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Anchor the private inline-interpreter hook to the interpreter's own arguments
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Backlog
Source
docs/backlog/archive/WI-096-hook-flag-anchoring.md
Status
done

Proposal (rationale)

F-060: the repository’s private PreToolUse hook .claude/hooks/no-inline-interpreter-scripts.mjs matches an inline-script flag anywhere after an interpreter token on the same line, so node src/cli.ts check … && git -c user.name=x commit … and node script.mjs && grep -c pattern file are blocked whenever the command spans lines. It also reads flags inside a heredoc body that is being written to a file, so cat > script.sh <<'EOF' whose content contains node -e '…' is blocked although nothing is piped into an interpreter. Measured 2026-09-06: three legitimate commands blocked in one session, each rewritten to dodge the pattern.

Decision

accepted — 2026-09-06, at the user’s request to tackle F-059 to F-063. Anchor the flag match to the interpreter’s own argument list and ignore heredoc bodies that are not fed to an interpreter; keep every refusal the hook exists for.

Plan

Requirements

  • An inline flag counts only when it follows the interpreter token within the same command segment (no &&, ||, ;, | between them).
  • A heredoc body is stripped before the inline-flag test; a heredoc that feeds an interpreter is still refused from the original text.
  • Still refused: a multi-line -e/-c script, python - <<'PY', node <<EOF.
  • Still allowed: single-line -e, git commit -F-, cat > x <<'EOF' with any body.

Impacts

  • .claude/hooks/no-inline-interpreter-scripts.mjs, test/core.test.js (a test that drives the hook with payloads).

Approach

Bound the regex segment with [^\n;|&]* and strip <<DELIM … DELIM bodies before applying it. Alternative — a shell parser — rejected as disproportionate for a private hook.

Acceptance criteria / tests

  1. A core test spawns the hook with nine payloads: the four refusals above exit 2 with the hook’s message; the five allowed forms exit 0; a non-Bash tool exits 0.
  2. Serial suite and rungs check pass.

Out of scope

  • Shipping this hook as a module (roadmap Phase 5 candidate); nothing else deferred.

Execution

Branch feature/WI-096-hook-flag-anchoring from 4f9f1603, 2026-09-06. As planned. The heredoc stripper keeps the <<DELIM line itself so the HEREDOC refusal, which runs on the original text, and the position of any following command are unaffected; only the body between the delimiter line and its terminator is removed before the inline-flag test.

Review

  1. node --test --test-name-pattern '^the private inline-interpreter hook' test/core.test.js: 1/1 (2026-09-06) — refused with exit 2: multi-line node -e, multi-line python3 -c, python - <<'PY', node <<EOF; allowed with exit 0: single-line -e, node … && git -c … commit over two lines, node … && grep -c … over two lines, a cat > file <<'EOF' whose body names node -e, and git commit -F- <<'EOF'; a non-Bash tool exits 0.
  2. npm test: 156 tests, 153 pass, 0 fail, 3 skipped, 150 s. node src/cli.ts check: 32 pass after archiving (the one pre-archive failure was the closure row’s link to this item’s archive path).