fix(skills): preserve replaced checkpoint locks

skills/develop/develop-workflow/scripts/checkpoint-record.mjs

@@ -38,6 +38,7 @@ const nodeIo = Object.freeze({
   open: (...args) => fs.open(...args),
   readFile: (...args) => fs.readFile(...args),
   rename: (...args) => fs.rename(...args),
+  stat: (...args) => fs.stat(...args),
   unlink: (...args) => fs.unlink(...args),
   randomUUID: () => randomUUID(),
 });
@@ -172,6 +173,10 @@ async function unlinkQuietly(io, path) {
   }
 }
 
+function sameFile(left, right) {
+  return left.dev === right.dev && left.ino === right.ino;
+}
+
 async function readExisting(io, target) {
   try {
     return { exists: true, bytes: await io.readFile(target) };
@@ -260,6 +265,7 @@ export async function checkpointRecord(request) {
   }
 
   let lockHandle = null;
+  let lockIdentity = null;
   let tempHandle = null;
   let tempPath = null;
   let primaryError;
@@ -267,13 +273,14 @@ export async function checkpointRecord(request) {
   try {
     try {
       lockHandle = await io.open(lock, "wx", FILE_MODE);
+      lockIdentity = await lockHandle.stat();
     } catch (error) {
       if (isAlreadyExists(error)) {
         throw new CheckpointError("LOCK_EXISTS", "checkpoint target is locked; refusing to recover or overwrite the lock", {
           cause: error,
         });
       }
-      throw new CheckpointError("LOCK_FAILED", `could not acquire checkpoint lock: ${messageFor(error)}`, {
+      throw new CheckpointError("LOCK_FAILED", `could not acquire and identify checkpoint lock: ${messageFor(error)}`, {
         cause: error,
       });
     }
@@ -369,12 +376,24 @@ export async function checkpointRecord(request) {
       cause: lockCloseError,
     });
   }
-  if (lockHandle !== null) {
-    const lockUnlinkError = await unlinkQuietly(io, lock);
-    if (lockUnlinkError !== undefined && !isMissing(lockUnlinkError) && primaryError === undefined) {
-      primaryError = new CheckpointError("LOCK_CLEANUP_FAILED", `could not remove checkpoint lock: ${messageFor(lockUnlinkError)}`, {
-        cause: lockUnlinkError,
-      });
+  if (lockIdentity !== null) {
+    let currentLockIdentity;
+    try {
+      currentLockIdentity = await io.stat(lock);
+    } catch (error) {
+      if (!isMissing(error) && primaryError === undefined) {
+        primaryError = new CheckpointError("LOCK_CLEANUP_FAILED", `could not verify checkpoint lock ownership: ${messageFor(error)}`, {
+          cause: error,
+        });
+      }
+    }
+    if (currentLockIdentity !== undefined && sameFile(lockIdentity, currentLockIdentity)) {
+      const lockUnlinkError = await unlinkQuietly(io, lock);
+      if (lockUnlinkError !== undefined && !isMissing(lockUnlinkError) && primaryError === undefined) {
+        primaryError = new CheckpointError("LOCK_CLEANUP_FAILED", `could not remove checkpoint lock: ${messageFor(lockUnlinkError)}`, {
+          cause: lockUnlinkError,
+        });
+      }
     }
   }