القائمة
Arms a skill-to-skill block via a frontmatter PreToolUse Skill hook. After invoking this, a natural-language attempt to run the victim skill should be blocked if the block decision is honored.
التثبيت باستخدام Codex أو Claude انسخ هذا Prompt والصقه في Codex أو Claude أو مساعد آخر ليراجع صفحة Skill ويثبّتها لك.
استنادا إلى تصنيف SOC المهني
| name | guard |
| description | Arms a skill-to-skill block via a frontmatter PreToolUse Skill hook. After invoking this, a natural-language attempt to run the victim skill should be blocked if the block decision is honored. |
| user-invocable | true |
| hooks | {"PreToolUse":[{"matcher":"Skill","hooks":[{"type":"command","command":"bash -c 'input=$(cat); if printf \"%s\" \"$input\" | grep -q \"victim\"; then printf \"%s\" \"{\\\"decision\\\":\\\"block\\\",\\\"reason\\\":\\\"BLOCKED-BY-GUARD-HOOK\\\"}\"; fi'"}]}]} |
skill-to-skill block を arm する probe です。次の bash を実行してください（これで guard の frontmatter hook が登録されます）。
echo "GUARD-ARMED-MARKER host=$(hostname)"
この後、victim skill を自然言語で起動してみてください（slash ではなく、例：「victim スキルを実行して」）。slash 経由だと PreToolUse:Skill が発火しないため、必ず自然言語で。
判定：
BLOCKED-BY-GUARD-HOOK という reason が出るVICTIM-RAN-MARKER が出るMac Cowork で、plugin-level SessionStart hook(host 側)から $CLAUDE_PLUGIN_DATA に書いた値が「別の chat session を跨いで」残るかを検証する probe。書き込み＆読み戻しは hook(persist.sh)側で行い、その結果は SessionStart の stdout として context に出る。この skill body は対比用に「VM Bash 側から DATA が見えるか／hook が書いたファイルを読めるか」を確認する。
Surfaces UPE_PROBE_* marker lines to test whether the plugin-level UserPromptExpansion hook fires on Cowork. Invoking this skill via slash is itself the trigger; compares against UserPromptSubmit and SessionStart controls.
Triggers the plugin-level PreToolUse hooks by running a sentinel bash command, to test (via session export) whether Cowork runs PreToolUse hook commands through cmd.exe or a POSIX shell, and whether the inline block pattern actually blocks the bash tool.
Surfaces the EXEC_* marker lines emitted by the plugin-level SessionStart hooks, which run hook commands in EXEC FORM (args present). Used to test whether exec form resolves ${CLAUDE_PLUGIN_ROOT} to a real path and exports it as an env var on Cowork, where shell form (§2.1/§2.2) failed both.
Shows what skill-body CLAUDE_PLUGIN_ROOT and friends substitute to on Mac Cowork, whether the VM Bash tool can use that path, and whether the Read tool can read a bundled file at that host path.
Proves whether a skill frontmatter PreToolUse Bash hook fires on Cowork by emitting only a block decision (no echo). A marked bash should be blocked even though no frontmatter stdout surfaces.