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cc-web/.codex/skills/planning-with-files/scripts/attest-plan.sh
2026-06-28 23:12:35 +08:00

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#!/bin/sh
# planning-with-files: lock the current task_plan.md content with a SHA-256 attestation.
#
# Use after you finalise (or intentionally edit) a plan. The hooks then refuse
# to inject plan content into the model context if the file diverges from the
# attested hash, surfacing a "[PLAN TAMPERED]" warning instead.
#
# Resolution:
# 1. $PLAN_ID env var → ./.planning/$PLAN_ID/
# 2. ./.planning/.active_plan
# 3. Newest ./.planning/<dir>/ by mtime
# 4. Legacy ./task_plan.md at project root
#
# Usage:
# sh scripts/attest-plan.sh # attest the active plan
# sh scripts/attest-plan.sh --show # print the stored hash
# sh scripts/attest-plan.sh --clear # remove the attestation (re-open the plan)
set -u
SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
RESOLVER="${SCRIPT_DIR}/resolve-plan-dir.sh"
resolve_plan_file() {
plan_dir=""
if [ -f "${RESOLVER}" ]; then
plan_dir="$(sh "${RESOLVER}" 2>/dev/null)"
fi
if [ -n "${plan_dir}" ] && [ -f "${plan_dir}/task_plan.md" ]; then
printf "%s\n" "${plan_dir}/task_plan.md"
return 0
fi
if [ -f "./task_plan.md" ]; then
printf "%s\n" "./task_plan.md"
return 0
fi
return 1
}
attestation_path_for() {
plan_file="$1"
plan_dir="$(dirname "${plan_file}")"
if [ "${plan_dir}" = "." ]; then
# Legacy mode: store at project root.
printf "%s\n" "./.plan-attestation"
else
printf "%s\n" "${plan_dir}/.attestation"
fi
}
compute_hash() {
target="$1"
if command -v sha256sum >/dev/null 2>&1; then
sha256sum "${target}" | awk '{print $1}'
elif command -v shasum >/dev/null 2>&1; then
shasum -a 256 "${target}" | awk '{print $1}'
else
printf "ERROR: no sha256 utility available\n" >&2
return 1
fi
}
mode="attest"
case "${1:-}" in
--show) mode="show" ;;
--clear) mode="clear" ;;
"") mode="attest" ;;
*)
printf "Usage: %s [--show|--clear]\n" "$0" >&2
exit 2
;;
esac
plan_file="$(resolve_plan_file)" || {
printf "[plan-attest] No task_plan.md found. Create a plan first.\n" >&2
exit 1
}
attestation_file="$(attestation_path_for "${plan_file}")"
case "${mode}" in
show)
if [ -f "${attestation_file}" ]; then
printf "Plan: %s\n" "${plan_file}"
printf "Attestation: %s\n" "${attestation_file}"
printf "SHA-256: %s\n" "$(cat "${attestation_file}")"
# Nonce (security A1.4): if init-session generated a per-plan nonce
# next to the attestation, surface it. Informational only here; the
# hooks consume it to build collision-proof BEGIN/END delimiters.
nonce_file="$(dirname "${attestation_file}")/.nonce"
if [ -f "${nonce_file}" ]; then
printf "Nonce: %s\n" "$(tr -d '\r\n[:space:]' < "${nonce_file}" 2>/dev/null)"
fi
else
printf "[plan-attest] No attestation set for %s.\n" "${plan_file}"
exit 1
fi
;;
clear)
if [ -f "${attestation_file}" ]; then
rm -f "${attestation_file}"
printf "[plan-attest] Cleared attestation for %s.\n" "${plan_file}"
else
printf "[plan-attest] No attestation to clear.\n"
fi
;;
attest)
