feat(logging): enhance S3 existence check with detailed logs

Author: MickaelCa

src/server/s3_utils.py

@@ -428,7 +428,10 @@ def check_s3_object_exists(s3_file_path: str) -> bool:
 
     """
     if not is_s3_enabled():
+        logger.info("S3 not enabled, skipping object existence check", extra={"s3_file_path": s3_file_path})
         return False
+
+    logger.info("Checking S3 object existence", extra={"s3_file_path": s3_file_path})
     _cache_lookup_counter.labels(url=s3_file_path).inc()
     try:
         s3_client = create_s3_client()
@@ -440,15 +443,38 @@ def check_s3_object_exists(s3_file_path: str) -> bool:
         # Object doesn't exist if we get a 404 error
         error_code = err.response.get("Error", {}).get("Code")
         if error_code == "404":
+            logger.info(
+                "S3 object not found",
+                extra={
+                    "s3_file_path": s3_file_path,
+                    "bucket_name": get_s3_bucket_name(),
+                    "error_code": error_code,
+                },
+            )
             _cache_miss_counter.labels(url=s3_file_path).inc()
             return False
         # Re-raise other errors (permissions, etc.)
         raise
-    except Exception:
+    except Exception as exc:
         # For any other exception, assume object doesn't exist
+        logger.info(
+            "S3 object check failed with exception, assuming not found",
+            extra={
+                "s3_file_path": s3_file_path,
+                "bucket_name": get_s3_bucket_name(),
+                "exception": str(exc),
+            },
+        )
         _cache_miss_counter.labels(url=s3_file_path).inc()
         return False
     else:
+        logger.info(
+            "S3 object found",
+            extra={
+                "s3_file_path": s3_file_path,
+                "bucket_name": get_s3_bucket_name(),
+            },
+        )
         _cache_hit_counter.labels(url=s3_file_path).inc()
         return True