugins"]}
+          showSectionHeadings={false}
+          class="space-y-2"
+        />
+      ),
+    },
+  ]
+
+  return (
+    <div class="status-tab-container">
+      <Show when={props.activeSession()}>
+        {(activeSession) => (
+          <ContextUsagePanel instanceId={props.instanceId} sessionId={activeSession().id} class="status-tab-context-panel" />
+        )}
+      </Show>
+
+      <Accordion.Root
+        class="right-panel-accordion"
+        collapsible
+        multiple
+        value={props.expandedItems()}
+        onChange={props.onExpandedItemsChange}
+      >
+        <For each={statusSections}>
+          {(section) => (
+            <Accordion.Item value={section.id} class="right-panel-accordion-item">
+              <Accordion.Header>
+                <Accordion.Trigger class="right-panel-accordion-trigger">
+                  <span>{props.t(section.labelKey)}</span>
+                  <ChevronDown
+                    class={`right-panel-accordion-chevron ${isSectionExpanded(section.id) ? "right-panel-accordion-chevron-expanded" : ""}`}
+                  />
+                </Accordion.Trigger>
+              </Accordion.Header>
+              <Accordion.Content class="right-panel-accordion-content">{section.render()}</Accordion.Content>
+            </Accordion.Item>
+          )}
+        </For>
+      </Accordion.Root>
+    </div>
+  )
+}
+
+export default StatusTab

packages/ui/src/components/instance/shell/right-panel/types.ts

@@ -0,0 +1,5 @@
+export type RightPanelTab = "changes" | "git-changes" | "files" | "status"
+
+export type DiffViewMode = "split" | "unified"
+
+export type DiffContextMode = "expanded" | "collapsed"

packages/ui/src/components/instance/shell/storage.ts

@@ -0,0 +1,92 @@
+export const DEFAULT_SESSION_SIDEBAR_WIDTH = 340
+export const MIN_SESSION_SIDEBAR_WIDTH = 220
+export const MAX_SESSION_SIDEBAR_WIDTH = 400
+
+export const RIGHT_DRAWER_WIDTH = 260
+export const MIN_RIGHT_DRAWER_WIDTH = 200
+export const MAX_RIGHT_DRAWER_WIDTH = 1200
+
+export const LEFT_DRAWER_STORAGE_KEY = "opencode-session-sidebar-width-v8"
+export const RIGHT_DRAWER_STORAGE_KEY = "opencode-session-right-drawer-width-v1"
+export const LEFT_PIN_STORAGE_KEY = "opencode-session-left-drawer-pinned-v1"
+export const RIGHT_PIN_STORAGE_KEY = "opencode-session-right-drawer-pinned-v1"
+export const RIGHT_PANEL_TAB_STORAGE_KEY = "opencode-session-right-panel-tab-v2"
+export const LEGACY_RIGHT_PANEL_TAB_STORAGE_KEY = "opencode-session-right-panel-tab-v1"
+export const RIGHT_PANEL_CHANGES_SPLIT_WIDTH_KEY = "opencode-session-right-panel-changes-split-width-v1"
+export const RIGHT_PANEL_FILES_SPLIT_WIDTH_KEY = "opencode-session-right-panel-files-split-width-v1"
+export const RIGHT_PANEL_GIT_CHANGES_SPLIT_WIDTH_KEY = "opencode-session-right-panel-git-changes-split-width-v1"
+export const RIGHT_PANEL_CHANGES_LIST_OPEN_NONPHONE_KEY = "opencode-session-right-panel-changes-list-open-nonphone-v1"
+export const RIGHT_PANEL_CHANGES_LIST_OPEN_PHONE_KEY = "opencode-session-right-panel-changes-list-open-phone-v1"
+export const RIGHT_PANEL_FILES_LIST_OPEN_NONPHONE_KEY = "opencode-session-right-panel-files-list-open-nonphone-v1"
+export const RIGHT_PANEL_FILES_LIST_OPEN_PHONE_KEY = "opencode-session-right-panel-files-list-open-phone-v1"
+export const RIGHT_PANEL_GIT_CHANGES_LIST_OPEN_NONPHONE_KEY = "opencode-session-right-panel-git-changes-list-open-nonphone-v1"
+export const RIGHT_PANEL_GIT_CHANGES_LIST_OPEN_PHONE_KEY = "opencode-session-right-panel-git-changes-list-open-phone-v1"
+export const RIGHT_PANEL_CHANGES_DIFF_VIEW_MODE_KEY = "opencode-session-right-panel-changes-diff-view-mode-v1"
+export const RIGHT_PANEL_CHANGES_DIFF_CONTEXT_MODE_KEY = "opencode-session-right-panel-changes-diff-context-mode-v1"
+
+export const clampWidth = (value: number) =>
+  Math.min(MAX_SESSION_SIDEBAR_WIDTH, Math.max(MIN_SESSION_SIDEBAR_WIDTH, value))
+
+export const clampRightWidth = (value: number) => {
+  const windowMax = typeof window !== "undefined" ? Math.floor(window.innerWidth * 0.7) : MAX_RIGHT_DRAWER_WIDTH
+  const max = Math.max(MIN_RIGHT_DRAWER_WIDTH, windowMax)
+  return Math.min(max, Math.max(MIN_RIGHT_DRAWER_WIDTH, value))
+}
+
+const getPinStorageKey = (side: "left" | "right") => (side === "left" ? LEFT_PIN_STORAGE_KEY : RIGHT_PIN_STORAGE_KEY)
+
+export function readStoredPinState(side: "left" | "right", defaultValue: boolean) {
+  if (typeof window === "undefined") return defaultValue
+  const stored = window.localStorage.getItem(getPinStorageKey(side))
+  if (stored === "true") return true
+  if (stored === "false") return false
+  return defaultValue
+}
+
+export function persistPinState(side: "left" | "right", value: boolean) {
+  if (typeof window === "undefined") return
+  window.localStorage.setItem(getPinStorageKey(side), value ? "true" : "false")
+}
+
+export function readStoredRightPanelTab(
+  defaultValue: "changes" | "git-changes" | "files" | "status",
+): "changes" | "git-changes" | "files" | "status" {
+  if (typeof window === "undefined") return defaultValue
+
+  const stored = window.localStorage.getItem(RIGHT_PANEL_TAB_STORAGE_KEY)
+  if (stored === "status") return "status"
+  if (stored === "changes") return "changes"
+  if (stored === "git-changes") return "git-changes"
+  if (stored === "files") return "files"
+
+  // Migrate from v1 (where the stored values were the internal tab ids).
+  const legacy = window.localStorage.getItem(LEGACY_RIGHT_PANEL_TAB_STORAGE_KEY)
+  if (legacy === "status") return "status"
+  if (legacy === "browser") return "files"
+  if (legacy === "files") return "changes"
+
+  return defaultValue
+}
+
+export function readStoredPanelWidth(key: string, fallback: number) {
+  if (typeof window === "undefined") return fallback
+  const stored = window.localStorage.getItem(key)
+  if (!stored) return fallback
+  const parsed = Number.parseInt(stored, 10)
+  return Number.isFinite(parsed) ? parsed : fallback
+}
+
+export function readStoredBool(key: string): boolean | null {
+  if (typeof window === "undefined") return null
+  const stored = window.localStorage.getItem(key)
+  if (stored === "true") return true
+  if (stored === "false") return false
+  return null
+}
+
+export function readStoredEnum<T extends string>(key: string, allowed: readonly T[]): T | null {
+  if (typeof window === "undefined") return null
+  const stored = window.localStorage.getItem(key)
+  if (!stored) return null
+  return (allowed as readonly string[]).includes(stored) ? (stored as T) : null
+}

packages/ui/src/components/instance/shell/types.ts

@@ -0,0 +1,3 @@
+export type LayoutMode = "desktop" | "tablet" | "phone"
+
+export type DrawerViewState = "pinned" | "floating-open" | "floating-closed"

packages/ui/src/components/instance/shell/useDrawerChrome.ts

@@ -0,0 +1,260 @@
+import {
+  batch,
+  createComponent,
+  createEffect,
+  createMemo,
+  createSignal,
+  onCleanup,
+  onMount,
+  type Accessor,
+  type JSX,
+  type Setter,
+} from "solid-js"
+import MenuIcon from "@suid/icons-material/Menu"
+
+import type { TranslateParams } from "../../../lib/i18n"
+
+import type { DrawerViewState, LayoutMode } from "./types"
+import { persistPinState, readStoredPinState } from "./storage"
+
+export interface UseDrawerChromeOptions {
+  t: (key: string, params?: TranslateParams) => string
+  layoutMode: Accessor<LayoutMode>
+  leftPinningSupported: Accessor<boolean>
+  rightPinningSupported: Accessor<boolean>
+  leftDrawerContentEl: Accessor<HTMLElement | null>
+  rightDrawerContentEl: Accessor<HTMLElement | null>
+  leftToggleButtonEl: Accessor<HTMLElement | null>
+  rightToggleButtonEl: Accessor<HTMLElement | null>
+  measureDrawerHost?: () => void
+}
+
+export interface DrawerChromeApi {
+  leftPinned: Accessor<boolean>
+  leftOpen: Accessor<boolean>
+  rightPinned: Accessor<boolean>
+  rightOpen: Accessor<boolean>
+  setLeftOpen: Setter<boolean>
+  setRightOpen: Setter<boolean>
+  leftDrawerState: Accessor<DrawerViewState>
+  rightDrawerState: Accessor<DrawerViewState>
+  pinLeft: () => void
+  unpinLeft: () => void
+  pinRight: () => void
+  unpinRight: () => void
+  closeLeft: () => void
+  closeRight: () => void
+  leftAppBarButtonLabel: Accessor<string>
+  rightAppBarButtonLabel: Accessor<string>
+  leftAppBarButtonIcon: Accessor<JSX.Element>
+  rightAppBarButtonIcon: Accessor<JSX.Element>
+  handleLeftAppBarButtonClick: () => void
+  handleRightAppBarButtonClick: () => void
+}
+
+export function useDrawerChrome(options: UseDrawerChromeOptions): DrawerChromeApi {
+  const [leftPinned, setLeftPinned] = createSignal(true)
+  const [leftOpen, setLeftOpen] = createSignal(true)
+  const [rightPinned, setRightPinned] = createSignal(true)
+  const [rightOpen, setRightOpen] = createSignal(true)
+
+  const measureDrawerHost = () => options.measureDrawerHost?.()
+
+  const focusTarget = (element: HTMLElement | null) => {
+    if (!element) return
+    requestAnimationFrame(() => {
+      element.focus()
+    })
+  }
+
+  const blurIfInside = (element: HTMLElement | null) => {
+    if (typeof document === "undefined" || !element) return
+    const active = document.activeElement as HTMLElement | null
+    if (active && element.contains(active)) {
+      active.blur()
+    }
+  }
+
+  const persistPinIfSupported = (side: "left" | "right", value: boolean) => {
+    if (side === "left" && !options.leftPinningSupported()) return
+    if (side === "right" && !options.rightPinningSupported()) return
+    persistPinState(side, value)
+  }
+
+  createEffect(() => {
+    switch (options.layoutMode()) {
+      case "desktop": {
+        const leftSaved = readStoredPinState("left", true)
+        const rightSaved = readStoredPinState("right", true)
+        setLeftPinned(leftSaved)
+        setLeftOpen(leftSaved)
+        setRightPinned(rightSaved)
+        setRightOpen(rightSaved)
+        break
+      }
+      case "tablet": {
+        setLeftPinned(true)
+        setLeftOpen(true)
+        setRightPinned(false)
+        setRightOpen(false)
+        break
+      }
+      default:
+        setLeftPinned(false)
+        setLeftOpen(false)
+        setRightPinned(false)
+        setRightOpen(false)
+        break
+    }
+  })
+
+  const leftDrawerState = createMemo<DrawerViewState>(() => {
+    if (leftPinned()) return "pinned"
+    return leftOpen() ? "floating-open" : "floating-closed"
+  })
+
+  const rightDrawerState = createMemo<DrawerViewState>(() => {
+    if (rightPinned()) return "pinned"
+    return rightOpen() ? "floating-open" : "floating-closed"
+  })
+
+  const leftAppBarButtonLabel = () => {
+    const state = leftDrawerState()
+    if (state === "pinned") return options.t("instanceShell.leftDrawer.toggle.pinned")
+    return options.t("instanceShell.leftDrawer.toggle.open")
+  }
+
+  const rightAppBarButtonLabel = () => {
+    const state = rightDrawerState()
+    if (state === "pinned") return options.t("instanceShell.rightDrawer.toggle.pinned")
+    return options.t("instanceShell.rightDrawer.toggle.open")
+  }
+
+  const leftAppBarButtonIcon = () => {
+    return createComponent(MenuIcon, { fontSize: "small" })
+  }
+
+  const rightAppBarButtonIcon = () => {
+    return createComponent(MenuIcon, { fontSize: "small", sx: { transform: "scaleX(-1)" } })
+  }
+
+  const pinLeft = () => {
+    blurIfInside(options.leftDrawerContentEl())
+    batch(() => {
+      setLeftPinned(true)
+      setLeftOpen(true)
+    })
+    persistPinIfSupported("left", true)
+    measureDrawerHost()
+  }
+
+  const unpinLeft = () => {
+    blurIfInside(options.leftDrawerContentEl())
+    batch(() => {
+      setLeftPinned(false)
+      setLeftOpen(true)
+    })
+    persistPinIfSupported("left", false)
+    measureDrawerHost()
+  }
+
+  const pinRight = () => {
+    blurIfInside(options.rightDrawerContentEl())
+    batch(() => {
+      setRightPinned(true)
+      setRightOpen(true)
+    })
+    persistPinIfSupported("right", true)
+    measureDrawerHost()
+  }
+
+  const unpinRight = () => {
+    blurIfInside(options.rightDrawerContentEl())
+    batch(() => {
+      setRightPinned(false)
+      setRightOpen(true)
+    })
+    persistPinIfSupported("right", false)
+    measureDrawerHost()
+  }
+
+  const handleLeftAppBarButtonClick = () => {
+    const state = leftDrawerState()
+    if (state !== "floating-closed") return
+    setLeftOpen(true)
+    measureDrawerHost()
+  }
+
+  const handleRightAppBarButtonClick = () => {
+    const state = rightDrawerState()
+    if (state !== "floating-closed") return
+    setRightOpen(true)
+    measureDrawerHost()
+  }
+
+  const closeLeft = () => {
+    if (leftDrawerState() === "pinned") return
+    blurIfInside(options.leftDrawerContentEl())
+    setLeftOpen(false)
+    focusTarget(options.leftToggleButtonEl())
+  }
+
+  const closeRight = () => {
+    if (rightDrawerState() === "pinned") return
+    blurIfInside(options.rightDrawerContentEl())
+    setRightOpen(false)
+    focusTarget(options.rightToggleButtonEl())
+  }
+
+  const closeFloatingDrawersIfAny = () => {
+    let handled = false
+    if (!leftPinned() && leftOpen()) {
+      setLeftOpen(false)
+      blurIfInside(options.leftDrawerContentEl())
+      focusTarget(options.leftToggleButtonEl())
+      handled = true
+    }
+    if (!rightPinned() && rightOpen()) {
+      setRightOpen(false)
+      blurIfInside(options.rightDrawerContentEl())
+      focusTarget(options.rightToggleButtonEl())
+      handled = true
+    }
+    return handled
+  }
+
+  onMount(() => {
+    if (typeof window === "undefined") return
+    const handleEscape = (event: KeyboardEvent) => {
+      if (event.key !== "Escape") return
+      if (!closeFloatingDrawersIfAny()) return
+      event.preventDefault()
+      event.stopPropagation()
+    }
+    window.addEventListener("keydown", handleEscape, true)
+    onCleanup(() => window.removeEventListener("keydown", handleEscape, true))
+  })
+
+  return {
+    leftPinned,
+    leftOpen,
+    rightPinned,
+    rightOpen,
+    setLeftOpen,
+    setRightOpen,
+    leftDrawerState,
+    rightDrawerState,
+    pinLeft,
+    unpinLeft,
+    pinRight,
+    unpinRight,
+    closeLeft,
+    closeRight,
+    leftAppBarButtonLabel,
+    rightAppBarButtonLabel,
+    leftAppBarButtonIcon,
+    rightAppBarButtonIcon,
+    handleLeftAppBarButtonClick,
+    handleRightAppBarButtonClick,
+  }
+}

packages/ui/src/components/instance/shell/useDrawerHostMeasure.ts

@@ -0,0 +1,65 @@
+import { createEffect, createSignal, type Accessor } from "solid-js"
+
+type DrawerHostMeasure = {
+  setDrawerHost: (element: HTMLElement) => void
+  drawerContainer: () => HTMLElement | undefined
+  measureDrawerHost: () => void
+  floatingTopPx: () => string
+  floatingHeight: () => string
+}
+
+export function useDrawerHostMeasure(tabBarOffset: Accessor<number>): DrawerHostMeasure {
+  const [drawerHost, setDrawerHost] = createSignal<HTMLElement | null>(null)
+  const [floatingDrawerTop, setFloatingDrawerTop] = createSignal(0)
+  const [floatingDrawerHeight, setFloatingDrawerHeight] = createSignal(0)
+
+  const storeDrawerHost = (element: HTMLElement) => {
+    setDrawerHost(element)
+  }
+
+  const measureDrawerHost = () => {
+    if (typeof window === "undefined") return
+    const host = drawerHost()
+    if (!host) return
+    const rect = host.getBoundingClientRect()
+    setFloatingDrawerTop(rect.top)
+    setFloatingDrawerHeight(Math.max(0, rect.height))
+  }
+
+  createEffect(() => {
+    tabBarOffset()
+    if (typeof window === "undefined") return
+    requestAnimationFrame(() => measureDrawerHost())
+  })
+
+  const drawerContainer = () => {
+    const host = drawerHost()
+    if (host) return host
+    if (typeof document !== "undefined") {
+      return document.body
+    }
+    return undefined
+  }
+
+  const fallbackDrawerTop = () => tabBarOffset()
+  const floatingTop = () => {
+    const measured = floatingDrawerTop()
+    if (measured > 0) return measured
+    return fallbackDrawerTop()
+  }
+
+  const floatingTopPx = () => `${floatingTop()}px`
+  const floatingHeight = () => {
+    const measured = floatingDrawerHeight()
+    if (measured > 0) return `${measured}px`
+    return `calc(100% - ${floatingTop()}px)`
+  }
+
+  return {
+    setDrawerHost: storeDrawerHost,
+    drawerContainer,
+    measureDrawerHost,
+    floatingTopPx,
+    floatingHeight,
+  }
+}

