Purpose
-------
Regression tests for :mod:`oct.mcp.validator` — Pydantic input models
and ``validate_tool_args()`` entry point.
Responsibilities
----------------
- Verify all 9 Pydantic tool-argument models.
- Verify path traversal rejection (T-01, T-02) and shell metacharacter
rejection (T-04).
- Verify unknown field rejection, integer clamping, and enum allowlists.
Diagnostics
-----------
Domain: MCP-TESTS
Levels:
L2 — test lifecycle
L3 — assertion details
L4 — deep tracing
Contracts
---------
- Tests are in-memory validation checks; no subprocess or filesystem
writes.