fix(gitea): handle AGit PRs and deleted head branches

neither has a branch on origin. forgejo reports refs/pull/N/head as
head.ref for both, so skip the refs/heads fallback and dont track
origin.

also try refs/pull/N/head on upstream for clones where origin is your
fork, like github does. that list lives in the shared util now.

packages/server/src/server/resolve-worktree-creation-intent.test.ts

@@ -182,6 +182,28 @@ describe("resolveWorktreeCreationIntent", () => {
     expect(deps.headRefLookups).toEqual([]);
   });
 
+  test("does not track origin for a same-repo head with no origin branch", async () => {
+    const deps = createResolverHarness();
+    deps.forgeService.getPullRequestCheckoutTarget = async () => ({
+      number: 42,
+      baseRefName: "main",
+      headRefName: "ford/towel",
+      headOwnerLogin: null,
+      headRepositorySshUrl: null,
+      headRepositoryUrl: null,
+      isCrossRepository: false,
+      hasOriginHeadBranch: false,
+    });
+
+    const intent = await resolveWorktreeCreationIntent(
+      { action: "checkout", githubPrNumber: 42 },
+      repoRoot,
+      deps,
+    );
+
+    expect(intent).not.toHaveProperty("trackOriginHead");
+  });
+
   test("configures the contributor remote for fork PR targets", async () => {
     const deps = createResolverHarness();
     deps.forgeService.getPullRequestCheckoutTarget = async () => ({

packages/server/src/server/resolve-worktree-creation-intent.ts

@@ -191,7 +191,8 @@ async function resolvePrCheckoutIntent(
   }) ?? [{ remoteName: "origin", remoteRef: `refs/heads/${headRef}` }];
   const localBranchName = service.buildPrLocalBranchName?.({ headRef, checkoutTarget });
   const crossRepository = resolveCrossRepositoryFields(checkoutTarget);
-  const trackOriginHead = !checkoutTarget.isCrossRepository;
+  const trackOriginHead =
+    !checkoutTarget.isCrossRepository && checkoutTarget.hasOriginHeadBranch !== false;
 
   return {
     kind: "checkout-change-request",

packages/server/src/services/forge-service.ts

@@ -39,6 +39,8 @@ export interface PullRequestCheckoutTarget {
   headRepositorySshUrl: string | null;
   headRepositoryUrl: string | null;
   isCrossRepository: boolean;
+  /** false when origin has no head branch to track */
+  hasOriginHeadBranch?: boolean;
 }
 
 export interface PullRequestCheckoutRef {

packages/server/src/services/gitea-service.test.ts

@@ -2297,11 +2297,13 @@ describe("createGiteaService", () => {
       checkoutRefs: [
         { remoteName: "origin", remoteRef: "refs/pull/5/head" },
         { remoteName: "origin", remoteRef: "refs/heads/feat/sample-change" },
+        { remoteName: "upstream", remoteRef: "refs/pull/5/head" },
       ],
       headOwnerLogin: null,
       headRepositorySshUrl: null,
       headRepositoryUrl: null,
       isCrossRepository: false,
+      hasOriginHeadBranch: true,
     });
   });
 
@@ -2330,16 +2332,62 @@ describe("createGiteaService", () => {
       number: 5,
       baseRefName: "main",
       headRefName: "feat/sample-change",
-      checkoutRefs: [{ remoteName: "origin", remoteRef: "refs/pull/5/head" }],
+      checkoutRefs: [
+        { remoteName: "origin", remoteRef: "refs/pull/5/head" },
+        { remoteName: "upstream", remoteRef: "refs/pull/5/head" },
+      ],
       headOwnerLogin: "contributor",
       headRepositorySshUrl: "git@gitea.com:contributor/sample-repo.git",
       headRepositoryUrl: "https://gitea.com/contributor/sample-repo",
       isCrossRepository: true,
+      hasOriginHeadBranch: false,
     });
 
     expect(calls).toContainEqual(["api", "repos/example-user/sample-repo/pulls/5"]);
   });
 
+  it("skips the origin branch fallback and tracking for an AGit pull request", async () => {
+    const { service } = makeService((args) =>
+      args[0] === "api"
+        ? ok(
+            JSON.stringify({
+              flow: 1,
+              head: { ref: "refs/pull/5/head", repo: { id: 1 } },
+              base: { repo: { id: 1 } },
+            }),
+          )
+        : ok(JSON.stringify(STATUS_PR_VIEW)),
+    );
+
+    const target = await service.getPullRequestCheckoutTarget({ cwd: "/repo", number: 5 });
+
+    expect(target).toMatchObject({
+      checkoutRefs: [
+        { remoteName: "origin", remoteRef: "refs/pull/5/head" },
+        { remoteName: "upstream", remoteRef: "refs/pull/5/head" },
+      ],
+      isCrossRepository: false,
+      hasOriginHeadBranch: false,
+    });
+  });
+
+  it("skips the origin branch fallback when the head branch was deleted", async () => {
+    const { service } = makeService((args) =>
+      args[0] === "api"
+        ? ok(
+            JSON.stringify({
+              head: { ref: "refs/pull/5/head", repo: { id: 1 } },
+              base: { repo: { id: 1 } },
+            }),
+          )
+        : ok(JSON.stringify(STATUS_PR_VIEW)),
+    );
+
+    const target = await service.getPullRequestCheckoutTarget({ cwd: "/repo", number: 5 });
+
+    expect(target.hasOriginHeadBranch).toBe(false);
+  });
+
   it("keeps a pull request from a deleted fork cross-repository", async () => {
     const { service } = makeService((args) =>
       args[0] === "api"
@@ -2350,12 +2398,32 @@ describe("createGiteaService", () => {
     const target = await service.getPullRequestCheckoutTarget({ cwd: "/repo", number: 5 });
 
