fix(status-line): deduplicate PR lookups across instances

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

@@ -1,7 +1,17 @@
 import { type RunGh, runGhDefault } from "../../../utils/gh";
 
 const STATUS_LINE_GH_TIMEOUT_MS = 5_000;
+const STATUS_LINE_PR_CACHE_TTL_MS = 60_000;
 const C0_C1_CONTROL_CHARACTERS = /[\u0000-\u001f\u007f-\u009f]/;
+type CurrentPr = { number: number; url: string } | null;
+
+interface PrCacheEntry {
+	value: CurrentPr;
+	expiresAt: number;
+}
+
+const prCache = new Map<string, PrCacheEntry>();
+const prLookupsInFlight = new Map<string, Promise<CurrentPr>>();
 
 function canonicalPrUrl(value: unknown, number: number): string | null {
 	if (typeof value !== "string" || C0_C1_CONTROL_CHARACTERS.test(value)) return null;
@@ -22,7 +32,7 @@ function canonicalPrUrl(value: unknown, number: number): string | null {
 	}
 }
 
-export async function lookupCurrentPr(runGh: RunGh = runGhDefault): Promise<{ number: number; url: string } | null> {
+export async function lookupCurrentPr(runGh: RunGh = runGhDefault): Promise<CurrentPr> {
 	try {
 		const result = await runGh(["pr", "view", "--json", "number,url"], { timeoutMs: STATUS_LINE_GH_TIMEOUT_MS });
 		if (result.exitCode !== 0 || result.timedOut) return null;
@@ -35,3 +45,31 @@ export async function lookupCurrentPr(runGh: RunGh = runGhDefault): Promise<{ nu
 		return null;
 	}
 }
+
+export function lookupCurrentPrCached(
+	cacheKey: string,
+	runGh: RunGh = runGhDefault,
+	now: () => number = Date.now,
+): Promise<CurrentPr> {
+	const cached = prCache.get(cacheKey);
+	if (cached && cached.expiresAt > now()) return Promise.resolve(cached.value);
+
+	const inFlight = prLookupsInFlight.get(cacheKey);
+	if (inFlight) return inFlight;
+
+	const lookup = lookupCurrentPr(runGh)
+		.then(value => {
+			prCache.set(cacheKey, { value, expiresAt: now() + STATUS_LINE_PR_CACHE_TTL_MS });
+			return value;
+		})
+		.finally(() => {
+			if (prLookupsInFlight.get(cacheKey) === lookup) prLookupsInFlight.delete(cacheKey);
+		});
+	prLookupsInFlight.set(cacheKey, lookup);
+	return lookup;
+}
+
+export function clearCurrentPrCache(): void {
+	prCache.clear();
+	prLookupsInFlight.clear();
+}

packages/coding-agent/src/modes/components/tool-status-header.ts

@@ -19,7 +19,7 @@ import type { ActionRegistry, FocusDomain } from "../action-registry";
 import { EMPTY_JOBS_SNAPSHOT, type JobsSnapshot } from "../jobs-observer";
 import { sanitizeStatusText } from "../shared";
 import { renderSkillHudBar } from "./skill-hud/render";
-import { lookupCurrentPr } from "./status-line/gh";
+import { lookupCurrentPrCached } from "./status-line/gh";
 import {
 	canReuseCachedPr,
 	createPrCacheContext,
@@ -399,6 +399,10 @@ export class StatusLineComponent implements Component {
 
 		this.#prLookupInFlight = true;
 		const lookupContext = currentContext;
+		if (!lookupContext) {
+			this.#prLookupInFlight = false;
+			return stalePr ?? null;
+		}
 
 		// Fire async lookup, keep stale value visible until resolved
 		(async () => {
@@ -415,7 +419,7 @@ export class StatusLineComponent implements Component {
 			};
 			try {
 				// Requires `gh repo set-default` to be configured; fails gracefully if not
-				const pr = await lookupCurrentPr();
+				const pr = await lookupCurrentPrCached(`${lookupContext.repoId ?? ""}\0${lookupContext.branch}`);
 				setCachedPr(pr);
 			} finally {
 				this.#prLookupInFlight = false;

packages/coding-agent/test/status-line-gh.test.ts

@@ -1,6 +1,10 @@
-import { afterEach, describe, expect, it, vi } from "bun:test";
+import { afterEach, beforeEach, describe, expect, it, vi } from "bun:test";
 import type { Subprocess } from "bun";
-import { lookupCurrentPr } from "../src/modes/components/status-line/gh";
+import {
+	clearCurrentPrCache,
+	lookupCurrentPr,
+	lookupCurrentPrCached,
+} from "../src/modes/components/status-line/gh";
 import type { RunGh } from "../src/utils/gh";
 
 function textStream(text: string): ReadableStream<Uint8Array> {
@@ -14,6 +18,10 @@ afterEach(() => {
 });
 
 describe("status-line GitHub PR lookup", () => {
+	beforeEach(() => {
+		clearCurrentPrCache();
+	});
+
 	it("detaches gh from TUI stdin", async () => {
 		const ghPath = "/usr/bin/gh";
 		vi.spyOn(Bun, "which").mockReturnValue(ghPath);
@@ -49,6 +57,36 @@ describe("status-line GitHub PR lookup", () => {
 		expect(timeoutMs).toBe(5_000);
 	});
 
+	it("negative-caches failed lookups across callers", async () => {
+		let calls = 0;
+		const runGh: RunGh = async () => {
+			calls += 1;
+			return { exitCode: 1, stdout: "", stderr: "no pull requests found", timedOut: false };
+		};
+
+		await expect(lookupCurrentPrCached("/repo/.git/HEAD\0feature", runGh, () => 1_000)).resolves.toBeNull();
+		await expect(lookupCurrentPrCached("/repo/.git/HEAD\0feature", runGh, () => 2_000)).resolves.toBeNull();
+		expect(calls).toBe(1);
+	});
+
+	it("deduplicates concurrent lookups across callers", async () => {
+		let calls = 0;
+		let resolveLookup!: (value: Awaited<ReturnType<RunGh>>) => void;
+		const result = new Promise<Awaited<ReturnType<RunGh>>>(resolve => {
+			resolveLookup = resolve;
+		});
+		const runGh: RunGh = async () => {
+			calls += 1;
+			return result;
+		};
+
+		const first = lookupCurrentPrCached("/repo/.git/HEAD\0feature", runGh);
+		const second = lookupCurrentPrCached("/repo/.git/HEAD\0feature", runGh);
+		expect(calls).toBe(1);
+		resolveLookup({ exitCode: 1, stdout: "", stderr: "no pull requests found", timedOut: false });
+		await expect(Promise.all([first, second])).resolves.toEqual([null, null]);
+	});
+
 	it("accepts canonical GitHub Enterprise PR URLs over HTTP(S)", async () => {
 		for (const url of [
 			"https://ghe.internal.example.com/teams/cli/pull/3354",