fix: harden residual flow boundaries and pending recovery

tests/test_pending_recovery.py

@@ -0,0 +1,35 @@
+import json
+import os
+import tempfile
+import unittest
+
+from account_outputs import retry_pending_file
+
+
+class PendingRecoveryTests(unittest.TestCase):
+    def test_retry_is_idempotent_after_target_was_already_written(self):
+        with tempfile.TemporaryDirectory() as directory:
+            pending = os.path.join(directory, "accounts.txt.pending.jsonl")
+            target = os.path.join(directory, "accounts.txt")
+            record = {"email": "a@example.com", "password": "pw", "sso": "token"}
+            with open(pending, "w", encoding="utf-8") as handle:
+                handle.write(json.dumps(record) + "\n")
+            with open(target, "w", encoding="utf-8") as handle:
+                handle.write("a@example.com----pw----token\n")
+            summary = retry_pending_file(pending)
+            self.assertEqual(summary["restored"], 1)
+            with open(target, "r", encoding="utf-8") as handle:
+                self.assertEqual(handle.readlines(), ["a@example.com----pw----token\n"])
+            self.assertFalse(os.path.exists(pending))
+
+    def test_rejects_same_input_and_output_path(self):
+        with tempfile.TemporaryDirectory() as directory:
+            pending = os.path.join(directory, "pending.jsonl")
+            with open(pending, "w", encoding="utf-8") as handle:
+                handle.write("{}\n")
+            with self.assertRaises(ValueError):
+                retry_pending_file(pending, output_path=pending)
+
+
+if __name__ == "__main__":
+    unittest.main()