fix(desktop): boot session pop-out/watch windows against the session's owning profile

`openSessionInNewWindow` → IPC `hermes🪟openSession` →
`buildSessionWindowUrl` emitted no `profile`, so a secondary window (⇧⌘-click
pop-out, subagent watch) was a full renderer that adopted the PRIMARY
backend's profile and resolved the session id against the wrong store —
blank/wrong session for any non-primary profile (#82768, #61286).

The owning profile now rides the URL as `&profile=`, exactly the carry the
HUD already does (buildHudWindowUrl / windowProfileOverride in
use-gateway-boot); the renderer picks it with the same ladder openHud uses:
the session's stamped owner wins, an unstamped/uncached id (a brand-new
subagent child) inherits the profile the user is looking at.

Diagnosis credit: @DomGrieco (#82794).

Co-authored-by: DomGrieco <6556434+DomGrieco@users.noreply.github.com>

apps/desktop/electron/main.ts

@@ -13053,7 +13053,11 @@ function focusWindow(win) {
   win.focus()
 }
 
-function spawnSecondaryWindow({ sessionId, watch }: { sessionId?: string; watch?: boolean } = {}) {
+function spawnSecondaryWindow({
+  sessionId,
+  profile,
+  watch
+}: { sessionId?: string; profile?: null | string; watch?: boolean } = {}) {
   const icon = getAppIconPath()
 
   const win = new BrowserWindow({
@@ -13115,6 +13119,7 @@ function spawnSecondaryWindow({ sessionId, watch }: { sessionId?: string; watch?
     win,
     buildSessionWindowUrl(sessionId, {
       devServer: DEV_SERVER,
+      profile,
       rendererIndexPath: DEV_SERVER ? undefined : resolveRendererIndex(),
       watch
     }),
@@ -13125,8 +13130,8 @@ function spawnSecondaryWindow({ sessionId, watch }: { sessionId?: string; watch?
 }
 
 // Open (or focus) a standalone window for a single chat session.
-function createSessionWindow(sessionId, { watch = false } = {}) {
-  return sessionWindows.openOrFocus(sessionId, () => spawnSecondaryWindow({ sessionId, watch }))
+function createSessionWindow(sessionId, { profile = null, watch = false } = {}) {
+  return sessionWindows.openOrFocus(sessionId, () => spawnSecondaryWindow({ sessionId, profile, watch }))
 }
 
 // Popped-out in-app Browser: same webview + address bar as a docked Browser
@@ -14613,7 +14618,10 @@ ipcMain.handle('hermes:window:openSession', async (_event, sessionId, opts) => {
     return { ok: false, error: 'invalid-session-id' }
   }
 
-  createSessionWindow(sessionId.trim(), { watch: opts?.watch === true })
+  createSessionWindow(sessionId.trim(), {
+    profile: typeof opts?.profile === 'string' ? opts.profile : null,
+    watch: opts?.watch === true
+  })
 
   return { ok: true }
 })

apps/desktop/electron/session-windows.test.ts

@@ -68,6 +68,12 @@ test('buildSessionWindowUrl avoids a double slash when the dev server has a trai
   assert.equal(url, 'http://localhost:5173/?win=secondary#/abc123')
 })
 
+test('buildSessionWindowUrl carries the owning profile in the query before the hash (#82768)', () => {
+  const url = buildSessionWindowUrl('abc123', { devServer: 'http://localhost:5173', profile: 'work', watch: true })
+
+  assert.equal(url, 'http://localhost:5173/?win=secondary&watch=1&profile=work#/abc123')
+})
+
 test('buildSessionWindowUrl encodes the session id in the hash route', () => {
   const url = buildSessionWindowUrl('a b/c', { devServer: 'http://localhost:5173' })
 

apps/desktop/electron/session-windows.ts

@@ -64,8 +64,13 @@ function chatWindowWebPreferences(preloadPath: string) {
 // onboarding overlays and the global session sidebar. `watch=1` marks a
 // spectator window (e.g. a running subagent's session): the renderer resumes it
 // lazily so the gateway never builds an agent just to stream into it.
-function buildSessionWindowUrl(sessionId: string, { devServer, rendererIndexPath, watch }: any = {}) {
-  const query = `?win=secondary${watch ? '&watch=1' : ''}`
+// `profile` names the backend the window must boot against (same carry as the
+// HUD's buildHudWindowUrl): without it a pop-out/watch window adopts the
+// PRIMARY profile and resolves the session id against the wrong backend
+// (#82768, #61286). Absent → unchanged primary adoption.
+function buildSessionWindowUrl(sessionId: string, { devServer, profile, rendererIndexPath, watch }: any = {}) {
+  const profileKey = typeof profile === 'string' ? profile.trim() : ''
+  const query = `?win=secondary${watch ? '&watch=1' : ''}${profileKey ? `&profile=${encodeURIComponent(profileKey)}` : ''}`
   const route = `#/${encodeURIComponent(sessionId)}`
 
