style(desktop): filled glyphs for in-thread tool icons

apps/desktop/src/components/assistant-ui/thread.tsx

@@ -722,8 +722,14 @@ function StickyHumanMessageContainer({ children }: { children: ReactNode }) {
 // edit composer render the same bubble surface (rounded glass card);
 // they only differ in border weight, cursor, and padding-right (the
 // read-only view reserves room for the restore icon).
+//
+// no-drag: sticky bubbles park at --sticky-human-top (~4px), sliding under the
+// titlebar's [-webkit-app-region:drag] strips (app-shell.tsx). Electron resolves
+// drag regions at the compositor level — z-index and pointer-events don't help —
+// so without the carve-out, clicking a stuck bubble drags the window instead of
+// opening the edit composer.
 const USER_BUBBLE_BASE_CLASS =
-  'composer-human-message standalone-glass relative flex w-full min-w-0 max-w-full flex-col gap-1.5 overflow-hidden rounded-xl border bg-(--dt-user-bubble) px-3 py-2 text-left'
+  'composer-human-message standalone-glass relative flex w-full min-w-0 max-w-full flex-col gap-1.5 overflow-hidden rounded-xl border bg-(--dt-user-bubble) px-3 py-2 text-left [-webkit-app-region:no-drag]'
 
 const USER_ACTION_ICON_BUTTON_CLASS =
   'grid place-items-center rounded-md bg-transparent text-(--ui-text-secondary) transition-colors hover:bg-(--ui-control-active-background) hover:text-foreground disabled:cursor-default disabled:text-(--ui-text-quaternary) disabled:opacity-70'

apps/desktop/src/components/assistant-ui/tool-fallback.tsx

@@ -13,9 +13,9 @@ import { DisclosureRow } from '@/components/chat/disclosure-row'
 import { PreviewAttachment } from '@/components/chat/preview-attachment'
 import { ZoomableImage } from '@/components/chat/zoomable-image'
 import { BrailleSpinner } from '@/components/ui/braille-spinner'
-import { Codicon } from '@/components/ui/codicon'
 import { CopyButton } from '@/components/ui/copy-button'
 import { FadeText } from '@/components/ui/fade-text'
+import { ToolIcon } from '@/components/ui/tool-icon'
 import { useI18n } from '@/i18n'
 import { PrettyLink, LinkifiedText as SharedLinkifiedText, urlSlugTitleLabel } from '@/lib/external-link'
 import { AlertCircle, CheckCircle2 } from '@/lib/icons'
@@ -136,7 +136,7 @@ function ToolGlyph({ copy, icon, status }: { copy: ToolStatusCopy; icon?: string
   const node = status ? (
     statusGlyph(status, copy)
   ) : icon ? (
-    <Codicon className="text-(--ui-text-tertiary)" name={icon} size="0.875rem" />
+    <ToolIcon className="text-(--ui-text-tertiary)" name={icon} size="0.875rem" />
   ) : null
 
   return node ? <span className={TOOL_HEADER_GLYPH_WRAP_CLASS}>{node}</span> : null

