Build a draft-then-gate reply pipeline

Four stages, each a small function: an input battery that can stop the pipeline before any LLM call; extract-then-select for the proposed date, with an acceptance threshold so an uncertain date never reaches the drafter; a claude -p drafter called with an argument list; and an output battery that sorts drafts into ready, needs editing or blocked. Both decision functions take plain probabilities, so you can reason about them and check them without any client, and the policies are dicts of (action threshold, action, review threshold), as in TypeSafe's guardrails cookbook. A ledger records Jev calls, input tokens, cost and time per stage.