fix: harden finalize retry metadata

src/plugins/hooks.before-agent-finalize.test.ts

@@ -97,6 +97,41 @@ describe("before_agent_finalize hook runner", () => {
     });
   });
 
+  it("skips malformed retry instructions when merging revise decisions", async () => {
+    const runner = createHookRunner(
+      createMockPluginRegistry([
+        {
+          hookName: "before_agent_finalize",
+          handler: vi.fn().mockResolvedValue({
+            action: "revise",
+            reason: "malformed retry payload should not crash",
+            retry: { instruction: 123, idempotencyKey: "bad-retry" } as never,
+          }),
+        },
+        {
+          hookName: "before_agent_finalize",
+          handler: vi.fn().mockResolvedValue({
+            action: "revise",
+            reason: "valid retry still applies",
+            retry: {
+              instruction: " rerun the focused tests ",
+              idempotencyKey: "valid-retry",
+            },
+          }),
+        },
+      ]),
+    );
+
+    await expect(runner.runBeforeAgentFinalize(EVENT, TEST_PLUGIN_AGENT_CTX)).resolves.toEqual({
+      action: "revise",
+      reason: "malformed retry payload should not crash\n\nvalid retry still applies",
+      retry: {
+        instruction: "rerun the focused tests",
+        idempotencyKey: "valid-retry",
+      },
+    });
+  });
+
   it("lets finalize override earlier revise decisions", async () => {
     const runner = createHookRunner(
       createMockPluginRegistry([

src/plugins/hooks.ts

@@ -322,7 +322,7 @@ export function createHookRunner(
     const normalizeRetry = (
       retry: PluginHookBeforeAgentFinalizeResult["retry"] | undefined,
     ): PluginHookBeforeAgentFinalizeResult["retry"] | undefined => {
-      const instruction = retry?.instruction.trim();
+      const instruction = typeof retry?.instruction === "string" ? retry.instruction.trim() : "";
       if (!instruction) {
         return undefined;
       }

src/plugins/host-hook-runtime.ts

@@ -115,6 +115,9 @@ function waitForTerminalEventHandlers(params: {
   }
   let timeout: NodeJS.Timeout | undefined;
   const settled = Promise.allSettled(pendingHandlers).then(() => "settled" as const);
+  // Promise.race bounds the host wait; JavaScript cannot cancel the plugin
+  // promises themselves, so timeout also marks the run expired to block late
+  // run-context resurrection by handlers that eventually settle.
   const timedOut = new Promise<"timeout">((resolve) => {
     timeout = setTimeout(() => {
       markTerminalEventCleanupExpired(runId);