diff --git a/packages/cli/src/config/binaries.ts b/packages/cli/src/config/binaries.ts
index e4981537..7b3d4f52 100644
--- a/packages/cli/src/config/binaries.ts
+++ b/packages/cli/src/config/binaries.ts
@@ -6,7 +6,7 @@ import {
 } from "../api-types"
 import { ConfigStore } from "./store"
 import { EventBus } from "../events/bus"
-import type { ConfigFileUpdate } from "./schema"
+import type { ConfigFile } from "./schema"
 import { Logger } from "../logger"
 
 export class BinaryRegistry {
@@ -39,17 +39,15 @@ export class BinaryRegistry {
     }
 
     const config = this.configStore.get()
-    const deduped = config.opencodeBinaries.filter((binary) => binary.path !== request.path)
-
-    const update: ConfigFileUpdate = {
-      opencodeBinaries: [entry, ...deduped],
-    }
+    const nextConfig = this.cloneConfig(config)
+    const deduped = nextConfig.opencodeBinaries.filter((binary) => binary.path !== request.path)
+    nextConfig.opencodeBinaries = [entry, ...deduped]
 
     if (request.makeDefault) {
-      update.preferences = { lastUsedBinary: request.path }
+      nextConfig.preferences.lastUsedBinary = request.path
     }
 
-    this.configStore.update(update)
+    this.configStore.replace(nextConfig)
     const record = this.getById(request.path)
     this.emitChange()
     return record
@@ -58,19 +56,16 @@ export class BinaryRegistry {
   update(id: string, updates: BinaryUpdateRequest): BinaryRecord {
     this.logger.debug({ id }, "Updating OpenCode binary")
     const config = this.configStore.get()
-    const updatedEntries = config.opencodeBinaries.map((binary) =>
+    const nextConfig = this.cloneConfig(config)
+    nextConfig.opencodeBinaries = nextConfig.opencodeBinaries.map((binary) =>
       binary.path === id ? { ...binary, label: updates.label ?? binary.label } : binary,
     )
 
-    const update: ConfigFileUpdate = {
-      opencodeBinaries: updatedEntries,
-    }
-
     if (updates.makeDefault) {
-      update.preferences = { lastUsedBinary: id }
+      nextConfig.preferences.lastUsedBinary = id
     }
 
-    this.configStore.update(update)
+    this.configStore.replace(nextConfig)
     const record = this.getById(id)
     this.emitChange()
     return record
@@ -79,14 +74,15 @@ export class BinaryRegistry {
   remove(id: string) {
     this.logger.debug({ id }, "Removing OpenCode binary")
     const config = this.configStore.get()
-    const remaining = config.opencodeBinaries.filter((binary) => binary.path !== id)
-    const update: ConfigFileUpdate = { opencodeBinaries: remaining }
+    const nextConfig = this.cloneConfig(config)
+    const remaining = nextConfig.opencodeBinaries.filter((binary) => binary.path !== id)
+    nextConfig.opencodeBinaries = remaining
 
-    if (config.preferences.lastUsedBinary === id) {
-      update.preferences = { lastUsedBinary: remaining[0]?.path }
+    if (nextConfig.preferences.lastUsedBinary === id) {
+      nextConfig.preferences.lastUsedBinary = remaining[0]?.path
     }
 
-    this.configStore.update(update)
+    this.configStore.replace(nextConfig)
     this.emitChange()
   }
 
@@ -100,7 +96,12 @@ export class BinaryRegistry {
     })
   }
 
+  private cloneConfig(config: ConfigFile): ConfigFile {
+    return JSON.parse(JSON.stringify(config)) as ConfigFile
+  }
+
   private mapRecords(): BinaryRecord[] {
+
     const config = this.configStore.get()
     const configuredBinaries = config.opencodeBinaries.map<BinaryRecord>((binary) => ({
       id: binary.path,
diff --git a/packages/cli/src/config/schema.ts b/packages/cli/src/config/schema.ts
index 0bd6aa88..2ebda652 100644
--- a/packages/cli/src/config/schema.ts
+++ b/packages/cli/src/config/schema.ts
@@ -19,17 +19,6 @@ const PreferencesSchema = z.object({
   diagnosticsExpansion: z.enum(["expanded", "collapsed"]).default("expanded"),
 })
 
-const PreferencesUpdateSchema = z.object({
-  showThinkingBlocks: z.boolean().optional(),
-  lastUsedBinary: z.string().optional(),
-  environmentVariables: z.record(z.string()).optional(),
-  modelRecents: z.array(ModelPreferenceSchema).optional(),
-  agentModelSelections: AgentModelSelectionsSchema.optional(),
-  diffViewMode: z.enum(["split", "unified"]).optional(),
-  toolOutputExpansion: z.enum(["expanded", "collapsed"]).optional(),
-  diagnosticsExpansion: z.enum(["expanded", "collapsed"]).optional(),
-})
-
 const RecentFolderSchema = z.object({
   path: z.string(),
   lastAccessed: z.number().nonnegative(),
@@ -49,13 +38,6 @@ const ConfigFileSchema = z.object({
   theme: z.enum(["light", "dark", "system"]).optional(),
 })
 
