fix(compaction): cancel failed handoff without biasing later folds

Author: TheGreatAxios

src/agent/compaction.test.ts

@@ -902,4 +902,35 @@ describe("handoff arming (/handoff)", () => {
       ),
     ).toBeNull();
   });
+
+  test("cancelManual clears sticky extraInstructions from a failed pivot", () => {
+    const governor = createCompactionGovernor(undefined);
+    governor.syncFromTurns(tenTurns);
+    expect(governor.requestHandoff("now do the UI audit")).toBe("armed");
+    governor.cancelManual();
+    expect(governor.extraInstructions).toBeUndefined();
+  });
+
+  test("threshold pending survives cancelManual so a tool pause still folds", () => {
+    const governor = createCompactionGovernor(undefined);
+    governor.noteInferenceDone(inferenceDone(overThreshold), tenTurns);
+    expect(
+      governor.interceptActions(toolDone(), inferAction, capabilities),
+    ).not.toBeNull();
+
+    const cancelled = createCompactionGovernor(undefined);
+    cancelled.noteInferenceDone(inferenceDone(overThreshold), tenTurns);
+    expect(cancelled.requestHandoff("now do the UI audit")).toBe("armed");
+    cancelled.cancelManual();
+    const actions = cancelled.interceptActions(
+      toolDone(),
+      inferAction,
+      capabilities,
+    );
+    expect(actions).not.toBeNull();
+    expect(actions?.some((a) => a.type === "compact")).toBe(true);
+    expect(actions?.find((a) => a.type === "compact")).toMatchObject({
+      reason: "context-threshold",
+    });
+  });
 });

src/agent/compaction.ts

@@ -397,9 +397,14 @@ export function createCompactionGovernor(
   }
 
   // Disarm after a pivot send that never delivered: without this the next
-  // operator message would fold unexpectedly.
+  // operator message would fold unexpectedly. Threshold `pending` is independent
+  // of the failed pivot and must still fire at the next tool pause. Sticky
+  // extraInstructions belong to a successful fold, not a cancelled one.
   function cancelManual(): void {
+    const thresholdPending = pending;
     clearManualArming();
+    pending = thresholdPending;
+    extraInstructions = undefined;
   }
 
   return {