fix(fb-32): address PR #122 round 2 review

- spec: add one-line cross-link to HOTFIXES entry per CLAUDE.md
  Spec-contract policy
- HOTFIXES: rename heading from "fb-32" to "p9-fb-32" matching
  the rest of the file's full-ID convention
- config: defensive assert before string-replace in negative TOML
  test guards against default-value drift causing unhelpful unwrap

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

crates/kebab-config/src/lib.rs

@@ -1096,6 +1096,10 @@ mod fb27_tests {
         // value rather than missing required sections.
         let cfg = Config::defaults();
         let mut toml_text = toml::to_string(&cfg).expect("default round-trips");
+        assert!(
+            toml_text.contains("stale_threshold_days = 30"),
+            "default value drifted; update test fixture"
+        );
         toml_text = toml_text.replace(
             "stale_threshold_days = 30",
             "stale_threshold_days = -5",

tasks/HOTFIXES.md

@@ -14,7 +14,7 @@ historical contract that was implemented; this file accumulates the
 deltas so phase 5+ readers can find the live behavior without diffing
 git history.
 
-## 2026-05-09 — fb-32: search_hit.v1 / citation.v1 required-field expansion
+## 2026-05-09 — p9-fb-32: search_hit.v1 / citation.v1 required-field expansion
 
 **무엇이 바뀌었나**: `search_hit.v1` 과 `citation.v1` 의 `required` 배열에 `indexed_at` (RFC3339) + `stale` (bool) 두 필드가 추가됨. `schema_version` 은 그대로 (`search_hit.v1` / `citation.v1`).
 

tasks/p9/p9-fb-32-stale-doc-indicator.md

@@ -14,6 +14,8 @@ source_feedback: 사용자 도그푸딩 2026-05-06 — Claude Code 가 kebab CLI
 
 # p9-fb-32 — Stale doc indicator
 
+> ✅ **구현 완료.** 본 spec 은 구현 시점의 frozen 상태. post-merge deviation (특히 search_hit.v1 / citation.v1 의 required-field 확장) 은 [HOTFIXES.md](../HOTFIXES.md) 의 `2026-05-09 — p9-fb-32` 항목 참조 — live source of truth.
+
 상세 설계: `docs/superpowers/specs/2026-05-08-p9-fb-32-stale-doc-indicator-design.md`.
 구현 계획: `docs/superpowers/plans/2026-05-09-p9-fb-32-stale-doc-indicator.md`.