diff --git a/packages/ui/src/components/instance/instance-shell2.tsx b/packages/ui/src/components/instance/instance-shell2.tsx
index 7675b586..68f76bc8 100644
--- a/packages/ui/src/components/instance/instance-shell2.tsx
+++ b/packages/ui/src/components/instance/instance-shell2.tsx
@@ -15,7 +15,6 @@ import { Accordion } from "@kobalte/core"
 import { ChevronDown, TerminalSquare, Trash2, XOctagon } from "lucide-solid"
 import AppBar from "@suid/material/AppBar"
 import Box from "@suid/material/Box"
-import Divider from "@suid/material/Divider"
 import Drawer from "@suid/material/Drawer"
 import IconButton from "@suid/material/IconButton"
 import Toolbar from "@suid/material/Toolbar"
@@ -916,7 +915,7 @@ const InstanceShell2: Component<InstanceShellProps> = (props) => {
           showFooter={false}
         />
 
-        <Divider />
+        <div class="session-sidebar-separator" />
         <Show when={activeSessionForInstance()}>
           {(activeSession) => (
             <>
diff --git a/packages/ui/src/components/markdown.tsx b/packages/ui/src/components/markdown.tsx
index dbd22428..39638e1b 100644
--- a/packages/ui/src/components/markdown.tsx
+++ b/packages/ui/src/components/markdown.tsx
@@ -1,5 +1,5 @@
 import { createEffect, createMemo, createSignal, onCleanup, onMount } from "solid-js"
-import { renderMarkdown, onLanguagesLoaded, decodeHtmlEntities } from "../lib/markdown"
+import { renderMarkdown, onLanguagesLoaded, decodeHtmlEntities, setMarkdownTheme } from "../lib/markdown"
 import { useGlobalCache } from "../lib/hooks/use-global-cache"
 import type { TextPart, RenderCache } from "../types/message"
 import { getLogger } from "../lib/logger"
@@ -72,6 +72,9 @@ export function Markdown(props: MarkdownProps) {
   createEffect(async () => {
     const { part, text, themeKey, highlightEnabled, version } = resolved()
 
+    // Ensure the markdown highlighter theme matches the active UI theme.
+    setMarkdownTheme(themeKey === "dark")
+
     latestRequestedText = text
 
     const cacheMatches = (cache: RenderCache | undefined) => {
@@ -171,6 +174,8 @@ export function Markdown(props: MarkdownProps) {
 
       const { part, text, themeKey, version } = resolved()
 
+      setMarkdownTheme(themeKey === "dark")
+
       if (latestRequestedText !== text) {
         return
       }
diff --git a/packages/ui/src/lib/markdown.ts b/packages/ui/src/lib/markdown.ts
index a8287d15..400d7476 100644
--- a/packages/ui/src/lib/markdown.ts
+++ b/packages/ui/src/lib/markdown.ts
@@ -329,6 +329,10 @@ export async function initMarkdown(isDark: boolean) {
   isInitialized = true
 }
 
+export function setMarkdownTheme(isDark: boolean) {
+  currentTheme = isDark ? "dark" : "light"
+}
+
 export function isMarkdownReady(): boolean {
   return isInitialized && highlighter !== null
 }
diff --git a/packages/ui/src/styles/messaging/message-base.css b/packages/ui/src/styles/messaging/message-base.css
index eccab659..5f329d19 100644
--- a/packages/ui/src/styles/messaging/message-base.css
+++ b/packages/ui/src/styles/messaging/message-base.css
@@ -175,7 +175,8 @@
 
 .message-reasoning {
   @apply my-2 border rounded;
-  border-color: var(--border-base);
+  --reasoning-border-color: color-mix(in oklab, var(--border-base) 62%, var(--text-primary));
+  border-color: var(--reasoning-border-color);
   background-color: var(--surface-secondary);
   color: inherit;
 }
@@ -286,6 +287,7 @@
 }
 