   if (devServer) {

apps/desktop/src/global.d.ts

@@ -52,7 +52,10 @@ declare global {
       // with an error code when the sessionId is empty/invalid. `watch` opens
       // a spectator window (lazy resume — no agent build) for live-streaming
       // a running subagent's session.
-      openSessionWindow: (sessionId: string, opts?: { watch?: boolean }) => Promise<{ ok: boolean; error?: string }>
+      openSessionWindow: (
+        sessionId: string,
+        opts?: { profile?: null | string; watch?: boolean }
+      ) => Promise<{ ok: boolean; error?: string }>
       // Resume this session in the user's own terminal emulator (`hermes --tui
       // --resume <id>`) — the external terminal, not the in-app pane.
       openSessionInTerminal: (

apps/desktop/src/store/windows.test.ts

@@ -1,5 +1,7 @@
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
 
+import { $activeGatewayProfile } from './profile'
+import { $sessions } from './session'
 import {
   canOpenBrowserWindow,
   canOpenNewWindow,
@@ -88,23 +90,17 @@ describe('openSessionInNewWindow', () => {
     expect(notifyError).not.toHaveBeenCalled()
   })
 
-  it('invokes the bridge with the session id', async () => {
+  it('carries the owning profile: stamped row wins, an unstamped child inherits the viewed profile (#82768)', async () => {
     const open = vi.fn().mockResolvedValue({ ok: true })
     installBridge(open)
+    $activeGatewayProfile.set('work')
+    $sessions.set([{ id: 's1', profile: 'research' } as never])
 
     await openSessionInNewWindow('s1')
+    await openSessionInNewWindow('child-not-listed-yet', { watch: true })
 
-    expect(open).toHaveBeenCalledWith('s1', undefined)
-    expect(notifyError).not.toHaveBeenCalled()
-  })
-
-  it('forwards the watch flag for spectator (subagent) windows', async () => {
-    const open = vi.fn().mockResolvedValue({ ok: true })
-    installBridge(open)
-
-    await openSessionInNewWindow('s1', { watch: true })
-
-    expect(open).toHaveBeenCalledWith('s1', { watch: true })
+    expect(open).toHaveBeenCalledWith('s1', { profile: 'research' })
+    expect(open).toHaveBeenCalledWith('child-not-listed-yet', { profile: 'work', watch: true })
     expect(notifyError).not.toHaveBeenCalled()
   })
 

apps/desktop/src/store/windows.ts

@@ -189,13 +189,26 @@ async function runWindowOpen(call: () => Promise<WindowOpenResult>, failMessage:
 // Open (or focus) a standalone OS window for a single chat session. No-ops
 // gracefully outside Electron so callers can wire it unconditionally.
 // `watch: true` opens a spectator window (lazy resume, live-mirror stream).
+// The window is a full renderer that adopts the PRIMARY profile unless told
+// otherwise, so the owning profile rides along (same ladder as openHud,
+// #82285): the session's stamped owner wins, and an unstamped/uncached id —
+// a brand-new subagent child — inherits the profile the user is looking at
+// (#82768, #61286).
 export async function openSessionInNewWindow(sessionId: string, opts?: { watch?: boolean }): Promise<void> {
   if (!sessionId || !canOpenSessionWindow()) {
     return
   }
 
+  // Lazy imports: `./profile` subscribes to the API client on load, so a
+  // static import here would drag it into every page that opens windows.
+  const [{ $activeGatewayProfile, normalizeProfileKey }, { $sessions, rememberedSessionProfile }] = await Promise.all([
+    import('./profile'),
+    import('./session')
+  ])
+  const profile = normalizeProfileKey(rememberedSessionProfile($sessions.get(), sessionId, $activeGatewayProfile.get()))
+
   await runWindowOpen(
-    () => window.hermesDesktop.openSessionWindow(sessionId, opts),
+    () => window.hermesDesktop.openSessionWindow(sessionId, { ...opts, profile }),
     'Could not open chat in a new window'
   )
 }