-const ConfigFileUpdateSchema = z.object({
-  preferences: PreferencesUpdateSchema.optional(),
-  recentFolders: z.array(RecentFolderSchema).optional(),
-  opencodeBinaries: z.array(OpenCodeBinarySchema).optional(),
-  theme: z.enum(["light", "dark", "system"]).optional(),
-})
-
 const DEFAULT_CONFIG = ConfigFileSchema.parse({})
 
 export {
@@ -66,7 +48,6 @@ export {
   RecentFolderSchema,
   OpenCodeBinarySchema,
   ConfigFileSchema,
-  ConfigFileUpdateSchema,
   DEFAULT_CONFIG,
 }
 
@@ -77,4 +58,3 @@ export type Preferences = z.infer<typeof PreferencesSchema>
 export type RecentFolder = z.infer<typeof RecentFolderSchema>
 export type OpenCodeBinary = z.infer<typeof OpenCodeBinarySchema>
 export type ConfigFile = z.infer<typeof ConfigFileSchema>
-export type ConfigFileUpdate = z.infer<typeof ConfigFileUpdateSchema>
diff --git a/packages/cli/src/config/store.ts b/packages/cli/src/config/store.ts
index dbfb1e88..7bfd8d2c 100644
--- a/packages/cli/src/config/store.ts
+++ b/packages/cli/src/config/store.ts
@@ -2,14 +2,7 @@ import fs from "fs"
 import path from "path"
 import { EventBus } from "../events/bus"
 import { Logger } from "../logger"
-import {
-  AgentModelSelections,
-  ConfigFile,
-  ConfigFileUpdate,
-  ConfigFileSchema,
-  ConfigFileUpdateSchema,
-  DEFAULT_CONFIG,
-} from "./schema"
+import { ConfigFile, ConfigFileSchema, DEFAULT_CONFIG } from "./schema"
 
 export class ConfigStore {
   private cache: ConfigFile = DEFAULT_CONFIG
@@ -50,54 +43,18 @@ export class ConfigStore {
     return this.load()
   }
 
-  update(partial: ConfigFile | ConfigFileUpdate) {
-    const safePartial =
-      "recentFolders" in partial && "opencodeBinaries" in partial
-        ? ConfigFileSchema.parse(partial)
-        : ConfigFileUpdateSchema.parse(partial ?? {})
-    const merged = this.mergeConfig(this.load(), safePartial)
-    this.cache = ConfigFileSchema.parse(merged)
+  replace(config: ConfigFile) {
+    const validated = ConfigFileSchema.parse(config)
+    this.commit(validated)
+  }
+
+  private commit(next: ConfigFile) {
+    this.cache = next
+    this.loaded = true
     this.persist()
     this.eventBus?.publish({ type: "config.appChanged", config: this.cache })
-    this.logger.debug("Config updated")
-  }
-
-  private mergeConfig(current: ConfigFile, partial: ConfigFile | ConfigFileUpdate): ConfigFile {
-    const mergedPreferences = {
-      ...current.preferences,
-      ...partial.preferences,
-      environmentVariables: {
-        ...current.preferences.environmentVariables,
-        ...(partial.preferences?.environmentVariables ?? {}),
-      },
-      agentModelSelections: this.mergeAgentSelections(
-        current.preferences.agentModelSelections,
-        partial.preferences?.agentModelSelections,
-      ),
-    }
-
-    return {
-      ...current,
-      ...partial,
-      preferences: mergedPreferences,
-      recentFolders: partial.recentFolders ?? current.recentFolders,
-      opencodeBinaries: partial.opencodeBinaries ?? current.opencodeBinaries,
-    }
-  }
-
-  private mergeAgentSelections(base: AgentModelSelections, update?: AgentModelSelections) {
-    if (!update) {
-      return base
-    }
-
-    const result: AgentModelSelections = { ...base }
-    for (const [instanceId, agentMap] of Object.entries(update)) {
-      result[instanceId] = {
-        ...(base[instanceId] ?? {}),
-        ...agentMap,
-      }
-    }
-    return result
+    this.logger.info("Config updated")
+    this.logger.debug({ config: this.cache }, "Config payload")
   }
 
