[dborowitz]

When create_session fails due to a typo in the project ID, region, or session template, surface the underlying error details instead of raising an opaque HTTP 404 or dropping structured gRPC metadata:

• Catch MethodNotImplemented alongside InvalidArgument and PermissionDenied, and translate HTTP 404 responses from the regional endpoint (<region> /usr/local/google/home/dborowitz/.gemini/config/-dataproc.googleapis.com) into an actionable message prompting the user to check that the location is a valid Managed Spark region.
• Surface structured DebugInfo details, ErrorInfo reasons (CONSUMER_INVALID, RESOURCE_PROJECT_INVALID, LOCATION_POLICY_VIOLATED), and BadRequest field violations when formatting session creation errors, plus a format hint when a malformed session_template reference fails with a generic InvalidArgument.
• Chain the original exception with from e and make ManagedSparkConnectException inherit from RuntimeError so callers catching either exception type continue to work and full tracebacks preserve the underlying gRPC error.
• Add unit and integration tests covering invalid project IDs, invalid regions, and nonexistent or malformed session templates.

[gemini-code-assist]

Code Review

This pull request improves error handling and reporting when creating a Managed Spark Session. Key changes include changing ManagedSparkConnectException to inherit from RuntimeError, adding detailed error extraction and formatting logic for API errors (such as invalid project IDs, invalid regions, and malformed session templates), and introducing a helper function to clean up failed session creations. Additionally, comprehensive integration and unit tests have been added to verify these error handling paths. There are no review comments to address, and I have no further feedback to provide.