fix(gitea): treat HTTP 404 as no-PR in the hosted-review branch lookup (#10411)

* fix(gitea): treat HTTP 404 as no-PR in throwing hosted-review lookup

hostedReview:forBranch always uses the throwing Gitea lookup variant, and
requestJsonAtBase threw on any non-OK status. A 404 (PR deleted, repo absent
on the forge, or Gitea masking a private repo) rejected the IPC handler and
spammed the main-process log on every refresh for every unaffiliated branch.

404 means the resource is absent — an accepted "no PR", not a transport or
auth failure. Map it to null even with throwOnFailure; 401/403/5xx/network
errors still throw so creation eligibility keeps reporting 'unavailable'.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* fix(gitea): scope the 404 no-PR exemption to the linked-PR fetch

A blanket status !== 404 exemption in the shared request helper also
covered the repo-level /pulls scan, where a 404 means a wrong API base
URL, a repo absent from the forge, or a token without scope. Collapsing
that to "no PR" would make a misconfigured Gitea host look permanently
PR-less instead of surfacing reviewLookupOutcome: 'unavailable'.

Gate the exemption on an explicit allowNotFound request option, set only
on the single-resource /pulls/{n} fetch.

Co-authored-by: Orca <help@stably.ai>

* test(gitea): pin the 200-with-empty-list no-PR shape alongside the 404 case

Co-authored-by: Orca <help@stably.ai>

* fix(gitea): preserve deleted linked pull request absence handling

Refresh the original Donach PR and its prior maintainer correction on current main, keeping the HTTP404 exemption limited to the linked pull resource.

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
Co-authored-by: Neil <4138956+nwparker@users.noreply.github.com>
Co-authored-by: Orca <help@stably.ai>

src/main/gitea/client.test.ts

@@ -261,6 +261,44 @@ describe('Gitea client', () => {
     )
   })
 
+  it('treats a 404 on the linked PR as "no PR" rather than a lookup failure', async () => {
+    const requested: string[] = []
+    const fetchMock = vi.fn(async (url: string | URL) => {
+      requested.push(new URL(String(url)).pathname)
+      // The branch scan succeeds and is simply empty; only PR #42 is gone.
+      return String(url).includes('/pulls/42')
+        ? Response.json({ message: 'not found' }, { status: 404 })
+        : Response.json([])
+    })
+    vi.stubGlobal('fetch', fetchMock)
+
+    await expect(
+      getGiteaPullRequestForBranchOrThrow('/repo', 'feature/gitea', 42)
+    ).resolves.toBeNull()
+    expect(requested).toEqual(['/api/v1/repos/team/repo/pulls', '/api/v1/repos/team/repo/pulls/42'])
+  })
+
+  it('resolves null without throwing when the scan returns an empty list', async () => {
+    // Gitea has no head-branch filter, so "branch has no PR" arrives as a 200
+    // with [] from the repo listing — never a 404. The throwing variant must
+    // still report that as a plain "no PR".
+    const fetchMock = vi.fn(async () => Response.json([]))
+    vi.stubGlobal('fetch', fetchMock)
+
+    await expect(getGiteaPullRequestForBranchOrThrow('/repo', 'feature/gitea')).resolves.toBeNull()
+  })
+
+  it('still throws on a 404 from the /pulls scan so a misconfigured host is not read as "no PR"', async () => {
+    const fetchMock = vi.fn(async () => Response.json({ message: 'not found' }, { status: 404 }))
+    vi.stubGlobal('fetch', fetchMock)
+
+    // A repo-level 404 means wrong base URL / repo absent / token lacks scope —
+    // collapsing it to "no PR" would hide the misconfiguration indefinitely.
+    await expect(getGiteaPullRequestForBranchOrThrow('/repo', 'feature/gitea')).rejects.toThrow(
+      /Gitea request failed: HTTP 404/
+    )
+  })
+
   it('expires successful scans and bounds retained repository listings', async () => {
     vi.useFakeTimers()
     try {

src/main/gitea/client.ts

@@ -37,6 +37,8 @@ export type GiteaAuthStatus = {
 type RequestOptions = {
   searchParams?: Record<string, string | number>
   timeoutMs?: number
+  // Why: only a single-resource fetch may read 404 as "absent". See requestJsonAtBase.
+  allowNotFound?: boolean
 }
 
 function envValue(name: string): string | null {
@@ -93,7 +95,8 @@ async function requestJsonAtBase<T>(
     })
     if (!response.ok) {
       await cancelUnreadResponseBody(response)
-      if (throwOnFailure) {
+      // Why: listing 404s still signal repository or access failures.
+      if (throwOnFailure && !(options.allowNotFound && response.status === 404)) {
         throw new Error(`Gitea request failed: HTTP ${response.status}`)
       }
       return null
@@ -299,7 +302,7 @@ export async function getGiteaPullRequestForBranch(
   const raw = await requestJson<RawGiteaPullRequest>(
     repo,
     `/repos/${encodedRepoPath(repo)}/pulls/${encodeURIComponent(String(linkedPRNumber))}`,
-    {},
+    { allowNotFound: true },
     throwOnFailure
   )
   return raw ? normalizePullRequest(repo, raw) : null