[TMHSDigital]

Fixes #26.

The problem. The runner retried every error an adapter raised, except a refusal, up to three attempts. That included:

• a WireContractError, whose own docstring says no retry fixes it;
• a CheckpointMismatchError;
• the missing optional dependency error;
• a ValueError;
• a 401.

Both SDKs also retried underneath (TypeSafe's default policy, Anthropic's max_retries=2), so one case could make nine billed calls, and a retried answer could be scored.

What changed

• is_transient() in runner/execute.py decides whether an error is worth another attempt. It goes by the error's shape, so the runner imports no SDK:
  • anything plumbline raises on purpose (PlumblineError) is permanent;
  • an error with a status code is transient only for 408, 409, 425, 429 and 5xx;
  • TimeoutError, ConnectionError, and classes named *ConnectionError or *TimeoutError are transient. Anthropic's connection errors subclass neither builtin, hence the name check;
  • anything else is permanent. A recorded failure is visible, and a retry costs money.
• Retry-After is waited for, up to 60 s.
• A permanent failure is recorded after its first attempt, with the number of attempts it actually made.
• SDK retries off: both adapters build their SDK client with retries disabled (RetryPolicy(max_retries=0) for TypeSafe, max_retries=0 for Anthropic). The runner is now the only retrying layer, so the artifact's attempts is the number of calls made.
• METHODOLOGY now says what is retried and what is not.

Checked

• New tests failed on main and pass now:
  • six permanent errors are each attempted once: WireContractError, CheckpointMismatchError, a plain PlumblineError, ValueError, 401 and 400;
  • 429, 503, ConnectionError, and an APIConnectionError-named class are retried;
  • Retry-After: 2 waits 2 s, and 600 is capped at 60;
  • both adapters build their client with retries off.
• The review's repro now shows one call, not three, for both a WireContractError and a 401.
• ruff, mypy --strict, and the full pytest suite pass.

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