- common/logging.py: improve format to timestamp|LEVEL|module:func:line - message
- core/ layer: DEBUG log every subprocess invocation (cmd, rc, byte counts),
JSON load/dump events, parsed application_id. ERROR log on failures.
- tools/ layer: DEBUG log every public tool entry with key parameters,
INFO log on business outcomes (saved/submitted/killed/...).
- New tests/unit/test_logging.py: capture loguru output via in-memory sink
and assert DEBUG + INFO messages are emitted for representative flows.
The plan's route signatures used query parameters, which worked for direct
HTTP callers and unit tests, but fastapi-mcp's HTTP transport passes
tools/call arguments as a JSON body. dict-typed parameters like
spark_conf arrived as a string and the route returned 422.
Refactor each route to take a single Pydantic body model (saved in
spark_executor/tools/requests.py). Underlying tool functions unchanged.
Integration tests in tests/integration/test_mcp_routes.py now exercise
the full body-based roundtrip (save_connection with spark_conf, prepare
→ list → get, list_connections with empty body).