Plans were vague because the gate accepted the bare minimum: PM
approach >=20 chars and title-only sub_tasks. minimax wrote exactly
the minimum.
- IWillPlanRequest.approach min_length 20 -> 150 (kept in sync with
_PM_APPROACH_MIN_LEN; the gate enforces it at the choreographer
layer too so direct/MCP callers can't bypass the HTTP boundary).
- New _thin_subtask_hint: every PM sub_task must have a title and a
description >= _PM_SUBTASK_DESC_MIN_LEN (60) saying what the step
does — each sub_task is both a delegate target AND a
progress-checklist item, so a title alone is not a plan.
- cell_pm/main_pm role prompts: explicit "the gate REJECTS thin plans"
framing + concrete sub_task example + the new minimums.
- Updated all affected test fixtures across the suite to use
substantive approaches/descriptions; added thin-sub_task rejection
coverage.
Commit 1 of 3 for the plan/progress quality work (#171/#172/#173).
Renn F
ed828a719b