Close GAN transcript streams cleanly

scripts/agent_gan_repl.py

@@ -60,6 +60,8 @@ def write(self, text: str) -> int:
             return 0
         with self._lock:
             self.terminal.write(text)
+            if self.log.closed:
+                return len(text)
             for part in text.splitlines(keepends=True):
                 if self._line_start:
                     self.log.write(f"[{self.timestamp_fn()}] ")
@@ -71,10 +73,13 @@ def write(self, text: str) -> int:
     def flush(self) -> None:
         with self._lock:
             self.terminal.flush()
-            self.log.flush()
+            if not self.log.closed:
+                self.log.flush()
 
     def log_only(self, event: str) -> None:
         with self._lock:
+            if self.log.closed:
+                return
             if not self._line_start:
                 self.log.write("\n")
             self.log.write(f"[{self.timestamp_fn()}] {event.rstrip()}\n")
@@ -83,6 +88,10 @@ def log_only(self, event: str) -> None:
 
     def close_log(self) -> None:
         with self._lock:
+            if sys.stdout is self:
+                sys.stdout = self.terminal
+            if sys.stderr is self:
+                sys.stderr = self.terminal
             if not self.log.closed:
                 self.log.flush()
                 self.log.close()

tests/inference_engine/bridge/test_agent_gan_repl.py

@@ -1,6 +1,7 @@
 import io
 import json
 import signal
+import sys
 import time
 from pathlib import Path
 
@@ -63,6 +64,22 @@ def test_timestamped_tee_preserves_terminal_and_flushes_log(tmp_path):
     )
 
 
+def test_timestamped_tee_shutdown_restores_streams_and_flush_is_safe(
+    tmp_path,
+    monkeypatch,
+):
+    terminal = io.StringIO()
+    tee = TimestampedTee(terminal, tmp_path / "agent.log")
+    monkeypatch.setattr(sys, "stdout", tee)
+    monkeypatch.setattr(sys, "stderr", tee)
+    tee.close_log()
+    assert sys.stdout is terminal
+    assert sys.stderr is terminal
+    tee.flush()
+    tee.write("after-close")
+    assert terminal.getvalue() == "after-close"
+
+
 def test_token_printer_streams_only_new_suffix(capsys):
     printer = TokenPrinter(Tokenizer(), "generator")
     printer([1])