Purpose
-------
Regression tests for :mod:`oct.mcp.audit` — ``McpAuditRecord`` and
``McpAuditLogger``.
Responsibilities
----------------
- Verify JSONL write and rotation (size and count thresholds).
- Verify pruning of old audit files.
- Verify session/request ID propagation and redaction flag.
Diagnostics
-----------
Domain: MCP-TESTS
Levels:
L2 — test lifecycle
L3 — assertion details
L4 — deep tracing
Contracts
---------
- All audit files are written to ``tmp_path``; no real logs directory
is touched.