   private persist() {
diff --git a/packages/cli/src/server/routes/config.ts b/packages/cli/src/server/routes/config.ts
index dc81ce27..fed364af 100644
--- a/packages/cli/src/server/routes/config.ts
+++ b/packages/cli/src/server/routes/config.ts
@@ -2,7 +2,7 @@ import { FastifyInstance } from "fastify"
 import { z } from "zod"
 import { ConfigStore } from "../../config/store"
 import { BinaryRegistry } from "../../config/binaries"
-import { ConfigFileSchema, ConfigFileUpdateSchema } from "../../config/schema"
+import { ConfigFileSchema } from "../../config/schema"
 
 interface RouteDeps {
   configStore: ConfigStore
@@ -29,13 +29,7 @@ export function registerConfigRoutes(app: FastifyInstance, deps: RouteDeps) {
 
   app.put("/api/config/app", async (request) => {
     const body = ConfigFileSchema.parse(request.body ?? {})
-    deps.configStore.update(body)
-    return deps.configStore.get()
-  })
-
-  app.patch("/api/config/app", async (request) => {
-    const body = ConfigFileUpdateSchema.parse(request.body ?? {})
-    deps.configStore.update(body)
+    deps.configStore.replace(body)
     return deps.configStore.get()
   })
 
diff --git a/packages/ui/src/App.tsx b/packages/ui/src/App.tsx
index 48780cc4..ea314e15 100644
--- a/packages/ui/src/App.tsx
+++ b/packages/ui/src/App.tsx
@@ -43,7 +43,7 @@ const App: Component = () => {
   const { isDark } = useTheme()
   const {
     preferences,
-    addRecentFolder,
+    recordWorkspaceLaunch,
     toggleShowThinkingBlocks,
     setDiffViewMode,
     setToolOutputExpansion,
@@ -92,7 +92,7 @@ const App: Component = () => {
     setIsSelectingFolder(true)
     const selectedBinary = binaryPath || preferences().lastUsedBinary || "opencode"
     try {
-      addRecentFolder(folderPath)
+      recordWorkspaceLaunch(folderPath, selectedBinary)
       clearLaunchError()
       const instanceId = await createInstance(folderPath, selectedBinary)
       setHasInstances(true)
diff --git a/packages/ui/src/components/folder-selection-view.tsx b/packages/ui/src/components/folder-selection-view.tsx
index cf1e199b..32a092b3 100644
--- a/packages/ui/src/components/folder-selection-view.tsx
+++ b/packages/ui/src/components/folder-selection-view.tsx
@@ -16,7 +16,7 @@ interface FolderSelectionViewProps {
 }
 
 const FolderSelectionView: Component<FolderSelectionViewProps> = (props) => {
-  const { recentFolders, removeRecentFolder, preferences, updateLastUsedBinary } = useConfig()
+  const { recentFolders, removeRecentFolder, preferences } = useConfig()
   const [selectedIndex, setSelectedIndex] = createSignal(0)
   const [focusMode, setFocusMode] = createSignal<"recent" | "new" | null>("recent")
   const [selectedBinary, setSelectedBinary] = createSignal(preferences().lastUsedBinary || "opencode")
@@ -169,7 +169,6 @@ const FolderSelectionView: Component<FolderSelectionViewProps> = (props) => {
 
   function handleFolderSelect(path: string) {
     if (isLoading()) return
-    updateLastUsedBinary(selectedBinary())
     props.onSelectFolder(path, selectedBinary())
   }
  
diff --git a/packages/ui/src/lib/api-client.ts b/packages/ui/src/lib/api-client.ts
index 62fdee54..eb1becfa 100644
--- a/packages/ui/src/lib/api-client.ts
+++ b/packages/ui/src/lib/api-client.ts
@@ -1,6 +1,5 @@
 import type {
   AppConfig,
-  AppConfigUpdateRequest,
   BinaryCreateRequest,
   BinaryListResponse,
   BinaryUpdateRequest,
@@ -115,12 +114,6 @@ export const cliApi = {
       body: JSON.stringify(payload),
     })
   },
-  patchConfig(payload: AppConfigUpdateRequest): Promise<AppConfig> {
-    return request<AppConfig>("/api/config/app", {
-      method: "PATCH",
-      body: JSON.stringify(payload),
-    })
-  },
   listBinaries(): Promise<BinaryListResponse> {
     return request<BinaryListResponse>("/api/config/binaries")
   },
diff --git a/packages/ui/src/lib/storage.ts b/packages/ui/src/lib/storage.ts
index b0568674..72d4603b 100644
--- a/packages/ui/src/lib/storage.ts
+++ b/packages/ui/src/lib/storage.ts
@@ -4,21 +4,58 @@ import { cliEvents } from "./cli-events"
 
