From 640f18404ccc7cd385b996d3dd72ae6cf7661d12 Mon Sep 17 00:00:00 2001
From: ghost <49853598+JSONbored@users.noreply.github.com>
Date: Tue, 7 Jul 2026 00:40:27 -0700
Subject: [PATCH] fix(queue): bound issue-linked re-gate fanout

---
 src/queue/processors.ts | 11 ++++++-----
 test/unit/queue.test.ts | 10 +++++-----
 2 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/src/queue/processors.ts b/src/queue/processors.ts
index 92e3ed89cd..c97eb1867b 100644
--- a/src/queue/processors.ts
+++ b/src/queue/processors.ts
@@ -4290,8 +4290,8 @@ async function maybeInvalidateCiCacheOnLegacyCiEvent(
  * Wake linked PRs on an issue-side signal (#2259). Labeling/unlabeling (e.g. maintainer-only) or
  * assigning/unassigning on a linked ISSUE can flip a linked-issue hard-rule verdict, but that only gets
  * re-evaluated when the PR ITSELF receives a webhook or the staleness-ordered sweep eventually reaches it —
- * which can lag for many cycles on a repo with more than a few open PRs. Enqueue staggered per-PR re-gate jobs
- * for EVERY open PR that links this issue instead of doing the expensive live re-review inline.
+ * which can lag for many cycles on a repo with more than a few open PRs. Enqueue a bounded, staggered batch of
+ * per-PR re-gate jobs instead of doing the expensive live re-review inline.
  * Uses its OWN coalesce window (issueLinkedPrReReviewCoalesced,
  * DISTINCT from CI-completion's — #2371): the two triggers are not interchangeable, so a shared window let an
  * unrelated CI re-review silently suppress a genuinely different issue-side signal. Within the issue-side
@@ -4320,11 +4320,12 @@ async function maybeReReviewOnLinkedIssueChange(
   if (isConvergenceRepoAllowed(env, repoFullName)) {
     const openPullRequests = await listOpenPullRequests(env, repoFullName);
     // Issue-side label/assignment changes can flip linked-issue hard-rule verdicts from mergeable to close.
-    // Wake every linked PR promptly: a silent tail can keep stale passing gate/check state after the issue flips
-    // to an ineligible hard-rule state. Stagger the jobs so the expensive re-gates do not run inline or stampede
-    // the queue consumer.
+    // Wake a bounded prompt batch: unbounded issue-side fan-out can turn one webhook into thousands of
+    // foreground re-gates, exhausting queue, REST, and AI-review budgets. The regular stale sweep continues to
+    // converge any tail while preserving the same SWEEP_MAX_PRS source budget used by rate-aware fan-out.
     const linkingPrs = openPullRequests
       .filter((pr) => pr.linkedIssues.includes(issueNumber))
+      .slice(0, SWEEP_MAX_PRS)
       .map((pr) => ({ number: pr.number, createdAt: pr.createdAt ?? null }));
     for (const [index, pr] of linkingPrs.entries()) {
       const prNumber = pr.number;
diff --git a/test/unit/queue.test.ts b/test/unit/queue.test.ts
index 4eaa7612a0..1f89fec5b0 100644
--- a/test/unit/queue.test.ts
+++ b/test/unit/queue.test.ts
@@ -2956,7 +2956,7 @@ describe("queue processors", () => {
     ]);
   });
 
-  it("REGRESSION: issue-side linked PR wake re-gates every linked PR instead of leaving a stale tail", async () => {
+  it("REGRESSION: issue-side linked PR wake keeps fan-out bounded when many PRs link the same issue", async () => {
     const sent: Array<{ message: import("../../src/types").JobMessage; options?: QueueSendOptions }> = [];
     const env = createTestEnv({
       GITHUB_APP_PRIVATE_KEY: await generatePrivateKeyPem(),
@@ -2981,7 +2981,7 @@ describe("queue processors", () => {
 
     await processJob(env, {
       type: "github-webhook",
-      deliveryId: "issue-label-all-linked-fanout",
+      deliveryId: "issue-label-bounded-linked-fanout",
       eventName: "issues",
       payload: {
         action: "labeled",
@@ -2993,13 +2993,13 @@ describe("queue processors", () => {
     });
 
     expect(fetchCount).toBe(0);
-    expect(sent).toHaveLength(SWEEP_MAX_PRS + 2);
+    expect(sent).toHaveLength(SWEEP_MAX_PRS);
     expect(sent.map(({ message }) => message)).toEqual(
-      Array.from({ length: SWEEP_MAX_PRS + 2 }, (_, index) =>
+      Array.from({ length: SWEEP_MAX_PRS }, (_, index) =>
         expect.objectContaining({ type: "agent-regate-pr", repoFullName: "owner/agent-repo", prNumber: index + 1, installationId: 9001 }),
       ),
     );
-    expect(sent.map(({ options }) => options)).toEqual([undefined, { delaySeconds: 10 }, { delaySeconds: 20 }, { delaySeconds: 30 }, { delaySeconds: 40 }]);
+    expect(sent.map(({ options }) => options)).toEqual([undefined, { delaySeconds: 10 }, { delaySeconds: 20 }]);
   });
 
   it("REGRESSION (#2371): a coalesced issue-side signal schedules a trailing re-review so an add-then-remove sequence is never lost", async () => {