packages/ui/src/components/instance/shell/useDrawerResize.ts

@@ -0,0 +1,113 @@
+import { createSignal, onCleanup, type Accessor, type Setter } from "solid-js"
+
+import { useGlobalPointerDrag } from "./useGlobalPointerDrag"
+
+type DrawerResizeSide = "left" | "right"
+
+type DrawerResizeOptions = {
+  sessionSidebarWidth: Accessor<number>
+  rightDrawerWidth: Accessor<number>
+  setSessionSidebarWidth: Setter<number>
+  setRightDrawerWidth: Setter<number>
+  clampLeft: (width: number) => number
+  clampRight: (width: number) => number
+  measureDrawerHost: () => void
+}
+
+type DrawerResizeApi = {
+  handleDrawerResizeMouseDown: (side: DrawerResizeSide) => (event: MouseEvent) => void
+  handleDrawerResizeTouchStart: (side: DrawerResizeSide) => (event: TouchEvent) => void
+}
+
+export function useDrawerResize(options: DrawerResizeOptions): DrawerResizeApi {
+  const [activeResizeSide, setActiveResizeSide] = createSignal<DrawerResizeSide | null>(null)
+  const [resizeStartX, setResizeStartX] = createSignal(0)
+  const [resizeStartWidth, setResizeStartWidth] = createSignal(0)
+
+  const scheduleDrawerMeasure = () => {
+    if (typeof window === "undefined") {
+      options.measureDrawerHost()
+      return
+    }
+    requestAnimationFrame(() => options.measureDrawerHost())
+  }
+
+  const applyDrawerWidth = (side: DrawerResizeSide, width: number) => {
+    if (side === "left") {
+      options.setSessionSidebarWidth(width)
+    } else {
+      options.setRightDrawerWidth(width)
+    }
+    scheduleDrawerMeasure()
+  }
+
+  const handleDrawerPointerMove = (clientX: number) => {
+    const side = activeResizeSide()
+    if (!side) return
+    const startWidth = resizeStartWidth()
+    const clamp = side === "left" ? options.clampLeft : options.clampRight
+    const delta = side === "left" ? clientX - resizeStartX() : resizeStartX() - clientX
+    const nextWidth = clamp(startWidth + delta)
+    applyDrawerWidth(side, nextWidth)
+  }
+
+  function drawerMouseMove(event: MouseEvent) {
+    event.preventDefault()
+    handleDrawerPointerMove(event.clientX)
+  }
+
+  function drawerMouseUp() {
+    stopDrawerResize()
+  }
+
+  function drawerTouchMove(event: TouchEvent) {
+    const touch = event.touches[0]
+    if (!touch) return
+    event.preventDefault()
+    handleDrawerPointerMove(touch.clientX)
+  }
+
+  function drawerTouchEnd() {
+    stopDrawerResize()
+  }
+
+  const drawerPointerDrag = useGlobalPointerDrag({
+    onMouseMove: drawerMouseMove,
+    onMouseUp: drawerMouseUp,
+    onTouchMove: drawerTouchMove,
+    onTouchEnd: drawerTouchEnd,
+  })
+
+  function stopDrawerResize() {
+    setActiveResizeSide(null)
+    drawerPointerDrag.stop()
+  }
+
+  const startDrawerResize = (side: DrawerResizeSide, clientX: number) => {
+    setActiveResizeSide(side)
+    setResizeStartX(clientX)
+    setResizeStartWidth(side === "left" ? options.sessionSidebarWidth() : options.rightDrawerWidth())
+    drawerPointerDrag.start()
+  }
+
+  const handleDrawerResizeMouseDown = (side: DrawerResizeSide) => (event: MouseEvent) => {
+    event.preventDefault()
+    startDrawerResize(side, event.clientX)
+  }
+
+  const handleDrawerResizeTouchStart = (side: DrawerResizeSide) => (event: TouchEvent) => {
+    const touch = event.touches[0]
+    if (!touch) return
+    event.preventDefault()
+    startDrawerResize(side, touch.clientX)
+  }
+
+  onCleanup(() => {
+    stopDrawerResize()
+  })
+
+  return {
+    handleDrawerResizeMouseDown,
+    handleDrawerResizeTouchStart,
+  }
+}

packages/ui/src/components/instance/shell/useGlobalPointerDrag.ts

@@ -0,0 +1,29 @@
+type GlobalPointerDragHandlers = {
+  onMouseMove: (event: MouseEvent) => void
+  onMouseUp: (event: MouseEvent) => void
+  onTouchMove: (event: TouchEvent) => void
+  onTouchEnd: (event: TouchEvent) => void
+}
+
+type GlobalPointerDrag = {
+  start: () => void
+  stop: () => void
+}
+
+export function useGlobalPointerDrag(handlers: GlobalPointerDragHandlers): GlobalPointerDrag {
+  const start = () => {
+    document.addEventListener("mousemove", handlers.onMouseMove)
+    document.addEventListener("mouseup", handlers.onMouseUp)
+    document.addEventListener("touchmove", handlers.onTouchMove, { passive: false })
+    document.addEventListener("touchend", handlers.onTouchEnd)
+  }
+
+  const stop = () => {
+    document.removeEventListener("mousemove", handlers.onMouseMove)
+    document.removeEventListener("mouseup", handlers.onMouseUp)
+    document.removeEventListener("touchmove", handlers.onTouchMove)
+    document.removeEventListener("touchend", handlers.onTouchEnd)
+  }
+
+  return { start, stop }
+}

packages/ui/src/components/instance/shell/useInstanceSessionContext.ts

@@ -0,0 +1,173 @@
+import { batch, createMemo, type Accessor } from "solid-js"
+import type { ToolState } from "@opencode-ai/sdk"
+import type { Session } from "../../../types/session"
+import {
+  activeParentSessionId,
+  activeSessionId as activeSessionMap,
+  getSessionFamily,
+  getSessionInfo,
+  getSessionThreads,
+  sessions,
+  setActiveParentSession,
+  setActiveSession,
+} from "../../../stores/sessions"
+import { messageStoreBus } from "../../../stores/message-v2/bus"
+import { getBackgroundProcesses } from "../../../stores/background-processes"
+import type { LatestTodoSnapshot, SessionUsageState } from "../../../stores/message-v2/types"
+
+type InstanceSessionContextOptions = {
+  instanceId: Accessor<string>
+}
+
+type InstanceSessionContextState = {
+  // Session collections and selections
+  allInstanceSessions: Accessor<Map<string, Session>>
+  sessionThreads: Accessor<ReturnType<typeof getSessionThreads>>
+  activeSessions: Accessor<Map<string, SessionFamilyMember>>
+  activeSessionIdForInstance: Accessor<string | null>
+  parentSessionIdForInstance: Accessor<string | null>
+  activeSessionForInstance: Accessor<SessionFamilyMember | null>
+  activeSessionDiffs: Accessor<SessionFamilyMember["diff"] | undefined>
+
+  // Usage / info summaries
+  activeSessionUsage: Accessor<SessionUsageState | null>
+  activeSessionInfoDetails: Accessor<ReturnType<typeof getSessionInfo> | null>
+  tokenStats: Accessor<{ used: number; avail: number | null }>
+
+  // Todo state
+  latestTodoSnapshot: Accessor<LatestTodoSnapshot | null>
+  latestTodoState: Accessor<ToolState | null>
+
+  // Background processes
+  backgroundProcessList: Accessor<ReturnType<typeof getBackgroundProcesses>>
+
+  // Controller
+  handleSessionSelect: (sessionId: string) => void
+}
+
+type SessionFamilyMember = ReturnType<typeof getSessionFamily>[number]
+
+export function useInstanceSessionContext(options: InstanceSessionContextOptions): InstanceSessionContextState {
+  const messageStore = createMemo(() => messageStoreBus.getOrCreate(options.instanceId()))
+
+  const allInstanceSessions = createMemo<Map<string, Session>>(() => {
+    return sessions().get(options.instanceId()) ?? new Map()
+  })
+
+  const sessionThreads = createMemo(() => getSessionThreads(options.instanceId()))
+
+  const activeSessions = createMemo(() => {
+    const parentId = activeParentSessionId().get(options.instanceId())
+    if (!parentId) return new Map<string, ReturnType<typeof getSessionFamily>[number]>()
+    const sessionFamily = getSessionFamily(options.instanceId(), parentId)
+    return new Map(sessionFamily.map((s) => [s.id, s]))
+  })
+
+  const activeSessionIdForInstance = createMemo(() => {
+    return activeSessionMap().get(options.instanceId()) || null
+  })
+
+  const parentSessionIdForInstance = createMemo(() => {
+    return activeParentSessionId().get(options.instanceId()) || null
+  })
+
+  const activeSessionForInstance = createMemo(() => {
+    const sessionId = activeSessionIdForInstance()
+    if (!sessionId || sessionId === "info") return null
+    return activeSessions().get(sessionId) ?? null
+  })
+
+  const activeSessionDiffs = createMemo(() => {
+    const session = activeSessionForInstance()
+    return session?.diff
+  })
+
+  const activeSessionUsage = createMemo(() => {
+    const sessionId = activeSessionIdForInstance()
+    if (!sessionId) return null
+    const store = messageStore()
+    return store?.getSessionUsage(sessionId) ?? null
+  })
+
+  const activeSessionInfoDetails = createMemo(() => {
+    const sessionId = activeSessionIdForInstance()
+    if (!sessionId) return null
+    return getSessionInfo(options.instanceId(), sessionId) ?? null
+  })
+
+  const tokenStats = createMemo(() => {
+    const usage = activeSessionUsage()
+    const info = activeSessionInfoDetails()
+    return {
+      used: usage?.actualUsageTokens ?? info?.actualUsageTokens ?? 0,
+      avail: info?.contextAvailableTokens ?? null,
+    }
+  })
+
+  const latestTodoSnapshot = createMemo(() => {
+    const sessionId = activeSessionIdForInstance()
+    if (!sessionId || sessionId === "info") return null
+    const store = messageStore()
+    if (!store) return null
+    const snapshot = store.state.latestTodos[sessionId]
+    return snapshot ?? null
+  })
+
+  const latestTodoState = createMemo<ToolState | null>(() => {
+    const snapshot = latestTodoSnapshot()
+    if (!snapshot) return null
+    const store = messageStore()
+    if (!store) return null
+    const message = store.getMessage(snapshot.messageId)
+    if (!message) return null
+    const partRecord = message.parts?.[snapshot.partId]
+    const part = partRecord?.data as { type?: string; tool?: string; state?: ToolState }
+    if (!part || part.type !== "tool" || part.tool !== "todowrite") return null
+    const state = part.state
+    if (!state || state.status !== "completed") return null
+    return state
+  })
+
+  const backgroundProcessList = createMemo(() => getBackgroundProcesses(options.instanceId()))
+
+  const handleSessionSelect = (sessionId: string) => {
+    const instanceId = options.instanceId()
+    if (sessionId === "info") {
+      setActiveSession(instanceId, sessionId)
+      return
+    }
+
+    const session = allInstanceSessions().get(sessionId)
+    if (!session) return
+
+    if (session.parentId === null) {
+      setActiveParentSession(instanceId, sessionId)
+      return
+    }
+
+    const parentId = session.parentId
+    if (!parentId) return
+
+    batch(() => {
+      setActiveParentSession(instanceId, parentId)
+      setActiveSession(instanceId, sessionId)
+    })
+  }
+
+  return {
+    allInstanceSessions,
+    sessionThreads,
+    activeSessions,
+    activeSessionIdForInstance,
+    parentSessionIdForInstance,
+    activeSessionForInstance,
+    activeSessionDiffs,
+    activeSessionUsage,
+    activeSessionInfoDetails,
+    tokenStats,
+    latestTodoSnapshot,
+    latestTodoState,
+    backgroundProcessList,
+    handleSessionSelect,
+  }
+}

packages/ui/src/components/instance/shell/useSessionCache.ts

@@ -0,0 +1,99 @@
+import { createEffect, createSignal, type Accessor } from "solid-js"
+import { messageStoreBus } from "../../../stores/message-v2/bus"
+import { clearSessionRenderCache } from "../../message-block"
+import { getLogger } from "../../../lib/logger"
+
+const log = getLogger("session")
+
+const SESSION_CACHE_LIMIT = 5
+
+type SessionCacheOptions = {
+  instanceId: Accessor<string>
+  instanceSessions: Accessor<Map<string, unknown>>
+  activeSessionId: Accessor<string | null>
+}
+
+type SessionCacheState = {
+  cachedSessionIds: Accessor<string[]>
+}
+
+export function useSessionCache(options: SessionCacheOptions): SessionCacheState {
+  const [cachedSessionIds, setCachedSessionIds] = createSignal<string[]>([])
+  const [pendingEvictions, setPendingEvictions] = createSignal<string[]>([])
+
+  const evictSession = (sessionId: string) => {
+    if (!sessionId) return
+    const instanceId = options.instanceId()
+    log.info("Evicting cached session", { instanceId, sessionId })
+    const store = messageStoreBus.getInstance(instanceId)
+    store?.clearSession(sessionId)
+    clearSessionRenderCache(instanceId, sessionId)
+  }
+
+  const scheduleEvictions = (ids: string[]) => {
+    if (!ids.length) return
+    setPendingEvictions((current) => {
+      const existing = new Set(current)
+      const next = [...current]
+      ids.forEach((id) => {
+        if (!existing.has(id)) {
+          next.push(id)
+          existing.add(id)
+        }
+      })
+      return next
+    })
+  }
+
+  createEffect(() => {
+    const pending = pendingEvictions()
+    if (!pending.length) return
+    const cached = new Set(cachedSessionIds())
+    const remaining: string[] = []
+    pending.forEach((id) => {
+      if (cached.has(id)) {
+        remaining.push(id)
+      } else {
+        evictSession(id)
+      }
+    })
+    if (remaining.length !== pending.length) {
+      setPendingEvictions(remaining)
+    }
+  })
+
+  createEffect(() => {
+    const instanceSessions = options.instanceSessions()
+    const activeId = options.activeSessionId()
+
+    setCachedSessionIds((current) => {
+      const next = current.filter((id) => id !== "info" && instanceSessions.has(id))
+
+      const touch = (id: string | null) => {
+        if (!id || id === "info") return
+        if (!instanceSessions.has(id)) return
+
+        const index = next.indexOf(id)
+        if (index !== -1) {
+          next.splice(index, 1)
+        }
+        next.unshift(id)
+      }
+
+      touch(activeId)
+
+      const trimmed = next.length > SESSION_CACHE_LIMIT ? next.slice(0, SESSION_CACHE_LIMIT) : next
+
+      const trimmedSet = new Set(trimmed)
+      const removed = current.filter((id) => !trimmedSet.has(id))
+      if (removed.length) {
+        scheduleEvictions(removed)
+      }
+      return trimmed
+    })
+  })
+
+  return {
+    cachedSessionIds,
+  }
+}

packages/ui/src/components/instance/shell/useSessionSidebarRequests.ts

@@ -0,0 +1,109 @@
+import { createEffect, createSignal, onCleanup, onMount, type Accessor } from "solid-js"
+import {
+  SESSION_SIDEBAR_EVENT,
+  type SessionSidebarRequestAction,
+  type SessionSidebarRequestDetail,
+} from "../../../lib/session-sidebar-events"
+
+interface PendingSidebarAction {
+  action: SessionSidebarRequestAction
+  id: number
+}
+
+interface UseSessionSidebarRequestsOptions {
+  instanceId: Accessor<string>
+  sidebarContentEl: Accessor<HTMLElement | null>
+  leftPinned: Accessor<boolean>
+  leftOpen: Accessor<boolean>
+  setLeftOpen: (next: boolean) => void
+  measureDrawerHost: () => void
+}
+
+export function useSessionSidebarRequests(options: UseSessionSidebarRequestsOptions) {
+  let sidebarActionId = 0
+  const [pendingSidebarAction, setPendingSidebarAction] = createSignal<PendingSidebarAction | null>(null)
+
+  const triggerKeyboardEvent = (target: HTMLElement, options: { key: string; code: string; keyCode: number }) => {
+    target.dispatchEvent(
+      new KeyboardEvent("keydown", {
+        key: options.key,
+        code: options.code,
+        keyCode: options.keyCode,
+        which: options.keyCode,
+        bubbles: true,
+        cancelable: true,
+      }),
+    )
+  }
+
+  const focusAgentSelectorControl = () => {
+    const agentTrigger = options.sidebarContentEl()?.querySelector("[data-agent-selector]") as HTMLElement | null
+    if (!agentTrigger) return false
+    agentTrigger.focus()
+    setTimeout(() => triggerKeyboardEvent(agentTrigger, { key: "Enter", code: "Enter", keyCode: 13 }), 10)
+    return true
+  }
+
+  const focusModelSelectorControl = () => {
+    const input = options.sidebarContentEl()?.querySelector<HTMLInputElement>("[data-model-selector]")
+    if (!input) return false
+    input.focus()
+    setTimeout(() => triggerKeyboardEvent(input, { key: "ArrowDown", code: "ArrowDown", keyCode: 40 }), 10)
+    return true
+  }
+
+  const focusVariantSelectorControl = () => {
+    const input = options.sidebarContentEl()?.querySelector<HTMLInputElement>("[data-thinking-selector]")
+    if (!input) return false
+    input.focus()
+    setTimeout(() => triggerKeyboardEvent(input, { key: "ArrowDown", code: "ArrowDown", keyCode: 40 }), 10)
+    return true
+  }
+
+  createEffect(() => {
+    const pending = pendingSidebarAction()
+    if (!pending) return
+    const action = pending.action
+    const contentReady = Boolean(options.sidebarContentEl())
+    if (!contentReady) {
+      return
+    }
+    if (action === "show-session-list") {
+      setPendingSidebarAction(null)
+      return
+    }
+    const handled =
+      action === "focus-agent-selector"
+        ? focusAgentSelectorControl()
+        : action === "focus-model-selector"
+          ? focusModelSelectorControl()
+          : focusVariantSelectorControl()
+    if (handled) {
+      setPendingSidebarAction(null)
+    }
+  })
+
+  const handleSidebarRequest = (action: SessionSidebarRequestAction) => {
+    setPendingSidebarAction({ action, id: sidebarActionId++ })
+    if (!options.leftPinned() && !options.leftOpen()) {
+      options.setLeftOpen(true)
+      options.measureDrawerHost()
+    }
+  }
+
+  onMount(() => {
+    if (typeof window === "undefined") return
+    const handler = (event: Event) => {
+      const detail = (event as CustomEvent<SessionSidebarRequestDetail>).detail
+      if (!detail || detail.instanceId !== options.instanceId()) return
+      handleSidebarRequest(detail.action)
+    }
+    window.addEventListener(SESSION_SIDEBAR_EVENT, handler)
+    onCleanup(() => window.removeEventListener(SESSION_SIDEBAR_EVENT, handler))
+  })
+
+  return {
+    handleSidebarRequest,
+    pendingSidebarAction,
+  }
+}

packages/ui/src/components/message-block.tsx

@@ -1,5 +1,5 @@
 import { For, Match, Show, Switch, createEffect, createMemo, createSignal, untrack } from "solid-js"
-import { ExternalLink, FoldVertical, Trash2 } from "lucide-solid"
+import { ChevronsDownUp, ChevronsUpDown, ExternalLink, FoldVertical, Trash2 } from "lucide-solid"
 import MessageItem from "./message-item"
 import ToolCall from "./tool-call"
 import type { InstanceMessageStore } from "../stores/message-v2/instance-store"
@@ -1010,10 +1010,13 @@ function ReasoningCard(props: ReasoningCardProps) {
 
   const toggle = () => setExpanded((prev) => !prev)
 
+  const viewHideLabel = () =>
+    expanded() ? t("messageBlock.reasoning.indicator.hide") : t("messageBlock.reasoning.indicator.view")
+
   const hasDeleteTarget = () => Boolean(props.partId)
   const canDelete = () => hasDeleteTarget() && !deleting()
 