 .message-reasoning-card {
+  --reasoning-border-color: color-mix(in oklab, var(--border-base) 62%, var(--text-primary));
   background-color: var(--message-assistant-bg);
   border-left: 4px solid var(--message-assistant-border);
   margin-top: 0;
@@ -339,7 +341,7 @@
   justify-content: center;
   height: 1.5rem;
   padding: 0 0.75rem;
-  border: 1px solid var(--border-base);
+  border: 1px solid var(--reasoning-border-color, var(--border-base));
   border-radius: 0.375rem;
   background-color: transparent;
   color: var(--text-muted);
@@ -381,6 +383,7 @@
   @apply flex flex-col;
   margin: 0;
   padding: 0.75rem;
+  border: 1px solid var(--reasoning-border-color, var(--border-base));
   max-height: 30rem;
   overflow-y: auto;
   scrollbar-width: thin;
@@ -397,4 +400,3 @@
   white-space: pre-wrap;
   margin: 0;
 }
-
diff --git a/packages/ui/src/styles/messaging/message-timeline.css b/packages/ui/src/styles/messaging/message-timeline.css
index 9fe5bc65..391bbc2e 100644
--- a/packages/ui/src/styles/messaging/message-timeline.css
+++ b/packages/ui/src/styles/messaging/message-timeline.css
@@ -103,7 +103,7 @@
 }
 
 .message-timeline-segment-active {
-  border-color: transparent;
+  border-color: color-mix(in oklab, var(--timeline-segment-active-bg) 92%, var(--timeline-segment-active-text));
   background-color: var(--timeline-segment-active-bg);
   color: var(--timeline-segment-active-text);
   font-weight: 700;
@@ -182,7 +182,7 @@
 
 .message-timeline-segment-active {
   background-color: var(--timeline-segment-active-bg) !important;
-  border-color: transparent !important;
+  border-color: color-mix(in oklab, var(--timeline-segment-active-bg) 92%, var(--timeline-segment-active-text)) !important;
   color: var(--timeline-segment-active-text) !important;
   font-weight: 700;
   box-shadow: var(--timeline-segment-active-ring);
diff --git a/packages/ui/src/styles/messaging/prompt-input.css b/packages/ui/src/styles/messaging/prompt-input.css
index b5507031..82f051e3 100644
--- a/packages/ui/src/styles/messaging/prompt-input.css
+++ b/packages/ui/src/styles/messaging/prompt-input.css
@@ -38,7 +38,8 @@
   @apply w-full pl-3 pr-10 pt-2.5 border text-sm resize-none outline-none transition-colors;
   font-family: inherit;
   background-color: var(--surface-base);
-  color: inherit;
+  color: var(--text-primary);
+  caret-color: var(--text-primary);
   border-color: var(--border-base);
   line-height: var(--line-height-normal);
   border-radius: 0;
diff --git a/packages/ui/src/styles/messaging/tool-call.css b/packages/ui/src/styles/messaging/tool-call.css
index f39f470a..38bfd1f4 100644
--- a/packages/ui/src/styles/messaging/tool-call.css
+++ b/packages/ui/src/styles/messaging/tool-call.css
@@ -21,7 +21,7 @@
 
 .tool-call-header-button {
   background-color: transparent;
-  border: 1px solid var(--border-base);
+  border: 1px solid var(--tool-call-border-color, var(--border-base));
   color: var(--text-secondary);
   padding: 0.15rem 0.75rem;
   border-radius: 0.375rem;
@@ -58,7 +58,7 @@
   font-family: var(--font-family-mono);
   color: inherit;
   background-color: var(--surface-secondary);
-  border: 1px solid var(--border-base);
+  border: 1px solid var(--tool-call-border-color, var(--border-base));
   padding: 2px 6px;
   border-radius: 3px;
   font-size: 13px;
@@ -66,7 +66,9 @@
 
 .tool-call {
   @apply border overflow-hidden;
-  border-color: var(--border-base);
+  /* Tool-call output borders need more contrast in light mode. */
+  --tool-call-border-color: color-mix(in oklab, var(--border-base) 62%, var(--text-primary));
+  border-color: var(--tool-call-border-color);
   color: inherit;
   --tool-call-line-unit: 1.4em;
   --tool-call-lines-compact: 15;
@@ -86,13 +88,14 @@
   font-family: var(--font-family-mono);
   font-size: 13px;
   border-radius: 0;
+  color: var(--text-primary);
 }
 