     expect(target).toMatchObject({
-      checkoutRefs: [{ remoteName: "origin", remoteRef: "refs/pull/5/head" }],
+      checkoutRefs: [
+        { remoteName: "origin", remoteRef: "refs/pull/5/head" },
+        { remoteName: "upstream", remoteRef: "refs/pull/5/head" },
+      ],
       headOwnerLogin: null,
       isCrossRepository: true,
+      hasOriginHeadBranch: false,
     });
   });
 
+  it("keeps the origin branch fallback when the server sends no head ref", async () => {
+    const { service } = makeService((args) =>
+      args[0] === "api"
+        ? ok(JSON.stringify({ head: { repo: { id: 1 } }, base: { repo: { id: 1 } } }))
+        : ok(JSON.stringify(STATUS_PR_VIEW)),
+    );
+
+    const target = await service.getPullRequestCheckoutTarget({ cwd: "/repo", number: 5 });
+
+    expect(target.checkoutRefs).toContainEqual({
+      remoteName: "origin",
+      remoteRef: "refs/heads/feat/sample-change",
+    });
+    expect(target.hasOriginHeadBranch).toBe(true);
+  });
+
   it("prefixes the local branch name with the fork owner for a cross-repository checkout", () => {
     const { service } = makeService(() => ok(""));
 
@@ -2380,6 +2448,7 @@ describe("createGiteaService", () => {
 
     expect(service.defaultCheckoutRefs?.({ changeRequestNumber: 5, headRef: "patch-1" })).toEqual([
       { remoteName: "origin", remoteRef: "refs/pull/5/head" },
+      { remoteName: "upstream", remoteRef: "refs/pull/5/head" },
     ]);
   });
 

packages/server/src/services/gitea-service.ts

@@ -5,7 +5,10 @@ import pLimit from "p-limit";
 import { parseGitHubRemoteIdentity, parseGitRemoteLocation } from "@getpaseo/protocol/git-remote";
 import { findExecutable } from "../executable-resolution/executable-resolution.js";
 import { runGitCommand } from "../utils/run-git-command.js";
-import { buildForkLocalBranchName } from "../utils/change-request-checkout.js";
+import {
+  buildForkLocalBranchName,
+  buildPullHeadCheckoutRefs,
+} from "../utils/change-request-checkout.js";
 import { execCommand } from "../utils/spawn.js";
 import {
   createCachedCliPathResolver,
@@ -76,6 +79,8 @@ const CURRENT_PR_HEAD_SHA_CACHE_TTL_MS = 30_000;
 // the sweep to the 250 most recent Actions tasks.
 const GITEA_ACTION_PAGE_LIMIT = 50;
 const GITEA_ACTION_MAX_PAGES = 5;
+// PullRequestFlowAGit in forgejo models/issues/pull.go
+const GITEA_PULL_REQUEST_FLOW_AGIT = 1;
 
 /**
  * Fields requested from `tea pr list -o json`. tea's default field set omits the
@@ -226,8 +231,12 @@ const GiteaPullRequestRepoSchema = z
 
 const GiteaPullRequestApiSchema = z
   .object({
+    flow: z.number().optional(),
     head: z
-      .object({ repo: GiteaPullRequestRepoSchema.nullable().optional() })
+      .object({
+        ref: z.string().optional(),
+        repo: GiteaPullRequestRepoSchema.nullable().optional(),
+      })
       .passthrough()
       .optional(),
     base: z
@@ -1441,12 +1450,14 @@ export function createGiteaService(options: CreateGiteaServiceOptions = {}): For
     summary: PullRequestSummary,
   ): Promise<{
     isCrossRepository: boolean;
+    hasHeadBranch: boolean;
     headOwnerLogin: string | null;
     headRepositorySshUrl: string | null;
     headRepositoryUrl: string | null;
   }> {
     const sameRepo = {
       isCrossRepository: false,
+      hasHeadBranch: true,
       headOwnerLogin: null,
       headRepositorySshUrl: null,
       headRepositoryUrl: null,
@@ -1465,18 +1476,21 @@ export function createGiteaService(options: CreateGiteaServiceOptions = {}): For
     );
     const headRepo = pr.head?.repo ?? null;
     const baseRepo = pr.base?.repo ?? null;
+    // head.ref only becomes the branch name when the branch still exists,
+    // agit PRs and deleted branches keep the pull ref
+    const hasHeadBranch =
+      pr.flow !== GITEA_PULL_REQUEST_FLOW_AGIT &&
+      pr.head?.ref !== `refs/pull/${summary.number}/head`;
     if (baseRepo?.id == null || headRepo?.id === baseRepo.id) {
-      return sameRepo;
-    }
-    if (headRepo?.id == null) {
-      // fork was deleted
-      return { ...sameRepo, isCrossRepository: true };
+      return { ...sameRepo, hasHeadBranch };
     }
+    // headRepo is null when the fork was deleted
     return {
       isCrossRepository: true,
-      headOwnerLogin: headRepo.owner?.login ?? null,
-      headRepositorySshUrl: headRepo.ssh_url ?? null,
-      headRepositoryUrl: headRepo.html_url ?? null,
+      hasHeadBranch,
+      headOwnerLogin: headRepo?.owner?.login ?? null,
+      headRepositorySshUrl: headRepo?.ssh_url ?? null,
+      headRepositoryUrl: headRepo?.html_url ?? null,
     };
   }
 
