diff --git a/AGENTS.md b/AGENTS.md
index 4d5724e..d17be0c 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -673,6 +673,20 @@ docs_v1.0/M4_workspace/YYYY-MM-DD_<topic>_test_report.md (測試報告)
 
 詳細規範見 `docs_v1.0/M4_workspace/M4_NOTIFICATION_PROTOCOL.md`。
 
+## UUID Naming Rule
+
+**Never use bare `uuid` in API route paths, query params, JSON keys, or code variable names. Always qualify:**
+
+| Context | Must use | Never |
+|---------|----------|-------|
+| Video/file resource | `file_uuid` | `uuid` |
+| Identity resource | `identity_uuid` | `uuid` |
+| Query parameter | `file_uuid=`, `identity_uuid=` | `uuid=` |
+| Route path | `:file_uuid`, `:identity_uuid` | `:uuid` |
+| JSON key | `"file_uuid"`, `"identity_uuid"` | `"uuid"` |
+
+This applies to docs, code, API responses, and curl examples. Exceptions: internal database primary key names (e.g. `identities.uuid` column).
+
 ## Document Compliance Checklist
 
 Before creating any `REFERENCE/*.md` file, verify all items below.
@@ -689,6 +703,13 @@ Before creating any `REFERENCE/*.md` file, verify all items below.
 | 6 | English content | Entire file in English |
 | 7 | REFERENCE/ path | File must reside under `docs_v1.0/REFERENCE/` |
 
+### P0b — UUID Naming
+
+| # | Check | Rule |
+|---|-------|------|
+| 8 | `file_uuid` not bare `uuid` | All file references use `file_uuid` (see UUID Naming Rule above) |
+| 9 | `identity_uuid` not bare `uuid` | All identity references use `identity_uuid` |
+
 ### P1 — Suggested (3 items)
 
 | # | Check | Note |
diff --git a/docs_v1.0/STANDARDS/DOCS_STANDARD.md b/docs_v1.0/STANDARDS/DOCS_STANDARD.md
index ebfd2f0..4ee471f 100644
--- a/docs_v1.0/STANDARDS/DOCS_STANDARD.md
+++ b/docs_v1.0/STANDARDS/DOCS_STANDARD.md
@@ -3,7 +3,7 @@ document_type: "standard_doc"
 service: "MOMENTRY_CORE"
 title: "文件創建規範"
 date: "2026-04-27"
-version: "V2.0"
+version: "V2.1"
 status: "active"
 owner: "Warren"
 created_by: "OpenCode"
@@ -35,11 +35,25 @@ related_documents:
 
 ---
 
+## UUID 命名規範
+
+API 路徑、查詢參數、JSON key、程式碼變數中**禁止使用裸 `uuid`**：
+
+| 情境 | 必須使用 | 禁止使用 |
+|------|----------|----------|
+| 影片/檔案資源 | `file_uuid` | `uuid` |
+| 身份資源 | `identity_uuid` | `uuid` |
+| 查詢參數 | `file_uuid=`, `identity_uuid=` | `uuid=` |
+| 路由路徑 | `:file_uuid`, `:identity_uuid` | `:uuid` |
+| JSON key | `"file_uuid"`, `"identity_uuid"` | `"uuid"` |
+
+例外：資料庫內部 primary key（如 `identities.uuid` 欄位）可保留原名。
+
 ## 版本歷史
 
 | 版本 | 日期 | 目的 | 操作人 | 工具/模型 |
 |------|------|------|--------|-----------|
-| V1.0 | 2026-03-18 | 創建文件規範 | Warren | OpenCode / MiniMax M2.5 |
+| V2.1 | 2026-05-14 | 新增 UUID 命名規範 | M5 | OpenCode |
 | V2.0 | 2026-04-27 | 添加 AI Agent 友好完整規範（10.6-10.12） | OpenCode | GLM-5 |
 
 ---