feat(desktop): open the session a @session ref names

An agent-written ref rendered as a chip that went nowhere on click. It now
renders as an ordinary inline link — the agent wrote it mid-sentence, so it
should read like one — with the funnel icon leading the resolved title.
Clicking either surface (that link, or the chip in the user's own message)
opens the session as a tab, the way its sidebar row does.

The tile store loads on click rather than at import: the composer's rich
editor pulls this module in, so a static import would boot the profile store
and its REST routing along with every transcript render.

apps/desktop/src/components/assistant-ui/directive-text.tsx

@@ -7,9 +7,11 @@ import { Fragment, useEffect, useMemo, useState } from 'react'
 
 import { ZoomableImage } from '@/components/chat/zoomable-image'
 import { extractEmbeddedImages } from '@/lib/embedded-images'
+import { triggerHaptic } from '@/lib/haptics'
 import { gatewayMediaDataUrl, isRemoteGateway } from '@/lib/media'
 import { useSessionLinkTitle } from '@/lib/session-link-title'
-import { sessionRefFallbackLabel } from '@/lib/session-refs'
+import { parseSessionRefValue, sessionRefFallbackLabel } from '@/lib/session-refs'
+import { cn } from '@/lib/utils'
 
 const HERMES_REF_TYPES = ['file', 'folder', 'url', 'image', 'tool', 'line', 'terminal', 'session'] as const
 type HermesRefType = (typeof HERMES_REF_TYPES)[number]
@@ -121,9 +123,12 @@ export function slashIconElement(kind: SlashChipKind) {
   return iconElementFromPaths(SLASH_ICON_PATHS[kind])
 }
 
-const DirectiveIcon: FC<{ type: string }> = ({ type }) => (
+const DirectiveIcon: FC<{ type: string; className?: string }> = ({
+  type,
+  className = 'size-3 shrink-0 opacity-80'
+}) => (
   <svg
-    className="size-3 shrink-0 opacity-80"
+    className={className}
     fill="none"
     stroke="currentColor"
     strokeLinecap="round"
@@ -447,31 +452,87 @@ const DirectiveImage: FC<{ id: string; label: string }> = ({ id, label }) => {
   )
 }
 
-/** A `@session:<profile>/<id>` reference, rendered as the session's title once
- *  resolved. Shared by the user transcript (directive segments) and assistant
- *  markdown (`#session/` links rewritten in `preprocessMarkdown`). */
+/** Opens the referenced session as a tab — same as middle-clicking its sidebar
+ *  row. The tile store loads on click, not at import: the composer's rich
+ *  editor pulls this module in, and a static import would boot the profile
+ *  store (and its REST routing) along with it. */
+function openSessionRef(value: string) {
+  const { sessionId } = parseSessionRefValue(value)
+
+  if (!sessionId) {
+    return
+  }
+
+  triggerHaptic('selection')
+  void import('@/store/session-states').then(({ openSessionTile }) => openSessionTile(sessionId, 'center'))
+}
+
+/** A `@session:<profile>/<id>` reference in the user transcript (directive
+ *  segments), rendered as a chip like the other composer refs. Clicking it
+ *  opens the session as a tab. */
 export const SessionRefChip: FC<{
   label?: string
   value: string
 }> = ({ label, value }) => {
   const resolved = useSessionLinkTitle(value, label)
 
-  return <DirectiveChip id={value} label={resolved} type="session" />
+  return <DirectiveChip id={value} label={resolved} onClick={() => openSessionRef(value)} type="session" />
 }
 
+/** A `@session:` reference in assistant markdown (`#session/` links rewritten
+ *  in `preprocessMarkdown`). Reads as an ordinary inline link — the agent wrote
+ *  it mid-sentence — with the funnel icon leading the resolved title. */
+export const SessionRefLink: FC<{
+  label?: string
+  value: string
+}> = ({ label, value }) => {
+  const resolved = useSessionLinkTitle(value, label)
+
+  return (
+    <a
+      className="font-semibold text-foreground underline underline-offset-4 decoration-current/20 wrap-anywhere"
+      href="#"
+      onClick={event => {
+        event.preventDefault()
+        event.stopPropagation()
+        openSessionRef(value)
+      }}
+      title={value}
+    >
+      <DirectiveIcon className="mr-1 inline size-[0.82em] align-[-0.08em] opacity-70" type="session" />
+      {resolved}
+    </a>
+  )
+}
+
+/** Inert by default; `onClick` promotes the chip to a real button (session
+ *  refs, which open the session they name). */
 const DirectiveChip: FC<{
   type: string
   label: string
   id: string
-}> = ({ type, label, id }) => (
-  <span
-    className={DIRECTIVE_CHIP_CLASS}
-    data-directive-id={id}
-    data-directive-type={type}
-    data-slot="aui_directive-chip"
-    title={id}
-  >
-    <DirectiveIcon type={type} />
-    <span className="truncate">{label}</span>
-  </span>
-)
+  onClick?: () => void
+}> = ({ type, label, id, onClick }) => {
+  const body = (
+    <>
+      <DirectiveIcon type={type} />
+      <span className="truncate">{label}</span>
+    </>
+  )
+
+  const props = {
+    className: cn(DIRECTIVE_CHIP_CLASS, onClick && 'cursor-pointer transition-colors hover:text-foreground'),
+    'data-directive-id': id,
+    'data-directive-type': type,
+    'data-slot': 'aui_directive-chip',
+    title: id
+  }
+
+  return onClick ? (
+    <button {...props} onClick={onClick} type="button">
+      {body}
+    </button>
+  ) : (
+    <span {...props}>{body}</span>
+  )
+}

