The clarifier (ClaudeClarifier._turn) called claude_invoke with no max_turns,
inheriting the single-shot default (1). When the model's one turn did not
terminate in a final result the SDK raised 'Reached maximum number of turns (1)'
and, with no salvageable text, the call failed and crashed the clarify node —
leaving the task wedged at clarify with NO question posted to Slack (the human
never sees a clarifier prompt). Observed live on the R720.
Same single-shot flake the planner hit and fixed in PR #58 (_PLANNER_MAX_TURNS=4);
the clarifier never got the headroom. Give it the same: pass max_turns=4 (tools
stay off — still a fast reasoning->JSON completion).
- clarifier_llm.py: _turn passes max_turns=_CLARIFIER_MAX_TURNS (=4).
- tests: clarifier passes max_turns headroom to the invoke seam.
Full suite 1505 passed; ruff clean.
Adds the billing-seam invoker (claude_agent_sdk subscription-OAuth, deferred import, API/Bedrock paths) and the Claude-backed clarifier callables (ConfidenceAssessor/QuestionGenerator, one call/turn memoized on (thread_id,len,content-hash), fail-safe to 0.0 so garbage never clears the 98% human gate).
