diff --git a/.agents/skills/mytoolkit/SKILL.md b/.agents/skills/mytoolkit/SKILL.md
index ddea7a3..7267432 100644
--- a/.agents/skills/mytoolkit/SKILL.md
+++ b/.agents/skills/mytoolkit/SKILL.md
@@ -72,16 +72,18 @@ mytoolkit completion zsh       # 打印 zsh 补全脚本
 | LaTeX 编译 | `mytoolkit latex compile paper.tex` |
 | BibTeX 转 Markdown | `mytoolkit convert refs.bib -o refs.md` |
 | AVI 视频转 MP4 | `mytoolkit convert video.avi -o video.mp4` |
-| 更新工具本身 | `cd mytoolkit && make install` |
+| 更新工具本身 | `cd <xiaohe-agent>/packages/mytoolkit && make install` |
 
 ## 安装与更新
 
 ```bash
-cd ~/workspace/packages/mytoolkit && make install
+cd <xiaohe-agent>/packages/mytoolkit && make install
+# 或：cd <xiaohe-agent> && make update / ./setup.sh
 mytoolkit --version
-mytoolkit templates list
+python3 -m pip show mytoolkit | grep Editable
+# 期望：.../xiaohe-agent/packages/mytoolkit
 ```
 
-> **重要**：修改 `packages/mytoolkit` 中的源码、或用 `git pull` / `git submodule update` 拉取更新后，**都必须重新执行 `make install`**（或 `mytoolkit update`）。Python 的 editable 安装不会自动跟踪源码改动，不重装则 CLI 调用的仍是旧版本。验证方式：`mytoolkit --version` 或 `which mytoolkit`。
+> **重要**：修改 `packages/mytoolkit` 源码或 `git submodule update` 后须重新 `make install`（或走 monorepo `make update`）。勿从 `~/.xiaohe/actions-runner/_work/...` 安装。旁路备份克隆（如 `~/Documents/myBin/mytoolkit`）不要用来 install。
 
-> **唯一真源**：mytoolkit 的具体用法、命令参数、模板说明以 **已安装的 mytoolkit 包** 为准（`mytoolkit info paths` 查路径、`mytoolkit info docs <name>` 打印参考文档）。**设计决策与仓库约定**（脚手架取舍、文档生成工作流、命名等）见仓库 `AGENTS.md`。若 `mytoolkit` 命令不可用，可按默认开发路径 `~/workspace/packages/mytoolkit/` 查找。本 skill 的 `references/` 仅作为 `info docs` 未覆盖命令的速查补充。
+> **唯一真源**：用法以已安装包为准（`mytoolkit info paths` / `info docs`）；仓库约定见 `AGENTS.md`。本 skill `references/` 仅作速查补充。
diff --git a/AGENTS.md b/AGENTS.md
index db545a3..dfe59f3 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -146,17 +146,18 @@ mytoolkit init journal springer mydir
 
 ### 本机安装（防串源）
 
-真源检出：`~/Documents/myBin/mytoolkit`（远程 `apaam/mytoolkit`）。
+真源检出：`xiaohe-agent/packages/mytoolkit`（submodule → `apaam/mytoolkit`）。
+本机旁路克隆（如 `~/Documents/myBin/mytoolkit`）仅作备份，不要用来 `make install`。
 
 ```bash
-cd ~/Documents/myBin/mytoolkit && make install
+cd <xiaohe-agent>/packages/mytoolkit && make install
+# 或随 monorepo：cd <xiaohe-agent> && make update / ./setup.sh
 python3 -m pip show mytoolkit | grep Editable
-# 必须是 .../Documents/myBin/mytoolkit
+# 必须是 .../xiaohe-agent/packages/mytoolkit
 ```
 
