fix: log primary model error before fallback

nanobot/providers/fallback_provider.py

@@ -150,13 +150,17 @@ class FallbackProvider(LLMProvider):
         on_stream_recover: Callable[[], Awaitable[None]] | None = None,
     ) -> LLMResponse:
         primary_model = kwargs.get("model") or self._primary.get_default_model()
+        primary_was_attempted = False
+        primary_error = "unknown error"
 
         if self._primary_available():
+            primary_was_attempted = True
             response = await call(self._primary, kwargs)
             if response.finish_reason != "error":
                 self._primary_failures = 0
                 self._primary_tripped_at = None
                 return response
+            primary_error = (response.content or primary_error)[:120]
 
             if has_streamed is not None and has_streamed[0]:
                 is_timeout = (response.error_kind or "").lower() == "timeout"
@@ -196,7 +200,7 @@ class FallbackProvider(LLMProvider):
             logger.debug("Primary model '{}' circuit open; skipping", primary_model)
 
         last_response: LLMResponse | None = None
-        primary_skipped = not self._primary_available()
+        primary_skipped = not primary_was_attempted
         for idx, fallback in enumerate(self._fallback_presets):
             fallback_model = fallback.model
             if has_streamed is not None and has_streamed[0]:
@@ -221,8 +225,8 @@ class FallbackProvider(LLMProvider):
                 )
             elif idx == 0:
                 logger.info(
-                    "Primary model '{}' failed, trying fallback '{}'",
-                    primary_model, fallback_model,
+                    "Primary model '{}' failed: {}; trying fallback '{}'",
+                    primary_model, primary_error, fallback_model,
                 )
             else:
                 logger.info(