 export type ConfigData = AppConfig
 
+function isDeepEqual(a: unknown, b: unknown): boolean {
+  if (a === b) {
+    return true
+  }
+
+  if (typeof a === "object" && a !== null && typeof b === "object" && b !== null) {
+    try {
+      return JSON.stringify(a) === JSON.stringify(b)
+    } catch (error) {
+      console.warn("Failed to compare config objects", error)
+    }
+  }
+
+  return false
+}
 
 export class ServerStorage {
-  private configChangeListeners: Set<() => void> = new Set()
+  private configChangeListeners: Set<(config: ConfigData) => void> = new Set()
+  private configCache: ConfigData | null = null
+  private loadPromise: Promise<ConfigData> | null = null
 
   constructor() {
-    cliEvents.on("config.appChanged", () => this.notifyConfigChanged())
+    cliEvents.on("config.appChanged", (event) => {
+      if (event.type !== "config.appChanged") return
+      this.setConfigCache(event.config)
+    })
   }
 
   async loadConfig(): Promise<ConfigData> {
-    const config = await cliApi.fetchConfig()
-    return config
+    if (this.configCache) {
+      return this.configCache
+    }
+
+    if (!this.loadPromise) {
+      this.loadPromise = cliApi
+        .fetchConfig()
+        .then((config) => {
+          this.setConfigCache(config)
+          return config
+        })
+        .finally(() => {
+          this.loadPromise = null
+        })
+    }
+
+    return this.loadPromise
   }
 
-  async saveConfig(config: ConfigData): Promise<void> {
-    await cliApi.updateConfig(config)
+  async updateConfig(next: ConfigData): Promise<ConfigData> {
+    const nextConfig = await cliApi.updateConfig(next)
+    this.setConfigCache(nextConfig)
+    return nextConfig
   }
 
   async loadInstanceData(instanceId: string): Promise<InstanceData> {
@@ -33,14 +70,26 @@ export class ServerStorage {
     await cliApi.deleteInstanceData(instanceId)
   }
 
-  onConfigChanged(listener: () => void): () => void {
+  onConfigChanged(listener: (config: ConfigData) => void): () => void {
     this.configChangeListeners.add(listener)
+    if (this.configCache) {
+      listener(this.configCache)
+    }
     return () => this.configChangeListeners.delete(listener)
   }
 
-  private notifyConfigChanged() {
+  private setConfigCache(config: ConfigData) {
+    if (this.configCache && isDeepEqual(this.configCache, config)) {
+      this.configCache = config
+      return
+    }
+    this.configCache = config
+    this.notifyConfigChanged(config)
+  }
+
+  private notifyConfigChanged(config: ConfigData) {
     for (const listener of this.configChangeListeners) {
-      listener()
+      listener(config)
     }
   }
 }
diff --git a/packages/ui/src/lib/theme.tsx b/packages/ui/src/lib/theme.tsx
index ac2c0eda..96b59551 100644
--- a/packages/ui/src/lib/theme.tsx
+++ b/packages/ui/src/lib/theme.tsx
@@ -1,5 +1,5 @@
-import { createContext, createSignal, useContext, onMount, createEffect, type JSX } from "solid-js"
-import { storage, type ConfigData } from "./storage"
+import { createContext, createEffect, createSignal, onMount, useContext, type JSX } from "solid-js"
+import { useConfig } from "../stores/preferences"
 
 interface ThemeContextValue {
   isDark: () => boolean
@@ -20,64 +20,30 @@ function applyTheme(dark: boolean) {
 
 export function ThemeProvider(props: { children: JSX.Element }) {
   const systemPrefersDark = window.matchMedia("(prefers-color-scheme: dark)")
-  const [isDark, setIsDarkSignal] = createSignal(true) //systemPrefersDark.matches)
-  let themePreference: "system" | "dark" | "light" = "dark"
+  const { themePreference, setThemePreference } = useConfig()
+  const [isDark, setIsDarkSignal] = createSignal(false)
 
-  applyTheme(true) //systemPrefersDark.matches)
-
-  async function loadTheme() {
-    try {
-      const config = await storage.loadConfig()
-      const savedTheme = config.theme
-      let themeDark: boolean
-
-      if (savedTheme === "system") {
-        themePreference = "system"
-        themeDark = systemPrefersDark.matches
-      } else if (savedTheme === "dark") {
-        themePreference = "dark"
-        themeDark = true
-      } else if (savedTheme === "light") {
-        themePreference = "light"
-        themeDark = false
-      } else {
-        themePreference = "dark"
-        themeDark = true
-      }
-
-      setIsDarkSignal(themeDark)
-      applyTheme(themeDark)
-    } catch (error) {
-      console.warn("Failed to load theme from config:", error)
-      themePreference = "dark"
-      const themeDark = true
-      setIsDarkSignal(themeDark)
-      applyTheme(themeDark)
+  const resolveDarkTheme = () => {
+    const preference = themePreference()
+    if (preference === "system") {
+      return systemPrefersDark.matches
     }
+    return preference === "dark"
   }
 