-  const handleDelete = async (event: Event) => {
+  const handleDelete = async (event: MouseEvent) => {
     event.preventDefault()
     event.stopPropagation()
     if (!canDelete()) return
@@ -1033,56 +1036,66 @@ function ReasoningCard(props: ReasoningCardProps) {
 
   return (
     <div class="message-reasoning-card">
-      <button
-        type="button"
-        class="message-reasoning-toggle"
-        onClick={toggle}
-        aria-expanded={expanded()}
-        aria-label={expanded() ? t("messageBlock.reasoning.collapseAriaLabel") : t("messageBlock.reasoning.expandAriaLabel")}
-      >
-        <span class="message-reasoning-label flex flex-wrap items-center gap-2">
-          <span>{t("messageBlock.reasoning.thinkingLabel")}</span>
-          <Show when={props.showAgentMeta && (agentIdentifier() || modelIdentifier())}>
-            <span class="message-step-meta-inline">
-              <Show when={agentIdentifier()}>
-                {(value) => (
-                  <span class="font-medium text-[var(--message-assistant-border)]">{t("messageBlock.step.agentLabel", { agent: value() })}</span>
-                )}
-              </Show>
-              <Show when={modelIdentifier()}>
-                {(value) => (
-                  <span class="font-medium text-[var(--message-assistant-border)]">{t("messageBlock.step.modelLabel", { model: value() })}</span>
-                )}
-              </Show>
-            </span>
-          </Show>
-        </span>
-        <span class="message-reasoning-meta">
-          <span class="message-reasoning-indicator">
-            {expanded() ? t("messageBlock.reasoning.indicator.hide") : t("messageBlock.reasoning.indicator.view")}
+      <div class="message-reasoning-header">
+        <button
+          type="button"
+          class="message-reasoning-toggle"
+          onClick={toggle}
+          aria-expanded={expanded()}
+          aria-label={expanded() ? t("messageBlock.reasoning.collapseAriaLabel") : t("messageBlock.reasoning.expandAriaLabel")}
+        >
+          <span class="message-reasoning-label flex flex-wrap items-center gap-2">
+            <span>{t("messageBlock.reasoning.thinkingLabel")}</span>
+            <Show when={props.showAgentMeta && (agentIdentifier() || modelIdentifier())}>
+              <span class="message-step-meta-inline">
+                <Show when={agentIdentifier()}>
+                  {(value) => (
+                    <span class="font-medium text-[var(--message-assistant-border)]">{t("messageBlock.step.agentLabel", { agent: value() })}</span>
+                  )}
+                </Show>
+                <Show when={modelIdentifier()}>
+                  {(value) => (
+                    <span class="font-medium text-[var(--message-assistant-border)]">{t("messageBlock.step.modelLabel", { model: value() })}</span>
+                  )}
+                </Show>
+              </span>
+            </Show>
           </span>
+        </button>
+
+        <div class="message-reasoning-actions">
+          <button
+            type="button"
+            class="message-action-button"
+            onClick={(event) => {
+              event.preventDefault()
+              event.stopPropagation()
+              toggle()
+            }}
+            aria-label={viewHideLabel()}
+            title={viewHideLabel()}
+          >
+            <Show when={expanded()} fallback={<ChevronsUpDown class="w-3.5 h-3.5" aria-hidden="true" />}>
+              <ChevronsDownUp class="w-3.5 h-3.5" aria-hidden="true" />
+            </Show>
+          </button>
 
           <Show when={hasDeleteTarget()}>
-            <span
-              class={`message-reasoning-indicator${canDelete() ? "" : " opacity-50 pointer-events-none"}`}
-              role="button"
-              tabIndex={0}
+            <button
+              type="button"
+              class="message-action-button"
               onClick={handleDelete}
-              onKeyDown={(event) => {
-                if (event.key === "Enter" || event.key === " ") {
-                  handleDelete(event)
-                }
-              }}
+              disabled={!canDelete()}
               aria-label={t("messagePart.actions.deleteTitle")}
               title={t("messagePart.actions.deleteTitle")}
             >
-              {deleting() ? t("messagePart.actions.deleting") : t("messagePart.actions.delete")}
-            </span>
+              <Trash2 class="w-3.5 h-3.5" aria-hidden="true" />
+            </button>
           </Show>
 
           <span class="message-reasoning-time">{timestamp()}</span>
-        </span>
-      </button>
+        </div>
+      </div>
 
       <Show when={expanded()}>
         <div class="message-reasoning-expanded">

packages/ui/src/components/message-item.tsx

@@ -268,87 +268,84 @@ export default function MessageItem(props: MessageItemProps) {
   return (
     <div class={containerClass()}>
       <header class={`message-item-header ${isUser() ? "pb-0.5" : "pb-0"}`}>
-        <div class="message-speaker">
-          <span class="message-speaker-label" data-role={isUser() ? "user" : "assistant"}>
-            {speakerLabel()}
-          </span>
-          <Show when={agentMeta()}>{(meta) => <span class="message-agent-meta">{meta()}</span>}</Show>
-        </div>
-        <div class="message-item-actions">
-          <Show when={isUser()}>
-            <div class="message-action-group">
-              <Show when={props.onRevert}>
-                <button
-                  class="message-action-button"
-                  onClick={handleRevert}
-                  title={t("messageItem.actions.revert")}
-                  aria-label={t("messageItem.actions.revert")}
-                >
-                  <Undo class="w-3.5 h-3.5" aria-hidden="true" />
-                </button>
-              </Show>
-              <Show when={props.onFork}>
-                <button
-                  class="message-action-button"
-                  onClick={() => props.onFork?.(props.record.id)}
-                  title={t("messageItem.actions.fork")}
-                  aria-label={t("messageItem.actions.fork")}
-                >
-                  <Split class="w-3.5 h-3.5" aria-hidden="true" />
-                </button>
-              </Show>
-              <button
-                class="message-action-button"
-                onClick={handleCopy}
-                title={copyLabel()}
-                aria-label={copyLabel()}
-              >
-                <Copy class="w-3.5 h-3.5" aria-hidden="true" />
-              </button>
-              <Show when={deletableTextPartId()}>
-                {(partId) => (
-                  <button
-                    class="message-action-button"
-                    onClick={() => void handleDeletePart(partId())}
-                    disabled={isDeletingPart(partId())}
-                    title={isDeletingPart(partId()) ? t("messagePart.actions.deleting") : t("messagePart.actions.delete")}
-                    aria-label={isDeletingPart(partId()) ? t("messagePart.actions.deleting") : t("messagePart.actions.delete")}
-                  >
-                    <Trash2 class="w-3.5 h-3.5" aria-hidden="true" />
-                  </button>
-                )}
-              </Show>
-            </div>
-          </Show>
-          <Show when={!isUser()}>
-            <div class="message-action-group">
-              <button
-                class="message-action-button"
-                onClick={handleCopy}
-                title={copyLabel()}
-                aria-label={copyLabel()}
-              >
-                <Copy class="w-3.5 h-3.5" aria-hidden="true" />
-              </button>
+        <div class="message-item-header-row message-item-header-row--top">
+          <div class="message-speaker">
+            <span class="message-speaker-label" data-role={isUser() ? "user" : "assistant"}>
+              {speakerLabel()}
+            </span>
+          </div>
 
-              <Show when={deletableTextPartId()}>
-                {(partId) => (
+          <div class="message-item-actions">
+            <Show when={isUser()}>
+              <div class="message-action-group">
+                <Show when={props.onRevert}>
                   <button
                     class="message-action-button"
-                    onClick={() => void handleDeletePart(partId())}
-                    disabled={isDeletingPart(partId())}
-                    title={isDeletingPart(partId()) ? t("messagePart.actions.deleting") : t("messagePart.actions.delete")}
-                    aria-label={isDeletingPart(partId()) ? t("messagePart.actions.deleting") : t("messagePart.actions.delete")}
+                    onClick={handleRevert}
+                    title={t("messageItem.actions.revert")}
+                    aria-label={t("messageItem.actions.revert")}
                   >
-                    <Trash2 class="w-3.5 h-3.5" aria-hidden="true" />
+                    <Undo class="w-3.5 h-3.5" aria-hidden="true" />
                   </button>
-                )}
-              </Show>
-            </div>
-          </Show>
-          <time class="message-timestamp" dateTime={timestampIso()}>{timestamp()}</time>
+                </Show>
+                <Show when={props.onFork}>
+                  <button
+                    class="message-action-button"
+                    onClick={() => props.onFork?.(props.record.id)}
+                    title={t("messageItem.actions.fork")}
+                    aria-label={t("messageItem.actions.fork")}
+                  >
+                    <Split class="w-3.5 h-3.5" aria-hidden="true" />
+                  </button>
+                </Show>
+                <button
+                  class="message-action-button"
+                  onClick={handleCopy}
+                  title={copyLabel()}
+                  aria-label={copyLabel()}
+                >
+                  <Copy class="w-3.5 h-3.5" aria-hidden="true" />
+                </button>
+              </div>
+            </Show>
+            <Show when={!isUser()}>
+              <div class="message-action-group">
+                <button
+                  class="message-action-button"
+                  onClick={handleCopy}
+                  title={copyLabel()}
+                  aria-label={copyLabel()}
+                >
+                  <Copy class="w-3.5 h-3.5" aria-hidden="true" />
+                </button>
+
+                <Show when={deletableTextPartId()}>
+                  {(partId) => (
+                    <button
+                      class="message-action-button"
+                      onClick={() => void handleDeletePart(partId())}
+                      disabled={isDeletingPart(partId())}
+                      title={isDeletingPart(partId()) ? t("messagePart.actions.deleting") : t("messagePart.actions.delete")}
+                      aria-label={isDeletingPart(partId()) ? t("messagePart.actions.deleting") : t("messagePart.actions.delete")}
+                    >
+                      <Trash2 class="w-3.5 h-3.5" aria-hidden="true" />
+                    </button>
+                  )}
+                </Show>
+              </div>
+            </Show>
+            <time class="message-timestamp" dateTime={timestampIso()}>{timestamp()}</time>
+          </div>
         </div>
 
+        <Show when={agentMeta()}>
+          {(meta) => (
+            <div class="message-item-header-row message-item-header-row--bottom">
+              <span class="message-agent-meta">{meta()}</span>
+            </div>
+          )}
+        </Show>
+
       </header>
 
       <div class="pt-1 whitespace-pre-wrap break-words leading-[1.1]">

packages/ui/src/components/prompt-input/PromptAttachmentsBar.tsx

@@ -0,0 +1,50 @@
+import { For, Show, type Component } from "solid-js"
+import { Expand } from "lucide-solid"
+import type { Attachment } from "../../types/attachment"
+import { useI18n } from "../../lib/i18n"
+
+interface PromptAttachmentsBarProps {
+  attachments: Attachment[]
+  onRemoveAttachment: (attachmentId: string) => void
+  onExpandTextAttachment: (attachmentId: string) => void
+}
+
+const PromptAttachmentsBar: Component<PromptAttachmentsBarProps> = (props) => {
+  const { t } = useI18n()
+
+  return (
+    <div class="flex flex-wrap items-center gap-1.5 border-t px-3 py-2" style="border-color: var(--border-base);">
+      <For each={props.attachments}>
+        {(attachment) => {
+          const isText = attachment.source.type === "text"
+          return (
+            <div class="attachment-chip" title={attachment.source.type === "file" ? attachment.source.path : undefined}>
+              <span class="font-mono">{attachment.display}</span>
+              <Show when={isText}>
+                <button
+                  type="button"
+                  class="attachment-expand"
+                  onClick={() => props.onExpandTextAttachment(attachment.id)}
+                  aria-label={t("sessionView.attachments.expandPastedTextAriaLabel")}
+                  title={t("sessionView.attachments.insertPastedTextTitle")}
+                >
+                  <Expand class="h-3 w-3" aria-hidden="true" />
+                </button>
+              </Show>
+              <button
+                type="button"
+                class="attachment-remove"
+                onClick={() => props.onRemoveAttachment(attachment.id)}
+                aria-label={t("sessionView.attachments.removeAriaLabel")}
+              >
+                ×
+              </button>
+            </div>
+          )
+        }}
+      </For>
+    </div>
+  )
+}
+
+export default PromptAttachmentsBar

packages/ui/src/components/prompt-input/attachmentPlaceholders.ts

@@ -0,0 +1,72 @@
+import type { Attachment } from "../../types/attachment"
+
+export function formatPastedPlaceholder(value: string | number) {
+  return `[pasted #${value}]`
+}
+
+export function formatImagePlaceholder(value: string | number) {
+  return `[Image #${value}]`
+}
+
+export function createPastedPlaceholderRegex() {
+  return /\[pasted #(\d+)\]/g
+}
+
+export function createImagePlaceholderRegex() {
+  return /\[Image #(\d+)\]/g
+}
+
+export function createMentionRegex() {
+  return /@(\S+)/g
+}
+
+export const pastedDisplayCounterRegex = /pasted #(\d+)/
+export const imageDisplayCounterRegex = /Image #(\d+)/
+export const bracketedImageDisplayCounterRegex = /\[Image #(\d+)\]/
+
+export function parseCounter(value: string) {
+  const parsed = Number.parseInt(value, 10)
+  return Number.isNaN(parsed) ? null : parsed
+}
+
+export function findHighestAttachmentCounters(currentPrompt: string, sessionAttachments: Attachment[]) {
+  let highestPaste = 0
+  let highestImage = 0
+
+  for (const match of currentPrompt.matchAll(createPastedPlaceholderRegex())) {
+    const parsed = parseCounter(match[1])
+    if (parsed !== null) {
+      highestPaste = Math.max(highestPaste, parsed)
+    }
+  }
+
+  for (const attachment of sessionAttachments) {
+    if (attachment.source.type === "text") {
+      const placeholderMatch = attachment.display.match(pastedDisplayCounterRegex)
+      if (placeholderMatch) {
+        const parsed = parseCounter(placeholderMatch[1])
+        if (parsed !== null) {
+          highestPaste = Math.max(highestPaste, parsed)
+        }
+      }
+    }
+    if (attachment.source.type === "file" && attachment.mediaType.startsWith("image/")) {
+      const imageMatch = attachment.display.match(imageDisplayCounterRegex)
+      if (imageMatch) {
+        const parsed = parseCounter(imageMatch[1])
+        if (parsed !== null) {
+          highestImage = Math.max(highestImage, parsed)
+        }
+      }
+    }
+  }
+
+  for (const match of currentPrompt.matchAll(createImagePlaceholderRegex())) {
+    const parsed = parseCounter(match[1])
+    if (parsed !== null) {
+      highestImage = Math.max(highestImage, parsed)
+    }
+  }
+
+  return { highestPaste, highestImage }
+}

packages/ui/src/components/prompt-input/types.ts

@@ -0,0 +1,26 @@
+import type { Attachment } from "../../types/attachment"
+
+export type PromptMode = "normal" | "shell"
+export type ExpandState = "normal" | "expanded"
+export type PickerMode = "mention" | "command"
+export type PromptInsertMode = "quote" | "code"
+
+export interface PromptInputApi {
+  insertSelection(text: string, mode: PromptInsertMode): void
+  expandTextAttachment(attachmentId: string): void
+  setPromptText(text: string, opts?: { focus?: boolean }): void
+  focus(): void
+}
+
+export interface PromptInputProps {
+  instanceId: string
+  instanceFolder: string
+  sessionId: string
+  onSend: (prompt: string, attachments: Attachment[]) => Promise<void>
+  onRunShell?: (command: string) => Promise<void>
+  disabled?: boolean
+  escapeInDebounce?: boolean
+  isSessionBusy?: boolean
+  onAbortSession?: () => Promise<void>
+  registerPromptInputApi?: (api: PromptInputApi) => void | (() => void)
+}

