phase29ap(p4): shrink joinir legacy loop pattern table

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

@@ -3,7 +3,7 @@
 ## Current Focus
 
 - Phase: `docs/development/current/main/phases/phase-29ap/README.md`
-- Next: Phase 29ap P4 (planned; see `docs/development/current/main/phases/phase-29ap/README.md`)
+- Next: Phase 29ap P5 (planned; see `docs/development/current/main/phases/phase-29ap/README.md`)
 
 ## Gate (SSOT)
 

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

@@ -5,7 +5,7 @@ Scope: 「次にやる候補」を短く列挙するメモ。入口は `docs/dev
 
 ## Active
 
-- Phase 29ap: `docs/development/current/main/phases/phase-29ap/README.md` (Next: P4 planned)
+- Phase 29ap: `docs/development/current/main/phases/phase-29ap/README.md` (Next: P5 planned)
 - JoinIR regression gate SSOT: `docs/development/current/main/phases/phase-29ae/README.md`
 - CorePlan hardening (docs-first): `docs/development/current/main/phases/phase-29al/README.md`
 

docs/development/current/main/design/coreplan-migration-roadmap-ssot.md

@@ -34,7 +34,7 @@ Related:
 ## 1.1 Current (active)
 
 - Active phase: `docs/development/current/main/phases/phase-29ap/README.md`
-- Next step: Phase 29ap P4 (planned)
+- Next step: Phase 29ap P5 (planned)
 
 ## 2. すでに固めた SSOT（再発防止の土台）
 

docs/development/current/main/phases/phase-29ap/README.md

@@ -53,7 +53,16 @@ Gate (SSOT):
   - No new logs or error strings.
   - Fallback remains `Ok(None)` when shape does not match.
 
+## P4: JoinIR legacy table shrink (Pattern8 removal) ✅
+
+- Scope:
+  - Remove Pattern8 from `LOOP_PATTERNS` so plan/composer stays SSOT for normal loops.
+  - Keep legacy table as last resort for Pattern2/4/9 only.
+- Guardrails:
+  - No change to logs or error strings.
+  - Legacy routing remains a last-resort fallback.
+
 ## Next (planned)
 
-- P4: Router pattern-name branching reduction (planner outcome + composer SSOT)
-- P5: Facts/Feature expansion if needed
+- P5: Router pattern-name branching reduction (planner outcome + composer SSOT)
+- P6: Facts/Feature expansion if needed