fix(desktop): pin the project '+' new chat to the profile its tree is shown under

workspace-session-target.ts never set $newChatProfile, so a new session
started from a project's "+" reached desktopSessionCreateParams with no
intent and fell back to $activeGatewayProfile — which an in-flight profile
swap can move between the click and Send, landing session.create on the
wrong backend (#79005 flaw 3, second path). Pin the tree's profile
(projectProfile()) via the same intent write newSessionInProfile uses.

Fixes #79005

apps/desktop/src/app/session/workspace-session-target.test.ts

@@ -1,5 +1,6 @@
 import { afterEach, describe, expect, it, vi } from 'vitest'
 
+import { $activeGatewayProfile, $newChatProfile } from '@/store/profile'
 import { $projectScope, $projectTree, ALL_PROJECTS } from '@/store/projects'
 import {
   $currentBranch,
@@ -22,6 +23,8 @@ describe('startWorkspaceSession', () => {
     setNewChatWorkspaceTarget(undefined)
     $projectScope.set(ALL_PROJECTS)
     $projectTree.set([])
+    $activeGatewayProfile.set('default')
+    $newChatProfile.set(null)
     vi.restoreAllMocks()
   })
 
@@ -107,4 +110,22 @@ describe('startWorkspaceSession', () => {
     expect($newChatWorkspaceTarget.get()).toBeNull()
     expect($currentCwd.get()).toBe('')
   })
+
+  // #79005 flaw 3: the project "+" must pin the profile the tree is shown
+  // under; otherwise session.create reads $activeGatewayProfile after a swap.
+  it('pins the new chat to the profile the project tree is displayed under', () => {
+    $activeGatewayProfile.set('work')
+    $newChatProfile.set(null)
+
+    startWorkspaceSession({
+      activeSessionIdRef: { current: null },
+      path: '/workspace-work',
+      requestGateway: vi.fn(() => new Promise<never>(() => {})),
+      startFreshSessionDraft: vi.fn()
+    })
+
+    $activeGatewayProfile.set('personal')
+
+    expect($newChatProfile.get()).toBe('work')
+  })
 })

apps/desktop/src/app/session/workspace-session-target.ts

@@ -1,6 +1,7 @@
 import type { MutableRefObject } from 'react'
 
-import { followActiveSessionCwd, resolveNewSessionCwd } from '@/store/projects'
+import { pinNewChatProfile } from '@/store/profile'
+import { followActiveSessionCwd, projectProfile, resolveNewSessionCwd } from '@/store/projects'
 import {
   $newChatWorkspaceTargetGeneration,
   type NewChatWorkspaceTarget,
@@ -26,6 +27,16 @@ export function startWorkspaceSession({
   requestGateway,
   startFreshSessionDraft
 }: WorkspaceSessionOptions): void {
+  // The project tree is rendered under one profile; the "+" belongs to it.
+  // Pin that intent now — otherwise desktopSessionCreateParams falls back to
+  // $activeGatewayProfile, which a still-settling profile swap can move
+  // between this click and Send (#79005). All-profiles view has no owner.
+  const profile = projectProfile()
+
+  if (profile) {
+    pinNewChatProfile(profile)
+  }
+
   // Home's "+" passes path=null on purpose ("no folder"). That must stay
   // detached — do NOT fall through to resolveNewSessionCwd(), which can still
   // return a default/remembered project folder and re-attach the last repo

apps/desktop/src/store/profile.ts

@@ -857,6 +857,18 @@ function activateOnCurrentSource(target: string): Promise<void> {
   return connectionId ? ensureGatewayAgent(connectionId, target) : ensureGatewayProfile(target)
 }
 
+// Pin the next new chat to `name` (legacy profile-only door) so session.create
+// reads the profile the user clicked "+" under, not whatever
+// $activeGatewayProfile holds once an in-flight profile swap settles (#79005).
+export function pinNewChatProfile(name: string): string {
+  const target = normalizeProfileKey(name)
+  $newChatProfile.set(target)
+  $newChatRoute.set(null)
+  captureNewChatSource(profilePickConnectionId(target))
+
+  return target
+}
+
 // Start a fresh session in `name` WITHOUT collapsing the "All profiles" browse
 // view. Unlike selectProfile, it leaves $showAllProfiles untouched, so the
 // unified sidebar stays put — used by the per-profile "+" in the all-profiles
@@ -864,10 +876,7 @@ function activateOnCurrentSource(target: string): Promise<void> {
 // is in. Points new chats at the profile and opens its backend so the next
 // message lands in the right place.
 export function newSessionInProfile(name: string): void {
-  const target = normalizeProfileKey(name)
-  $newChatProfile.set(target)
-  $newChatRoute.set(null)
-  captureNewChatSource(profilePickConnectionId(target))
+  const target = pinNewChatProfile(name)
   requestFreshSession()
   // #81094: surface the failed dial instead of failing silently.
   void activateOnCurrentSource(target).catch((error: unknown) => {

apps/desktop/src/store/projects.ts

@@ -349,7 +349,7 @@ async function gatewayRequest<T>(method: string, params: Record<string, unknown>
   return gateway.request<T>(method, params)
 }
 
-function projectProfile(): null | string {
+export function projectProfile(): null | string {
   const profile = normalizeProfileKey($activeGatewayProfile.get())
 
   return $profileScope.get() === ALL_PROFILES || profile === ALL_PROFILES ? null : profile