fix: guard run completion boundary

src/main/worker/entry/index.ts

@@ -90,11 +90,14 @@ async function startRun(job: RunJob) {
     await runner.run(job);
   } finally {
     cancelledRuns.delete(job.runId);
-    active.delete(job.runId);
-    tickQueue();
   }
 }
 
+function acknowledgeRunCompletion(runId: string) {
+  const released = active.delete(runId);
+  if (released) tickQueue();
+}
+
 function cancelRun(runId: string) {
   const queuedIndex = queue.findIndex((entry) => entry.runId === runId);
   if (queuedIndex >= 0) {
@@ -129,6 +132,10 @@ parentPort.on("message", (event) => {
     cancelRun(message.runId);
     return;
   }
+  if (message.type === "run-completion-ack") {
+    acknowledgeRunCompletion(message.runId);
+    return;
+  }
   if (message.type === "steer-run") {
     const accepted = runner.steer(message.runId, message.message);
     post({