feat: add TUI-safe logging mode that disables RichHandler

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/utils/logging.py

@@ -77,6 +77,21 @@ def setup_logging(
     )
 
 
+def setup_logging_for_tui() -> None:
+    """Reconfigure logging for Textual TUI mode.
+
+    Removes the RichHandler (which writes to stdout and corrupts the TUI)
+    while preserving any file handlers. Call this from the Textual App's
+    on_mount() before any agent work begins.
+    """
+    from rich.logging import RichHandler
+
+    root_logger = logging.getLogger()
+    root_logger.handlers = [
+        h for h in root_logger.handlers if not isinstance(h, RichHandler)
+    ]
+
+
 def get_logger(name: str) -> structlog.stdlib.BoundLogger:
     """Get a named structlog logger.
 

tests/unit/test_logging_tui.py

@@ -0,0 +1,31 @@
+"""Tests for TUI-safe logging configuration."""
+
+import logging
+
+from app.utils.logging import setup_logging, setup_logging_for_tui
+
+
+class TestTuiLogging:
+    def test_setup_logging_for_tui_removes_rich_handler(self) -> None:
+        """TUI mode should have no RichHandler on root logger."""
+        from rich.logging import RichHandler
+
+        # First set up normal logging (adds RichHandler)
+        setup_logging()
+        root = logging.getLogger()
+        assert any(isinstance(h, RichHandler) for h in root.handlers)
+
+        # Switch to TUI mode
+        setup_logging_for_tui()
+        root = logging.getLogger()
+        assert not any(isinstance(h, RichHandler) for h in root.handlers)
+
+    def test_setup_logging_for_tui_keeps_file_handler(self, tmp_path) -> None:
+        """TUI mode should preserve file handler if configured."""
+        log_file = tmp_path / "test.log"
+        setup_logging(log_file=log_file)
+        setup_logging_for_tui()
+
+        root = logging.getLogger()
+        file_handlers = [h for h in root.handlers if isinstance(h, logging.FileHandler)]
+        assert len(file_handlers) == 1