Stamp X-Codeflow-Rev before opening the snapshot fd. An atomic save after fs.open can bump the path rev while the handle still reads the old inode; sampling after open then made retainCliWatchPathsAfterAnalysis treat that SSE event as already in the snapshot.

Co-authored-by: Braedon Saunders <braedonsaunders@users.noreply.github.com>

Author: cursoragent

cli/codeflow.mjs

@@ -221,16 +221,23 @@ function sendFileError(res, status, message) {
   res.end(message);
 }
 
+function resolveSnapshotRev(options) {
+  options = options || {};
+  return typeof options.snapshotRev === 'function' ? options.snapshotRev() : options.snapshotRev;
+}
+
 function pipeSafeFile(res, filePath, contentType, maxBytes, options) {
   options = options || {};
+  // Sample before open so an atomic save cannot bump the path rev onto
+  // bytes later read from the already-bound (stale) inode.
+  const snapshotRev = resolveSnapshotRev(options);
   return fs.open(filePath, 'r').then(async (fh) => {
     try {
       const st = await fh.stat();
       if (!st.isFile()) {
         sendFileError(res, 404, 'Not found');
         return;
       }
-      const snapshotRev = typeof options.snapshotRev === 'function' ? options.snapshotRev() : options.snapshotRev;
       if (Number.isFinite(maxBytes) && st.size > maxBytes) {
         sendFileError(res, 413, 'File too large');
         return;

tests/cli-codeflow.test.mjs

@@ -133,8 +133,12 @@ test('CLI server serves the same UI and folder files', async (t) => {
   assert.match(fileBody, /function/);
   assert.equal(file.headers.get('content-length'), String(Buffer.byteLength(fileBody)));
   assert.equal(file.headers.get('x-codeflow-rev'), '0');
+  // An atomic save after open would bump the live rev; the header must
+  // still reflect the pre-open sample so retainCliWatchPathsAfterAnalysis
+  // treats that SSE rev as newer than the snapshot.
   const cliSource = await readFile(join(repoRoot, 'cli/codeflow.mjs'), 'utf8');
-  assert.match(cliSource, /function pipeSafeFile[\s\S]*?fs\.open\(filePath, 'r'\)[\s\S]*?readOpenedSnapshot\(fh, st\.size\)/);
+  assert.match(cliSource, /function pipeSafeFile[\s\S]*?resolveSnapshotRev\(options\)[\s\S]*?fs\.open\(filePath, 'r'\)[\s\S]*?readOpenedSnapshot\(fh, st\.size\)/);
+  assert.doesNotMatch(cliSource, /function pipeSafeFile[\s\S]*?fs\.open\(filePath, 'r'\)[\s\S]*?resolveSnapshotRev\(/);
   assert.match(cliSource, /isMissingFsError\(err\)[\s\S]*?sendFileError\(res, 404/);
   assert.match(cliSource, /sendFileError\(res, 500, 'Read failed'\)/);
   assert.match(cliSource, /X-Codeflow-Rev/);