From 9a0fd13ec2ee01e6c918c5c881c4a78ef60bffe8 Mon Sep 17 00:00:00 2001
From: luvs01 <luvs01@hanmail.net>
Date: Sun, 16 Aug 2026 13:03:44 +0900
Subject: [PATCH] fix(lab): retain grace period for stale ledger locks

---
 src/lab/ledger/store.ts                | 11 ++++++++---
 tests/lab-ledger-mutation-lock.test.ts |  4 ++--
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/src/lab/ledger/store.ts b/src/lab/ledger/store.ts
index cd1d37fc4e..bdc6b5e665 100644
--- a/src/lab/ledger/store.ts
+++ b/src/lab/ledger/store.ts
@@ -76,7 +76,7 @@ function isLockHolderAlive(pid: number): boolean {
   }
 }
 
-/** Return true when a ledger lock file has dead metadata and can be recovered. */
+/** Return true when a ledger lock file has old, dead metadata and can be recovered. */
 function isLedgerLockStale(lockPath: string): boolean {
   const meta = readLedgerLockMeta(lockPath);
   if (!meta) {
@@ -86,7 +86,12 @@ function isLedgerLockStale(lockPath: string): boolean {
       return false;
     }
   }
-  return !isLockHolderAlive(meta.pid);
+  // A dead PID alone is not enough: between checking its liveness and
+  // unlinking, another process can replace the path with its own live lock.
+  // Keeping the same grace period as malformed locks prevents a freshly
+  // replaced lock from being selected for stale recovery.
+  return Date.now() - meta.createdAt > LEDGER_LOCK_STALE_MS
+    && !isLockHolderAlive(meta.pid);
 }
 
 /** Write lock ownership metadata to a newly created exclusive lock file. */
@@ -529,4 +534,4 @@ export function openLedgerStore(configDir?: string): LedgerStore {
 
 export function defaultLedgerPath(configDir?: string): string {
   return labLedgerPath(configDir);
-}
\ No newline at end of file
+}
diff --git a/tests/lab-ledger-mutation-lock.test.ts b/tests/lab-ledger-mutation-lock.test.ts
index d659ca4d73..11b915fd16 100644
--- a/tests/lab-ledger-mutation-lock.test.ts
+++ b/tests/lab-ledger-mutation-lock.test.ts
@@ -147,7 +147,7 @@ test("appendLabEvent waits for the shared ledger mutation lock", async () => {
   }
 });
 
-test("appendLabEventIfAbsent immediately recovers a lock owned by an exited process", async () => {
+test("appendLabEventIfAbsent recovers an aged lock owned by an exited process", async () => {
   const home = tempHome();
   const ledgerPath = join(home, "lab", "compatibility.jsonl");
   const lockPath = `${ledgerPath}.lock`;
@@ -158,7 +158,7 @@ test("appendLabEventIfAbsent immediately recovers a lock owned by an exited proc
     import { writeFileSync } from "node:fs";
     writeFileSync(
       ${JSON.stringify(lockPath)},
-      JSON.stringify({ pid: process.pid, createdAt: Date.now(), token: "dead-holder" }),
+      JSON.stringify({ pid: process.pid, createdAt: Date.now() - 61_000, token: "dead-holder" }),
       { mode: 0o600 },
     );
     writeFileSync(${JSON.stringify(readyPath)}, "ready");