packages/ui/src/components/prompt-input/usePromptAttachments.ts

@@ -0,0 +1,296 @@
+import { createSignal, type Accessor } from "solid-js"
+import { addAttachment, getAttachments, removeAttachment } from "../../stores/attachments"
+import { createFileAttachment, createTextAttachment } from "../../types/attachment"
+import type { Attachment } from "../../types/attachment"
+import {
+  bracketedImageDisplayCounterRegex,
+  findHighestAttachmentCounters,
+  formatImagePlaceholder,
+  formatPastedPlaceholder,
+  pastedDisplayCounterRegex,
+} from "./attachmentPlaceholders"
+
+type PromptAttachmentsOptions = {
+  instanceId: Accessor<string>
+  sessionId: Accessor<string>
+  instanceFolder: Accessor<string>
+  prompt: Accessor<string>
+  setPrompt: (value: string) => void
+  getTextarea: () => HTMLTextAreaElement | null
+}
+
+type PromptAttachments = {
+  attachments: Accessor<Attachment[]>
+  pasteCount: Accessor<number>
+  imageCount: Accessor<number>
+  syncAttachmentCounters: (promptText: string, sessionAttachments: Attachment[]) => void
+
+  handlePaste: (e: ClipboardEvent) => Promise<void>
+  isDragging: Accessor<boolean>
+  handleDragOver: (e: DragEvent) => void
+  handleDragLeave: (e: DragEvent) => void
+  handleDrop: (e: DragEvent) => void
+
+  handleRemoveAttachment: (attachmentId: string) => void
+  handleExpandTextAttachment: (attachment: Attachment) => void
+}
+
+export function usePromptAttachments(options: PromptAttachmentsOptions): PromptAttachments {
+  const attachments = () => getAttachments(options.instanceId(), options.sessionId())
+  const [isDragging, setIsDragging] = createSignal(false)
+  const [pasteCount, setPasteCount] = createSignal(0)
+  const [imageCount, setImageCount] = createSignal(0)
+
+  function syncAttachmentCounters(currentPrompt: string, sessionAttachments: Attachment[]) {
+    const { highestPaste, highestImage } = findHighestAttachmentCounters(currentPrompt, sessionAttachments)
+    setPasteCount(highestPaste)
+    setImageCount(highestImage)
+  }
+
+  function handleRemoveAttachment(attachmentId: string) {
+    const currentAttachments = attachments()
+    const attachment = currentAttachments.find((a) => a.id === attachmentId)
+
+    removeAttachment(options.instanceId(), options.sessionId(), attachmentId)
+
+    if (attachment) {
+      const currentPrompt = options.prompt()
+      let newPrompt = currentPrompt
+
+      if (attachment.source.type === "file") {
+        if (attachment.mediaType.startsWith("image/")) {
+          const imageMatch = attachment.display.match(bracketedImageDisplayCounterRegex)
+          if (imageMatch) {
+            const placeholder = formatImagePlaceholder(imageMatch[1])
+            newPrompt = currentPrompt.replace(placeholder, "").replace(/\s+/g, " ").trim()
+          }
+        } else {
+          const filename = attachment.filename
+          newPrompt = currentPrompt.replace(`@${filename}`, "").replace(/\s+/g, " ").trim()
+        }
+      } else if (attachment.source.type === "agent") {
+        const agentName = attachment.filename
+        newPrompt = currentPrompt.replace(`@${agentName}`, "").replace(/\s+/g, " ").trim()
+      } else if (attachment.source.type === "text") {
+        const placeholderMatch = attachment.display.match(pastedDisplayCounterRegex)
+        if (placeholderMatch) {
+          const placeholder = formatPastedPlaceholder(placeholderMatch[1])
+          newPrompt = currentPrompt.replace(placeholder, "").replace(/\s+/g, " ").trim()
+        }
+      }
+
+      options.setPrompt(newPrompt)
+    }
+  }
+
+  function handleExpandTextAttachment(attachment: Attachment) {
+    if (attachment.source.type !== "text") return
+
+    const textarea = options.getTextarea()
+    const value = attachment.source.value
+    const match = attachment.display.match(pastedDisplayCounterRegex)
+    const placeholder = match ? formatPastedPlaceholder(match[1]) : null
+    const currentText = options.prompt()
+
+    let nextText = currentText
+    let selectionTarget: number | null = null
+
+    if (placeholder) {
+      const placeholderIndex = currentText.indexOf(placeholder)
+      if (placeholderIndex !== -1) {
+        nextText =
+          currentText.substring(0, placeholderIndex) +
+          value +
+          currentText.substring(placeholderIndex + placeholder.length)
+        selectionTarget = placeholderIndex + value.length
+      }
+    }
+
+    if (nextText === currentText) {
+      if (textarea) {
+        const start = textarea.selectionStart
+        const end = textarea.selectionEnd
+        nextText = currentText.substring(0, start) + value + currentText.substring(end)
+        selectionTarget = start + value.length
+      } else {
+        nextText = currentText + value
+      }
+    }
+
+    options.setPrompt(nextText)
+    removeAttachment(options.instanceId(), options.sessionId(), attachment.id)
+
+    if (textarea) {
+      setTimeout(() => {
+        textarea.focus()
+        if (selectionTarget !== null) {
+          textarea.setSelectionRange(selectionTarget, selectionTarget)
+        }
+      }, 0)
+    }
+  }
+
+  async function handlePaste(e: ClipboardEvent) {
+    const items = e.clipboardData?.items
+    if (!items) return
+
+    for (let i = 0; i < items.length; i++) {
+      const item = items[i]
+
+      if (item.type.startsWith("image/")) {
+        e.preventDefault()
+
+        const blob = item.getAsFile()
+        if (!blob) continue
+
+        const count = imageCount() + 1
+        setImageCount(count)
+
+        const reader = new FileReader()
+        reader.onload = () => {
+          const base64Data = (reader.result as string).split(",")[1]
+          const display = formatImagePlaceholder(count)
+          const filename = `image-${count}.png`
+
+          const attachment = createFileAttachment(
+            filename,
+            filename,
+            "image/png",
+            new TextEncoder().encode(base64Data),
+            options.instanceFolder(),
+          )
+          attachment.url = `data:image/png;base64,${base64Data}`
+          attachment.display = display
+          addAttachment(options.instanceId(), options.sessionId(), attachment)
+
+          const textarea = options.getTextarea()
+          if (textarea) {
+            const start = textarea.selectionStart
+            const end = textarea.selectionEnd
+            const currentText = options.prompt()
+            const placeholder = formatImagePlaceholder(count)
+            const newText = currentText.substring(0, start) + placeholder + currentText.substring(end)
+            options.setPrompt(newText)
+
+            setTimeout(() => {
+              const newCursorPos = start + placeholder.length
+              textarea.setSelectionRange(newCursorPos, newCursorPos)
+              textarea.focus()
+            }, 0)
+          }
+        }
+        reader.readAsDataURL(blob)
+
+        return
+      }
+    }
+
+    const pastedText = e.clipboardData?.getData("text/plain")
+    if (!pastedText) return
+
+    const lineCount = pastedText.split("\n").length
+    const charCount = pastedText.length
+
+    const isLongPaste = charCount > 150 || lineCount > 3
+
+    if (isLongPaste) {
+      e.preventDefault()
+
+      const count = pasteCount() + 1
+      setPasteCount(count)
+
+      const summary = lineCount > 1 ? `${lineCount} lines` : `${charCount} chars`
+      const display = `pasted #${count} (${summary})`
+      const filename = `paste-${count}.txt`
+
+      const attachment = createTextAttachment(pastedText, display, filename)
+      addAttachment(options.instanceId(), options.sessionId(), attachment)
+
+      const textarea = options.getTextarea()
+      if (textarea) {
+        const start = textarea.selectionStart
+        const end = textarea.selectionEnd
+        const currentText = options.prompt()
+        const placeholder = formatPastedPlaceholder(count)
+        const newText = currentText.substring(0, start) + placeholder + currentText.substring(end)
+        options.setPrompt(newText)
+
+        setTimeout(() => {
+          const newCursorPos = start + placeholder.length
+          textarea.setSelectionRange(newCursorPos, newCursorPos)
+          textarea.focus()
+        }, 0)
+      }
+    }
+  }
+
+  function handleDragOver(e: DragEvent) {
+    e.preventDefault()
+    e.stopPropagation()
+    setIsDragging(true)
+  }
+
+  function handleDragLeave(e: DragEvent) {
+    e.preventDefault()
+    e.stopPropagation()
+    setIsDragging(false)
+  }
+
+  function handleDrop(e: DragEvent) {
+    e.preventDefault()
+    e.stopPropagation()
+    setIsDragging(false)
+
+    const files = e.dataTransfer?.files
+    if (!files || files.length === 0) return
+
+    for (let i = 0; i < files.length; i++) {
+      const file = files[i]
+      const path = (file as File & { path?: string }).path || file.name
+      const filename = file.name
+      const mime = file.type || "text/plain"
+
+      const createAndStoreAttachment = (previewUrl?: string) => {
+        const attachment = createFileAttachment(path, filename, mime, undefined, options.instanceFolder())
+        if (previewUrl && (mime.startsWith("image/") || mime.startsWith("text/"))) {
+          attachment.url = previewUrl
+        }
+        addAttachment(options.instanceId(), options.sessionId(), attachment)
+      }
+
+      if (mime.startsWith("image/") && typeof FileReader !== "undefined") {
+        const reader = new FileReader()
+        reader.onload = () => {
+          const result = typeof reader.result === "string" ? reader.result : undefined
+          createAndStoreAttachment(result)
+        }
+        reader.readAsDataURL(file)
+      } else if (mime.startsWith("text/") && typeof FileReader !== "undefined") {
+        const reader = new FileReader()
+        reader.onload = () => {
+          const dataUrl = typeof reader.result === "string" ? reader.result : undefined
+          createAndStoreAttachment(dataUrl)
+        }
+        reader.readAsDataURL(file)
+      } else {
+        createAndStoreAttachment()
+      }
+    }
+
+    options.getTextarea()?.focus()
+  }
+
+  return {
+    attachments,
+    pasteCount,
+    imageCount,
+    syncAttachmentCounters,
+    handlePaste,
+    isDragging,
+    handleDragOver,
+    handleDragLeave,
+    handleDrop,
+    handleRemoveAttachment,
+    handleExpandTextAttachment,
+  }
+}

packages/ui/src/components/prompt-input/usePromptKeyDown.ts

@@ -0,0 +1,272 @@
+import type { Accessor } from "solid-js"
+import type { Attachment } from "../../types/attachment"
+import type { PromptMode } from "./types"
+import {
+  createImagePlaceholderRegex,
+  createMentionRegex,
+  createPastedPlaceholderRegex,
+} from "./attachmentPlaceholders"
+
+export type UsePromptKeyDownOptions = {
+  getTextarea: () => HTMLTextAreaElement | null
+
+  prompt: Accessor<string>
+  setPrompt: (v: string) => void
+
+  mode: Accessor<PromptMode>
+  setMode: (m: PromptMode) => void
+
+  isPickerOpen: Accessor<boolean>
+  closePicker: () => void
+
+  ignoredAtPositions: Accessor<Set<number>>
+  setIgnoredAtPositions: (next: Set<number> | ((s: Set<number>) => Set<number>)) => void
+
+  getAttachments: Accessor<Attachment[]>
+  removeAttachment: (attachmentId: string) => void
+
+  submitOnEnter: Accessor<boolean>
+  onSend: () => void
+
+  selectPreviousHistory: (force?: boolean) => boolean
+  selectNextHistory: (force?: boolean) => boolean
+}
+
+export function usePromptKeyDown(options: UsePromptKeyDownOptions) {
+  const insertNewlineAtCursor = () => {
+    const textarea = options.getTextarea()
+    const current = options.prompt()
+    const start = textarea ? textarea.selectionStart : current.length
+    const end = textarea ? textarea.selectionEnd : current.length
+    const nextValue = current.substring(0, start) + "\n" + current.substring(end)
+    const nextCursor = start + 1
+
+    options.setPrompt(nextValue)
+
+    setTimeout(() => {
+      const nextTextarea = options.getTextarea()
+      if (!nextTextarea) return
+      nextTextarea.focus()
+      nextTextarea.setSelectionRange(nextCursor, nextCursor)
+    }, 0)
+  }
+
+  return function handleKeyDown(e: KeyboardEvent) {
+    const textarea = options.getTextarea()
+    if (!textarea) return
+
+    const currentText = options.prompt()
+    const cursorAtBufferStart = textarea.selectionStart === 0 && textarea.selectionEnd === 0
+    const isShellMode = options.mode() === "shell"
+
+    if (!isShellMode && e.key === "!" && cursorAtBufferStart && currentText.length === 0 && !textarea.disabled) {
+      e.preventDefault()
+      options.setMode("shell")
+      return
+    }
+
+    if (options.isPickerOpen() && e.key === "Escape") {
+      e.preventDefault()
+      e.stopPropagation()
+      options.closePicker()
+      return
+    }
+
+    if (isShellMode) {
+      if (e.key === "Escape") {
+        e.preventDefault()
+        e.stopPropagation()
+        options.setMode("normal")
+        return
+      }
+      if (e.key === "Backspace" && cursorAtBufferStart && currentText.length === 0) {
+        e.preventDefault()
+        options.setMode("normal")
+        return
+      }
+    }
+
+    if (e.key === "Backspace" || e.key === "Delete") {
+      const cursorPos = textarea.selectionStart
+      const text = currentText
+
+      const pastePlaceholderRegex = createPastedPlaceholderRegex()
+      let pasteMatch
+
+      while ((pasteMatch = pastePlaceholderRegex.exec(text)) !== null) {
+        const placeholderStart = pasteMatch.index
+        const placeholderEnd = pasteMatch.index + pasteMatch[0].length
+        const pasteNumber = pasteMatch[1]
+
+        const isDeletingFromEnd = e.key === "Backspace" && cursorPos === placeholderEnd
+        const isDeletingFromStart = e.key === "Delete" && cursorPos === placeholderStart
+        const isSelected =
+          textarea.selectionStart <= placeholderStart &&
+          textarea.selectionEnd >= placeholderEnd &&
+          textarea.selectionStart !== textarea.selectionEnd
+
+        if (isDeletingFromEnd || isDeletingFromStart || isSelected) {
+          e.preventDefault()
+
+          const currentAttachments = options.getAttachments()
+          const attachment = currentAttachments.find(
+            (a) => a.source.type === "text" && a.display.includes(`pasted #${pasteNumber}`),
+          )
+
+          if (attachment) {
+            options.removeAttachment(attachment.id)
+          }
+
+          const newText = text.substring(0, placeholderStart) + text.substring(placeholderEnd)
+          options.setPrompt(newText)
+
+          setTimeout(() => {
+            textarea.setSelectionRange(placeholderStart, placeholderStart)
+          }, 0)
+
+          return
+        }
+      }
+
+      const imagePlaceholderRegex = createImagePlaceholderRegex()
+      let imageMatch
+
+      while ((imageMatch = imagePlaceholderRegex.exec(text)) !== null) {
+        const placeholderStart = imageMatch.index
+        const placeholderEnd = imageMatch.index + imageMatch[0].length
+        const imageNumber = imageMatch[1]
+
+        const isDeletingFromEnd = e.key === "Backspace" && cursorPos === placeholderEnd
+        const isDeletingFromStart = e.key === "Delete" && cursorPos === placeholderStart
+        const isSelected =
+          textarea.selectionStart <= placeholderStart &&
+          textarea.selectionEnd >= placeholderEnd &&
+          textarea.selectionStart !== textarea.selectionEnd
+
+        if (isDeletingFromEnd || isDeletingFromStart || isSelected) {
+          e.preventDefault()
+
+          const currentAttachments = options.getAttachments()
+          const attachment = currentAttachments.find(
+            (a) => a.source.type === "file" && a.mediaType.startsWith("image/") && a.display.includes(`Image #${imageNumber}`),
+          )
+
+          if (attachment) {
+            options.removeAttachment(attachment.id)
+          }
+
+          const newText = text.substring(0, placeholderStart) + text.substring(placeholderEnd)
+          options.setPrompt(newText)
+
+          setTimeout(() => {
+            textarea.setSelectionRange(placeholderStart, placeholderStart)
+          }, 0)
+
+          return
+        }
+      }
+
+      const mentionRegex = createMentionRegex()
+      let mentionMatch
+
+      while ((mentionMatch = mentionRegex.exec(text)) !== null) {
+        const mentionStart = mentionMatch.index
+        const mentionEnd = mentionMatch.index + mentionMatch[0].length
+        const name = mentionMatch[1]
+
+        const isDeletingFromEnd = e.key === "Backspace" && cursorPos === mentionEnd
+        const isDeletingFromStart = e.key === "Delete" && cursorPos === mentionStart
+        const isSelected =
+          textarea.selectionStart <= mentionStart &&
+          textarea.selectionEnd >= mentionEnd &&
+          textarea.selectionStart !== textarea.selectionEnd
+
+        if (isDeletingFromEnd || isDeletingFromStart || isSelected) {
+          const currentAttachments = options.getAttachments()
+          const attachment = currentAttachments.find(
+            (a) => (a.source.type === "file" || a.source.type === "agent") && a.filename === name,
+          )
+
+          if (attachment) {
+            e.preventDefault()
+
+            options.removeAttachment(attachment.id)
+
+            options.setIgnoredAtPositions((prev) => {
+              const next = new Set(prev)
+              next.delete(mentionStart)
+              return next
+            })
+
+            const newText = text.substring(0, mentionStart) + text.substring(mentionEnd)
+            options.setPrompt(newText)
+
+            setTimeout(() => {
+              textarea.setSelectionRange(mentionStart, mentionStart)
+            }, 0)
+
+            return
+          }
+        }
+      }
+    }
+
+    if (e.key === "Enter") {
+      const isModified = e.metaKey || e.ctrlKey
+
+      // If the picker is open, Enter should select from it.
+      if (!isModified && options.isPickerOpen()) {
+        return
+      }
+
+      if (options.submitOnEnter()) {
+        // Swapped mode: Enter submits, Cmd/Ctrl+Enter inserts a newline.
+        if (isModified) {
+          e.preventDefault()
+          e.stopPropagation()
+          insertNewlineAtCursor()
+          return
+        }
+
+        // Shift+Enter always inserts a newline.
+        if (e.shiftKey) {
+          // If the picker is open, avoid selecting an item on Enter.
+          if (options.isPickerOpen()) {
+            e.stopPropagation()
+          }
+          return
+        }
+
+        e.preventDefault()
+        options.onSend()
+        return
+      }
+
+      // Default: Cmd/Ctrl+Enter submits.
+      if (isModified) {
+        e.preventDefault()
+        if (options.isPickerOpen()) {
+          options.closePicker()
+        }
+        options.onSend()
+        return
+      }
+    }
+
+    if (e.key === "ArrowUp") {
+      const handled = options.selectPreviousHistory()
+      if (handled) {
+        e.preventDefault()
+        return
+      }
+    }
+
+    if (e.key === "ArrowDown") {
+      const handled = options.selectNextHistory()
+      if (handled) {
+        e.preventDefault()
+        return
+      }
+    }
+  }
+}

