fix(joinir): Phase 283 P0 - Pattern3 Undefined ValueId Bug Fix

- Fix: extract_if_condition() moved after local_cond_env construction
  (loop_with_if_phi_if_sum.rs:175)
  - Root cause: condition extraction before i_param/sum_param creation
  - Result: i % 2 referenced caller's ConditionEnv with unmapped ValueId
- Fail-Fast: Add condition_bindings validation in merge (mod.rs)
- Fixture: Update loop_if_phi.hako for C2 compatibility (sum.toString())
- Verified: VM execution outputs sum=9 ✅

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

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

@@ -8,12 +8,9 @@ Related:
 
 ## 直近（JoinIR/selfhost）
 
-- **Phase 281（planned）: Pattern6 を compose へ段階吸収**
-  - 入口: `docs/development/current/main/phases/phase-281/README.md`
-  - P0（Pattern7）✅ 完了、次は P1（Pattern6 early-exit）
-
-- **Phase 282（planned）: Router shrinkage**
-  - 目的: pattern番号を “症状ラベル” に縮退させ、合成SSOTへ寄せた後に router の分岐を減らす
+- **Phase 282（planned, design-first）: Router shrinkage**
+  - 入口: `docs/development/current/main/phases/phase-282/README.md`
+  - 目的: pattern番号を “症状ラベル” に縮退し、router の責務を「抽出の配線」へ収束させる
 
 （✅ done）**Phase 279 P0**: Type propagation pipeline SSOT 統一（lifecycle / JoinIR / LLVM の二重化解消）
   - 完了: `docs/development/current/main/phases/phase-279/README.md`
@@ -27,6 +24,12 @@ Related:
 - （✅ done）**Phase 273**: Plan line SSOT（Pattern6/7）
   - 完了: `docs/development/current/main/phases/phase-273/README.md`
 
+- （✅ done）**Phase 280**: Frag composition SSOT positioning
+  - 完了: `docs/development/current/main/phases/phase-280/README.md`
+
+- （✅ done）**Phase 281**: compose adoption（Pattern6/7, P0–P3）
+  - 完了: `docs/development/current/main/phases/phase-281/README.md`
+
 - （✅ done）**Phase 277/278**: PHI strict + env var 収束
   - 完了: `docs/development/current/main/phases/phase-277/README.md`
   - 完了: `docs/development/current/main/phases/phase-278/README.md`