fix(coding-agent): preserve VCS cache refresh semantics

(cherry picked from commit 3f3e475109deb7b9e7690720827876fc982b5b8d)

packages/coding-agent/src/modes/components/status-line/component.ts

@@ -262,6 +262,7 @@ export class StatusLineComponent implements Component {
 	#cachedBranch: string | null | undefined = undefined;
 	#cachedBranchRepoId: string | null | undefined = undefined;
 	#cachedBranchCwd: string | undefined = undefined;
+	#cachedBranchHasGitRepository = false;
 	// In-flight reftable resolve slot. Ownership is the launch id, not the cwd:
 	// two live resolves can share a cwd string across an invalidation, and a
 	// stale one must never free (or poison) a slot it no longer owns.
@@ -677,6 +678,9 @@ export class StatusLineComponent implements Component {
 		// event, re-introducing the render-path spawn churn the async resolve
 		// was designed to avoid. Explicit Git/repository invalidation (watcher
 		// HEAD-move, cwd/repo switch) goes through {@link invalidateGitCaches}.
+		// A tool may open, close, or merge a PR without moving HEAD. Expire the
+		// settled PR context on ordinary activity while leaving HEAD work intact.
+		this.#cachedPrContext = undefined;
 	}
 	#invalidateSessionCaches(): void {
 		this.#clearUsageStartTimer();
@@ -700,6 +704,7 @@ export class StatusLineComponent implements Component {
 		this.#cachedBranch = undefined;
 		this.#cachedBranchRepoId = undefined;
 		this.#cachedBranchCwd = undefined;
+		this.#cachedBranchHasGitRepository = false;
 		// Abort before releasing the in-flight slot. Releasing alone would allow
 		// repeated invalidations to fan out still-running git subprocesses.
 		this.#branchResolveActive?.controller.abort();
@@ -805,6 +810,7 @@ export class StatusLineComponent implements Component {
 				const prev = this.#cachedBranchCwd === gitCwd ? this.#cachedBranch : undefined;
 				this.#cachedBranchCwd = gitCwd;
 				this.#cachedBranchRepoId = repoId;
+				this.#cachedBranchHasGitRepository = next === null;
 				this.#cachedBranch = next;
 				this.#branchLastFetch = Date.now();
 				if (prev !== next && this.#onBranchChange) this.#onBranchChange();
@@ -1397,7 +1403,10 @@ export class StatusLineComponent implements Component {
 		// so it must not be mistaken for an absent Git checkout and fall through to
 		// an ancestor jj workspace.
 		const gitHeadResolvePending = this.#branchResolveActive?.cwd === activeRepoCache.effectiveGitCwd;
-		const gitHeadIsJjLike = !gitHeadResolvePending && (gitBranch === "detached" || gitBranch === null);
+		const gitHeadIsJjLike =
+			!this.#cachedBranchHasGitRepository &&
+			!gitHeadResolvePending &&
+			(gitBranch === "detached" || gitBranch === null);
 		if (includeGit && gitHeadIsJjLike) {
 			gitBranch = this.#getJjBranch(activeRepoCache.effectiveGitCwd) ?? gitBranch;
 		}

packages/coding-agent/test/status-line-vcs-refresh.test.ts

@@ -408,6 +408,32 @@ describe("StatusLineComponent reftable branch resolve honors mid-flight invalida
 			await fs.rm(jjRootDir, { recursive: true, force: true });
 		}
 	});
+
+	it("does not query an ancestor jj workspace after nested Git HEAD resolution fails", async () => {
+		const fakeRepo = {
+			commonDir: "/nested/.git",
+			gitDir: "/nested/.git",
+			gitEntryPath: "/nested/.git",
+			headPath: "/nested/.git/HEAD",
+			repoRoot: "/nested",
+		} satisfies GitRepository;
+		vi.spyOn(git.repo, "resolveSync").mockReturnValue(fakeRepo);
+		vi.spyOn(git.repo, "isReftableSync").mockReturnValue(true);
+		vi.spyOn(git.head, "resolve").mockResolvedValue(null);
+		vi.spyOn(git.status, "summary").mockReturnValue(Promise.withResolvers<GitStatus | null>().promise);
+		const jjRoot = vi.spyOn(jj.repo, "rootSync").mockReturnValue("/workspace/jj-root");
+
+		const component = new StatusLineComponent(makeSession());
+		component.updateSettings(gitSegment);
+		component.getTopBorder(80);
+		await Promise.resolve();
+		await Promise.resolve();
+		component.getTopBorder(80);
+
+		expect(git.head.resolve).toHaveBeenCalledTimes(1);
+		expect(jjRoot).not.toHaveBeenCalled();
+		component.dispose();
+	});
 });
 
 describe("StatusLineComponent VCS watcher and jj request lifecycle", () => {