docs: update Now/INDEX for Phase 129-B join_k as-last

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

@@ -1,10 +1,10 @@
 # Self Current Task — Now (main)
 
-## Next: Phase 129 P1（実装待ち）
+## Next: Phase 129-C（post-if / post_k）
 
 **Phase 129: Materialize join_k continuation（dev-only）**
-- 現状: P0/P2/P3 は完了（VM/LLVM EXE parity, fixture, docs）
-- 残り: P1 join_k を JoinModule 上で実体化（then/else は TailCall(join_k)、post-if は post_k）
+- 現状: Phase 129-B で join_k “if-as-last” を実体化（then/else は TailCall(join_k)）
+- 残り: post-if（`if { x=2 }; return x`）を post_k continuation で表現（join_k → post_k の tailcall）
 - 入口: `docs/development/current/main/phases/phase-129/README.md`
 
 ## 2025-12-18：Phase 127 完了 ✅

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

@@ -21,7 +21,7 @@ Related:
   - ねらい: `loop/if` ネストの "構造" を SSOT（ControlTree/StepTree）で表せるようにする
   - 注意: canonicalizer は観測/構造SSOTまで（ValueId/PHI配線は Normalized 側へ）
   - 現状: Phase 119–128（if-only Normalized: reads/inputs/unknown-read/partial-assign keep/merge）まで完了
-  - 次候補: Phase 129 P1（join_k continuation の実体化）
+  - 次候補: Phase 129-C（post-if を post_k continuation で表現）
   - 入口: `docs/development/current/main/design/control-tree.md`
 
 ## 中期（ループ在庫の残り）

docs/development/current/main/phases/phase-129/PROGRESS.md

@@ -1,6 +1,6 @@
 # Phase 129 Progress Report
 
-## Status: P0-P3 Complete, P1 Requires User Decision
+## Status: P0/P2/P3 Complete, P1 in Progress (129-B complete)
 
 ### Completed Tasks ✅
 
@@ -37,7 +37,7 @@
 
 #### P1: Materialize join_k Continuation
 
-**Current State**: Analysis complete, awaiting user decision
+**Current State**: Phase 129-B (if-as-last) implemented; Phase 129-C (post-if) remains.
 
 **Key Findings**:
 1. Current `lower_if_node` is Phase 123-124 minimal (incomplete)
@@ -63,7 +63,7 @@
 - Pros: Incremental testing, clear rollback points
 - Cons: More commits (3), slightly slower
 
-**Decision Needed**: User/ChatGPT should choose Option A or B
+**Decision Needed**: None for 129-B; next is 129-C (post-if via post_k continuation).
 
 ## Test Results Summary
 

docs/development/current/main/phases/phase-129/README.md

@@ -134,8 +134,8 @@ x=1; flag=1; if flag==1 { x=2 }; print(x); return "OK"
 ## Acceptance Criteria
 
 - ✅ P0: Phase 128 LLVM EXE smoke passes
-- [ ] P1: join_k materialized in builder.rs
-- [ ] P1: verify_normalized_structure enforces join_k properties
+- ✅ P1-B: join_k materialized for if-as-last (then/else tail-call join_k)
+- ✅ P1-B: verify_normalized_structure enforces join_k tailcall + PHI禁止
 - [ ] P2: Phase 129 fixture + VM smoke passes
 - [ ] P3: Documentation updated
 - [ ] Regression: phase103, phase118, phase128 all PASS