docs(phase29ab): record P4 derived-slot realworld seg

docs/development/current/main/10-Now.md

@@ -1,6 +1,6 @@
 # Self Current Task — Now (main)
 
-## Current Focus: Phase 29ab P3（Pattern2 PromoteDecision contract）
+## Current Focus: Phase 29ab P4（Phase 263 realworld seg: Derived slot）
 
 **2025-12-28: Phase 29ab P1 完了** ✅
 - 目的: Pattern2 の LoopBodyLocal promotion の最小ケースを fixture+integration smoke で固定
@@ -22,6 +22,11 @@
 - smokes: `tools/smokes/v2/profiles/integration/apps/phase29ab_pattern2_seg_{notapplicable,freeze}_min_vm.sh`
 - 検証: `./tools/smokes/v2/run.sh --profile integration --filter "phase29ab_pattern2_*"` PASS（4/4）
 
+**2025-12-28: Phase 29ab P4 完了** ✅
+- 目的: Phase 263 の実ログ seg を Derived slot 方針で通し、fixture+integration smoke で PASS 固定
+- Smoke: `tools/smokes/v2/profiles/integration/apps/phase263_pattern2_seg_realworld_min_vm.sh`
+- 追加/調整: `String.indexOf(search, fromIndex)` の2引数対応（arity解決を含む）を VM/JoinIR lowering 側で整備
+
 **2025-12-28: Phase 29aa P5 完了** ✅
 - 目的: Return block が複数 predecessor のとき、incoming state が完全一致する場合のみ ReturnCleanup を成立させる
 - 入口: `docs/development/current/main/phases/phase-29aa/README.md`

docs/development/current/main/30-Backlog.md

@@ -8,11 +8,12 @@ Related:
 
 ## 直近（JoinIR/selfhost）
 
-- **Phase 29ab（P3 ✅ done / P4 planned）: JoinIR completion triage**
+- **Phase 29ab（P4 ✅ done / P5 planned）: JoinIR completion triage**
   - P1: Pattern2 LoopBodyLocal minimal fixture+smoke fixed（`phase29ab_pattern2_loopbodylocal_min_vm`）
   - P2: Pattern2 Trim seg minimal fixture+smoke fixed（`phase29ab_pattern2_loopbodylocal_seg_min_vm`）
   - P3: PromoteDecision の “NotApplicable/Freeze” 境界を contract+smoke で固定（JoinIR-only前提）
-  - P4: Phase 263（Stage‑B 実ログ seg）を fixture で再現し、対応方針（Derived vs Promote）を SSOT 化
+  - P4: Phase 263（Stage‑B 実ログ seg）を Derived slot 方針で通し、fixture+smoke で固定
+  - P5: Pattern6/7（joinir/edgecfg）first-fail を fixture で固定して、Frag/compose へ収束方針を決める
 
 - **Phase 288（✅ P0–P3 + 288.1 complete）: REPL mode**
   - 入口: `docs/development/current/main/phases/phase-288/README.md`