packages/ui/src/components/prompt-input/usePromptPicker.ts

@@ -0,0 +1,272 @@
+import { createSignal, type Accessor, type Setter } from "solid-js"
+import type { Command as SDKCommand } from "@opencode-ai/sdk/v2"
+import type { Agent } from "../../types/session"
+import { createAgentAttachment, createFileAttachment } from "../../types/attachment"
+import { addAttachment, getAttachments } from "../../stores/attachments"
+import type { PickerMode } from "./types"
+
+type PickerItem =
+  | { type: "agent"; agent: Agent }
+  | { type: "file"; file: { path: string; relativePath?: string; isGitFile: boolean; isDirectory?: boolean } }
+  | { type: "command"; command: SDKCommand }
+
+type PromptPickerOptions = {
+  instanceId: Accessor<string>
+  sessionId: Accessor<string>
+  instanceFolder: Accessor<string>
+
+  prompt: Accessor<string>
+  setPrompt: (value: string) => void
+  getTextarea: () => HTMLTextAreaElement | null
+
+  instanceAgents: Accessor<Agent[]>
+  commands: Accessor<SDKCommand[]>
+}
+
+type PromptPickerController = {
+  showPicker: Accessor<boolean>
+  pickerMode: Accessor<PickerMode>
+  searchQuery: Accessor<string>
+  atPosition: Accessor<number | null>
+  ignoredAtPositions: Accessor<Set<number>>
+
+  setShowPicker: Setter<boolean>
+  setPickerMode: Setter<PickerMode>
+  setSearchQuery: Setter<string>
+  setAtPosition: Setter<number | null>
+  setIgnoredAtPositions: Setter<Set<number>>
+
+  handleInput: (e: Event) => void
+  handlePickerSelect: (item: PickerItem) => void
+  handlePickerClose: () => void
+}
+
+export function usePromptPicker(options: PromptPickerOptions): PromptPickerController {
+  const [showPicker, setShowPicker] = createSignal(false)
+  const [pickerMode, setPickerMode] = createSignal<PickerMode>("mention")
+  const [searchQuery, setSearchQuery] = createSignal("")
+  const [atPosition, setAtPosition] = createSignal<number | null>(null)
+  const [ignoredAtPositions, setIgnoredAtPositions] = createSignal<Set<number>>(new Set<number>())
+
+  function handleInput(e: Event) {
+    const target = e.target as HTMLTextAreaElement
+    const value = target.value
+    options.setPrompt(value)
+
+    const cursorPos = target.selectionStart
+
+    // Slash command picker (only when editing the command token: "/<query>")
+    if (value.startsWith("/") && cursorPos >= 1) {
+      const firstWhitespaceIndex = value.slice(1).search(/\s/)
+      const tokenEnd = firstWhitespaceIndex === -1 ? value.length : firstWhitespaceIndex + 1
+
+      if (cursorPos <= tokenEnd) {
+        setPickerMode("command")
+        setAtPosition(0)
+        setSearchQuery(value.substring(1, cursorPos))
+        setShowPicker(true)
+        return
+      }
+    }
+
+    const textBeforeCursor = value.substring(0, cursorPos)
+    const lastAtIndex = textBeforeCursor.lastIndexOf("@")
+
+    const previousAtPosition = atPosition()
+
+    if (lastAtIndex === -1) {
+      setIgnoredAtPositions(new Set<number>())
+    } else if (previousAtPosition !== null && lastAtIndex !== previousAtPosition) {
+      setIgnoredAtPositions((prev) => {
+        const next = new Set(prev)
+        next.delete(previousAtPosition)
+        return next
+      })
+    }
+
+    if (lastAtIndex !== -1) {
+      const textAfterAt = value.substring(lastAtIndex + 1, cursorPos)
+      const hasSpace = textAfterAt.includes(" ") || textAfterAt.includes("\n")
+
+      if (!hasSpace && cursorPos === lastAtIndex + textAfterAt.length + 1) {
+        if (!ignoredAtPositions().has(lastAtIndex)) {
+          setPickerMode("mention")
+          setAtPosition(lastAtIndex)
+          setSearchQuery(textAfterAt)
+          setShowPicker(true)
+        }
+        return
+      }
+    }
+
+    setShowPicker(false)
+    setAtPosition(null)
+  }
+
+  function handlePickerSelect(item: PickerItem) {
+    const textarea = options.getTextarea()
+
+    if (item.type === "command") {
+      const name = item.command.name
+      const currentPrompt = options.prompt()
+
+      const afterSlash = currentPrompt.slice(1)
+      const firstWhitespaceIndex = afterSlash.search(/\s/)
+      const tokenEnd = firstWhitespaceIndex === -1 ? currentPrompt.length : firstWhitespaceIndex + 1
+
+      const before = ""
+      const after = currentPrompt.substring(tokenEnd)
+      const newPrompt = before + `/${name} ` + after
+      options.setPrompt(newPrompt)
+
+      setTimeout(() => {
+        const nextTextarea = options.getTextarea()
+        if (nextTextarea) {
+          const newCursorPos = `/${name} `.length
+          nextTextarea.setSelectionRange(newCursorPos, newCursorPos)
+          nextTextarea.focus()
+        }
+      }, 0)
+    } else if (item.type === "agent") {
+      const agentName = item.agent.name
+      const existingAttachments = getAttachments(options.instanceId(), options.sessionId())
+      const alreadyAttached = existingAttachments.some(
+        (att) => att.source.type === "agent" && att.source.name === agentName,
+      )
+
+      if (!alreadyAttached) {
+        const attachment = createAgentAttachment(agentName)
+        addAttachment(options.instanceId(), options.sessionId(), attachment)
+      }
+
+      const currentPrompt = options.prompt()
+      const pos = atPosition()
+      const cursorPos = textarea?.selectionStart || 0
+
+      if (pos !== null) {
+        const before = currentPrompt.substring(0, pos)
+        const after = currentPrompt.substring(cursorPos)
+        const attachmentText = `@${agentName}`
+        const newPrompt = before + attachmentText + " " + after
+        options.setPrompt(newPrompt)
+
+        setTimeout(() => {
+          const nextTextarea = options.getTextarea()
+          if (nextTextarea) {
+            const newCursorPos = pos + attachmentText.length + 1
+            nextTextarea.setSelectionRange(newCursorPos, newCursorPos)
+          }
+        }, 0)
+      }
+    } else if (item.type === "file") {
+      const displayPath = item.file.path
+      const relativePath = item.file.relativePath ?? displayPath
+      const isFolder = item.file.isDirectory ?? displayPath.endsWith("/")
+
+      if (isFolder) {
+        const currentPrompt = options.prompt()
+        const pos = atPosition()
+        const cursorPos = textarea?.selectionStart || 0
+        const folderMention =
+          relativePath === "." || relativePath === ""
+            ? "/"
+            : relativePath.replace(/\/+$/, "") + "/"
+
+        if (pos !== null) {
+          const before = currentPrompt.substring(0, pos + 1)
+          const after = currentPrompt.substring(cursorPos)
+          const newPrompt = before + folderMention + after
+          options.setPrompt(newPrompt)
+          setSearchQuery(folderMention)
+
+          setTimeout(() => {
+            const nextTextarea = options.getTextarea()
+            if (nextTextarea) {
+              const newCursorPos = pos + 1 + folderMention.length
+              nextTextarea.setSelectionRange(newCursorPos, newCursorPos)
+            }
+          }, 0)
+        }
+
+        return
+      }
+
+      const normalizedPath = relativePath.replace(/\/+$/, "") || relativePath
+      const pathSegments = normalizedPath.split("/")
+      const filename = (() => {
+        const candidate = pathSegments[pathSegments.length - 1] || normalizedPath
+        return candidate === "." ? "/" : candidate
+      })()
+
+      const existingAttachments = getAttachments(options.instanceId(), options.sessionId())
+      const alreadyAttached = existingAttachments.some(
+        (att) => att.source.type === "file" && att.source.path === normalizedPath,
+      )
+
+      if (!alreadyAttached) {
+        const attachment = createFileAttachment(
+          normalizedPath,
+          filename,
+          "text/plain",
+          undefined,
+          options.instanceFolder(),
+        )
+        addAttachment(options.instanceId(), options.sessionId(), attachment)
+      }
+
+      const currentPrompt = options.prompt()
+      const pos = atPosition()
+      const cursorPos = textarea?.selectionStart || 0
+
+      if (pos !== null) {
+        const before = currentPrompt.substring(0, pos)
+        const after = currentPrompt.substring(cursorPos)
+        const attachmentText = `@${normalizedPath}`
+        const newPrompt = before + attachmentText + " " + after
+        options.setPrompt(newPrompt)
+
+        setTimeout(() => {
+          const nextTextarea = options.getTextarea()
+          if (nextTextarea) {
+            const newCursorPos = pos + attachmentText.length + 1
+            nextTextarea.setSelectionRange(newCursorPos, newCursorPos)
+          }
+        }, 0)
+      }
+    }
+
+    setShowPicker(false)
+    setAtPosition(null)
+    setSearchQuery("")
+    textarea?.focus()
+  }
+
+  function handlePickerClose() {
+    const pos = atPosition()
+    if (pickerMode() === "mention" && pos !== null) {
+      setIgnoredAtPositions((prev) => new Set(prev).add(pos))
+    }
+    setShowPicker(false)
+    setAtPosition(null)
+    setSearchQuery("")
+    setTimeout(() => options.getTextarea()?.focus(), 0)
+  }
+
+  return {
+    showPicker,
+    pickerMode,
+    searchQuery,
+    atPosition,
+    ignoredAtPositions,
+
+    setShowPicker,
+    setPickerMode,
+    setSearchQuery,
+    setAtPosition,
+    setIgnoredAtPositions,
+
+    handleInput,
+    handlePickerSelect,
+    handlePickerClose,
+  }
+}

packages/ui/src/components/prompt-input/usePromptState.ts

@@ -0,0 +1,203 @@
+import { createEffect, createSignal, on, onCleanup, onMount, type Accessor } from "solid-js"
+import { addToHistory, getHistory } from "../../stores/message-history"
+import { clearSessionDraftPrompt, getSessionDraftPrompt, setSessionDraftPrompt } from "../../stores/sessions"
+import { getLogger } from "../../lib/logger"
+
+const log = getLogger("actions")
+
+type GetTextarea = () => HTMLTextAreaElement | undefined | null
+
+type PromptStateOptions = {
+  instanceId: Accessor<string>
+  sessionId: Accessor<string>
+  instanceFolder: Accessor<string>
+  onSessionDraftLoaded?: (draft: string) => void
+}
+
+type HistorySelectOptions = {
+  force?: boolean
+  isPickerOpen: boolean
+  getTextarea: GetTextarea
+}
+
+type PromptState = {
+  prompt: Accessor<string>
+  setPrompt: (value: string) => void
+  clearPrompt: () => void
+
+  draftLoadedNonce: Accessor<number>
+
+  history: Accessor<string[]>
+  historyIndex: Accessor<number>
+  historyDraft: Accessor<string | null>
+
+  resetHistoryNavigation: () => void
+  clearHistoryDraft: () => void
+  recordHistoryEntry: (entry: string) => Promise<void>
+
+  selectPreviousHistory: (options: HistorySelectOptions) => boolean
+  selectNextHistory: (options: HistorySelectOptions) => boolean
+}
+
+const HISTORY_LIMIT = 100
+
+export function usePromptState(options: PromptStateOptions): PromptState {
+  const [prompt, setPromptInternal] = createSignal("")
+  const [history, setHistory] = createSignal<string[]>([])
+  const [historyIndex, setHistoryIndex] = createSignal(-1)
+  const [historyDraft, setHistoryDraft] = createSignal<string | null>(null)
+  const [draftLoadedNonce, setDraftLoadedNonce] = createSignal(0)
+
+  const setPrompt = (value: string) => {
+    setPromptInternal(value)
+    // Persist drafts only when the user is at the "fresh" position (not browsing history).
+    // This keeps the bottom-of-history draft stable even if the user edits recalled history entries.
+    if (historyIndex() === -1) {
+      setSessionDraftPrompt(options.instanceId(), options.sessionId(), value)
+    }
+  }
+
+  const clearPrompt = () => {
+    clearSessionDraftPrompt(options.instanceId(), options.sessionId())
+    setPromptInternal("")
+  }
+
+  const resetHistoryNavigation = () => {
+    setHistoryIndex(-1)
+    setHistoryDraft(null)
+  }
+
+  const clearHistoryDraft = () => {
+    setHistoryDraft(null)
+  }
+
+  createEffect(
+    on(
+      () => `${options.instanceId()}:${options.sessionId()}`,
+      () => {
+        const instanceId = options.instanceId()
+        const sessionId = options.sessionId()
+
+        onCleanup(() => {
+          // Persist the previous session's draft when switching sessions.
+          setSessionDraftPrompt(instanceId, sessionId, prompt())
+        })
+
+        const storedPrompt = getSessionDraftPrompt(instanceId, sessionId)
+
+        setPromptInternal(storedPrompt)
+        setSessionDraftPrompt(instanceId, sessionId, storedPrompt)
+
+        resetHistoryNavigation()
+
+        setDraftLoadedNonce((prev) => prev + 1)
+        options.onSessionDraftLoaded?.(storedPrompt)
+      },
+    ),
+  )
+
+  onMount(() => {
+    void (async () => {
+      const loaded = await getHistory(options.instanceFolder())
+      setHistory(loaded)
+    })()
+  })
+
+  const recordHistoryEntry = async (entry: string) => {
+    try {
+      await addToHistory(options.instanceFolder(), entry)
+      setHistory((prev) => {
+        const next = [entry, ...prev]
+        if (next.length > HISTORY_LIMIT) {
+          next.length = HISTORY_LIMIT
+        }
+        return next
+      })
+      setHistoryIndex(-1)
+    } catch (historyError) {
+      log.error("Failed to update prompt history:", historyError)
+    }
+  }
+
+  const canUseHistory = (selectOptions: HistorySelectOptions) => {
+    if (selectOptions.force) return true
+    if (selectOptions.isPickerOpen) return false
+
+    const textarea = selectOptions.getTextarea()
+    if (!textarea) return false
+
+    // Only require the cursor to be at the buffer start when *entering* history navigation.
+    // Once we're already navigating history (historyIndex >= 0), allow ArrowUp/ArrowDown
+    // regardless of cursor position (we focus the end of the entry).
+    if (historyIndex() !== -1) return true
+
+    return textarea.selectionStart === 0 && textarea.selectionEnd === 0
+  }
+
+  const focusTextareaEnd = (getTextarea: GetTextarea) => {
+    const textarea = getTextarea()
+    if (!textarea) return
+    setTimeout(() => {
+      const next = getTextarea()
+      if (!next) return
+      const pos = next.value.length
+      next.setSelectionRange(pos, pos)
+      next.focus()
+    }, 0)
+  }
+
+  const selectPreviousHistory = (selectOptions: HistorySelectOptions) => {
+    const entries = history()
+    if (entries.length === 0) return false
+    if (!canUseHistory(selectOptions)) return false
+
+    if (historyIndex() === -1) {
+      setHistoryDraft(prompt())
+    }
+
+    const newIndex = historyIndex() === -1 ? 0 : Math.min(historyIndex() + 1, entries.length - 1)
+    setHistoryIndex(newIndex)
+    setPrompt(entries[newIndex])
+    focusTextareaEnd(selectOptions.getTextarea)
+    return true
+  }
+
+  const selectNextHistory = (selectOptions: HistorySelectOptions) => {
+    const entries = history()
+    if (entries.length === 0) return false
+    if (!canUseHistory(selectOptions)) return false
+    if (historyIndex() === -1) return false
+
+    const newIndex = historyIndex() - 1
+    if (newIndex >= 0) {
+      setHistoryIndex(newIndex)
+      setPrompt(entries[newIndex])
+    } else {
+      setHistoryIndex(-1)
+      const draft = historyDraft() ?? getSessionDraftPrompt(options.instanceId(), options.sessionId())
+      setPrompt(draft ?? "")
+      setHistoryDraft(null)
+    }
+    focusTextareaEnd(selectOptions.getTextarea)
+    return true
+  }
+
+  return {
+    prompt,
+    setPrompt,
+    clearPrompt,
+
+    draftLoadedNonce,
+
+    history,
+    historyIndex,
+    historyDraft,
+
+    resetHistoryNavigation,
+    clearHistoryDraft,
+    recordHistoryEntry,
+
+    selectPreviousHistory,
+    selectNextHistory,
+  }
+}

packages/ui/src/components/session/session-view.tsx

@@ -1,12 +1,11 @@
-import { Show, For, createMemo, createEffect, on, type Component } from "solid-js"
-import { Expand } from "lucide-solid"
+import { Show, createMemo, createEffect, on, type Component } from "solid-js"
 import type { Session } from "../../types/session"
 import type { Attachment } from "../../types/attachment"
 import type { ClientPart } from "../../types/message"
 import MessageSection from "../message-section"
 import { messageStoreBus } from "../../stores/message-v2/bus"
 import PromptInput from "../prompt-input"
-import type { Attachment as PromptAttachment } from "../../types/attachment"
+import PromptAttachmentsBar from "../prompt-input/PromptAttachmentsBar"
 import { getAttachments, removeAttachment } from "../../stores/attachments"
 import { instances } from "../../stores/instances"
 import { loadMessages, sendMessage, forkSession, renameSession, isSessionMessagesLoading, setActiveParentSession, setActiveSession, runShellCommand, abortSession } from "../../stores/sessions"
@@ -15,6 +14,7 @@ import { showAlertDialog } from "../../stores/alerts"
 import { getLogger } from "../../lib/logger"
 import { requestData } from "../../lib/opencode-api"
 import { useI18n } from "../../lib/i18n"
+import type { PromptInputApi, PromptInsertMode } from "../prompt-input/types"
 
 const log = getLogger("session")
 
@@ -53,52 +53,9 @@ export const SessionView: Component<SessionViewProps> = (props) => {
 
   const attachments = createMemo(() => getAttachments(props.instanceId, props.sessionId))
 
-  function handleExpandTextAttachment(attachment: PromptAttachment) {
-    if (attachment.source.type !== "text") return
-
-    const textarea = rootRef?.querySelector(".prompt-input") as HTMLTextAreaElement | null
-    const value = attachment.source.value
-    const match = attachment.display.match(/pasted #(\d+)/)
-    const placeholder = match ? `[pasted #${match[1]}]` : null
-
-    const currentText = textarea?.value ?? ""
-
-    let nextText = currentText
-    let selectionTarget: number | null = null
-
-    if (placeholder) {
-      const placeholderIndex = currentText.indexOf(placeholder)
-      if (placeholderIndex !== -1) {
-        nextText =
-          currentText.substring(0, placeholderIndex) +
-          value +
-          currentText.substring(placeholderIndex + placeholder.length)
-        selectionTarget = placeholderIndex + value.length
-      }
-    }
-
-    if (nextText === currentText) {
-      if (textarea) {
-        const start = textarea.selectionStart
-        const end = textarea.selectionEnd
-        nextText = currentText.substring(0, start) + value + currentText.substring(end)
-        selectionTarget = start + value.length
-      } else {
-        nextText = currentText + value
-      }
-    }
-
-    if (textarea) {
-      textarea.value = nextText
-      textarea.dispatchEvent(new Event("input", { bubbles: true }))
-      textarea.focus()
-      if (selectionTarget !== null) {
-        textarea.setSelectionRange(selectionTarget, selectionTarget)
-      }
-    }
-
-    removeAttachment(props.instanceId, props.sessionId, attachment.id)
-  }
+  let promptInputApi: PromptInputApi | null = null
+  let pendingPromptText: string | null = null
+  let pendingSelectionInsert: { text: string; mode: PromptInsertMode } | null = null
 
   let scrollToBottomHandle: (() => void) | undefined
   let rootRef: HTMLDivElement | undefined
@@ -135,6 +92,11 @@ export const SessionView: Component<SessionViewProps> = (props) => {
         // Defer until the session pane is visible and the textarea is mounted.
         requestAnimationFrame(() => {
           requestAnimationFrame(() => {
+            if (promptInputApi) {
+              promptInputApi.focus()
+              return
+            }
+
             const textarea = rootRef?.querySelector<HTMLTextAreaElement>(".prompt-input")
             if (!textarea) return
             if (textarea.disabled) return
@@ -149,8 +111,7 @@ export const SessionView: Component<SessionViewProps> = (props) => {
       },
     ),
   )
-  let quoteHandler: ((text: string, mode: "quote" | "code") => void) | null = null
- 
+
   createEffect(() => {
     const currentSession = session()
     if (currentSession) {
@@ -158,18 +119,31 @@ export const SessionView: Component<SessionViewProps> = (props) => {
     }
   })
 
-  function registerQuoteHandler(handler: (text: string, mode: "quote" | "code") => void) {
-    quoteHandler = handler
+  function registerPromptInputApi(api: PromptInputApi) {
+    promptInputApi = api
+
+    if (pendingPromptText) {
+      api.setPromptText(pendingPromptText, { focus: true })
+      pendingPromptText = null
+    }
+
+    if (pendingSelectionInsert) {
+      api.insertSelection(pendingSelectionInsert.text, pendingSelectionInsert.mode)
+      pendingSelectionInsert = null
+    }
+
     return () => {
-      if (quoteHandler === handler) {
-        quoteHandler = null
+      if (promptInputApi === api) {
+        promptInputApi = null
       }
     }
   }
 
-  function handleQuoteSelection(text: string, mode: "quote" | "code") {
-    if (quoteHandler) {
-      quoteHandler(text, mode)
+  function handleQuoteSelection(text: string, mode: PromptInsertMode) {
+    if (promptInputApi) {
+      promptInputApi.insertSelection(text, mode)
+    } else {
+      pendingSelectionInsert = { text, mode }
     }
   }
  
@@ -230,14 +204,13 @@ export const SessionView: Component<SessionViewProps> = (props) => {
       )
 
       const restoredText = getUserMessageText(messageId)
-      if (restoredText) {
-        const textarea = rootRef?.querySelector(".prompt-input") as HTMLTextAreaElement | undefined
-        if (textarea) {
-          textarea.value = restoredText
-          textarea.dispatchEvent(new Event("input", { bubbles: true }))
-          textarea.focus()
-        }
-      }
+       if (restoredText) {
+         if (promptInputApi) {
+           promptInputApi.setPromptText(restoredText, { focus: true })
+         } else {
+           pendingPromptText = restoredText
+         }
+       }
     } catch (error) {
       log.error("Failed to revert message", error)
       showAlertDialog(t("sessionView.alerts.revertFailed.message"), {
@@ -271,14 +244,13 @@ export const SessionView: Component<SessionViewProps> = (props) => {
 
       await loadMessages(props.instanceId, forkedSession.id).catch((error) => log.error("Failed to load forked session messages", error))
 
-      if (restoredText) {
-        const textarea = rootRef?.querySelector(".prompt-input") as HTMLTextAreaElement | undefined
-        if (textarea) {
-          textarea.value = restoredText
-          textarea.dispatchEvent(new Event("input", { bubbles: true }))
-          textarea.focus()
-        }
-      }
+       if (restoredText) {
+         if (promptInputApi) {
+           promptInputApi.setPromptText(restoredText, { focus: true })
+         } else {
+           pendingPromptText = restoredText
+         }
+       }
     } catch (error) {
       log.error("Failed to fork session", error)
       showAlertDialog(t("sessionView.alerts.forkFailed.message"), {
@@ -327,39 +299,13 @@ export const SessionView: Component<SessionViewProps> = (props) => {
              />
 
