fix(server): preserve live instruction locks

Co-Authored-By: Paperclip <noreply@paperclip.ing>

server/src/__tests__/agent-instructions-service.test.ts

@@ -667,7 +667,7 @@ describe("agent instructions service", () => {
   });
 
   it.skipIf(process.platform !== "linux")(
-    "does not evict a live lock when process identity falls back to another scheme",
+    "does not evict a live lock with a stale heartbeat when identity falls back to another scheme",
     async () => {
       const paperclipHome = await makeTempDir("paperclip-agent-instructions-marker-fallback-");
       cleanupDirs.add(paperclipHome);
@@ -698,7 +698,10 @@ describe("agent instructions service", () => {
         })}\n`,
         "utf8",
       );
-      await fs.writeFile(path.join(lockPath, `heartbeat-${token}`), "", "utf8");
+      const heartbeatPath = path.join(lockPath, `heartbeat-${token}`);
+      await fs.writeFile(heartbeatPath, "", "utf8");
+      const staleHeartbeat = new Date(Date.now() - 60_000);
+      await fs.utimes(heartbeatPath, staleHeartbeat, staleHeartbeat);
 
       const materialization = svc.materializeManagedBundle(agent, { "AGENTS.md": "# Stock\n" });
       const firstOutcome = await Promise.race([

server/src/services/agent-instructions.ts

@@ -278,15 +278,11 @@ async function removeStaleManagedBundleLock(lockPath: string): Promise<boolean>
     ownerSnapshot = await fs.readFile(path.join(lockPath, "owner.json"), "utf8");
     const owner = JSON.parse(ownerSnapshot) as {
       pid?: unknown;
-      token?: unknown;
       processStartMarker?: unknown;
     };
     const pid = typeof owner.pid === "number" && Number.isInteger(owner.pid) && owner.pid > 0
       ? owner.pid
       : null;
-    const token = typeof owner.token === "string" && /^[0-9a-f-]{36}$/i.test(owner.token)
-      ? owner.token
-      : null;
     if (pid !== null && isProcessAlive(pid)) {
       const recordedStart = typeof owner.processStartMarker === "string"
         ? owner.processStartMarker
@@ -298,12 +294,11 @@ async function removeStaleManagedBundleLock(lockPath: string): Promise<boolean>
         && processStartMarkersComparable(recordedStart, currentStart)
       ) {
         shouldRemove = recordedStart !== currentStart;
-      } else if (token) {
-        shouldRemove = await managedBundleLockAgeMs(
-          path.join(lockPath, `heartbeat-${token}`),
-        ) > MANAGED_BUNDLE_LOCK_STALE_MS;
       } else {
-        shouldRemove = await managedBundleLockAgeMs(lockPath) > MANAGED_BUNDLE_LOCK_STALE_MS;
+        // A delayed heartbeat does not prove that a live process has stopped
+        // materializing. Only a comparable process-start marker can safely
+        // distinguish a reused PID from the original owner.
+        shouldRemove = false;
       }
     } else if (pid !== null) {
       shouldRemove = true;