From 7bff50b45745473c1bfb964f5cb32ffaa593b5ce Mon Sep 17 00:00:00 2001
From: Neil <4138956+nwparker@users.noreply.github.com>
Date: Mon, 19 Oct 2026 13:58:12 -0700
Subject: [PATCH] fix(native-chat): a new chat in a twin folder, or a twin with
 no copy picked, refuses instead of starting on this computer (#30838)

---
 .../runtime/structured-agent-session-owner.ts |  8 ++--
 .../store/host-twin-owner-refusals.test.ts    | 47 +++++++++++++++++++
 2 files changed, 52 insertions(+), 3 deletions(-)

diff --git a/src/renderer/src/runtime/structured-agent-session-owner.ts b/src/renderer/src/runtime/structured-agent-session-owner.ts
index bd3dcc09a7b..fecda534f39 100644
--- a/src/renderer/src/runtime/structured-agent-session-owner.ts
+++ b/src/renderer/src/runtime/structured-agent-session-owner.ts
@@ -7,7 +7,7 @@ import {
 import type { Tab } from '../../../shared/tab-types'
 import { getExecutionHostIdForWorktree } from '@/lib/worktree-runtime-owner'
 import type { WorktreeRuntimeOwnerState } from '@/lib/worktree-runtime-owner-state'
-import { resolveIndexedWorktreeOwner } from '@/lib/worktree-runtime-owner-index'
+import { isTwinWorkspace, namedHostForOwnerRef } from '@/lib/resolve-owner'
 import { LOCAL_STRUCTURED_SESSION_OWNER } from './local-structured-session-owner'
 import { runtimeRpcTargetForAuthorityKey } from './runtime-client-target'
 import type { RuntimeClientTarget } from '../../../shared/runtime-client-target'
@@ -33,9 +33,11 @@ export function resolveStructuredAgentSessionOwner(
   state: WorktreeRuntimeOwnerState,
   worktreeId: string
 ): ExecutionHostId | null {
+  // Why resolveOwner's twin rule: an id-only check missed folder twins and an active twin with no
+  // host picked, and the fallback below reads both as this machine.
   if (
-    state.activeWorktreeId !== worktreeId &&
-    resolveIndexedWorktreeOwner(state.worktreesByRepo, worktreeId).kind === 'ambiguous'
+    !namedHostForOwnerRef(state, { workspaceId: worktreeId }) &&
+    isTwinWorkspace(state, worktreeId)
   ) {
     return null
   }
diff --git a/src/renderer/src/store/host-twin-owner-refusals.test.ts b/src/renderer/src/store/host-twin-owner-refusals.test.ts
index a009a9ca55c..05699e3d755 100644
--- a/src/renderer/src/store/host-twin-owner-refusals.test.ts
+++ b/src/renderer/src/store/host-twin-owner-refusals.test.ts
@@ -45,6 +45,8 @@ const { resolveNativeChatSkillDiscoveryContext, selectNativeChatSkillStateInputs
   await import('@/components/native-chat/native-chat-skill-discovery-context')
 const { mirroredRuntimeEnvironmentIdForWorkspace } =
   await import('@/runtime/web-session-tabs-sync/mirrored-workspace-owner')
+const { resolveStructuredAgentSessionOwner } =
+  await import('@/runtime/structured-agent-session-owner')
 
 const RUNTIME_HOST: ExecutionHostId = `runtime:${TWIN_RUNTIME_ENV}`
 
@@ -213,6 +215,51 @@ describe('folder workspace twin', () => {
   )
 })
 
+describe('a new structured chat', () => {
+  it.each<HostTwinKind>(['folder local+ssh', 'folder group local+ssh'])(
+    'refuses a %s twin instead of starting on this computer',
+    (kind) => {
+      const { store, workspaceKey } = bind(createHostTwinFixture(kind))
+      expect(resolveStructuredAgentSessionOwner(store.getState(), workspaceKey)).toBeNull()
+      store.setState({ activeWorktreeId: workspaceKey, activeWorkspaceExecutionHostId: null })
+      expect(resolveStructuredAgentSessionOwner(store.getState(), workspaceKey)).toBeNull()
+    }
+  )
+
+  it('refuses an active worktree twin with no copy picked, and starts on the picked one', () => {
+    const { store, workspaceKey } = bind(createHostTwinFixture('local+runtime'))
+    store.setState({ activeWorktreeId: workspaceKey, activeWorkspaceExecutionHostId: null })
+    expect(resolveStructuredAgentSessionOwner(store.getState(), workspaceKey)).toBeNull()
+    store.setState({ activeWorkspaceExecutionHostId: RUNTIME_HOST })
+    expect(resolveStructuredAgentSessionOwner(store.getState(), workspaceKey)).toBe(RUNTIME_HOST)
+  })
+
+  it("starts on the copy the user picked, and on a lone unstamped folder's computer", () => {
+    const { store, workspaceKey, projectId } = bind(createHostTwinFixture('folder local+ssh'))
+    store.setState({ activeWorktreeId: workspaceKey, activeWorkspaceExecutionHostId: 'local' })
+    expect(resolveStructuredAgentSessionOwner(store.getState(), workspaceKey)).toBe('local')
+    store.setState({
+      activeWorktreeId: null,
+      activeWorkspaceExecutionHostId: null,
+      projectGroups: [],
+      folderWorkspaces: [makeFolderWorkspace({ id: projectId, folderPath: '/work/twin' })]
+    })
+    expect(resolveStructuredAgentSessionOwner(store.getState(), workspaceKey)).toBe('local')
+  })
+
+  it('starts a lone unstamped worktree on this computer', () => {
+    const fixture = bind(createHostTwinFixture('local+ssh'))
+    const { store, workspaceKey, projectId } = fixture
+    store.setState({
+      repos: store.getState().repos.filter((repo) => !repo.connectionId),
+      worktreesByRepo: {
+        [projectId]: [makeWorktree({ id: workspaceKey, repoId: projectId, path: '/work/twin' })]
+      }
+    })
+    expect(resolveStructuredAgentSessionOwner(store.getState(), workspaceKey)).toBe('local')
+  })
+})
+
 describe('a workspace selected on the unresolved-owner sentinel', () => {
   it('neither reopens a terminal locally nor uploads an attachment', () => {
     const { store, workspaceKey } = runtimeOnly()