 
-              <Show when={attachments().length > 0}>
-                <div class="flex flex-wrap items-center gap-1.5 border-t px-3 py-2" style="border-color: var(--border-base);">
-                  <For each={attachments()}>
-                    {(attachment) => {
-                      const isText = attachment.source.type === "text"
-                      return (
-                        <div class="attachment-chip" title={attachment.source.type === "file" ? attachment.source.path : undefined}>
-                          <span class="font-mono">{attachment.display}</span>
-                          <Show when={isText}>
-                            <button
-                              type="button"
-                              class="attachment-expand"
-                              onClick={() => handleExpandTextAttachment(attachment)}
-                              aria-label={t("sessionView.attachments.expandPastedTextAriaLabel")}
-                              title={t("sessionView.attachments.insertPastedTextTitle")}
-                            >
-                              <Expand class="h-3 w-3" aria-hidden="true" />
-                            </button>
-                          </Show>
-                          <button
-                            type="button"
-                            class="attachment-remove"
-                            onClick={() => removeAttachment(props.instanceId, props.sessionId, attachment.id)}
-                            aria-label={t("sessionView.attachments.removeAriaLabel")}
-                          >
-                            ×
-                          </button>
-                        </div>
-                      )
-                    }}
-                  </For>
-                </div>
-              </Show>
+               <Show when={attachments().length > 0}>
+                 <PromptAttachmentsBar
+                   attachments={attachments()}
+                   onRemoveAttachment={(attachmentId) => removeAttachment(props.instanceId, props.sessionId, attachmentId)}
+                   onExpandTextAttachment={(attachmentId) => promptInputApi?.expandTextAttachment(attachmentId)}
+                 />
+               </Show>
 
               <PromptInput
                instanceId={props.instanceId}
@@ -371,11 +317,11 @@ export const SessionView: Component<SessionViewProps> = (props) => {
                isSessionBusy={sessionBusy()}
                disabled={sessionNeedsInput()}
                onAbortSession={handleAbortSession}
-               registerQuoteHandler={registerQuoteHandler}
-             />
-          </div>
-        )
-      }}
+               registerPromptInputApi={registerPromptInputApi}
+               />
+            </div>
+          )
+        }}
     </Show>
   )
 }

packages/ui/src/lib/i18n/messages/en/instance.ts

@@ -86,12 +86,32 @@ export const instanceMessages = {
   "instanceShell.empty.description": "Select a session to view messages",
 
   "instanceShell.rightPanel.title": "Status Panel",
+  "instanceShell.rightPanel.tabs.changes": "Session Changes",
+  "instanceShell.rightPanel.tabs.gitChanges": "Git Changes",
+  "instanceShell.rightPanel.tabs.files": "Files",
+  "instanceShell.rightPanel.tabs.status": "Status",
+  "instanceShell.rightPanel.tabs.ariaLabel": "Right panel tabs",
+  "instanceShell.rightPanel.actions.refresh": "Refresh",
+  "instanceShell.rightPanel.sections.sessionChanges": "Session Changes",
   "instanceShell.rightPanel.sections.plan": "Plan",
   "instanceShell.rightPanel.sections.backgroundProcesses": "Background Shells",
   "instanceShell.rightPanel.sections.mcp": "MCP Servers",
   "instanceShell.rightPanel.sections.lsp": "LSP Servers",
   "instanceShell.rightPanel.sections.plugins": "Plugins",
 
+  "instanceShell.sessionChanges.noSessionSelected": "Select a session to view changes.",
+  "instanceShell.sessionChanges.loading": "Fetching session changes...",
+  "instanceShell.sessionChanges.empty": "No session changes yet.",
+  "instanceShell.sessionChanges.filesChanged": "{count} files changed",
+  "instanceShell.sessionChanges.actions.show": "Show changes",
+
+  "instanceShell.filesShell.fileListTitle": "File list",
+  "instanceShell.filesShell.mobileSelectorLabel": "Select file",
+  "instanceShell.filesShell.mobileSelectorEmpty": "Select a file",
+  "instanceShell.filesShell.viewerTitle": "Change viewer",
+  "instanceShell.filesShell.viewerPlaceholder": "Detailed change rendering will be added in the next step.",
+  "instanceShell.filesShell.viewerEmpty": "No file selected.",
+
   "instanceShell.plan.noSessionSelected": "Select a session to view plan.",
   "instanceShell.plan.empty": "Nothing planned yet.",
 

packages/ui/src/lib/i18n/messages/es/instance.ts

@@ -86,12 +86,30 @@ export const instanceMessages = {
   "instanceShell.empty.description": "Selecciona una sesión para ver mensajes",
 
   "instanceShell.rightPanel.title": "Panel de estado",
+  "instanceShell.rightPanel.tabs.changes": "Cambios",
+  "instanceShell.rightPanel.tabs.files": "Archivos",
+  "instanceShell.rightPanel.tabs.status": "Estado",
+  "instanceShell.rightPanel.tabs.ariaLabel": "Pestañas del panel derecho",
+  "instanceShell.rightPanel.sections.sessionChanges": "Cambios de sesion",
   "instanceShell.rightPanel.sections.plan": "Plan",
   "instanceShell.rightPanel.sections.backgroundProcesses": "Shells en segundo plano",
   "instanceShell.rightPanel.sections.mcp": "Servidores MCP",
   "instanceShell.rightPanel.sections.lsp": "Servidores LSP",
   "instanceShell.rightPanel.sections.plugins": "Plugins",
 
+  "instanceShell.sessionChanges.noSessionSelected": "Selecciona una sesion para ver los cambios.",
+  "instanceShell.sessionChanges.loading": "Obteniendo cambios de la sesion...",
+  "instanceShell.sessionChanges.empty": "Aun no hay cambios.",
+  "instanceShell.sessionChanges.filesChanged": "{count} archivos cambiados",
+  "instanceShell.sessionChanges.actions.show": "Mostrar cambios",
+
+  "instanceShell.filesShell.fileListTitle": "Lista de archivos",
+  "instanceShell.filesShell.mobileSelectorLabel": "Seleccionar archivo",
+  "instanceShell.filesShell.mobileSelectorEmpty": "Selecciona un archivo",
+  "instanceShell.filesShell.viewerTitle": "Visor de cambios",
+  "instanceShell.filesShell.viewerPlaceholder": "La vista detallada se agregará en el siguiente paso.",
+  "instanceShell.filesShell.viewerEmpty": "Ningún archivo seleccionado.",
+
   "instanceShell.plan.noSessionSelected": "Selecciona una sesión para ver el plan.",
   "instanceShell.plan.empty": "Aún no hay nada planificado.",
 

packages/ui/src/lib/i18n/messages/fr/instance.ts

@@ -86,12 +86,30 @@ export const instanceMessages = {
   "instanceShell.empty.description": "Sélectionnez une session pour voir les messages",
 
   "instanceShell.rightPanel.title": "Panneau d'état",
+  "instanceShell.rightPanel.tabs.changes": "Modifications",
+  "instanceShell.rightPanel.tabs.files": "Fichiers",
+  "instanceShell.rightPanel.tabs.status": "Statut",
+  "instanceShell.rightPanel.tabs.ariaLabel": "Onglets du panneau droit",
+  "instanceShell.rightPanel.sections.sessionChanges": "Changements de session",
   "instanceShell.rightPanel.sections.plan": "Plan",
   "instanceShell.rightPanel.sections.backgroundProcesses": "Shells en arrière-plan",
   "instanceShell.rightPanel.sections.mcp": "Serveurs MCP",
   "instanceShell.rightPanel.sections.lsp": "Serveurs LSP",
   "instanceShell.rightPanel.sections.plugins": "Plugins",
 
+  "instanceShell.sessionChanges.noSessionSelected": "Sélectionnez une session pour voir les changements.",
+  "instanceShell.sessionChanges.loading": "Récupération des changements...",
+  "instanceShell.sessionChanges.empty": "Aucun changement pour l'instant.",
+  "instanceShell.sessionChanges.filesChanged": "{count} fichiers modifiés",
+  "instanceShell.sessionChanges.actions.show": "Afficher les changements",
+
+  "instanceShell.filesShell.fileListTitle": "Liste des fichiers",
+  "instanceShell.filesShell.mobileSelectorLabel": "Sélectionner un fichier",
+  "instanceShell.filesShell.mobileSelectorEmpty": "Sélectionnez un fichier",
+  "instanceShell.filesShell.viewerTitle": "Visionneuse de changements",
+  "instanceShell.filesShell.viewerPlaceholder": "Le rendu détaillé sera ajouté à l'étape suivante.",
+  "instanceShell.filesShell.viewerEmpty": "Aucun fichier sélectionné.",
+
   "instanceShell.plan.noSessionSelected": "Sélectionnez une session pour voir le plan.",
   "instanceShell.plan.empty": "Aucun plan pour l'instant.",
 

packages/ui/src/lib/i18n/messages/ja/instance.ts

@@ -86,12 +86,30 @@ export const instanceMessages = {
   "instanceShell.empty.description": "メッセージを表示するにはセッションを選択してください",
 
   "instanceShell.rightPanel.title": "ステータスパネル",
+  "instanceShell.rightPanel.tabs.changes": "変更",
+  "instanceShell.rightPanel.tabs.files": "ファイル",
+  "instanceShell.rightPanel.tabs.status": "ステータス",
+  "instanceShell.rightPanel.tabs.ariaLabel": "右パネルのタブ",
+  "instanceShell.rightPanel.sections.sessionChanges": "セッション変更",
   "instanceShell.rightPanel.sections.plan": "計画",
   "instanceShell.rightPanel.sections.backgroundProcesses": "バックグラウンドシェル",
   "instanceShell.rightPanel.sections.mcp": "MCP サーバー",
   "instanceShell.rightPanel.sections.lsp": "LSP サーバー",
   "instanceShell.rightPanel.sections.plugins": "プラグイン",
 
+  "instanceShell.sessionChanges.noSessionSelected": "変更を表示するにはセッションを選択してください。",
+  "instanceShell.sessionChanges.loading": "変更を取得中...",
+  "instanceShell.sessionChanges.empty": "まだ変更はありません。",
+  "instanceShell.sessionChanges.filesChanged": "{count} 個のファイルが変更されました",
+  "instanceShell.sessionChanges.actions.show": "変更を表示",
+
+  "instanceShell.filesShell.fileListTitle": "ファイル一覧",
+  "instanceShell.filesShell.mobileSelectorLabel": "ファイルを選択",
+  "instanceShell.filesShell.mobileSelectorEmpty": "ファイルを選択してください",
+  "instanceShell.filesShell.viewerTitle": "変更ビューア",
+  "instanceShell.filesShell.viewerPlaceholder": "詳細な変更表示は次のステップで追加します。",
+  "instanceShell.filesShell.viewerEmpty": "ファイルが選択されていません。",
+
   "instanceShell.plan.noSessionSelected": "計画を表示するにはセッションを選択してください。",
   "instanceShell.plan.empty": "まだ計画はありません。",
 

packages/ui/src/lib/i18n/messages/ru/instance.ts

@@ -86,12 +86,30 @@ export const instanceMessages = {
   "instanceShell.empty.description": "Выберите сессию, чтобы просмотреть сообщения",
 
   "instanceShell.rightPanel.title": "Панель состояния",
+  "instanceShell.rightPanel.tabs.changes": "Изменения",
+  "instanceShell.rightPanel.tabs.files": "Файлы",
+  "instanceShell.rightPanel.tabs.status": "Статус",
+  "instanceShell.rightPanel.tabs.ariaLabel": "Вкладки правой панели",
+  "instanceShell.rightPanel.sections.sessionChanges": "Изменения сессии",
   "instanceShell.rightPanel.sections.plan": "План",
   "instanceShell.rightPanel.sections.backgroundProcesses": "Фоновые Shell",
   "instanceShell.rightPanel.sections.mcp": "MCP-серверы",
   "instanceShell.rightPanel.sections.lsp": "LSP-серверы",
   "instanceShell.rightPanel.sections.plugins": "Плагины",
 
+  "instanceShell.sessionChanges.noSessionSelected": "Выберите сессию, чтобы просмотреть изменения.",
+  "instanceShell.sessionChanges.loading": "Загрузка изменений...",
+  "instanceShell.sessionChanges.empty": "Пока нет изменений.",
+  "instanceShell.sessionChanges.filesChanged": "Изменено файлов: {count}",
+  "instanceShell.sessionChanges.actions.show": "Показать изменения",
+
+  "instanceShell.filesShell.fileListTitle": "Список файлов",
+  "instanceShell.filesShell.mobileSelectorLabel": "Выбрать файл",
+  "instanceShell.filesShell.mobileSelectorEmpty": "Выберите файл",
+  "instanceShell.filesShell.viewerTitle": "Просмотр изменений",
+  "instanceShell.filesShell.viewerPlaceholder": "Подробный рендер изменений будет добавлен на следующем этапе.",
+  "instanceShell.filesShell.viewerEmpty": "Файл не выбран.",
+
   "instanceShell.plan.noSessionSelected": "Выберите сессию, чтобы просмотреть план.",
   "instanceShell.plan.empty": "Пока ничего не запланировано.",
 

packages/ui/src/lib/i18n/messages/zh-Hans/instance.ts

@@ -86,12 +86,30 @@ export const instanceMessages = {
   "instanceShell.empty.description": "选择会话以查看消息",
 
   "instanceShell.rightPanel.title": "状态面板",
+  "instanceShell.rightPanel.tabs.changes": "更改",
+  "instanceShell.rightPanel.tabs.files": "文件",
+  "instanceShell.rightPanel.tabs.status": "状态",
+  "instanceShell.rightPanel.tabs.ariaLabel": "右侧面板标签页",
+  "instanceShell.rightPanel.sections.sessionChanges": "会话更改",
   "instanceShell.rightPanel.sections.plan": "计划",
   "instanceShell.rightPanel.sections.backgroundProcesses": "后台 Shell",
   "instanceShell.rightPanel.sections.mcp": "MCP 服务器",
   "instanceShell.rightPanel.sections.lsp": "LSP 服务器",
   "instanceShell.rightPanel.sections.plugins": "插件",
 
+  "instanceShell.sessionChanges.noSessionSelected": "选择会话以查看更改。",
+  "instanceShell.sessionChanges.loading": "正在获取会话更改...",
+  "instanceShell.sessionChanges.empty": "暂无会话更改。",
+  "instanceShell.sessionChanges.filesChanged": "已更改 {count} 个文件",
+  "instanceShell.sessionChanges.actions.show": "显示更改",
+
+  "instanceShell.filesShell.fileListTitle": "文件列表",
+  "instanceShell.filesShell.mobileSelectorLabel": "选择文件",
+  "instanceShell.filesShell.mobileSelectorEmpty": "请选择文件",
+  "instanceShell.filesShell.viewerTitle": "更改查看器",
+  "instanceShell.filesShell.viewerPlaceholder": "详细更改渲染将在下一步中添加。",
+  "instanceShell.filesShell.viewerEmpty": "未选择文件。",
+
   "instanceShell.plan.noSessionSelected": "选择会话以查看计划。",
   "instanceShell.plan.empty": "暂无计划。",
 

packages/ui/src/lib/monaco/language.ts

@@ -0,0 +1,70 @@
+type MonacoApi = any
+
+let cachedLanguageMaps:
+  | {
+      fileNameToId: Map<string, string>
+      extToId: Map<string, string>
+    }
+  | null = null
+
+function buildLanguageMaps(monaco: MonacoApi) {
+  if (cachedLanguageMaps) return cachedLanguageMaps
+
+  const fileNameToId = new Map<string, string>()
+  const extToId = new Map<string, string>()
+
+  const languages = typeof monaco?.languages?.getLanguages === "function" ? monaco.languages.getLanguages() : []
+  if (Array.isArray(languages)) {
+    for (const lang of languages) {
+      const id = typeof lang?.id === "string" ? lang.id : null
+      if (!id) continue
+
+      const filenames = Array.isArray(lang?.filenames) ? lang.filenames : []
+      for (const name of filenames) {
+        if (typeof name !== "string") continue
+        if (!fileNameToId.has(name)) fileNameToId.set(name, id)
+      }
+
+      const extensions = Array.isArray(lang?.extensions) ? lang.extensions : []
+      for (const ext of extensions) {
+        if (typeof ext !== "string") continue
+        // Monaco uses leading dots for extensions (e.g. ".ts").
+        if (!extToId.has(ext)) extToId.set(ext, id)
+      }
+    }
+  }
+
+  cachedLanguageMaps = { fileNameToId, extToId }
+  return cachedLanguageMaps
+}
+
+function overrideLanguageId(fileName: string): string | null {
+  // Git-style ignore/config files: treat as shell-like.
+  if (fileName === ".gitignore" || fileName === ".gitattributes" || fileName === ".gitmodules") return "shell"
+
+  // Monaco doesn't ship a dedicated Makefile tokenizer in our baseline.
+  if (fileName === "Makefile" || fileName.startsWith("Makefile.")) return "shell"
+
+  return null
+}
+
+export function inferMonacoLanguageId(monaco: MonacoApi, path: string | undefined | null): string {
+  const raw = String(path || "").trim()
+  const fileName = raw.split("/").pop() || raw
+
+  const override = overrideLanguageId(fileName)
+  if (override) return override
+
+  const maps = buildLanguageMaps(monaco)
+  const byName = maps.fileNameToId.get(fileName)
+  if (byName) return byName
+
+  const dot = fileName.lastIndexOf(".")
+  if (dot > 0) {
+    const ext = fileName.slice(dot)
+    const byExt = maps.extToId.get(ext)
+    if (byExt) return byExt
+  }
+
+  return "plaintext"
+}

packages/ui/src/lib/monaco/model-cache.ts

@@ -0,0 +1,53 @@
+type MonacoApi = any
+
+type CachedModel = {
+  model: any
+}
+
+const MAX_MODELS = 5
+
+// LRU map: newest at the end.
+const models = new Map<string, CachedModel>()
+
+function touch(key: string, entry: CachedModel) {
+  models.delete(key)
+  models.set(key, entry)
+}
+
+function evictIfNeeded() {
+  while (models.size > MAX_MODELS) {
+    const oldestKey = models.keys().next().value as string | undefined
+    if (!oldestKey) return
+    const entry = models.get(oldestKey)
+    models.delete(oldestKey)
+    try {
+      entry?.model.dispose()
+    } catch {
+      // ignore
+    }
+  }
+}
+
+export function getOrCreateTextModel(params: {
+  monaco: MonacoApi
+  cacheKey: string
+  value: string
+  languageId: string
+}): any {
+  const existing = models.get(params.cacheKey)
+  if (existing) {
+    touch(params.cacheKey, existing)
+    if (existing.model.getValue() !== params.value) {
+      existing.model.setValue(params.value)
+    }
+    return existing.model
+  }
+
+  const uri = params.monaco.Uri.parse(`opencode://model/${encodeURIComponent(params.cacheKey)}`)
+  // Create as plaintext. We'll set the final language after its contribution is loaded.
+  const model = params.monaco.editor.createModel(params.value, "plaintext", uri)
+  const entry = { model }
+  models.set(params.cacheKey, entry)
+  evictIfNeeded()
+  return model
+}

