From 7d219bd6e7bd593ecea1a9b1be9bc1df20f9c02c Mon Sep 17 00:00:00 2001
From: Vincent Koc <25068+vincentkoc@users.noreply.github.com>
Date: Fri, 19 Jun 2026 14:21:37 +0800
Subject: [PATCH] fix(copilot): bound background compaction waits

---
 extensions/copilot/src/attempt.test.ts | 25 +++++++++++++++++++++++++
 extensions/copilot/src/attempt.ts      |  9 +++++++--
 2 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/extensions/copilot/src/attempt.test.ts b/extensions/copilot/src/attempt.test.ts
index 7e4a1bc3f2d2..00d98d54b83b 100644
--- a/extensions/copilot/src/attempt.test.ts
+++ b/extensions/copilot/src/attempt.test.ts
@@ -441,6 +441,31 @@ describe("runCopilotAttempt", () => {
     expect(beforeCompaction.mock.calls[0]?.[0]).not.toHaveProperty("messages");
   });
 
+  it("bounds successful background compaction when the SDK omits completion", async () => {
+    vi.useFakeTimers();
+    const sdk = makeFakeSdk({
+      onCreateSession: (session) => {
+        session.sendAndWait.mockImplementationOnce(async () => {
+          session.emit("session.compaction_start", {});
+          return makeAssistantMessageEvent("done");
+        });
+      },
+    });
+    const pool = makeFakePool(sdk);
+
+    const attempt = runCopilotAttempt(makeParams(), { pool });
+    await vi.advanceTimersByTimeAsync(0);
+    await vi.advanceTimersByTimeAsync(180_000);
+    const result = await attempt;
+
+    expect(result.timedOut).toBe(false);
+    expect(result.promptError).toBeUndefined();
+    expect(sdk.sessions[0]?.rpc.history.cancelBackgroundCompaction).toHaveBeenCalledTimes(1);
+    expect(sdk.sessions[0]?.disconnect).toHaveBeenCalledTimes(1);
+    expect(sdk.client.deleteSession).toHaveBeenCalledWith("sess-1");
+    expect(pool.release).toHaveBeenCalledTimes(1);
+  });
+
   it("defers and cancels compaction when the caller aborts after a turn result", async () => {
     const controller = new AbortController();
     const onDeferredCompaction = vi.fn();
diff --git a/extensions/copilot/src/attempt.ts b/extensions/copilot/src/attempt.ts
index c09aba9c11f4..c62fe06d7842 100644
--- a/extensions/copilot/src/attempt.ts
+++ b/extensions/copilot/src/attempt.ts
@@ -783,7 +783,11 @@ export async function runCopilotAttempt(
     settled = true;
     const compactionCompletionOutcome =
       waitForCompactionCompletion && !aborted && !params.abortSignal?.aborted
-        ? await awaitCompactionCompletionOrAbort(bridge!, params.abortSignal)
+        ? await awaitCompactionCompletionBeforeDeadline({
+            abortSignal: params.abortSignal,
+            bridge: bridge!,
+            timeoutMs: resolveCompactionTimeoutMs(input.config),
+          })
         : undefined;
     const deferCompactionCleanup =
       bridge?.isCompacting() &&
@@ -791,12 +795,13 @@ export async function runCopilotAttempt(
       handle &&
       (timedOut ||
         compactionCompletionOutcome === "aborted" ||
+        compactionCompletionOutcome === "deadline" ||
         params.abortSignal?.aborted === true);
     if (deferCompactionCleanup && bridge && session && handle) {
       timedOutDuringCompaction ||= timedOut;
       const cleanupAbort = new AbortController();
       const abortCleanup = () => cleanupAbort.abort();
-      if (params.abortSignal?.aborted) {
+      if (params.abortSignal?.aborted || compactionCompletionOutcome === "deadline") {
         abortCleanup();
       } else {
         params.abortSignal?.addEventListener("abort", abortCleanup, { once: true });