-  async function saveTheme(dark: boolean) {
-    try {
-      const config = await storage.loadConfig()
-      const nextPreference = dark ? "dark" : "light"
-      config.theme = nextPreference
-      themePreference = nextPreference
-      await storage.saveConfig(config)
-    } catch (error) {
-      console.warn("Failed to save theme to config:", error)
-    }
+  const applyResolvedTheme = () => {
+    const dark = resolveDarkTheme()
+    setIsDarkSignal(dark)
+    applyTheme(dark)
   }
 
+  createEffect(() => {
+    applyResolvedTheme()
+  })
+
   onMount(() => {
-    loadTheme()
-
-    const unsubscribe = storage.onConfigChanged(() => {
-      loadTheme()
-    })
-
-    // Listen for system theme changes
     const handleSystemThemeChange = (event: MediaQueryListEvent) => {
-      if (themePreference === "system") {
+      if (themePreference() === "system") {
         setIsDarkSignal(event.matches)
         applyTheme(event.matches)
       }
@@ -86,19 +52,12 @@ export function ThemeProvider(props: { children: JSX.Element }) {
     systemPrefersDark.addEventListener("change", handleSystemThemeChange)
 
     return () => {
-      unsubscribe()
       systemPrefersDark.removeEventListener("change", handleSystemThemeChange)
     }
   })
 
-  createEffect(() => {
-    applyTheme(isDark())
-  })
-
   const setTheme = (dark: boolean) => {
-    setIsDarkSignal(dark)
-    applyTheme(dark)
-    saveTheme(dark)
+    setThemePreference(dark ? "dark" : "light")
   }
 
   const toggleTheme = () => {
diff --git a/packages/ui/src/stores/instances.ts b/packages/ui/src/stores/instances.ts
index ccd80776..ed0c0bfa 100644
--- a/packages/ui/src/stores/instances.ts
+++ b/packages/ui/src/stores/instances.ts
@@ -15,7 +15,7 @@ import {
   clearInstanceDraftPrompts,
 } from "./sessions"
 import { fetchCommands, clearCommands } from "./commands"
-import { preferences, updateLastUsedBinary } from "./preferences"
+import { preferences } from "./preferences"
 import { computeDisplayParts } from "./session-messages"
 import { withSession, setSessionPendingPermission } from "./session-state"
 import { setHasInstances } from "./ui"
@@ -294,11 +294,7 @@ function removeInstance(id: string) {
   clearInstanceDraftPrompts(id)
 }
 
-async function createInstance(folder: string, binaryPath?: string): Promise<string> {
-  if (binaryPath) {
-    updateLastUsedBinary(binaryPath)
-  }
-
+async function createInstance(folder: string, _binaryPath?: string): Promise<string> {
   try {
     const workspace = await cliApi.createWorkspace({ path: folder })
     upsertWorkspace(workspace)
diff --git a/packages/ui/src/stores/preferences.tsx b/packages/ui/src/stores/preferences.tsx
index e17bd1fb..b54dbe85 100644
--- a/packages/ui/src/stores/preferences.tsx
+++ b/packages/ui/src/stores/preferences.tsx
@@ -1,7 +1,15 @@
-import { createContext, createSignal, onMount, useContext } from "solid-js"
+import { createContext, createMemo, createSignal, onMount, useContext } from "solid-js"
 import type { Accessor, ParentComponent } from "solid-js"
 import { storage, type ConfigData } from "../lib/storage"
 
+type DeepReadonly<T> = T extends (...args: any[]) => unknown
+  ? T
+  : T extends Array<infer U>
+    ? ReadonlyArray<DeepReadonly<U>>
+    : T extends object
+      ? { readonly [K in keyof T]: DeepReadonly<T[K]> }
+      : T
+
 export interface ModelPreference {
   providerId: string
   modelId: string
@@ -36,6 +44,8 @@ export interface RecentFolder {
   lastAccessed: number
 }
 
+export type ThemePreference = NonNullable<ConfigData["theme"]>
+
 const MAX_RECENT_FOLDERS = 20
 const MAX_RECENT_MODELS = 5
 
@@ -49,6 +59,18 @@ const defaultPreferences: Preferences = {
   diagnosticsExpansion: "expanded",
 }
 
+function deepEqual(a: unknown, b: unknown): boolean {
+  if (a === b) return true
+  if (typeof a === "object" && a !== null && typeof b === "object" && b !== null) {
+    try {
+      return JSON.stringify(a) === JSON.stringify(b)
+    } catch (error) {
+      console.warn("Failed to compare preference values", error)
+    }
+  }
+  return false
+}
+
 function normalizePreferences(pref?: Partial<Preferences>): Preferences {
   const environmentVariables = {
     ...defaultPreferences.environmentVariables,
@@ -78,73 +100,148 @@ function normalizePreferences(pref?: Partial<Preferences>): Preferences {
   }
 }
 
