fix(gate): evidence-incomplete no longer hard-blocks task completion when session state confirms gates passed

[Copilot]

update_task_status("in_progress") always creates .swarm/evidence/<task>.json with gates: {}. If evidence recording in the delegation hook subsequently fails silently (lock timeout, permission error), the gates stay empty on disk — causing checkReviewerGate to return blocked: true permanently, even though the in-memory session state was correctly advanced to tests_run by the same hook.

Root cause

checkReviewerGate treated an evidence file with incomplete gates as immediately authoritative, returning blocked without consulting session state, delegation chains, or plan.json:

// Before: hard block, all fallbacks skipped
if (!allGatesMet) {
  return { blocked: true, reason: `...missing gates...` };
}

// After: save reason, fall through to the same fallbacks used for ENOENT
evidenceIncompleteReason = `Task ${taskId} is missing required gates: [${missingGates.join(', ')}]...`;
// falls through to session state → plan.json → delegation chain checks

State advancement (in-memory) and evidence recording are independent operations in the toolAfter hook — state advances first and always; evidence write can fail silently. The fix aligns the incomplete-evidence path with the existing ENOENT path: session state and delegation chains become the authority when evidence is untrustworthy.

Changes

• src/tools/update-task-status.ts — checkReviewerGate: incomplete evidence saves the specific missing-gates reason and falls through to all existing session-state / delegation-chain fallbacks; the evidence reason is used in the final blocked return (more informative than the generic session message)
• src/hooks/delegation-gate.ts — replace /^\d+\.\d+$/ (two occurrences) with isStrictTaskId(), which correctly accepts N.M.P format task IDs
• src/tools/update-task-status.gates.test.ts — three new regression tests: gates:{} + tests_run → pass, gates:{} + idle → block (with gate names), partial gates + tests_run → pass