Resolve PR repo probe without active branch to avoid forever spinner

Previously, checking if a repository is a GitHub remote required an
active branch. In a detached HEAD or mid-rebase state (where the branch
is null), the probe never resolved, leaving the PR panel on a forever
spinner.

Decouple the repository probe from the branch presence so the panel
can correctly display the "Current branch unavailable" state. Also,
hide the PR status chip when no branch is active to avoid a spinner
on the chip.

mobile/src/session/use-mobile-pr-sidebar-controller-probe.test.ts

@@ -0,0 +1,100 @@
+import { createElement } from 'react'
+import { act, create, type ReactTestRenderer } from 'react-test-renderer'
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import type { RpcClient } from '../transport/rpc-client'
+
+const fetchGithubRepoSlugMock = vi.fn()
+
+// Only the repo probe matters here; the load path never runs without a branch.
+vi.mock('./github-pr-rpc', () => ({
+  fetchGithubRepoSlug: (...args: unknown[]) => fetchGithubRepoSlugMock(...args),
+  fetchHostedReviewForBranch: vi.fn(),
+  fetchPRChecks: vi.fn(),
+  fetchPRForBranch: vi.fn(),
+  fetchWorkItemDetails: vi.fn()
+}))
+vi.mock('../source-control/mobile-pr-link', () => ({
+  fetchWorktreeLinkedPR: vi.fn(async () => null)
+}))
+
+import {
+  useMobilePrSidebarController,
+  type MobilePrSidebarController
+} from './use-mobile-pr-sidebar-controller'
+
+let captured: MobilePrSidebarController | null = null
+
+function Harness(props: Parameters<typeof useMobilePrSidebarController>[0]) {
+  captured = useMobilePrSidebarController(props)
+  return null
+}
+
+async function flush(): Promise<void> {
+  // Two ticks: the probe's resolved promise (.then) plus its setState commit.
+  await act(async () => {
+    await Promise.resolve()
+    await Promise.resolve()
+  })
+}
+
+describe('useMobilePrSidebarController repo probe', () => {
+  const client = { sendRequest: vi.fn() } as unknown as RpcClient
+  let renderer: ReactTestRenderer | null = null
+
+  beforeEach(() => {
+    captured = null
+    fetchGithubRepoSlugMock.mockReset()
+  })
+
+  afterEach(() => {
+    act(() => {
+      renderer?.unmount()
+    })
+    renderer = null
+  })
+
+  // Regression: repo eligibility must not be gated on a branch. A detached HEAD /
+  // mid-rebase worktree (branch === null) still has to resolve the probe, or the
+  // Pull Request segment gets stranded on a forever spinner instead of the
+  // "Current branch unavailable" state.
+  it('resolves the probe when connected without a branch (detached HEAD)', async () => {
+    fetchGithubRepoSlugMock.mockResolvedValue({ ok: true, result: { owner: 'o', repo: 'r' } })
+    await act(async () => {
+      renderer = create(
+        createElement(Harness, {
+          client,
+          connState: 'connected',
+          worktreeId: 'w',
+          branch: null,
+          headSha: 'sha'
+        })
+      )
+    })
+    await flush()
+
+    expect(fetchGithubRepoSlugMock).toHaveBeenCalledWith(client, 'w')
+    expect(captured?.prSidebarRepoProbeLoaded).toBe(true)
+    expect(captured?.prSidebarIsGithubRepo).toBe(true)
+    // No branch means no PR load ran — state stays hidden, never a spinner.
+    expect(captured?.prSidebarState.kind).toBe('hidden')
+  })
+
+  it('does not probe until the client is connected', async () => {
+    fetchGithubRepoSlugMock.mockResolvedValue({ ok: true, result: { owner: 'o', repo: 'r' } })
+    await act(async () => {
+      renderer = create(
+        createElement(Harness, {
+          client,
+          connState: 'connecting',
+          worktreeId: 'w',
+          branch: null,
+          headSha: 'sha'
+        })
+      )
+    })
+    await flush()
+
+    expect(fetchGithubRepoSlugMock).not.toHaveBeenCalled()
+    expect(captured?.prSidebarRepoProbeLoaded).toBe(false)
+  })
+})

mobile/src/session/use-mobile-pr-sidebar-controller.ts

@@ -70,7 +70,11 @@ export function useMobilePrSidebarController(input: PrSidebarControllerInput) {
   stateRef.current = state
   const headShaRef = useRef(headSha)
 
-  const ready = client !== null && connState === 'connected' && !!branch
+  // Repo eligibility (a GitHub remote) is independent of the branch, so the probe
+  // must not require one: a detached HEAD / mid-rebase worktree (branch === null)
+  // would otherwise never set repoProbeLoaded, stranding the PR segment on a
+  // forever spinner instead of the "Current branch unavailable" state.
+  const probeReady = client !== null && connState === 'connected'
   const identity = buildMobilePrSidebarIdentity({ worktreeId, branch })
 
   const buildDeps = useCallback((): PrSidebarLoadDeps | null => {
@@ -96,7 +100,7 @@ export function useMobilePrSidebarController(input: PrSidebarControllerInput) {
 
   useEffect(() => {
     let cancelled = false
-    if (!ready || !client) {
+    if (!probeReady || !client) {
       return
     }
     void fetchGithubRepoSlug(client, worktreeId).then((outcome) => {
@@ -108,7 +112,7 @@ export function useMobilePrSidebarController(input: PrSidebarControllerInput) {
     return () => {
       cancelled = true
     }
-  }, [ready, client, worktreeId])
+  }, [probeReady, client, worktreeId])
 
   useEffect(() => {
     if (!identity) {

mobile/src/source-control/MobileSourceControlPanel.tsx

@@ -200,7 +200,10 @@ export function MobileSourceControlPanel({
   }, [activeTab, isHostedRepo, prBranch, prSidebarKind, prDetailsMissingFor])
 
   const prChip = useMemo(() => {
-    if (!isHostedRepo) {
+    // No branch (detached HEAD / mid-rebase) never runs a PR load, so the shared
+    // state stays 'hidden' — which the chip would render as a forever spinner.
+    // Hide the chip instead; the Pull Request segment shows "branch unavailable".
+    if (!isHostedRepo || !prBranch) {
       return null
     }
     const commentCount =
@@ -208,7 +211,7 @@ export function MobileSourceControlPanel({
         ? countUnresolvedReviewThreads(prController.prSidebarState.data.details?.comments)
         : null
     return buildMobilePrChipSummary(prController.prSidebarState, commentCount)
-  }, [isHostedRepo, prController.prSidebarState])
+  }, [isHostedRepo, prBranch, prController.prSidebarState])
 
   // Design: refresh the active segment's body work, plus git.status for the shared
   // branch card (counts/sync stay honest even while on History). Preserve ready