[CLAUDE] Docs: S40 finish bulletin MUC 2+4 gaps (tiered agent-def + rag.json path fix + archive dirs)

MUC 2 (Tiered Memory) finish:
- investigator-codebase.md: ">20KB force-read" + ">25KB suggest curate" -> tiered L1/L2/L3 (last agent-def with old policy wording; gotcha count 53->55)
- archive/ created for 3 new seed agents (investigator-api/implementer-frontend/test-specialist) via .gitkeep

MUC 4 (RAG v1.3) finish:
- rag.json extra_corpus slug FIX: D--Dropbox-CONG-VIEC-SOLUTION -> ...-SOLUTION-SOLUTION-ERP (27 user-memory feedback entries were NOT indexed). Re-index = AI_INFRA op (flagged).
- chunk_size 1500 deviation UNCHANGED (AI_INFRA mechanism decision, trial 2026-06-16). JSON valid verified.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.claude/agents/investigator-codebase.md

@@ -32,7 +32,7 @@ You are an investigative read-only agent focused on **INTERNAL codebase + DB sch
 - Skills preload: `contract-workflow` + `permission-matrix` + `ef-core-migration`
 
 ### 2. Decide memory re-read
-Force Read full MEMORY.md when: task touches schema/architecture/cross-stack · memory >20KB · first task new topic · PE V2 / Contract V2 / Proposal / workflow / permission gotchas. Otherwise trust auto-injected.
+Tiered Memory v1: L1 auto-inject đủ cho routine. Read L2 `archive/` + search L3 RAG `search_memory` when: task touches schema/architecture/cross-stack · first task new topic · PE V2 / Contract V2 / Proposal / workflow / permission gotchas. (Bỏ ngưỡng cứng >20KB force-read.)
 
 ### 3. Investigate (INTERNAL)
 - Read/Grep/Glob scan codebase
@@ -52,7 +52,7 @@ Token cost estimate: [tokens]
 ```
 
 ### 5. Update MEMORY.md BEFORE stop (BẮT BUỘC)
-Append "Recent activity" FIFO last 10: patterns / anti-patterns / gotchas new (cross-ref `docs/gotchas.md` 53 hiện tại) / schema findings. Skip duplicates. If >25KB → suggest curate em main. **Keep entry ≤ 1.5K chars** (gotcha #53 truncation mitigation — Investigator MEMORY hit 32KB S37).
+Append "Recent activity" FIFO 5-8 entry gần nhất: patterns / anti-patterns / gotchas new (cross-ref `docs/gotchas.md` 55 hiện tại) / schema findings. Skip duplicates. Tiered Memory v1: L1 soft-cap ~30KB → nếu vượt suggest curate em main (archive cũ → L2 `archive/<YYYY-MM>.md`). **Keep entry ≤ 1.5K chars** (gotcha #53 truncation mitigation — Investigator MEMORY hit 32KB S37).
 
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