feat(ui): add real-time diagnostic logs console (#974)

* feat(diagnostics): add admin-gated real-time diagnostics logs terminal UI

* feat(ui): resolve diagnostics logs feedback and optimize client-side caching

* feat(ui): resolve diagnostics logs feedback

app.py

@@ -69,10 +69,37 @@ from src.generated_images import GENERATED_IMAGE_HEADERS, resolve_generated_imag
 from starlette.responses import RedirectResponse
 
 # ========= LOGGING =========
-logging.basicConfig(
-    level=logging.INFO,
-    format='%(asctime)s - %(name)s - %(levelname)s - %(message)s',
-)
+import logging.handlers
+from core.constants import DATA_DIR
+
+_root_logger = logging.getLogger()
+_root_logger.setLevel(logging.INFO)
+_formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
+
+# Clear existing handlers to avoid duplicates
+for _h in list(_root_logger.handlers):
+    _root_logger.removeHandler(_h)
+
+_console_h = logging.StreamHandler()
+_console_h.setFormatter(_formatter)
+_root_logger.addHandler(_console_h)
+
+try:
+    _log_dir = os.path.join(DATA_DIR, "logs")
+    os.makedirs(_log_dir, exist_ok=True)
+    _log_file = os.path.join(_log_dir, "app.log")
+
+    # RotatingFileHandler is not multi-process safe (e.g. if uvicorn is run with --workers N).
+    # Odysseus is single-process by convention, so this is acceptable, but be aware that
+    # concurrent log rotation issues can arise if multiple workers are configured.
+    _file_h = logging.handlers.RotatingFileHandler(
+        _log_file, maxBytes=5 * 1024 * 1024, backupCount=3, encoding="utf-8"
+    )
+    _file_h.setFormatter(_formatter)
+    _root_logger.addHandler(_file_h)
+except Exception as e:
+    _root_logger.warning(f"Failed to initialize file logging handler (falling back to console-only): {e}")
+
 logger = logging.getLogger(__name__)
 
 # ========= APP =========