tolerate a concurrent delete during the post-write stat

packages/server-core/src/write-coalescer.js

@@ -31,9 +31,19 @@ async function writeToDisk(absPath, data, encoding) {
   );
 
   lastWriteTime.set(absPath, Date.now());
-  const stat = await fs.promises.stat(absPath);
 
-  return { mtime: stat.mtimeMs, size: stat.size };
+  // A concurrent delete can remove the file between the write and the stat (a rapid write-then-delete on the same path).
+  // The write itself succeeds, so report synthetic metadata rather than failing the request on the now-missing file.
+  try {
+    const stat = await fs.promises.stat(absPath);
+    return { mtime: stat.mtimeMs, size: stat.size };
+  } catch (e) {
+    if (e.code === "ENOENT") {
+      return { mtime: Date.now(), size: estimateSize(data, encoding) };
+    }
+
+    throw e;
+  }
 }
 
 function flushEntry(absPath) {

packages/server-core/src/write-coalescer.test.mjs

@@ -99,6 +99,18 @@ describe("writeCoalesced", () => {
 
     expect(elapsed).toBeLessThan(20);
   });
+
+  it("returns synthetic metadata when the file is deleted before the post-write stat", async () => {
+    const filePath = path.join(tmpDir, "race.txt");
+    vi.spyOn(fs.promises, "stat").mockRejectedValueOnce(
+      Object.assign(new Error("ENOENT"), { code: "ENOENT" }),
+    );
+
+    const result = await coalescer.writeCoalesced(filePath, "hello", "utf-8");
+
+    expect(result.size).toBe(5);
+    expect(result.mtime).toBeGreaterThan(0);
+  });
 });
 
 describe("getPending", () => {