-- **禁止**在 `~/.xiaohe/actions-runner/_work/...` 或任意 GHA worktree 里 `pip install -e`
-- **禁止**把 `xiaohe-agent/packages/mytoolkit` submodule 当开发树安装（那只是 pin）
-- `make install` 会拒绝上述路径，并装进 PATH 上 `mytoolkit` 所用的 Python
+- **禁止**在 `~/.xiaohe/actions-runner/_work/...` 里 `pip install -e`（会把 CLI 指到 ephemeral 树）
+- `make install` 会拒绝上述 runner worktree
 
 ### 测试
 
diff --git a/Makefile b/Makefile
index fcffb9c..2d49c74 100644
--- a/Makefile
+++ b/Makefile
@@ -1,9 +1,15 @@
 ROOT_DIR := $(shell pwd)
-# Prefer an explicit PYTHON=; else the interpreter behind `mytoolkit` on PATH;
-# else python3. Never silently install into a different Python than the CLI.
+
+# Prefer PYTHON= override. Else shebang of `mytoolkit` on PATH. Else python3.
+ifndef PYTHON
 CLI_BIN := $(shell command -v mytoolkit 2>/dev/null)
-CLI_PY := $(if $(CLI_BIN),$(shell head -1 "$(CLI_BIN)" 2>/dev/null | sed 's|^#!||'),)
-PYTHON ?= $(if $(CLI_PY),$(CLI_PY),python3)
+ifneq ($(CLI_BIN),)
+PYTHON := $(shell head -1 "$(CLI_BIN)" 2>/dev/null | sed 's|^#!||')
+endif
+ifeq ($(strip $(PYTHON)),)
+PYTHON := python3
+endif
+endif
 
 .PHONY: help install uninstall sync-skill test
 
@@ -11,18 +17,19 @@ help:
 	@echo "Usage: make [target]"
 	@echo ""
 	@echo "  install     Editable install into CLI Python + sync skill"
-	@echo "              (refuse runner/_work trees; PYTHON=$(PYTHON))"
+	@echo "              (refuse GHA runner/_work trees; PYTHON=$(PYTHON))"
 	@echo "  sync-skill  Copy the bundled agent skill to ~/.agents/skills/mytoolkit/"
 	@echo "  test        Run the pytest suite"
 	@echo "  uninstall   Uninstall mytoolkit and remove shell completions"
 
-# Canonical checkout: ~/Documents/myBin/mytoolkit (apaam/mytoolkit).
-# Do NOT `pip install -e` from GHA _work or xiaohe packages/ submodule.
+# Truth source for day-to-day work: xiaohe-agent/packages/mytoolkit (submodule).
+# Refuse ephemeral GHA runner checkouts so PATH CLI cannot silently point at _work.
 install:
 	@case "$(ROOT_DIR)" in \
-	  */_work/*|*/actions-runner/*|*/.xiaohe/actions-runner/*) \
-	    echo "ERROR: refuse install from runner/worktree: $(ROOT_DIR)" >&2; \
-	    echo "Use: cd ~/Documents/myBin/mytoolkit && make install" >&2; \
+	  */_work/*|*/.xiaohe/actions-runner/*) \
+	    echo "ERROR: refuse install from GHA runner worktree: $(ROOT_DIR)" >&2; \
+	    echo "Use: cd <xiaohe-agent>/packages/mytoolkit && make install" >&2; \
+	    echo "  or: cd <xiaohe-agent> && make update / ./setup.sh" >&2; \
 	    exit 1 ;; \
 	esac
 	@echo "Installing editable mytoolkit"
@@ -36,7 +43,7 @@ install:
 	@$(PYTHON) -m pip show mytoolkit | awk '/^(Name|Version|Location|Editable project location):/'
 	@ed="$$($(PYTHON) -m pip show mytoolkit | awk -F': ' '/Editable project location:/ {print $$2}')"; \
 	  case "$$ed" in \
-	    */_work/*|*/actions-runner/*) \
+	    */_work/*|*/.xiaohe/actions-runner/*) \
 	      echo "ERROR: Editable still points at runner tree: $$ed" >&2; exit 1 ;; \
 	  esac