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§2.7. In Cowork, hook side effects (file writes) don't reach the shell sandbox. Only stdout/additionalContext flows through. This probe writes a canary file from a hook (via the inline command below) then tries to read it from Bash tool.
Codex または Claude でインストール この Prompt をコピーして Codex、Claude、または他のアシスタントに貼り付けると、Skill ページを確認してインストールできます。
SOC 職業分類に基づく
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 ${CLAUDE_PLUGIN_ROOT} to a real path and exports it as an env var on Cowork, where shell form (§2.1/§2.2) failed both.
Shows what skill-body CLAUDE_PLUGIN_ROOT and friends substitute to on Mac Cowork, whether the VM Bash tool can use that path, and whether the Read tool can read a bundled file at that host path.
Proves whether a skill frontmatter PreToolUse Bash hook fires on Cowork by emitting only a block decision (no echo). A marked bash should be blocked even though no frontmatter stdout surfaces.
| name | 15-cowork-file-io |
| description | §2.7. In Cowork, hook side effects (file writes) don't reach the shell sandbox. Only stdout/additionalContext flows through. This probe writes a canary file from a hook (via the inline command below) then tries to read it from Bash tool. |
| user-invocable | true |
| hooks | {"PreToolUse":[{"matcher":"Bash","hooks":[{"type":"command","command":"ts=$(date +%s%N); marker_path=\"/tmp/file-io-canary-$ts.txt\"; printf \"[15-FM marker_path=%s wrote_at=%s]\" \"$marker_path\" \"$(date -Iseconds)\" > \"$marker_path\" 2>/dev/null; printf \"[15-FM-hook fired marker_path=%s]\\n\" \"$marker_path\" >> \"$CLAUDE_PROJECT_DIR/findings/${VERIFIER_VERSION_DIR:-v-unknown}/${CLAUDE_SESSION_ID:-no-sid}/probe.log\" 2>/dev/null"}]}]} |
§2.7 — Cowork で hook 内 file write が届かない。
proj="${CLAUDE_PROJECT_DIR:-$PWD}"
ver="${VERIFIER_VERSION_DIR:-v-unknown}"
sid="${CLAUDE_SESSION_ID:-no-sid}"
out_dir="$proj/findings/$ver/$sid"
mkdir -p "$out_dir"
{
printf '[15-BODY %s] tag=alive-check\n' "$(date -Iseconds)"
printf '[15-BODY] file-io-canary files in /tmp:\n'
ls -la /tmp/file-io-canary-*.txt 2>&1
} | tee -a "$out_dir/probe.log"
echo
echo "=== probe.log: 15-FM-hook lines (proves hook was called) ==="
grep "15-FM-hook" "$out_dir/probe.log" 2>&1
完了して exit、./scripts/assert.sh 15。