packages/ui/src/lib/monaco/setup.ts

@@ -0,0 +1,207 @@
+type RequireFn = (deps: string[], callback: (...args: any[]) => void, errback?: (err: any) => void) => void
+type MonacoApi = any
+
+const MONACO_VERSION = "0.52.2"
+const CDN_VS_ROOT = `https://cdn.jsdelivr.net/npm/monaco-editor@${MONACO_VERSION}/min/vs`
+const LOCAL_VS_ROOT = "/monaco/vs"
+
+let monacoPromise: Promise<MonacoApi> | null = null
+
+function withTimeout<T>(promise: Promise<T>, ms: number): Promise<T> {
+  return new Promise((resolve, reject) => {
+    const id = setTimeout(() => reject(new Error("timeout")), ms)
+    promise
+      .then((value) => {
+        clearTimeout(id)
+        resolve(value)
+      })
+      .catch((err) => {
+        clearTimeout(id)
+        reject(err)
+      })
+  })
+}
+
+async function canReachCdn(): Promise<boolean> {
+  if (typeof fetch === "undefined") return false
+  try {
+    const controller = new AbortController()
+    const task = fetch(`${CDN_VS_ROOT}/loader.js`, { method: "HEAD", signal: controller.signal })
+    const response = await withTimeout(task, 1200)
+    controller.abort()
+    return response.ok
+  } catch {
+    return false
+  }
+}
+
+function ensureLoaderScript(): Promise<void> {
+  if (typeof document === "undefined") return Promise.resolve()
+  const existing = document.querySelector('script[data-monaco-loader="true"]')
+  if (existing) return Promise.resolve()
+
+  return new Promise((resolve, reject) => {
+    const script = document.createElement("script")
+    script.dataset.monacoLoader = "true"
+    script.src = `${LOCAL_VS_ROOT}/loader.js`
+    script.async = true
+    script.onload = () => resolve()
+    script.onerror = () => reject(new Error("Failed to load Monaco AMD loader"))
+    document.head.appendChild(script)
+  })
+}
+
+function ensureEditorCss(): void {
+  if (typeof document === "undefined") return
+  const existing = document.querySelector('link[data-monaco-editor-css="true"]')
+  if (existing) return
+
+  // Some environments don't reliably load `vs/css!` plugin resources.
+  // Loading the core stylesheet explicitly keeps Monaco visible.
+  const link = document.createElement("link")
+  link.rel = "stylesheet"
+  link.href = `${LOCAL_VS_ROOT}/editor/editor.main.css`
+  ;(link as any).dataset.monacoEditorCss = "true"
+  document.head.appendChild(link)
+}
+
+function configureWorkers() {
+  const globalAny = globalThis as any
+  const prevEnv = globalAny.MonacoEnvironment ?? {}
+
+  // Monaco's AMD build no longer ships `editor.worker.js` (and language workers are
+  // `jsonWorker.js`, `cssWorker.js`, etc). The robust approach is to always boot
+  // `vs/base/worker/workerMain.js` and let it `require(...)` the requested module.
+  //
+  // Important: `workerMain.js` expects `MonacoEnvironment.baseUrl` to be the
+  // directory containing the `vs/` folder (so `/monaco/`, not `/monaco/vs`).
+  // Use a static worker bootstrap script rather than a `data:` URL.
+  // This avoids CSP issues and makes worker requests visible in DevTools.
+  const workerUrl = "/monaco.worker.js"
+
+  globalAny.MonacoEnvironment = {
+    ...prevEnv,
+    getWorkerUrl(_moduleId: string, _label: string) {
+      return workerUrl
+    },
+  }
+}
+
+function getRequire(): RequireFn {
+  const req = (globalThis as any).require as RequireFn | undefined
+  if (!req) throw new Error("Monaco AMD loader is not available")
+  return req
+}
+
+function getRequireConfig(): ((config: any) => void) {
+  const req = getRequire() as any
+  const cfg = req.config as ((config: any) => void) | undefined
+  if (!cfg) throw new Error("require.config is not available")
+  return cfg
+}
+
+function requireAsync(deps: string[]): Promise<any[]> {
+  const req = getRequire()
+  return new Promise((resolve, reject) => {
+    req(deps, (...args: any[]) => resolve(args), (err: any) => reject(err))
+  })
+}
+
+function getContributionModuleId(languageId: string): string | null {
+  const id = String(languageId || "plaintext")
+  if (!id || id === "plaintext") return null
+
+  // Rich contributions
+  if (id === "typescript" || id === "javascript") return "vs/language/typescript/monaco.contribution"
+  if (id === "json") return "vs/language/json/monaco.contribution"
+  if (id === "css" || id === "scss" || id === "less") return "vs/language/css/monaco.contribution"
+  if (id === "html") return "vs/language/html/monaco.contribution"
+
+  // Basic tokenizers
+  // Monaco's `min/vs/basic-languages/<id>/` ships `<id>.js` (no `*.contribution.js`).
+  // Loading the tokenizer module is enough; it registers itself with the language service.
+  if (id === "toml") return "vs/basic-languages/toml/toml"
+  return `vs/basic-languages/${id}/${id}`
+}
+
+const loadedContributions = new Set<string>()
+const pendingContributions = new Map<string, Promise<void>>()
+
+export async function ensureMonacoLanguageLoaded(languageId: string): Promise<void> {
+  const moduleId = getContributionModuleId(languageId)
+  if (!moduleId) return
+
+  if (loadedContributions.has(moduleId)) return
+  const pending = pendingContributions.get(moduleId)
+  if (pending) return pending
+
+  const task = (async () => {
+    let loaded = false
+    try {
+      await requireAsync([moduleId])
+      loaded = true
+    } catch {
+      // ignore
+    } finally {
+      if (loaded) loadedContributions.add(moduleId)
+      pendingContributions.delete(moduleId)
+    }
+  })()
+
+  pendingContributions.set(moduleId, task)
+  return task
+}
+
+export async function loadMonaco(): Promise<MonacoApi> {
+  if (monacoPromise) return monacoPromise
+
+  monacoPromise = (async () => {
+    await ensureLoaderScript()
+    configureWorkers()
+    ensureEditorCss()
+
+    const online = await canReachCdn()
+    const requireConfig = getRequireConfig()
+
+    const paths: Record<string, string> = {
+      vs: LOCAL_VS_ROOT,
+    }
+
+    if (online) {
+      paths["vs/basic-languages"] = `${CDN_VS_ROOT}/basic-languages`
+      paths["vs/language"] = `${CDN_VS_ROOT}/language`
+
+      // Baseline languages should remain available offline too.
+      paths["vs/basic-languages/python"] = `${LOCAL_VS_ROOT}/basic-languages/python`
+      paths["vs/basic-languages/markdown"] = `${LOCAL_VS_ROOT}/basic-languages/markdown`
+      paths["vs/basic-languages/cpp"] = `${LOCAL_VS_ROOT}/basic-languages/cpp`
+      paths["vs/basic-languages/kotlin"] = `${LOCAL_VS_ROOT}/basic-languages/kotlin`
+
+      paths["vs/language/typescript"] = `${LOCAL_VS_ROOT}/language/typescript`
+      paths["vs/language/html"] = `${LOCAL_VS_ROOT}/language/html`
+      paths["vs/language/json"] = `${LOCAL_VS_ROOT}/language/json`
+      paths["vs/language/css"] = `${LOCAL_VS_ROOT}/language/css`
+    }
+
+    requireConfig({
+      paths,
+      ignoreDuplicateModules: ["vs/editor/editor.main"],
+    })
+
+    // Load editor core.
+    const [monaco] = await requireAsync(["vs/editor/editor.main"])
+
+    // Load language metadata so we can infer language IDs from paths.
+    // (This is small and should remain local for offline support.)
+    // Note: In Monaco 0.52.x, `vs/basic-languages/monaco.contribution` is bundled
+    // into `vs/editor/editor.main` already. Older builds had additional
+    // `vs/basic-languages/_.contribution` metadata, but that module isn't present
+    // in the current AMD bundle; attempting to load it can trigger a hard
+    // `Unexpected token '<'` if the server falls back to `index.html`.
+    await requireAsync(["vs/basic-languages/monaco.contribution"]).catch(() => [])
+
+    return (globalThis as any).monaco ?? monaco
+  })()
+
+  return monacoPromise
+}

packages/ui/src/lib/sse-manager.ts

@@ -9,6 +9,7 @@ import type {
   EventLspUpdated,
 
   EventSessionCompacted,
+  EventSessionDiff,
   EventSessionError,
   EventSessionIdle,
   EventSessionUpdated,
@@ -59,8 +60,10 @@ type SSEEvent =
   | MessagePartRemovedEvent
   | EventSessionUpdated
   | EventSessionCompacted
+  | EventSessionDiff
   | EventSessionError
   | EventSessionIdle
+  | EventSessionStatus
   | { type: "permission.updated" | "permission.asked"; properties?: any }
   | { type: "permission.replied"; properties?: any }
   | { type: "question.asked"; properties?: any }
@@ -139,6 +142,9 @@ class SSEManager {
       case "session.status":
         this.onSessionStatus?.(instanceId, event as EventSessionStatus)
         break
+      case "session.diff":
+        this.onSessionDiff?.(instanceId, event as EventSessionDiff)
+        break
       case "permission.updated":
       case "permission.asked":
         this.onPermissionUpdated?.(instanceId, event as any)
@@ -185,6 +191,7 @@ class SSEManager {
   onTuiToast?: (instanceId: string, event: TuiToastEvent) => void
   onSessionIdle?: (instanceId: string, event: EventSessionIdle) => void
   onSessionStatus?: (instanceId: string, event: EventSessionStatus) => void
+  onSessionDiff?: (instanceId: string, event: EventSessionDiff) => void
   onPermissionUpdated?: (instanceId: string, event: any) => void
   onPermissionReplied?: (instanceId: string, event: any) => void
   onQuestionAsked?: (instanceId: string, event: any) => void

packages/ui/src/lib/unified-diff-reverse.ts

@@ -0,0 +1,86 @@
+import { applyPatch, parsePatch } from "diff"
+
+type ParsedPatchIndex = ReturnType<typeof parsePatch>[number]
+type ParsedHunk = ParsedPatchIndex["hunks"][number]
+
+type SdkPatch = {
+  oldFileName: string
+  newFileName: string
+  oldHeader?: string
+  newHeader?: string
+  hunks: Array<{
+    oldStart: number
+    oldLines: number
+    newStart: number
+    newLines: number
+    lines: Array<string>
+  }>
+  index?: string
+}
+
+function invertPatchLine(line: string): string {
+  if (!line) return line
+  const op = line[0]
+  if (op === "+") return `-${line.slice(1)}`
+  if (op === "-") return `+${line.slice(1)}`
+  return line
+}
+
+function reverseParsedHunk(hunk: ParsedHunk): ParsedHunk {
+  return {
+    oldStart: hunk.newStart,
+    oldLines: hunk.newLines,
+    newStart: hunk.oldStart,
+    newLines: hunk.oldLines,
+    lines: hunk.lines.map(invertPatchLine),
+    linedelimiters: Array.isArray((hunk as any).linedelimiters) ? (hunk as any).linedelimiters : [],
+  } as ParsedHunk
+}
+
+function reverseParsedIndex(index: ParsedPatchIndex): ParsedPatchIndex {
+  const hunks = Array.isArray(index.hunks) ? index.hunks : []
+  return {
+    ...index,
+    oldFileName: (index as any).newFileName,
+    newFileName: (index as any).oldFileName,
+    oldHeader: (index as any).newHeader,
+    newHeader: (index as any).oldHeader,
+    hunks: hunks.map(reverseParsedHunk),
+  } as ParsedPatchIndex
+}
+
+export function buildUnifiedDiffFromSdkPatch(patch: SdkPatch): string {
+  const oldName = patch.oldFileName || "a/file"
+  const newName = patch.newFileName || "b/file"
+  const oldHeader = patch.oldHeader ? `\t${patch.oldHeader}` : ""
+  const newHeader = patch.newHeader ? `\t${patch.newHeader}` : ""
+
+  const lines: string[] = []
+  if (patch.index) {
+    // jsdiff can parse arbitrary metadata lines before file headers.
+    lines.push(`Index: ${patch.index}`)
+  }
+  lines.push(`--- ${oldName}${oldHeader}`)
+  lines.push(`+++ ${newName}${newHeader}`)
+  for (const hunk of patch.hunks || []) {
+    const oldRange = hunk.oldLines === 1 ? `${hunk.oldStart}` : `${hunk.oldStart},${hunk.oldLines}`
+    const newRange = hunk.newLines === 1 ? `${hunk.newStart}` : `${hunk.newStart},${hunk.newLines}`
+    lines.push(`@@ -${oldRange} +${newRange} @@`)
+    for (const line of hunk.lines || []) {
+      lines.push(line)
+    }
+  }
+  return `${lines.join("\n")}\n`
+}
+
+export function tryReverseApplyUnifiedDiff(afterText: string, diffText: string): string | null {
+  const normalized = (diffText ?? "").trim()
+  if (!normalized) return null
+
+  const parsed = parsePatch(diffText)
+  if (!Array.isArray(parsed) || parsed.length === 0) return null
+
+  const reversed = reverseParsedIndex(parsed[0])
+  const result = applyPatch(afterText ?? "", reversed)
+  return typeof result === "string" ? result : null
+}

packages/ui/src/renderer/public/monaco.worker.js

@@ -0,0 +1,7 @@
+// Monaco web worker bootstrap.
+//
+// `workerMain.js` expects `MonacoEnvironment.baseUrl` to be the directory that
+// contains the `vs/` folder (so `/monaco/`, not `/monaco/vs`).
+self.MonacoEnvironment = { baseUrl: "/monaco/" }
+
+importScripts("/monaco/vs/base/worker/workerMain.js")

packages/ui/src/stores/session-api.ts

@@ -1,5 +1,6 @@
 import { mapSdkSessionStatus, type Session, type SessionStatus } from "../types/session"
 import type { Message } from "../types/message"
+import type { FileDiff } from "@opencode-ai/sdk/v2/client"
 
 import { instances } from "./instances"
 import { preferences, setAgentModelPreference } from "./preferences"
@@ -19,6 +20,7 @@ import {
   setSessionInfoByInstance,
   setSessions,
   sessions,
+  withSession,
   loading,
   setLoading,
   cleanupBlankSessions,
@@ -42,6 +44,49 @@ import {
 
 const log = getLogger("api")
 
+const pendingSessionDiffFetches = new Map<string, Promise<void>>()
+
+async function loadSessionDiff(instanceId: string, sessionId: string, force = false): Promise<void> {
+  if (!instanceId || !sessionId) return
+
+  const key = `${instanceId}:${sessionId}`
+  if (!force) {
+    const existing = sessions().get(instanceId)?.get(sessionId)
+    if (existing?.diff !== undefined) return
+    const pending = pendingSessionDiffFetches.get(key)
+    if (pending) return pending
+  }
+
+  const promise = (async () => {
+    const instance = instances().get(instanceId)
+    if (!instance?.client) return
+
+    const worktreeSlug = getWorktreeSlugForSession(instanceId, sessionId)
+    const client = getOrCreateWorktreeClient(instanceId, worktreeSlug)
+
+    try {
+      const diffs = await requestData<FileDiff[]>(
+        client.session.diff({ sessionID: sessionId }),
+        "session.diff",
+      )
+
+      if (!Array.isArray(diffs)) {
+        return
+      }
+
+      withSession(instanceId, sessionId, (session) => {
+        session.diff = diffs
+      })
+    } catch (error) {
+      log.warn("Failed to fetch session diff", { instanceId, sessionId, error })
+    }
+  })()
+
+  pendingSessionDiffFetches.set(key, promise)
+  void promise.finally(() => pendingSessionDiffFetches.delete(key))
+  return promise
+}
+
 interface SessionForkResponse {
   id: string
   title?: string
@@ -570,6 +615,11 @@ async function loadMessages(instanceId: string, sessionId: string, force = false
     throw new Error("Session not found")
   }
 
+  // Fetch session-level diffs in the background once the session is opened.
+  void loadSessionDiff(instanceId, sessionId).catch((error) => {
+    log.warn("Failed to load session diff", { instanceId, sessionId, error })
+  })
+
   setLoading((prev) => {
     const next = { ...prev }
     const loadingSet = next.loadingMessages.get(instanceId) || new Set()

packages/ui/src/stores/session-events.ts

@@ -7,6 +7,7 @@ import type {
 } from "../types/message"
 import type {
   EventSessionCompacted,
+  EventSessionDiff,
   EventSessionError,
   EventSessionIdle,
   EventSessionUpdated,
@@ -428,6 +429,31 @@ function handleSessionUpdate(instanceId: string, event: EventSessionUpdated): vo
   }
 }
 
+function handleSessionDiff(instanceId: string, event: EventSessionDiff): void {
+  const sessionId = event.properties?.sessionID
+  if (!sessionId) return
+
+  const diffs = event.properties?.diff
+  if (!Array.isArray(diffs)) return
+
+  const existing = sessions().get(instanceId)?.get(sessionId)
+  if (existing) {
+    withSession(instanceId, sessionId, (session) => {
+      session.diff = diffs
+    })
+    return
+  }
+
+  // A diff event can arrive before we have hydrated the session list.
+  // Best-effort: fetch the session record so the diff has somewhere to live.
+  void (async () => {
+    await fetchSessionInfo(instanceId, sessionId, (event as any)?.directory)
+    withSession(instanceId, sessionId, (session) => {
+      session.diff = diffs
+    })
+  })().catch((error) => log.warn("Failed to hydrate session for diff event", { instanceId, sessionId, error }))
+}
+
 function handleSessionIdle(instanceId: string, event: EventSessionIdle): void {
   const sessionId = event.properties?.sessionID
   if (!sessionId) return
@@ -605,6 +631,7 @@ export {
   handleQuestionAsked,
   handleQuestionAnswered,
   handleSessionCompacted,
+  handleSessionDiff,
   handleSessionError,
   handleSessionIdle,
   handleSessionStatus,

packages/ui/src/stores/sessions.ts

@@ -64,6 +64,7 @@ import {
   handleQuestionAnswered,
   handleQuestionAsked,
   handleSessionCompacted,
+  handleSessionDiff,
   handleSessionError,
   handleSessionIdle,
   handleSessionStatus,
@@ -77,6 +78,7 @@ sseManager.onMessageRemoved = handleMessageRemoved
 sseManager.onMessagePartRemoved = handleMessagePartRemoved
 sseManager.onSessionUpdate = handleSessionUpdate
 sseManager.onSessionCompacted = handleSessionCompacted
+sseManager.onSessionDiff = handleSessionDiff
 sseManager.onSessionError = handleSessionError
 sseManager.onSessionIdle = handleSessionIdle
 sseManager.onSessionStatus = handleSessionStatus

packages/ui/src/styles/messaging/message-base.css

@@ -4,15 +4,28 @@
 }
 
 .message-item-header {
+  @apply flex flex-col gap-0.5;
+}
+
+.message-item-header-row {
+  @apply w-full;
+}
+
+.message-item-header-row--top {
   @apply flex justify-between items-start gap-2.5;
 }
 
+.message-item-header-row--bottom {
+  @apply flex items-start;
+}
+
 .message-speaker {
   @apply flex flex-col gap-0.5 text-xs;
 }
 
 .message-speaker-label {
   font-weight: var(--font-weight-semibold);
+  font-size: var(--font-size-sm);
 }
 
 .message-speaker-label[data-role="user"] {
@@ -298,11 +311,25 @@
   gap: 0;
 }
 
+.message-reasoning-header {
+  display: flex;
+  align-items: stretch;
+  justify-content: space-between;
+  gap: 0.5rem;
+  transition: background-color 0.2s ease, box-shadow 0.2s ease;
+}
+
+.message-reasoning-header:hover {
+  background-color: var(--surface-hover);
+}
+
 .message-reasoning-toggle {
-  width: 100%;
+  flex: 1 1 auto;
+  min-width: 0;
+  width: auto;
   display: flex;
   align-items: center;
-  justify-content: space-between;
+  justify-content: flex-start;
   gap: 0.65rem;
   background: none;
   border: none;
@@ -314,13 +341,20 @@
   transition: background-color 0.2s ease, box-shadow 0.2s ease;
 }
 
+.message-reasoning-actions {
+  display: inline-flex;
+  align-items: center;
+  gap: 0.5rem;
+  padding: 0.25rem 0.6rem 0.25rem 0;
+}
+
 .message-reasoning-toggle:hover {
-  background-color: var(--surface-hover);
+  background-color: transparent;
 }
 