-const [preferences, setPreferences] = createSignal<Preferences>(normalizePreferences())
-const [recentFolders, setRecentFolders] = createSignal<RecentFolder[]>([])
-const [opencodeBinaries, setOpenCodeBinaries] = createSignal<OpenCodeBinary[]>([])
+const [internalConfig, setInternalConfig] = createSignal<ConfigData>(buildFallbackConfig())
+const config = createMemo<DeepReadonly<ConfigData>>(() => internalConfig())
 const [isConfigLoaded, setIsConfigLoaded] = createSignal(false)
-let cachedConfig: ConfigData = {
-  preferences: normalizePreferences(),
-  recentFolders: [],
-  opencodeBinaries: [],
-}
+const preferences = createMemo<Preferences>(() => internalConfig().preferences)
+const recentFolders = createMemo<RecentFolder[]>(() => internalConfig().recentFolders ?? [])
+const opencodeBinaries = createMemo<OpenCodeBinary[]>(() => internalConfig().opencodeBinaries ?? [])
+const themePreference = createMemo<ThemePreference>(() => internalConfig().theme ?? "dark")
 let loadPromise: Promise<void> | null = null
 
-async function loadConfig(): Promise<void> {
+function normalizeConfig(config?: ConfigData | null): ConfigData {
+  return {
+    preferences: normalizePreferences(config?.preferences),
+    recentFolders: (config?.recentFolders ?? []).map((folder) => ({ ...folder })),
+    opencodeBinaries: (config?.opencodeBinaries ?? []).map((binary) => ({ ...binary })),
+    theme: config?.theme ?? "dark",
+  }
+}
+
+function buildFallbackConfig(): ConfigData {
+  return normalizeConfig()
+}
+
+async function syncConfig(source?: ConfigData): Promise<void> {
   try {
-    const config = await storage.loadConfig()
-    cachedConfig = {
-      ...config,
-      preferences: normalizePreferences(config.preferences),
-      recentFolders: config.recentFolders ?? [],
-      opencodeBinaries: config.opencodeBinaries ?? [],
-    }
+    const configData = source ?? (await storage.loadConfig())
+    applyConfig(configData)
   } catch (error) {
     console.error("Failed to load config:", error)
-    cachedConfig = {
-      ...cachedConfig,
-      preferences: normalizePreferences(),
-      recentFolders: [],
-      opencodeBinaries: [],
-    }
+    applyConfig(buildFallbackConfig())
   }
+}
 
-  setPreferences(cachedConfig.preferences)
-  setRecentFolders(cachedConfig.recentFolders)
-  setOpenCodeBinaries(cachedConfig.opencodeBinaries)
+function applyConfig(next: ConfigData) {
+  setInternalConfig(normalizeConfig(next))
   setIsConfigLoaded(true)
 }
 
-async function saveConfig(): Promise<void> {
+function cloneConfigForUpdate(): ConfigData {
+  return normalizeConfig(internalConfig())
+}
+
+function logConfigDiff(previous: ConfigData, next: ConfigData) {
+  if (deepEqual(previous, next)) {
+    return
+  }
+  const changes = diffObjects(previous, next)
+  if (changes.length > 0) {
+    console.debug("[Config] Changes", changes)
+  }
+}
+
+function diffObjects(previous: unknown, next: unknown, path: string[] = []): string[] {
+  if (previous === next) {
+    return []
+  }
+
+  if (typeof previous !== "object" || previous === null || typeof next !== "object" || next === null) {
+    return [path.join(".")]
+  }
+
+  const prevKeys = Object.keys(previous as Record<string, unknown>)
+  const nextKeys = Object.keys(next as Record<string, unknown>)
+  const allKeys = new Set([...prevKeys, ...nextKeys])
+  const changes: string[] = []
+
+  for (const key of allKeys) {
+    const childPath = [...path, key]
+    const prevValue = (previous as Record<string, unknown>)[key]
+    const nextValue = (next as Record<string, unknown>)[key]
+    changes.push(...diffObjects(prevValue, nextValue, childPath))
+  }
+
+  return changes
+}
+
+function updateConfig(mutator: (draft: ConfigData) => void): void {
+  const previous = internalConfig()
+  const draft = cloneConfigForUpdate()
+  mutator(draft)
+  logConfigDiff(previous, draft)
+  applyConfig(draft)
+  void persistFullConfig(draft)
+}
+
+async function persistFullConfig(next: ConfigData): Promise<void> {
   try {
     await ensureConfigLoaded()
-    const config: ConfigData = {
-      ...cachedConfig,
-      preferences: preferences(),
-      recentFolders: recentFolders(),
-      opencodeBinaries: opencodeBinaries(),
-    }
-    cachedConfig = config
-    await storage.saveConfig(config)
+    await storage.updateConfig(next)
   } catch (error) {
     console.error("Failed to save config:", error)
+    void syncConfig().catch((syncError: unknown) => {
+      console.error("Failed to refresh config:", syncError)
+    })
   }
 }
 
