patroza · patroza · Aug 15, 2026 · Aug 15, 2026
diff --git a/apps/server/src/pullRequest/PullRequestService.test.ts b/apps/server/src/pullRequest/PullRequestService.test.ts
@@ -2770,6 +2770,107 @@ it("falls back to the path's last segment where an Azure identity has no name",
   assert.strictEqual(selector, "checkout");
 });
 
+it("lists origin and upstream so a fork PR is still this project's", () => {
+  const names = PullRequestService.repositoriesOf({
+    repositoryIdentity: {
+      provider: "github",
+      displayName: "pingdotgg/t3code",
+      owner: "pingdotgg",
+      name: "t3code",
+      remotes: [
+        {
+          remoteName: "origin",
+          remoteUrl: "https://github.com/patroza/t3code.git",
+          owner: "patroza",
+          name: "t3code",
+          canonicalKey: "github.com/patroza/t3code",
+        },
+        {
+          remoteName: "upstream",
+          remoteUrl: "https://github.com/pingdotgg/t3code.git",
+          owner: "pingdotgg",
+          name: "t3code",
+          canonicalKey: "github.com/pingdotgg/t3code",
+        },
+      ],
+    },
+  } as never);
+  assert.deepStrictEqual(names.toSorted(), ["patroza/t3code", "pingdotgg/t3code"]);
+});
+
+it.effect("reads a fork pull request against origin, not the upstream identity", () =>
+  Effect.gen(function* () {
+    let requested: string | null = null;
+    const fork = project({
+      id: "p1",
+      title: "t3code",
+      workspaceRoot: "/t3code",
+      repository: "pingdotgg/t3code",
+    });
+    const identity = fork.repositoryIdentity!;
+    const withRemotes = {
+      ...fork,
+      repositoryIdentity: {
+        ...identity,
+        remotes: [
+          {
+            remoteName: "origin",
+            remoteUrl: "https://github.com/patroza/t3code.git",
+            owner: "patroza",
+            name: "t3code",
+            canonicalKey: "github.com/patroza/t3code",
+          },
+          {
+            remoteName: "upstream",
+            remoteUrl: "https://github.com/pingdotgg/t3code.git",
+            owner: "pingdotgg",
+            name: "t3code",
+            canonicalKey: "github.com/pingdotgg/t3code",
+          },
+        ],
+      },
+    };
+    const service = yield* makeService({
+      projects: [withRemotes],
+      providers: [
+        fakeProvider("github", {
+          getChangeRequest: (input) => {
+            requested = input.repository;
+            return Effect.succeed({
+              ...changeRequest(410, "2026-08-15T00:00:00Z"),
+              url: "https://github.com/patroza/t3code/pull/410",
+              body: "",
+              changedFiles: 1,
+              mergedAt: null,
+              closedAt: null,
+              reviewers: [],
+              checks: [],
+              mergeCapabilities: { merge: true, squash: true, rebase: true },
+              viewerPermissions: {
+                actions: ["merge"],
+                comment: true,
+                resolve: true,
+                verdicts: ["comment", "approve", "request-changes"],
+                requestReviewers: true,
+              },
+            });
+          },
+        }),
+      ],
+    });
+
+    const detail = yield* service.detail({
+      projectId: "p1" as ProjectId,
+      repository: "patroza/t3code",
+      number: 410,
+    });
+
+    assert.strictEqual(requested, "patroza/t3code");
+    assert.strictEqual(detail.repository, "patroza/t3code");
+    assert.strictEqual(detail.number, 410);
+  }),
+);
+
 it("keeps a GitLab identity's whole path, because a nested group is part of the name", () => {
   const selector = PullRequestService.repositoryIdentityOf({
     repositoryIdentity: {

diff --git a/apps/server/src/pullRequest/PullRequestService.ts b/apps/server/src/pullRequest/PullRequestService.ts
@@ -390,6 +390,23 @@ export function repositoryIdentityOf(project: OrchestrationProjectShell): string
   return identity.owner && identity.name ? `${identity.owner}/${identity.name}` : null;
 }
 