 .message-reasoning-toggle:focus-visible {
   outline: none;
-  box-shadow: 0 0 0 1px var(--accent-primary);
+  box-shadow: 0 0 0 1px var(--border-base);
 }
 
 .message-reasoning-label {

packages/ui/src/styles/panels.css

@@ -3,6 +3,7 @@
 @import "./panels/modal.css";
 @import "./panels/panel-shell.css";
 @import "./panels/session-layout.css";
+@import "./panels/right-panel.css";
 
 
 .tab-bar-instance {
@@ -32,11 +33,13 @@
 .tab-active {
   background-color: var(--tab-active-bg);
   color: var(--tab-active-text);
+  border-bottom: 2px solid var(--accent-primary);
 }
 
 .tab-inactive {
   background-color: var(--tab-inactive-bg);
   color: var(--tab-inactive-text);
+  border-bottom: 2px solid var(--tab-active-bg);
 }
 
 .tab-inactive:hover {

packages/ui/src/styles/panels/right-panel.css

@@ -0,0 +1,485 @@
+/* Right Panel / Drawer specific styles */
+
+/* Right panel tab bar - browser-style tabs */
+.right-panel-tab-bar {
+  background-color: var(--surface-secondary);
+  border-bottom: 1px solid var(--border-base);
+  position: relative;
+}
+
+.right-panel-tab-bar::after {
+  content: '';
+  position: absolute;
+  bottom: -1px;
+  left: 0;
+  right: 0;
+  height: 1px;
+  background-color: var(--border-base);
+  z-index: 0;
+}
+
+.right-panel-tab-bar .tab-container {
+  @apply flex items-center justify-between gap-1 px-2 pt-2 pb-0;
+}
+
+/* Keep the shortcuts (close/pin) fixed; only the tabs should scroll. */
+.right-panel-tab-bar .tab-scroll {
+  @apply flex-1;
+  width: auto;
+}
+
+/* Shortcuts on the left side - match left drawer icon colors */
+.tab-strip-shortcuts {
+  @apply flex items-center gap-1 flex-shrink-0;
+  color: var(--text-primary);
+}
+
+/* Browser-style tabs - using INSTANCE tab color scheme */
+.right-panel-tab {
+  @apply inline-flex items-center gap-2 px-4 py-2 text-xs font-medium transition-all duration-150 relative;
+  font-family: var(--font-family-sans);
+  outline: none;
+  border: 1px solid transparent;
+  border-bottom: none;
+  border-radius: 8px 8px 0 0;
+  margin-right: 2px;
+  z-index: 1;
+}
+
+.right-panel-tab:focus-visible {
+  @apply ring-2 ring-offset-1;
+  ring-color: var(--accent-primary);
+  ring-offset-color: var(--surface-secondary);
+}
+
+.right-panel-tab-active {
+  background-color: var(--tab-active-bg);
+  border-color: transparent;
+  border-bottom: 2px solid var(--accent-primary);
+  color: var(--tab-active-text);
+  z-index: 2;
+}
+
+.right-panel-tab-inactive {
+  background-color: var(--tab-inactive-bg);
+  color: var(--tab-inactive-text);
+  border-color: transparent;
+  border-bottom: 2px solid var(--tab-active-bg);
+}
+
+.right-panel-tab-inactive:hover {
+  background-color: var(--tab-inactive-hover-bg);
+  color: var(--text-secondary);
+  border-color: var(--border-base);
+  border-bottom-color: transparent;
+}
+
+/* Files tab layout */
+.files-tab-container {
+  @apply flex flex-col h-full min-h-0;
+}
+
+/* Split view (file list + viewer) */
+.files-split {
+  display: grid;
+  grid-template-columns: var(--files-pane-width, 320px) 10px minmax(0, 1fr);
+  min-height: 0;
+  flex: 1 1 auto;
+}
+
+.file-split-handle {
+  cursor: col-resize;
+  background-color: transparent;
+  border-left: 1px solid var(--border-base);
+  border-right: 1px solid var(--border-base);
+  user-select: none;
+  touch-action: none;
+}
+
+.file-split-handle:hover {
+  background-color: var(--surface-hover);
+}
+
+.files-tab-header {
+  @apply flex items-center justify-between gap-2 px-3 py-2 border-b;
+  border-color: var(--border-base);
+}
+
+.files-tab-header-row {
+  @apply flex items-center gap-2 w-full min-w-0;
+}
+
+.files-toggle-button {
+  @apply text-[11px] px-2 py-1 border border-base transition-colors;
+  background-color: var(--surface-base);
+  color: var(--text-secondary);
+}
+
+.files-toggle-button:hover {
+  background-color: var(--surface-hover);
+  color: var(--text-primary);
+}
+
+.files-header-icon-button {
+  @apply inline-flex items-center justify-center shrink-0 w-7 h-7 border border-base transition-colors;
+  background-color: var(--surface-base);
+  color: var(--text-secondary);
+}
+
+.files-header-icon-button:hover {
+  background-color: var(--surface-hover);
+  color: var(--text-primary);
+}
+
+.files-header-icon-button:disabled {
+  opacity: 0.55;
+  cursor: default;
+}
+
+.files-tab-body {
+  @apply flex flex-col flex-1 min-h-0;
+  position: relative;
+  isolation: isolate;
+}
+
+.file-list-overlay {
+  position: absolute;
+  inset: 0;
+  display: flex;
+  flex-direction: column;
+  background-color: var(--surface-secondary);
+  border-left: 1px solid var(--border-base);
+  /* Monaco uses layered positioned elements; keep overlay well above it. */
+  z-index: 200;
+}
+
+/* Phone overlay: header removed; use main header toggle. */
+
+.files-tab-stats {
+  @apply flex items-center gap-3 text-[11px];
+  color: var(--text-muted);
+}
+
+.files-tab-selected-path {
+  @apply text-xs font-mono min-w-0 flex-1 overflow-hidden whitespace-nowrap;
+  color: var(--text-primary);
+  text-overflow: ellipsis;
+  /* Truncate from the start; keep filename visible. */
+  direction: rtl;
+  text-align: left;
+  unicode-bidi: isolate;
+}
+
+.files-tab-selected-path .file-path-text {
+  direction: ltr;
+  unicode-bidi: isolate;
+}
+
+.files-tab-stat {
+  @apply flex items-center gap-1.5;
+}
+
+.files-tab-stat-value {
+  @apply font-semibold;
+}
+
+.files-tab-stat-additions {
+  color: var(--session-status-idle-fg);
+}
+
+.files-tab-stat-deletions {
+  color: var(--session-status-working-fg);
+}
+
+/* File list panel */
+.file-list-panel {
+  @apply flex flex-col min-h-0;
+  background-color: transparent;
+}
+
+.file-list-header {
+  @apply flex items-center justify-between gap-2 px-3 py-2 border-b;
+  border-color: var(--border-base);
+  background-color: transparent;
+}
+
+.file-list-title {
+  @apply text-[11px] font-semibold uppercase tracking-wide;
+  color: var(--text-muted);
+}
+
+.file-list-count {
+  @apply text-[10px] px-1.5 py-0.5 rounded-full;
+  background-color: var(--surface-base);
+  color: var(--text-muted);
+  border: 1px solid var(--border-base);
+}
+
+.file-list-scroll {
+  @apply flex-1 overflow-y-auto min-h-0;
+}
+
+.file-list-item {
+  @apply px-3 py-2.5 border-b cursor-pointer transition-all duration-150;
+  border-color: var(--border-base);
+  background-color: transparent;
+}
+
+.file-list-item:last-child {
+  @apply border-b-0;
+}
+
+.file-list-item:hover {
+  background-color: var(--surface-hover);
+}
+
+.file-list-item-active {
+  background-color: var(--surface-base);
+  box-shadow: inset 0 0 0 1px var(--accent-primary);
+}
+
+.file-list-item-content {
+  @apply flex items-center justify-between gap-3;
+}
+
+.file-list-item-path {
+  @apply text-xs font-mono min-w-0 flex-1 overflow-hidden whitespace-nowrap;
+  color: var(--text-primary);
+  text-overflow: ellipsis;
+  /* Truncate from the start; keep filename visible. */
+  direction: rtl;
+  text-align: left;
+  unicode-bidi: isolate;
+}
+
+.file-list-item-path .file-path-text {
+  direction: ltr;
+  unicode-bidi: isolate;
+}
+
+.file-list-item-stats {
+  @apply flex items-center gap-2 text-[11px] flex-shrink-0;
+}
+
+.file-list-item-additions {
+  color: var(--session-status-idle-fg);
+}
+
+.file-list-item-deletions {
+  color: var(--session-status-working-fg);
+}
+
+/* File viewer panel */
+.file-viewer-panel {
+  @apply flex flex-col min-h-0;
+  background-color: transparent;
+}
+
+.file-viewer-header {
+  @apply flex items-center gap-2 px-3 py-2 border-b;
+  border-color: var(--border-base);
+  background-color: transparent;
+}
+
+.file-viewer-toolbar {
+  @apply ml-auto flex items-center gap-1;
+}
+
+.file-viewer-toolbar-button {
+  @apply text-[11px] px-2 py-1 rounded border border-base transition-colors;
+  background-color: var(--surface-base);
+  color: var(--text-secondary);
+}
+
+.file-viewer-toolbar-button:hover {
+  background-color: var(--surface-hover);
+  color: var(--text-primary);
+}
+
+.file-viewer-toolbar-button.active {
+  color: var(--text-primary);
+  box-shadow: inset 0 0 0 1px var(--accent-primary);
+}
+
+.file-viewer-title {
+  @apply text-[11px] font-semibold uppercase tracking-wide;
+  color: var(--text-muted);
+}
+
+.file-viewer-content {
+  @apply flex-1 p-4 overflow-auto min-h-0;
+}
+
+.file-viewer-content--monaco {
+  @apply flex-1 overflow-hidden min-h-0;
+  padding: 0;
+}
+
+.monaco-viewer {
+  width: 100%;
+  height: 100%;
+}
+
+.file-viewer-empty {
+  @apply flex flex-col items-center justify-center h-full gap-3 text-center;
+  color: var(--text-muted);
+}
+
+.file-viewer-empty-icon {
+  @apply w-8 h-8 opacity-40;
+  color: var(--text-muted);
+}
+
+.file-viewer-empty-text {
+  @apply text-xs;
+}
+
+.file-viewer-placeholder {
+  @apply text-xs leading-relaxed;
+  color: var(--text-muted);
+}
+
+.file-viewer-selected-file {
+  @apply flex flex-col gap-2;
+}
+
+.file-viewer-file-name {
+  @apply text-xs font-mono px-2 py-1.5 rounded border;
+  background-color: var(--surface-base);
+  border-color: var(--border-base);
+  color: var(--text-primary);
+  word-break: break-all;
+}
+
+/* Mobile file selector */
+.mobile-file-selector {
+  @apply rounded-lg border flex flex-col gap-3 p-3;
+  background-color: var(--surface-secondary);
+  border-color: var(--border-base);
+}
+
+.mobile-file-selector-label {
+  @apply text-[11px] font-semibold uppercase tracking-wide;
+  color: var(--text-muted);
+}
+
+.mobile-file-selector-trigger {
+  @apply w-full;
+}
+
+.mobile-file-viewer {
+  @apply rounded-lg border flex flex-col min-h-[220px];
+  background-color: var(--surface-secondary);
+  border-color: var(--border-base);
+}
+
+/* Status tab layout */
+.status-tab-container {
+  @apply flex flex-col h-full min-h-0;
+}
+
+.status-tab-context-panel {
+  @apply border-b;
+  border-color: var(--border-base);
+  background-color: var(--surface-secondary);
+}
+
+/* Accordion improvements for right panel */
+.right-panel-accordion {
+  @apply flex flex-col;
+}
+
+.right-panel-accordion-item {
+  @apply border-b last:border-b-0;
+  border-color: var(--border-base);
+  background-color: var(--surface-secondary);
+}
+
+.right-panel-accordion-trigger {
+  @apply w-full flex items-center justify-between gap-3 px-3 py-2.5 text-[11px] font-semibold uppercase tracking-wide transition-colors duration-150;
+  color: var(--text-secondary);
+  background-color: transparent;
+}
+
+.right-panel-accordion-trigger:hover {
+  background-color: var(--surface-hover);
+  color: var(--text-primary);
+}
+
+.right-panel-accordion-chevron {
+  @apply h-4 w-4 transition-transform duration-200;
+  color: var(--text-muted);
+}
+
+.right-panel-accordion-chevron-expanded {
+  transform: rotate(180deg);
+}
+
+.right-panel-accordion-content {
+  @apply w-full px-3 pb-3 text-sm;
+  color: var(--text-primary);
+  min-height: 0;
+}
+
+.right-panel-accordion-content [data-accordion-content] {
+  min-height: 0;
+}
+
+/* Background process cards in status panel */
+.status-process-card {
+  @apply rounded-lg border flex flex-col gap-2 p-3 transition-all duration-150;
+  background-color: var(--surface-base);
+  border-color: var(--border-base);
+}
+
+.status-process-card:hover {
+  border-color: var(--border-strong);
+  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.05);
+}
+
+.status-process-header {
+  @apply flex flex-col gap-1;
+}
+
+.status-process-title {
+  @apply text-xs font-semibold;
+  color: var(--text-primary);
+}
+
+.status-process-meta {
+  @apply flex flex-wrap gap-2 text-[11px];
+  color: var(--text-muted);
+}
+
+.status-process-actions {
+  @apply grid grid-cols-3 gap-2;
+}
+
+/* Empty states */
+.right-panel-empty {
+  @apply flex flex-col items-center justify-center text-center gap-2;
+  color: var(--text-muted);
+}
+
+.right-panel-empty--left {
+  @apply items-start justify-start text-left w-full;
+}
+
+.right-panel-empty-text {
+  @apply text-xs;
+}
+
+/* Dark mode adjustments */
+[data-theme="dark"] .right-panel-tab-active {
+  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.2);
+}
+
+[data-theme="dark"] .file-list-item-active {
+  box-shadow: inset 0 0 0 1px var(--accent-primary), 0 0 0 1px var(--surface-secondary);
+}
+
+@media (prefers-color-scheme: dark) {
+  :root:not([data-theme]) .right-panel-tab-active {
+    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.2);
+  }
+}

packages/ui/src/styles/panels/tabs.css

@@ -58,11 +58,13 @@
 .tab-active {
   background-color: var(--tab-active-bg);
   color: var(--tab-active-text);
+  border-bottom: 2px solid var(--accent-primary);
 }
 
 .tab-inactive {
   background-color: var(--tab-inactive-bg);
   color: var(--tab-inactive-text);
+  border-bottom: 2px solid var(--tab-active-bg);
 }
 
 .tab-inactive:hover {

packages/ui/src/styles/utilities.css

@@ -153,6 +153,16 @@
   @apply opacity-50;
 }
 
+/* Truncate from the start (keeps end visible; good for paths) */
+.truncate-start {
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+  direction: rtl;
+  text-align: left;
+  unicode-bidi: plaintext;
+}
+
 /* Prevent iOS Safari auto-zoom on text input focus */
 @media (pointer: coarse) {
   input[type="text"],

packages/ui/src/types/diff.d.ts

@@ -0,0 +1,5 @@
+declare module "diff" {
+  // Minimal types for the jsdiff package used in git-change reconstruction.
+  export function parsePatch(input: string, options?: any): any[]
+  export function applyPatch(source: string, patch: any, options?: any): string | false
+}

packages/ui/src/types/session.ts

@@ -5,6 +5,7 @@ import type {
   Model as SDKModel,
 } from "@opencode-ai/sdk"
 import type { SessionStatus as SDKSessionStatus } from "@opencode-ai/sdk/v2/client"
+import type { FileDiff } from "@opencode-ai/sdk/v2/client"
 
 // Export SDK types for external use
 export type { 
@@ -39,6 +40,7 @@ export interface Session
   pendingPermission?: boolean // Indicates if session is waiting on user permission
   pendingQuestion?: boolean // Indicates if session is waiting on user input
   status: SessionStatus // Single source of truth for session status
+  diff?: FileDiff[] // Session-level file diffs (hydrated via session.diff)
 }
 
 // Adapter function to convert SDK Session to client Session

packages/ui/vite.config.ts

@@ -3,6 +3,7 @@ import { defineConfig } from "vite"
 import solid from "vite-plugin-solid"
 import { VitePWA } from "vite-plugin-pwa"
 import { resolve } from "path"
+import { copyMonacoPublicAssets } from "./scripts/monaco-public-assets.js"
 
 const uiPackageJson = JSON.parse(fs.readFileSync(resolve(__dirname, "package.json"), "utf-8")) as { version?: string }
 const uiVersion = uiPackageJson.version ?? "0.0.0"
@@ -11,6 +12,31 @@ export default defineConfig({
   root: "./src/renderer",
   plugins: [
     solid(),
+    {
+      name: "prepare-monaco-public-assets",
+      // Ensure Monaco's AMD assets exist in `root/public` for both dev server and builds.
+      // These files are gitignored and generated on demand.
+      configureServer(server) {
+        copyMonacoPublicAssets({
+          uiRendererRoot: resolve(__dirname, "src/renderer"),
+          warn: (msg) => server.config.logger.warn(msg),
+          sourceRoots: [
+            resolve(__dirname, "../../node_modules/monaco-editor/min/vs"),
+            resolve(__dirname, "node_modules/monaco-editor/min/vs"),
+          ],
+        })
+      },
+      buildStart() {
+        copyMonacoPublicAssets({
+          uiRendererRoot: resolve(__dirname, "src/renderer"),
+          warn: (msg) => this.warn(msg),
+          sourceRoots: [
+            resolve(__dirname, "../../node_modules/monaco-editor/min/vs"),
+            resolve(__dirname, "node_modules/monaco-editor/min/vs"),
+          ],
+        })
+      },
+    },
     {
       name: "emit-ui-version",
       generateBundle() {
@@ -51,14 +77,23 @@ export default defineConfig({
         theme_color: "#1a1a1a",
       },
       workbox: {
-        // Preserve server-side auth redirects (e.g., /login) instead of serving cached index.html.
-        navigateFallback: null,
-        // Only precache static assets (avoid caching HTML documents / routes).
-        globPatterns: ["**/*.{js,css,png,jpg,jpeg,svg,webp,ico,woff,woff2,ttf,eot,json,webmanifest}"],
-        globIgnores: ["**/*.html"],
-        // Only cache static UI assets; never cache API traffic.
-        runtimeCaching: [
-          {
+         // Workbox defaults to 2 MiB; our main bundle can slightly exceed that.
+         // This is a build-time limit for the precache manifest, not a hard runtime cap.
+         maximumFileSizeToCacheInBytes: 3 * 1024 * 1024,
+          // Preserve server-side auth redirects (e.g., /login) instead of serving cached index.html.
+          navigateFallback: null,
+          // Only precache static assets (avoid caching HTML documents / routes).
+          globPatterns: ["**/*.{js,css,png,jpg,jpeg,svg,webp,ico,woff,woff2,ttf,eot,json,webmanifest}"],
+         // Monaco assets can be large; cache them at runtime instead.
+         globIgnores: [
+           "**/*.html",
+           "**/assets/*worker-*.js",
+           "**/assets/editor.api-*.js",
+           "**/monaco/vs/**/*",
+         ],
+         // Only cache static UI assets; never cache API traffic.
+         runtimeCaching: [
+           {
             urlPattern: ({ url, request }) => {
               if (url.pathname.startsWith("/api/")) return false
               if (request.destination === "document") return false