+function setThemePreference(preference: ThemePreference): void {
+  if (themePreference() === preference) {
+    return
+  }
+  updateConfig((draft) => {
+    draft.theme = preference
+  })
+}
+
 async function ensureConfigLoaded(): Promise<void> {
   if (isConfigLoaded()) return
   if (!loadPromise) {
-    loadPromise = loadConfig().finally(() => {
+    loadPromise = syncConfig().finally(() => {
       loadPromise = null
     })
   }
   await loadPromise
 }
 
+function buildRecentFolderList(path: string, source: RecentFolder[]): RecentFolder[] {
+  const folders = source.filter((f) => f.path !== path)
+  folders.unshift({ path, lastAccessed: Date.now() })
+  return folders.slice(0, MAX_RECENT_FOLDERS)
+}
+
+function buildBinaryList(path: string, version: string | undefined, source: OpenCodeBinary[]): OpenCodeBinary[] {
+  const timestamp = Date.now()
+  const existing = source.find((b) => b.path === path)
+  if (existing) {
+    const updatedEntry: OpenCodeBinary = { ...existing, lastUsed: timestamp }
+    const remaining = source.filter((b) => b.path !== path)
+    return [updatedEntry, ...remaining]
+  }
+  const nextEntry: OpenCodeBinary = version ? { path, version, lastUsed: timestamp } : { path, lastUsed: timestamp }
+  return [nextEntry, ...source].slice(0, 10)
+}
 
 function updatePreferences(updates: Partial<Preferences>): void {
-  const updated = normalizePreferences({ ...preferences(), ...updates })
-  setPreferences(updated)
-  saveConfig().catch(console.error)
+  const current = internalConfig().preferences
+  const merged = normalizePreferences({ ...current, ...updates })
+  if (deepEqual(current, merged)) {
+    return
+  }
+  updateConfig((draft) => {
+    draft.preferences = merged
+  })
 }
 
 function setDiffViewMode(mode: DiffViewMode): void {
@@ -167,54 +264,44 @@ function toggleShowThinkingBlocks(): void {
 }
 
 function addRecentFolder(path: string): void {
-  const folders = recentFolders().filter((f) => f.path !== path)
-  folders.unshift({ path, lastAccessed: Date.now() })
-
-  const trimmed = folders.slice(0, MAX_RECENT_FOLDERS)
-  setRecentFolders(trimmed)
-  saveConfig().catch(console.error)
+  updateConfig((draft) => {
+    draft.recentFolders = buildRecentFolderList(path, draft.recentFolders)
+  })
 }
 
 function removeRecentFolder(path: string): void {
-  const folders = recentFolders().filter((f) => f.path !== path)
-  setRecentFolders(folders)
-  saveConfig().catch(console.error)
+  updateConfig((draft) => {
+    draft.recentFolders = draft.recentFolders.filter((f) => f.path !== path)
+  })
 }
 
 function addOpenCodeBinary(path: string, version?: string): void {
-  const binaries = opencodeBinaries().filter((b) => b.path !== path)
-  const lastUsed = Date.now()
-  const binaryEntry: OpenCodeBinary = version ? { path, version, lastUsed } : { path, lastUsed }
-  binaries.unshift(binaryEntry)
-
-  const trimmed = binaries.slice(0, 10) // Keep max 10 binaries
-  setOpenCodeBinaries(trimmed)
-  saveConfig().catch(console.error)
+  updateConfig((draft) => {
+    draft.opencodeBinaries = buildBinaryList(path, version, draft.opencodeBinaries)
+  })
 }
 
 function removeOpenCodeBinary(path: string): void {
-  const binaries = opencodeBinaries().filter((b) => b.path !== path)
-  setOpenCodeBinaries(binaries)
-  saveConfig().catch(console.error)
+  updateConfig((draft) => {
+    draft.opencodeBinaries = draft.opencodeBinaries.filter((b) => b.path !== path)
+  })
 }
 
 function updateLastUsedBinary(path: string): void {
-  updatePreferences({ lastUsedBinary: path })
+  const target = path || preferences().lastUsedBinary || "opencode"
+  updateConfig((draft) => {
+    draft.preferences = normalizePreferences({ ...draft.preferences, lastUsedBinary: target })
+    draft.opencodeBinaries = buildBinaryList(target, undefined, draft.opencodeBinaries)
+  })
+}
 
