feat(P02): complete integration + tech-debt + NFR measurement phase — v0.1.12 tagged

Phase 2 (Integration + Tech-Debt + NFR Measurement) complete.
4 slices, 2 waves, 9 tasks. 4 REQs covered. 60 new tests (469 total).
8 v0.4 P1+ tech-debt findings addressed. Verify: APPROVE_WITH_NOTES.

NFR measurement (p95 latency + guardrail FP/FN), cohort aggregation
assist metrics (5 new metrics, no schema change), assist cost tracking
+ C-3 budget check, tech-debt wave (argon2id offload, cookie-secret
validation, credential enum, f-string SQL, cache persistence, zoneinfo,
audit log, 429 mock).

---ci---
project: praxis
phase: 2
milestone: v0.5
status: complete
requirements:
  covered: [REQ-NFR-ASSIST-01, REQ-IDEATE-04, REQ-IDEATE-06, REQ-IDEATE-07]
  partial: []
---/ci---

server/operator/mastery.py

@@ -1,8 +1,13 @@
-"""GET /api/operator/mastery — mastery progression view (TASK-08-02, D-053).
+"""GET /api/operator/mastery — mastery progression view (TASK-08-02, D-053, D-063).
 
 Auth-gated. Returns mastery progression metrics: gate_open_rate,
 median_mastery_score, rubric_criterion_means (cells with metric prefix
 `rubric_criterion_mean:`). All k-anonymized (suppressed if < 10).
+
+D-063 (binding): assist does NOT update mastery. This view is unchanged from
+v0.4 — assist metrics (assist_shifts_count, assist_turns_count) are NOT
+mastery metrics and are NOT included here. They appear in the cohort view
+(TASK-10-02). The assist metrics are separate from practice/mastery metrics.
 """
 
 from __future__ import annotations
@@ -26,6 +31,9 @@ MASTERY_METRICS = {"gate_open_rate", "median_mastery_score"}
 
 
 def _is_mastery_metric(metric: str) -> bool:
+    # D-063: assist metrics are NOT mastery metrics. Only practice mastery
+    # metrics (gate_open_rate, median_mastery_score, rubric_criterion_mean:*)
+    # are included in this view.
     return metric in MASTERY_METRICS or metric.startswith("rubric_criterion_mean:")