fix(tests): retry EBUSY when removing test DB dirs on Windows

src/__tests__/helpers/createTestDb.ts

@@ -54,7 +54,32 @@ export async function createTestDb(): Promise<TestDb> {
       // Close before unlinking: the file, and its WAL/SHM siblings, stay
       // locked on Windows while the handle is open.
       await db.close()
-      await fs.rm(path.dirname(tmpFile), { recursive: true, force: true })
+      await rmWithRetry(path.dirname(tmpFile))
     },
   }
 }
+
+/**
+ * Remove a test DB directory, retrying EBUSY with exponential backoff.
+ *
+ * On Windows the OS can keep the WAL/SHM siblings locked for a while after
+ * the last SQLite handle is closed — the release is asynchronous, and
+ * real-time antivirus scanners may hold a freshly written file for seconds
+ * (observed up to ~5s on CI workstations). Every handle in the process is
+ * already closed, so retrying is safe and turns a flaky teardown into a
+ * clean one; on POSIX the first attempt always succeeds.
+ */
+async function rmWithRetry(dir: string): Promise<void> {
+  const deadline = Date.now() + 15_000
+  let waitMs = 100
+  for (;;) {
+    try {
+      await fs.rm(dir, { recursive: true, force: true })
+      return
+    } catch (err) {
+      if ((err as NodeJS.ErrnoException)?.code !== 'EBUSY' || Date.now() + waitMs > deadline) throw err
+      await new Promise((resolve) => setTimeout(resolve, waitMs))
+      waitMs = Math.min(waitMs * 2, 1000)
+    }
+  }
+}