apps/desktop/src/components/assistant-ui/markdown-text.session.test.tsx

@@ -35,26 +35,26 @@ afterEach(() => {
 
 // End-to-end for the agent-authored path: a bare ref in assistant markdown has
 // to survive preprocessMarkdown -> Streamdown -> MarkdownLink and come out as
-// the session chip, not as literal text or a dead anchor.
+// an inline link titled after the session, not as literal text.
 describe('MarkdownTextContent session refs', () => {
-  it('renders an agent-written @session ref as a chip showing the session title', async () => {
+  it('renders an agent-written @session ref as a link showing the session title', async () => {
     $sessions.set([makeSession()])
 
     render(<MarkdownTextContent isRunning={false} text="Context lives in @session:work/20260101_abc123 today." />)
 
-    const chip = await screen.findByTitle('work/20260101_abc123')
+    const link = await screen.findByTitle('work/20260101_abc123')
 
-    expect(chip.dataset.directiveType).toBe('session')
-    expect(chip.textContent).toBe('Branch plan')
+    expect(link.tagName).toBe('A')
+    expect(link.textContent).toBe('Branch plan')
     expect(screen.queryByText(/@session:/)).toBeNull()
   })
 
   it('falls back to a short id when the session is unknown', async () => {
     render(<MarkdownTextContent isRunning={false} text="See @session:work/20260101_abc123 for context." />)
 
-    const chip = await screen.findByTitle('work/20260101_abc123')
+    const link = await screen.findByTitle('work/20260101_abc123')
 
-    expect(chip.textContent).toBe('20260101…')
+    expect(link.textContent).toBe('20260101…')
   })
 
   it('leaves a ref inside inline code as literal text', () => {

apps/desktop/src/components/assistant-ui/markdown-text.tsx

@@ -33,7 +33,7 @@ import { previewTargetFromMarkdownHref } from '@/lib/preview-targets'
 import { sessionRefFromMarkdownHref } from '@/lib/session-refs'
 import { cn } from '@/lib/utils'
 
-import { SessionRefChip } from './directive-text'
+import { SessionRefLink } from './directive-text'
 import { detectEmbed, extractAlert, MarkdownAlert, RichCodeBlock, UrlEmbed } from './embeds'
 
 // Math rendering plugin (KaTeX). Configured once at module scope — the
@@ -238,7 +238,7 @@ function MarkdownLink({ children, className, href, ...props }: ComponentProps<'a
   const sessionRef = sessionRefFromMarkdownHref(href)
 
   if (sessionRef) {
-    return <SessionRefChip value={sessionRef} />
+    return <SessionRefLink value={sessionRef} />
   }
 
   const target = href ? normalizeExternalUrl(href) : href

apps/desktop/src/components/assistant-ui/session-ref-open.test.tsx

@@ -0,0 +1,43 @@
+import { cleanup, fireEvent, render, screen } from '@testing-library/react'
+import { afterEach, describe, expect, it, vi } from 'vitest'
+
+import { __resetSessionLinkTitleCache } from '@/lib/session-link-title'
+
+import { DirectiveContent } from './directive-text'
+import { MarkdownTextContent } from './markdown-text'
+
+const openSessionTile = vi.fn()
+
+vi.mock('@/store/session-states', () => ({
+  openSessionTile: (...args: unknown[]) => openSessionTile(...args)
+}))
+
+afterEach(() => {
+  cleanup()
+  openSessionTile.mockClear()
+  __resetSessionLinkTitleCache()
+})
+
+// Both surfaces render a session ref differently — an inline link in agent
+// prose, a chip in the user's own message — but either one opens the session
+// it names, the way its sidebar row would.
+describe('session refs open the session', () => {
+  it('opens the session from an agent-written link', async () => {
+    render(<MarkdownTextContent isRunning={false} text="Picked up in @session:work/20260101_abc123 last night." />)
+
+    fireEvent.click(await screen.findByTitle('work/20260101_abc123'))
+
+    await vi.waitFor(() => expect(openSessionTile).toHaveBeenCalledWith('20260101_abc123', 'center'))
+  })
+
+  it('opens the session from a chip in the user transcript', async () => {
+    render(<DirectiveContent text="pick up @session:work/20260101_abc123 please" />)
+
+    const chip = screen.getByTitle('work/20260101_abc123')
+
+    expect(chip.tagName).toBe('BUTTON')
+    fireEvent.click(chip)
+
+    await vi.waitFor(() => expect(openSessionTile).toHaveBeenCalledWith('20260101_abc123', 'center'))
+  })
+})