apps/desktop/src/components/assistant-ui/user-message-edit.test.tsx

@@ -0,0 +1,141 @@
+import { ExportedMessageRepository } from '@assistant-ui/core/internal'
+// Clicking a user bubble must open the inline edit composer — through the
+// app's incremental external-store runtime (which reimplements capability
+// resolution, incl. `edit: onEdit !== undefined`) and the stock runtime.
+//
+// Note: this covers the React/runtime wiring only. The Electron-level failure
+// mode (titlebar -webkit-app-region:drag swallowing clicks on *stuck* sticky
+// bubbles) is not reproducible in jsdom — see USER_BUBBLE_BASE_CLASS's no-drag
+// carve-out in thread.tsx.
+import { AssistantRuntimeProvider, type ThreadMessage, useExternalStoreRuntime } from '@assistant-ui/react'
+import { fireEvent, render, screen, waitFor } from '@testing-library/react'
+import { describe, expect, it, vi } from 'vitest'
+
+import { useIncrementalExternalStoreRuntime } from '@/lib/incremental-external-store-runtime'
+
+import { Thread } from './thread'
+
+const createdAt = new Date('2026-05-01T00:00:00.000Z')
+
+class TestResizeObserver {
+  observe() {}
+  unobserve() {}
+  disconnect() {}
+}
+
+vi.stubGlobal('ResizeObserver', TestResizeObserver)
+vi.stubGlobal('requestAnimationFrame', (callback: FrameRequestCallback) =>
+  window.setTimeout(() => callback(performance.now()), 0)
+)
+vi.stubGlobal('cancelAnimationFrame', (id: number) => window.clearTimeout(id))
+
+Element.prototype.scrollTo = function scrollTo() {}
+
+function stubOffsetDimension(
+  prop: 'offsetHeight' | 'offsetWidth',
+  clientProp: 'clientHeight' | 'clientWidth',
+  fallback: number
+) {
+  const previous = Object.getOwnPropertyDescriptor(HTMLElement.prototype, prop)
+
+  Object.defineProperty(HTMLElement.prototype, prop, {
+    configurable: true,
+    get() {
+      return previous?.get?.call(this) || (this as HTMLElement)[clientProp] || fallback
+    }
+  })
+}
+
+stubOffsetDimension('offsetWidth', 'clientWidth', 800)
+stubOffsetDimension('offsetHeight', 'clientHeight', 600)
+
+function userMessage(): ThreadMessage {
+  return {
+    id: 'user-1',
+    role: 'user',
+    content: [{ type: 'text', text: 'edit me please' }],
+    attachments: [],
+    createdAt,
+    metadata: { custom: {} }
+  } as ThreadMessage
+}
+
+function assistantMessage(): ThreadMessage {
+  return {
+    id: 'assistant-1',
+    role: 'assistant',
+    content: [{ type: 'text', text: 'done' }],
+    status: { type: 'complete', reason: 'stop' },
+    createdAt,
+    metadata: {
+      unstable_state: null,
+      unstable_annotations: [],
+      unstable_data: [],
+      steps: [],
+      custom: {}
+    }
+  } as ThreadMessage
+}
+
+// Mirrors chat/index.tsx: incremental runtime + messageRepository + onEdit.
+function IncrementalHarness({ onEdit }: { onEdit: () => Promise<void> }) {
+  const repository = ExportedMessageRepository.fromArray([userMessage(), assistantMessage()])
+
+  const runtime = useIncrementalExternalStoreRuntime<ThreadMessage>({
+    messageRepository: repository,
+    isRunning: false,
+    setMessages: () => {},
+    onNew: async () => {},
+    onEdit,
+    onCancel: async () => {},
+    onReload: async () => {}
+  })
+
+  return (
+    <AssistantRuntimeProvider runtime={runtime}>
+      <Thread />
+    </AssistantRuntimeProvider>
+  )
+}
+
+// Control: stock external store runtime.
+function StockHarness({ onEdit }: { onEdit: () => Promise<void> }) {
+  const runtime = useExternalStoreRuntime<ThreadMessage>({
+    messages: [userMessage(), assistantMessage()],
+    isRunning: false,
+    onNew: async () => {},
+    onEdit
+  })
+
+  return (
+    <AssistantRuntimeProvider runtime={runtime}>
+      <Thread />
+    </AssistantRuntimeProvider>
+  )
+}
+
+describe('click-to-edit user message', () => {
+  it('opens the edit composer with the incremental runtime', async () => {
+    const { container } = render(<IncrementalHarness onEdit={async () => {}} />)
+
+    const bubble = await screen.findByRole('button', { name: 'Edit message' })
+
+    fireEvent.click(bubble)
+
+    await waitFor(() => {
+      expect(container.querySelector('[data-slot="aui_edit-composer-root"]')).toBeTruthy()
+    })
+  })
+
+  it('opens the edit composer with the stock runtime', async () => {
+    const { container } = render(<StockHarness onEdit={async () => {}} />)
+
+    const bubble = await screen.findByRole('button', { name: 'Edit message' })
+
+    fireEvent.click(bubble)
+
+    await waitFor(() => {
+      expect(container.querySelector('[data-slot="aui_edit-composer-root"]')).toBeTruthy()
+    })
+  })
+})

apps/desktop/src/components/ui/tool-icon.tsx

@@ -0,0 +1,65 @@
+import type * as React from 'react'
+
+import { Codicon } from '@/components/ui/codicon'
+import { cn } from '@/lib/utils'
+
+// Solid (filled) glyphs for in-thread tool rows. Codicons are an outline icon
+// *font*, so an outline glyph has no separate fillable region — a filled look
+// can't be derived from it (stroke-thickening just bolds the outline). To get
+// the Cursor-style filled tool icons we render dedicated solid SVG paths,
+// keyed by the same names used in `TOOL_META` (tool-fallback-model.ts).
+//
+// Paths are Phosphor Icons (MIT) "fill" weight, 256×256 viewBox. Inlining the
+// path data mirrors the existing precedent in `directive-text.tsx`.
+const TOOL_ICON_PATHS: Record<string, string> = {
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+  question:
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+  terminal:
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+  tools:
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+  watch:
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+}
+
+export interface ToolIconProps {
+  className?: string
+  name: string
+  size?: number | string
+}
+
+/** Filled tool glyph. Falls back to the outline codicon font for any name not
+ *  covered by the solid set so new tools still render an icon. */
+export function ToolIcon({ className, name, size = '0.875rem' }: ToolIconProps) {
+  const path = TOOL_ICON_PATHS[name]
+
+  if (!path) {
+    return <Codicon className={className} name={name} size={size} />
+  }
+
+  const dimension: React.CSSProperties = { height: size, width: size }
+
+  return (
+    <svg
+      aria-hidden="true"
+      className={cn('shrink-0', className)}
+      fill="currentColor"
+      style={dimension}
+      viewBox="0 0 256 256"
+    >
+      <path d={path} />
+    </svg>
+  )
+}