 .tool-call-header::before {
   content: "▶";
   font-size: 11px;
   margin-right: 0.35rem;
-  color: var(--text-muted);
+  color: var(--text-secondary);
 }
 
 .tool-call-header[aria-expanded="true"]::before {
@@ -115,6 +118,7 @@
 
 .tool-call-summary {
   @apply flex-1 text-left inline-flex items-center gap-2;
+  color: var(--text-primary);
 }
 
 .tool-call-summary::before {
@@ -130,6 +134,8 @@
   margin-right: 0.35rem;
 }
 
+/* ToolState uses status="completed"; keep "success" as a legacy alias. */
+.tool-call-status-completed,
 .tool-call-status-success {
   border-left: 3px solid var(--status-success);
 }
@@ -157,7 +163,7 @@
 .tool-call-preview {
   @apply p-2 flex flex-col gap-1.5;
   background-color: var(--surface-code);
-  border-top: 1px solid var(--border-base);
+  border-top: 1px solid var(--tool-call-border-color);
 }
 
 .tool-call-preview-label {
@@ -186,7 +192,8 @@
 
 .tool-call-markdown {
   background-color: var(--surface-code);
-  border: none;
+  /* Keep a visible frame around the scroll viewport (not the content). */
+  border: 1px solid var(--tool-call-border-color);
   border-radius: 0;
   padding: 0;
   font-size: var(--font-size-xs);
@@ -199,6 +206,16 @@
   position: relative;
 }
 
+/* Inner code blocks should not own the frame border; the scroll container does. */
+.tool-call-markdown .markdown-code-block {
+  border: none;
+}
+
+/* Avoid double borders when ANSI output uses .tool-call-content inside tool-call-markdown. */
+.tool-call-markdown .tool-call-content {
+  border: none;
+}
+
 .tool-call-markdown-large {
   max-height: var(--tool-call-max-height-large, calc(48 * 1.4em));
 }
@@ -216,7 +233,7 @@
 .tool-call-diff-toolbar {
   @apply flex items-center justify-between gap-3 px-3 py-2;
   background-color: var(--surface-secondary);
-  border-bottom: 1px solid var(--border-base);
+  border-bottom: 1px solid var(--tool-call-border-color);
   position: sticky;
   top: 0;
   z-index: 2;
@@ -242,7 +259,7 @@
 
 .tool-call-diff-mode-button {
   @apply border text-xs font-semibold px-3 py-1 rounded transition-all duration-150;
-  border-color: var(--border-base);
+  border-color: var(--tool-call-border-color, var(--border-base));
   background-color: transparent;
   color: var(--text-secondary);
 }
@@ -303,7 +320,7 @@
   font-size: 12px;
   padding: 2px 6px;
   border-radius: 0.375rem;
-  border: 1px solid var(--border-base);
+  border: 1px solid var(--tool-call-border-color, var(--border-base));
   background-color: var(--surface-code);
 }
 
@@ -312,7 +329,7 @@
   font-size: 13px;
   color: var(--text-primary);
   background-color: var(--surface-code);
-  border: 1px solid var(--border-base);
+  border: 1px solid var(--tool-call-border-color, var(--border-base));
   border-radius: 0.5rem;
   padding: 0.5rem 0.75rem;
   word-break: break-word;
@@ -395,12 +412,6 @@
 .tool-call-markdown .markdown-code-block {
   margin: 0;
   border-radius: 0;
-}
-
-
-.tool-call-markdown .markdown-code-block {
-  margin: 0;
-  border: none;
   background-color: transparent;
 }
 
@@ -408,7 +419,25 @@
   position: sticky;
   top: 0;
   z-index: auto;
-  box-shadow: 0 1px 0 var(--border-base);
+  background-color: color-mix(in oklab, var(--surface-secondary) 70%, var(--text-primary));
+  border-bottom: 1px solid var(--tool-call-border-color);
+  box-shadow: none;
+}
+
+/* Tool output header (language + copy) needs stronger contrast in light mode. */
+.tool-call-markdown .code-block-language {
+  color: var(--text-primary);
+}
+
+.tool-call-markdown .code-block-copy {
+  border-color: var(--tool-call-border-color);
+  color: var(--text-primary);
+}
+
+/* Plain (non-highlighted) tool output must remain readable in light mode. */
+.tool-call-markdown .markdown-code-block pre:not(.shiki),
+.tool-call-markdown .markdown-code-block pre:not(.shiki) code {
+  color: var(--text-primary);
 }
 