+/**
+ * Every repository this checkout answers to. A fork records both origin and
+ * upstream; the primary identity prefers upstream, but a change request on the
+ * fork is still this project's.
+ */
+export function repositoriesOf(project: OrchestrationProjectShell): ReadonlyArray<string> {
+  const names = new Set<string>();
+  const primary = repositoryIdentityOf(project);
+  if (primary) names.add(primary.toLowerCase());
+  for (const remote of project.repositoryIdentity?.remotes ?? []) {
+    if (remote.owner && remote.name) {
+      names.add(`${remote.owner}/${remote.name}`.toLowerCase());
+    }
+  }
+  return [...names];
+}
+
 export const make = Effect.gen(function* () {
   const registry = yield* PullRequestProviderRegistry;
   const projections = yield* ProjectionSnapshotQuery.ProjectionSnapshotQuery;
@@ -524,17 +541,23 @@ export const make = Effect.gen(function* () {
         if (!match) {
           return Effect.fail(new PullRequestUnavailableError({ reason: "provider-unsupported" }));
         }
-        // The repository travels through the client, so it is checked against the project's
-        // own remote rather than being handed to a provider verbatim.
-        if (match.repository.toLowerCase() !== ref.repository.trim().toLowerCase()) {
+        // The repository travels through the client, so it is checked against the
+        // checkout's remotes rather than being handed to a provider verbatim.
+        // Upstream is the primary identity on a fork; origin is still ours.
+        const requested = ref.repository.trim().toLowerCase();
+        if (!repositoriesOf(match.project).includes(requested)) {
           return Effect.fail(
             new PullRequestOperationError({
               operation: "resolveRepository",
               detail: "The change request does not belong to the selected project.",
             }),
           );
         }
-        return Effect.succeed(match);
+        return Effect.succeed(
+          requested === match.repository.toLowerCase()
+            ? match
+            : { ...match, repository: ref.repository.trim() },
+        );
       }),
     );
 

diff --git a/apps/web/src/components/ChatView.tsx b/apps/web/src/components/ChatView.tsx
@@ -153,7 +153,10 @@ import {
   selectThreadPreviewMiniPlayer,
   usePreviewMiniPlayerStore,
 } from "../previewMiniPlayerStore";
-import { isThreadOwnPullRequest } from "./pullRequest/pullRequestDetail.logic";
+import {
+  isThreadOwnPullRequest,
+  repositoryFromChangeRequestUrl,
+} from "./pullRequest/pullRequestDetail.logic";
 import { PullRequestDetailPanel } from "./pullRequest/PullRequestDetailPanel";
 import { PullRequestDetailGhost } from "./pullRequest/PullRequestGhosts";
 import { PullRequestsUnavailableState } from "./pullRequest/PullRequestsUnavailableState";
@@ -3511,18 +3514,19 @@ function ChatViewContent(props: ChatViewProps) {
   // project there is nothing to resolve it against, so the caller falls back to the browser.
   const threadRepository = activeProject?.repositoryIdentity?.displayName ?? null;
   const openThreadPullRequest = useCallback(
-    (number: number) => {
+    (number: number, repository: string | null = threadRepository) => {
+      const selectedRepository = repository ?? threadRepository;
       if (
         !supportsPullRequests ||
         !activeThreadRef ||
         !activeProject ||
-        threadRepository === null
+        selectedRepository === null
       ) {
         return;
       }
       useRightPanelStore.getState().openPullRequest(activeThreadRef, {
         projectId: activeProject.id,
-        repository: threadRepository,
+        repository: selectedRepository,
         number,
       });
     },
@@ -4464,12 +4468,15 @@ function ChatViewContent(props: ChatViewProps) {
   });
   // The right panel offers the thread's own change request, so it can only offer it once the
   // branch has one; until then the picker says so rather than opening an empty panel.
+  const threadPullRequestRepository =
+    (activeThreadPr !== null ? repositoryFromChangeRequestUrl(activeThreadPr.url) : null) ??
+    threadRepository;
   const addPullRequestSurface = useCallback(() => {
     if (activeThreadPr === null) return;
-    openThreadPullRequest(activeThreadPr.number);
-  }, [activeThreadPr, openThreadPullRequest]);
+    openThreadPullRequest(activeThreadPr.number, threadPullRequestRepository);
+  }, [activeThreadPr, openThreadPullRequest, threadPullRequestRepository]);
   const pullRequestSurfaceAvailable =
-    supportsPullRequests && activeThreadPr !== null && threadRepository !== null;
+    supportsPullRequests && activeThreadPr !== null && threadPullRequestRepository !== null;
   const supportsSettlement = serverConfig?.environment.capabilities.threadSettlement === true;
   const supportsSnooze = serverConfig?.environment.capabilities.threadSnooze === true;
   const nowMinute = useNowMinute();
@@ -6739,7 +6746,7 @@ function ChatViewContent(props: ChatViewProps) {
           isThreadOwnPullRequest(
             {
               projectId: activeProject?.id ?? null,
-              repository: threadRepository,
+              repository: threadPullRequestRepository,
               number: activeThreadPr?.number ?? null,
             },
             {

