fix(git): skip upstream remote probes when the remote is absent (#18455)

* fix(git): skip upstream remote probes when the remote is absent

Issue and PR resolvers listed remotes by probing `git remote get-url
upstream` on every poll, including origin-only clones where that remote
cannot exist. List remotes once, cache against git config, and skip the
probe unless `upstream` is present.

* fix(git): avoid stale remote probe cache entries

* fix(github): observe origin repository probe failures

* fix(github): observe verified origin probe failures

* fix(github): skip missing upstream probe for PR lists

* test(github): scope the #9171 lazy-resolution guard to default-branch commands

The guard asserted that no git command runs for an open PR, using "no git at
all" as a proxy for "no default-branch resolution". Remote-name listing is a
separate concern, so allow it and keep every other command forbidden; the
symbolic-ref/rev-parse resolution this issue is about stays unreachable.

---------

Co-authored-by: Neil <neil@stably.ai>

src/main/github/client-work-items.test.ts

@@ -116,6 +116,7 @@ import {
   _resetOwnerRepoCache
 } from './client'
 import { GITHUB_WORK_ITEMS_QUERY_MAX_BYTES } from '../../shared/github/work-items-query-bounds'
+import { _resetRemoteNameListingCache } from '../git/remote-name-listing'
 
 import { _resetOriginGitHubApiRepositoryCache } from './github-api-repository'
 
@@ -156,6 +157,7 @@ describe('listWorkItems', () => {
         remoteName === 'origin' ? getOwnerRepoMock(repoPath, connectionId, opts) : null
     )
     _resetOwnerRepoCache()
+    _resetRemoteNameListingCache()
     _resetMergeQueueCacheForTests()
   })
 
@@ -383,6 +385,31 @@ describe('listWorkItems', () => {
     )
   })
 
+  it('skips upstream PR source probing when the clone only has origin', async () => {
+    getIssueOwnerRepoMock.mockResolvedValue(null)
+    getOwnerRepoMock.mockResolvedValue({ owner: 'fork', repo: 'orca' })
+    gitExecFileAsyncMock.mockResolvedValue({ stdout: 'origin\n' })
+    ghExecFileAsyncMock.mockResolvedValue({ stdout: '[]' })
+
+    await expect(listWorkItems('/origin-only-repo', 10, 'is:pr')).resolves.toMatchObject({
+      items: [],
+      sources: {
+        issues: null,
+        prs: { owner: 'fork', repo: 'orca' },
+        originCandidate: { owner: 'fork', repo: 'orca' },
+        upstreamCandidate: null
+      }
+    })
+
+    expect(getOwnerRepoForRemoteMock.mock.calls.map(([, remote]) => remote)).not.toContain(
+      'upstream'
+    )
+    expect(gitExecFileAsyncMock).toHaveBeenCalledWith(
+      ['remote'],
+      expect.objectContaining({ cwd: '/origin-only-repo' })
+    )
+  })
+
   it('rejects oversized queries before resolving repo sources or executing gh', async () => {
     const secret = 'main-github-work-items-secret'
     const oversizedQuery = secret + 'x'.repeat(GITHUB_WORK_ITEMS_QUERY_MAX_BYTES)