 .tool-call-markdown .markdown-code-block pre {
@@ -458,12 +487,12 @@
   flex-direction: column;
   gap: var(--space-xs);
   padding: var(--space-sm) var(--space-md);
-  border-top: 1px solid var(--border-base);
+  border-top: 1px solid var(--tool-call-border-color);
   background-color: var(--surface-base);
 }
 
 .tool-call-diagnostics-wrapper {
-  border-top: 1px solid var(--border-base);
+  border-top: 1px solid var(--tool-call-border-color);
   background-color: var(--surface-base);
   margin-top: var(--space-md);
 }
@@ -515,7 +544,7 @@
   width: 1.25rem;
   height: 1.25rem;
   border-radius: var(--radius-sm);
-  border: 1px solid var(--border-base);
+  border: 1px solid var(--tool-call-border-color, var(--border-base));
   font-size: 12px;
 }
 
@@ -616,7 +645,7 @@
   margin: 0;
   padding: 8px;
   background-color: var(--surface-code);
-  border: 1px solid var(--border-base);
+  border: 1px solid var(--tool-call-border-color);
   border-radius: 0px;
   overflow-x: auto;
   max-height: var(--tool-call-max-height-compact, calc(25 * 1.4em));
@@ -659,7 +688,7 @@
 
 .tool-call-action-button {
   @apply border text-xs font-semibold px-3 py-1 rounded transition-colors h-8 flex items-center;
-  border-color: var(--border-base);
+  border-color: var(--tool-call-border-color, var(--border-base));
   color: var(--text-secondary);
   background-color: transparent;
 }
@@ -681,7 +710,7 @@
 
 .tool-call-content {
   background-color: var(--surface-code);
-  border: 1px solid var(--border-base);
+  border: 1px solid var(--tool-call-border-color);
   border-radius: 0;
   padding: 8px 12px;
   font-family: var(--font-family-mono);
diff --git a/packages/ui/src/styles/messaging/tool-call/task.css b/packages/ui/src/styles/messaging/tool-call/task.css
index 2756cca2..a98d6500 100644
--- a/packages/ui/src/styles/messaging/tool-call/task.css
+++ b/packages/ui/src/styles/messaging/tool-call/task.css
@@ -6,7 +6,7 @@
 }
 
 .tool-call-task-section {
-  border: 1px solid var(--border-base);
+  border: 1px solid var(--tool-call-border-color, var(--border-base));
   overflow: hidden;
   background-color: transparent;
   border-radius: 0;
@@ -19,7 +19,7 @@
   gap: 0.75rem;
   padding: 0.5rem;
   background-color: var(--surface-secondary);
-  border-bottom: 1px solid var(--border-base);
+  border-bottom: 1px solid var(--tool-call-border-color, var(--border-base));
   font-family: var(--font-family-mono);
   font-size: 13px;
   color: inherit;
@@ -81,7 +81,7 @@
   align-items: center;
   gap: 0.4rem;
   padding: 0.35rem 0.5rem 0.35rem 0.75rem;
-  border-left: 2px solid var(--border-base);
+  border-left: 2px solid var(--tool-call-border-color, var(--border-base));
   font-size: var(--font-size-sm);
   font-family: var(--font-family-mono);
   line-height: 1.35;
diff --git a/packages/ui/src/styles/messaging/tool-call/todo.css b/packages/ui/src/styles/messaging/tool-call/todo.css
index bc25d0e0..50071667 100644
--- a/packages/ui/src/styles/messaging/tool-call/todo.css
+++ b/packages/ui/src/styles/messaging/tool-call/todo.css
@@ -16,7 +16,7 @@
 