diff --git a/apps/web/src/components/GitActionsControl.tsx b/apps/web/src/components/GitActionsControl.tsx
@@ -37,6 +37,7 @@ import {
 } from "lucide-react";
 import { Radio as RadioPrimitive } from "@base-ui/react/radio";
 import { AzureDevOpsIcon, BitbucketIcon, GitHubIcon, GitLabIcon } from "~/components/Icons";
+import { repositoryFromChangeRequestUrl } from "~/components/pullRequest/pullRequestDetail.logic";
 import { RadioGroup } from "~/components/ui/radio-group";
 import { Spinner } from "~/components/ui/spinner";
 import { cn } from "~/lib/utils";
@@ -105,7 +106,7 @@ interface GitActionsControlProps {
    * Opens the thread's own change request beside it. Absent when the thread has no project to
    * place it against, in which case it still opens in the browser.
    */
-  onOpenPullRequest?: ((number: number) => void) | undefined;
+  onOpenPullRequest?: ((number: number, repository?: string | null) => void) | undefined;
 }
 
 interface PendingDefaultBranchAction {
@@ -1239,7 +1240,7 @@ export default function GitActionsControl({
     // Beside the thread where it was made, the way the browser opens beside it. Checked before
     // the shell, which opening in the app does not need.
     if (openPr && onOpenPullRequest) {
-      onOpenPullRequest(openPr.number);
+      onOpenPullRequest(openPr.number, repositoryFromChangeRequestUrl(openPr.url));
       return;
     }
     const api = readLocalApi();

diff --git a/apps/web/src/components/chat/ChatHeader.tsx b/apps/web/src/components/chat/ChatHeader.tsx
@@ -78,7 +78,7 @@ interface ChatHeaderProps {
   /** For showing usage dot on the active thread's model at conversation level. */
   activeThreadDriverKind?: ProviderDriverKind | null;
   activeThreadModel?: string | null;
-  readonly onOpenPullRequest?: ((number: number) => void) | undefined;
+  readonly onOpenPullRequest?: ((number: number, repository?: string | null) => void) | undefined;
   onNewThreadInProject: () => void;
   onRunProjectScript: (script: ProjectScript) => void;
   onAddProjectScript: (input: NewProjectScriptInput) => Promise<ProjectScriptActionResult>;

diff --git a/apps/web/src/components/pullRequest/pullRequestDetail.logic.test.ts b/apps/web/src/components/pullRequest/pullRequestDetail.logic.test.ts
@@ -17,6 +17,7 @@ import {
   handoffPrompt,
   handoffReviewComments,
   isThreadOwnPullRequest,
+  repositoryFromChangeRequestUrl,
   orderPullRequestComments,
   pullRequestActionNeedsHostRefresh,
   pullRequestActionMenuHasGroup,
@@ -917,6 +918,27 @@ describe("whether the panel is showing the thread's own pull request", () => {
   });
 });
 
+describe("repositoryFromChangeRequestUrl", () => {
+  it("reads owner/name from a GitHub pull request URL", () => {
+    expect(repositoryFromChangeRequestUrl("https://github.com/patroza/t3code/pull/410")).toBe(
+      "patroza/t3code",
+    );
+    expect(
+      repositoryFromChangeRequestUrl("https://github.com/pingdotgg/t3code/pull/6613/files"),
+    ).toBe("pingdotgg/t3code");
+  });
+
+  it("reads a nested GitLab path", () => {
+    expect(
+      repositoryFromChangeRequestUrl("https://gitlab.com/group/sub/service/-/merge_requests/12"),
+    ).toBe("group/sub/service");
+  });
+
+  it("returns null when the URL is not a change request", () => {
+    expect(repositoryFromChangeRequestUrl("https://github.com/patroza/t3code")).toBeNull();
+  });
+});
+
 describe("which actions need the host read again after they run", () => {
   it("classifies every action the contract knows about", () => {
     // Imported from the contract rather than hand-listed, so a new PullRequestAction fails this

diff --git a/apps/web/src/components/pullRequest/pullRequestDetail.logic.ts b/apps/web/src/components/pullRequest/pullRequestDetail.logic.ts
@@ -19,6 +19,16 @@ import { inferReviewCommentFenceLanguage, type ReviewCommentContext } from "~/re
  * number are not enough: one environment can hold two checkouts of the same repository under
  * different projects, and the other project's checkout is somebody else's branch.
  */
+/** Owner/name from a change-request URL, so a fork PR is not opened against upstream. */
+export function repositoryFromChangeRequestUrl(url: string): string | null {
+  const trimmed = url.trim();
+  const github = /^https:\/\/[^/\s]+\/([^/\s]+\/[^/\s]+)\/pull\/\d+(?:[/?#].*)?$/i.exec(trimmed);
+  if (github?.[1]) return github[1];
+  const gitlab = /^https:\/\/[^/\s]+\/(.+)\/-\/merge_requests\/\d+(?:[/?#].*)?$/i.exec(trimmed);
+  if (gitlab?.[1]) return gitlab[1];
+  return null;
+}
+
 export function isThreadOwnPullRequest(
   thread: {
     readonly projectId: string | null;