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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.
Codex 또는 Claude로 설치 이 Prompt를 복사해 Codex, Claude 또는 다른 어시스턴트에 붙여 넣으면 Skill 페이지를 검토하고 설치를 진행할 수 있습니다.
SOC 직업 분류 기준
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 ${CLAUDE_PLUGIN_ROOT} to a real path and exports it as an env var on Cowork, where shell form (§2.1/§2.2) failed both.
Shows what skill-body CLAUDE_PLUGIN_ROOT and friends substitute to on Mac Cowork, whether the VM Bash tool can use that path, and whether the Read tool can read a bundled file at that host path.
Proves whether a skill frontmatter PreToolUse Bash hook fires on Cowork by emitting only a block decision (no echo). A marked bash should be blocked even though no frontmatter stdout surfaces.
| name | guard |
| description | Arms a skill-to-skill block via a frontmatter PreToolUse Skill hook. After invoking this, a natural-language attempt to run the victim skill should be blocked if the block decision is honored. |
| user-invocable | true |
| hooks | {"PreToolUse":[{"matcher":"Skill","hooks":[{"type":"command","command":"bash -c 'input=$(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