-  const binaries = opencodeBinaries()
-  let binary = binaries.find((b) => b.path === path)
-
-  // If binary not found in list, add it (for system PATH "opencode")
-  if (!binary) {
-    addOpenCodeBinary(path)
-    binary = { path, lastUsed: Date.now() }
-  } else {
-    binary.lastUsed = Date.now()
-    // Move to front
-    const sorted = [binary, ...binaries.filter((b) => b.path !== path)]
-    setOpenCodeBinaries(sorted)
-    saveConfig().catch(console.error)
-  }
+function recordWorkspaceLaunch(folderPath: string, binaryPath?: string): void {
+  updateConfig((draft) => {
+    const targetBinary = binaryPath && binaryPath.trim().length > 0 ? binaryPath : draft.preferences.lastUsedBinary || "opencode"
+    draft.recentFolders = buildRecentFolderList(folderPath, draft.recentFolders)
+    draft.preferences = normalizePreferences({ ...draft.preferences, lastUsedBinary: targetBinary })
+    draft.opencodeBinaries = buildBinaryList(targetBinary, undefined, draft.opencodeBinaries)
+  })
 }
 
 function updateEnvironmentVariables(envVars: Record<string, string>): void {
@@ -264,15 +351,19 @@ function getAgentModelPreference(instanceId: string, agent: string): ModelPrefer
   return preferences().agentModelSelections?.[instanceId]?.[agent]
 }
 
-void ensureConfigLoaded().catch((error) => {
+void ensureConfigLoaded().catch((error: unknown) => {
   console.error("Failed to initialize config:", error)
 })
 
 interface ConfigContextValue {
   isLoaded: Accessor<boolean>
+  config: typeof config
   preferences: typeof preferences
   recentFolders: typeof recentFolders
   opencodeBinaries: typeof opencodeBinaries
+  themePreference: typeof themePreference
+  setThemePreference: typeof setThemePreference
+  updateConfig: typeof updateConfig
   toggleShowThinkingBlocks: typeof toggleShowThinkingBlocks
   setDiffViewMode: typeof setDiffViewMode
   setToolOutputExpansion: typeof setToolOutputExpansion
@@ -282,6 +373,7 @@ interface ConfigContextValue {
   addOpenCodeBinary: typeof addOpenCodeBinary
   removeOpenCodeBinary: typeof removeOpenCodeBinary
   updateLastUsedBinary: typeof updateLastUsedBinary
+  recordWorkspaceLaunch: typeof recordWorkspaceLaunch
   updatePreferences: typeof updatePreferences
   updateEnvironmentVariables: typeof updateEnvironmentVariables
   addEnvironmentVariable: typeof addEnvironmentVariable
@@ -295,9 +387,13 @@ const ConfigContext = createContext<ConfigContextValue>()
 
 const configContextValue: ConfigContextValue = {
   isLoaded: isConfigLoaded,
+  config,
   preferences,
   recentFolders,
   opencodeBinaries,
+  themePreference,
+  setThemePreference,
+  updateConfig,
   toggleShowThinkingBlocks,
   setDiffViewMode,
   setToolOutputExpansion,
@@ -307,6 +403,7 @@ const configContextValue: ConfigContextValue = {
   addOpenCodeBinary,
   removeOpenCodeBinary,
   updateLastUsedBinary,
+  recordWorkspaceLaunch,
   updatePreferences,
   updateEnvironmentVariables,
   addEnvironmentVariable,
@@ -318,12 +415,12 @@ const configContextValue: ConfigContextValue = {
 
 const ConfigProvider: ParentComponent = (props) => {
   onMount(() => {
-    ensureConfigLoaded().catch((error) => {
+    ensureConfigLoaded().catch((error: unknown) => {
       console.error("Failed to initialize config:", error)
     })
 
-    const unsubscribe = storage.onConfigChanged(() => {
-      loadConfig().catch((error) => {
+    const unsubscribe = storage.onConfigChanged((config) => {
+      syncConfig(config).catch((error: unknown) => {
         console.error("Failed to refresh config:", error)
       })
     })
@@ -347,7 +444,9 @@ function useConfig(): ConfigContextValue {
 export {
   ConfigProvider,
   useConfig,
+  config,
   preferences,
+  updateConfig,
   updatePreferences,
   toggleShowThinkingBlocks,
   recentFolders,
@@ -366,4 +465,7 @@ export {
   setDiffViewMode,
   setToolOutputExpansion,
   setDiagnosticsExpansion,
+  themePreference,
+  setThemePreference,
+  recordWorkspaceLaunch,
 }