@@ -2003,7 +2017,7 @@ export function createGiteaService(options: CreateGiteaServiceOptions = {}): For
     },
 
     defaultCheckoutRefs({ changeRequestNumber }) {
-      return [{ remoteName: "origin", remoteRef: `refs/pull/${changeRequestNumber}/head` }];
+      return buildPullHeadCheckoutRefs(changeRequestNumber);
     },
 
     buildPrLocalBranchName({ headRef, checkoutTarget }) {
@@ -2015,13 +2029,16 @@ export function createGiteaService(options: CreateGiteaServiceOptions = {}): For
     ): Promise<PullRequestCheckoutTarget> {
       const summary = await this.getPullRequest(input);
       const fork = await resolveForkCheckoutFacts(input.cwd, summary);
-      const checkoutRefs = [
-        { remoteName: "origin", remoteRef: `refs/pull/${summary.number}/head` },
-      ];
-      // on a fork PR thats the base repos branch
-      if (summary.headRefName && !fork.isCrossRepository) {
+      const [originPullRef, upstreamPullRef] = buildPullHeadCheckoutRefs(summary.number);
+      const checkoutRefs = [originPullRef];
+      // for a fork PR a branch with that name on origin belongs to the base repo
+      const headBranchOnOrigin =
+        !fork.isCrossRepository && fork.hasHeadBranch && Boolean(summary.headRefName);
+      if (headBranchOnOrigin) {
         checkoutRefs.push({ remoteName: "origin", remoteRef: `refs/heads/${summary.headRefName}` });
       }
+      // upstream can hold a different PR with the same number, so it goes last
+      checkoutRefs.push(upstreamPullRef);
       return {
         number: summary.number,
         baseRefName: summary.baseRefName,
@@ -2031,6 +2048,7 @@ export function createGiteaService(options: CreateGiteaServiceOptions = {}): For
         headRepositorySshUrl: fork.headRepositorySshUrl,
         headRepositoryUrl: fork.headRepositoryUrl,
         isCrossRepository: fork.isCrossRepository,
+        hasOriginHeadBranch: headBranchOnOrigin,
       };
     },
 

packages/server/src/services/github-service.ts

@@ -6,7 +6,10 @@ import {
 } from "@getpaseo/protocol/git-remote";
 import { findExecutable } from "../executable-resolution/executable-resolution.js";
 import { runGitCommand } from "../utils/run-git-command.js";
-import { buildForkLocalBranchName } from "../utils/change-request-checkout.js";
+import {
+  buildForkLocalBranchName,
+  buildPullHeadCheckoutRefs,
+} from "../utils/change-request-checkout.js";
 import { execCommand } from "../utils/spawn.js";
 import { resolveSshHostname } from "../utils/ssh-hostname.js";
 import {
@@ -2105,10 +2108,7 @@ export function createGitHubService(options: CreateGitHubServiceOptions = {}): G
     },
 
     defaultCheckoutRefs({ changeRequestNumber }) {
-      return [
-        { remoteName: "origin", remoteRef: `refs/pull/${changeRequestNumber}/head` },
-        { remoteName: "upstream", remoteRef: `refs/pull/${changeRequestNumber}/head` },
-      ];
+      return buildPullHeadCheckoutRefs(changeRequestNumber);
     },
 
     buildPrLocalBranchName({ headRef, checkoutTarget }) {

packages/server/src/utils/change-request-checkout.ts

@@ -1,3 +1,13 @@
+import type { PullRequestCheckoutRef } from "../services/forge-service.js";
+
+// upstream for clones where origin is your fork
+export function buildPullHeadCheckoutRefs(number: number): PullRequestCheckoutRef[] {
+  return [
+    { remoteName: "origin", remoteRef: `refs/pull/${number}/head` },
+    { remoteName: "upstream", remoteRef: `refs/pull/${number}/head` },
+  ];
+}
+
 // forgejo username pattern, covers github logins too
 export function normalizeForgeOwnerForBranch(owner: string | null): string | null {
   const normalized = owner?.trim().toLowerCase() ?? "";