MCP stdio transport uses stdout for JSON-RPC messages. AsyncLogger
was writing Rich progress output to stdout (the default Console()
target), which caused clients to receive garbled JSON and log lines
interleaved in the same stream.
Changes:
- Pass stderr=True to Console() so all log output goes to stderr,
which is the correct channel for library diagnostics and aligns
with the behaviour of Python's own logging.StreamHandler.
- Add an injectable console parameter so downstream wrappers
(e.g. mcp-crawl4ai, FastMCP integrations) can override the target
stream without monkey-patching.
- Add import sys (used in docstring example).
- Add tests/test_async_logger_stderr.py with 7 tests covering the
default-to-stderr behaviour, custom console injection, verbose=False
suppression, file logging, and an end-to-end MCP scenario.
Fixes#1968