 .tool-call-todo-item {
   @apply flex items-start gap-3;
-  border: 1px solid var(--border-base);
+  border: 1px solid var(--tool-call-border-color, var(--border-base));
   border-radius: 0;
   padding: 10px 12px;
   background-color: var(--surface-secondary);
@@ -40,7 +40,7 @@
   width: 1.1rem;
   height: 1.1rem;
   border-radius: 9999px;
-  border: 2px solid var(--border-base);
+  border: 2px solid var(--tool-call-border-color, var(--border-base));
   display: inline-flex;
   align-items: center;
   justify-content: center;
diff --git a/packages/ui/src/styles/panels/tabs.css b/packages/ui/src/styles/panels/tabs.css
index 98bae37e..50f3cb8a 100644
--- a/packages/ui/src/styles/panels/tabs.css
+++ b/packages/ui/src/styles/panels/tabs.css
@@ -87,6 +87,23 @@
   ring-offset-color: inherit;
 }
 
+/* Instance tabs: session-status dots should be lighter/softer than list/status pills. */
+.tab-base .status-indicator.session-status.session-working {
+  --session-status-dot: color-mix(in oklab, var(--session-status-working-fg) 55%, var(--surface-base));
+}
+
+.tab-base .status-indicator.session-status.session-compacting {
+  --session-status-dot: color-mix(in oklab, var(--session-status-compacting-fg) 55%, var(--surface-base));
+}
+
+.tab-base .status-indicator.session-status.session-idle {
+  --session-status-dot: color-mix(in oklab, var(--session-status-idle-fg) 55%, var(--surface-base));
+}
+
+.tab-base .status-indicator.session-status.session-permission {
+  --session-status-dot: color-mix(in oklab, var(--session-status-permission-fg) 55%, var(--surface-base));
+}
+
 .new-tab-button {
   @apply inline-flex items-center justify-center w-8 h-8 rounded-md transition-colors;
   background-color: var(--new-tab-bg);
diff --git a/packages/ui/src/styles/tokens.css b/packages/ui/src/styles/tokens.css
index 4f8763df..19edbf6a 100644
--- a/packages/ui/src/styles/tokens.css
+++ b/packages/ui/src/styles/tokens.css
@@ -57,6 +57,7 @@
   --attachment-chip-ring: rgba(0, 102, 255, 0.1);
   --badge-neutral-bg: rgba(0, 102, 255, 0.05);
   --badge-neutral-text: #0066ff;
+  --badge-success-bg: rgba(76, 175, 80, 0.12);
   --status-ready-fg: #16a34a;
   --status-ready-bg: rgba(34, 197, 94, 0.1);
   --status-starting-fg: #ca8a04;
@@ -94,9 +95,10 @@
   --status-success-ring: color-mix(in oklab, var(--status-success) 45%, transparent);
   --border-critical: var(--status-error);
 
-  --timeline-segment-active-bg: #0f5b44;
-  --timeline-segment-active-text: #ffffff;
-  --timeline-segment-active-ring: inset 0 0 0 1px rgba(0, 0, 0, 0.22);
+  /* Message timeline active segment (light theme should be a light tint). */
+  --timeline-segment-active-bg: #b7e6d6;
+  --timeline-segment-active-text: #032f23;
+  --timeline-segment-active-ring: inset 0 0 0 1px rgba(3, 47, 35, 0.28);
 
   --button-danger-bg: color-mix(in oklab, var(--status-error) 85%, var(--surface-base));
   --button-danger-hover-bg: color-mix(in oklab, var(--status-error) 90%, var(--surface-base));
@@ -223,6 +225,7 @@
     --attachment-chip-ring: rgba(0, 128, 255, 0.2);
   --badge-neutral-bg: rgba(0, 128, 255, 0.15);
   --badge-neutral-text: #0080ff;
+  --badge-success-bg: rgba(76, 175, 80, 0.22);
   --status-ready-fg: #22c55e;
   --status-ready-bg: rgba(34, 197, 94, 0.2);
   --status-starting-fg: #facc15;
@@ -385,6 +388,7 @@
   --attachment-chip-ring: rgba(0, 128, 255, 0.2);
   --badge-neutral-bg: rgba(0, 128, 255, 0.15);
   --badge-neutral-text: #0080ff;
+  --badge-success-bg: rgba(76, 175, 80, 0.22);
   --status-ready-fg: #22c55e;
   --status-ready-bg: rgba(34, 197, 94, 0.2);
   --status-starting-fg: #facc15;