hash_val="$(compute_hash "${plan_file}")" || exit 1
# v2.40: protect the write with an advisory flock when available so
# concurrent legacy-mode sessions (no PLAN_ID, both at the same project
# root) cannot corrupt the .plan-attestation file mid-write. Atomic
# rename of a temp file is the real guarantee on POSIX; flock is the
# cooperative gate around the rename for slow-disk writes.
#
# Note: legacy single-file mode is inherently racey across concurrent
# sessions because both can edit task_plan.md without coordination. The
# canonical parallel-session pattern is slug-mode under
# .planning/<slug>/, where each session pins PLAN_ID and gets its own
# .attestation file. We surface a hint when concurrent activity is
# detected.
if [ -f "${attestation_file}" ]; then
mtime_now="$(date +%s 2>/dev/null || echo 0)"
mtime_prev="$(stat -c '%Y' "${attestation_file}" 2>/dev/null \
|| stat -f '%m' "${attestation_file}" 2>/dev/null \
|| echo 0)"
age=$((mtime_now - mtime_prev))
if [ "${age}" -ge 0 ] && [ "${age}" -lt 30 ] 2>/dev/null; then
# If we're in legacy mode (root .plan-attestation) and another
# session just wrote, warn. Slug-mode files in .planning/<slug>/
# are per-session by construction; no need to warn there.
case "${attestation_file}" in
*./.plan-attestation|*/.plan-attestation)
case "${attestation_file}" in
*./.planning/*) : ;; # slug-mode, ignore
*)
printf "[plan-attest] Note: %s was modified %ss ago by another process.\n" \
"${attestation_file}" "${age}" >&2
printf "[plan-attest] For parallel sessions, prefer slug-mode (init-session.sh <name>) so each session gets its own .attestation file.\n" >&2
;;
esac
;;
esac
fi
fi
tmp_file="${attestation_file}.tmp.$$"
printf "%s\n" "${hash_val}" > "${tmp_file}" 2>/dev/null || {
printf "[plan-attest] Failed to write %s\n" "${tmp_file}" >&2
exit 1
}
mv_ok=1
if command -v flock >/dev/null 2>&1; then
# Advisory lock around the rename. lock_dir is the dir containing
# the target file. The {} subshell pattern keeps the lock scoped to
# the mv call.
lock_dir="$(dirname "${attestation_file}")"
(
flock -w 5 9 || true
mv -f "${tmp_file}" "${attestation_file}"
) 9>"${lock_dir}/.attestation.lock" 2>/dev/null || mv_ok=0
rm -f "${lock_dir}/.attestation.lock" 2>/dev/null
else
mv -f "${tmp_file}" "${attestation_file}" 2>/dev/null || mv_ok=0
fi
# Integrity gap fix (security A2.1): a failed atomic rename must not be
# allowed to silently leave a stale attestation when the target already
# existed. The old fallback only wrote when the file was absent, so a
# cross-device or permission-denied mv on an existing attestation left
# the OLD hash in place with a success exit. On mv failure we re-write
# the intended hash through a second atomic rename (never a bare
# redirect onto the live file, which would expose torn reads to
# concurrent verifiers), then verify the on-disk content.
if [ "${mv_ok}" -eq 0 ] || [ ! -f "${attestation_file}" ]; then
fb_tmp="${attestation_file}.fb.$$"
printf "%s\n" "${hash_val}" > "${fb_tmp}" 2>/dev/null \
&& mv -f "${fb_tmp}" "${attestation_file}" 2>/dev/null || {
rm -f "${fb_tmp}" "${tmp_file}" 2>/dev/null
printf "[plan-attest] Failed to write attestation %s\n" "${attestation_file}" >&2
exit 1
}
fi
rm -f "${tmp_file}" 2>/dev/null
# Read-back verification. Both write paths above are atomic renames, so
# a concurrent verifier always reads a complete 64-hex hash — either our
# own or an identical one from a peer attesting the same plan content.
# A mismatch here therefore means our intended hash genuinely did not
# land (stale content, failed write); fail loudly with a nonzero exit so
# callers never trust a stale attestation.
stored_hash="$(tr -d '\r\n[:space:]' < "${attestation_file}" 2>/dev/null)"
if [ "${stored_hash}" != "${hash_val}" ]; then
printf "[plan-attest] Attestation write verification FAILED for %s\n" "${attestation_file}" >&2
printf "[plan-attest] Expected %s, found %s. The plan is NOT attested.\n" "${hash_val}" "${stored_hash}" >&2
exit 1
fi
short_hash="$(printf "%s" "${hash_val}" | cut -c1-12)"
printf "[plan-attest] Locked %s\n" "${plan_file}"
printf "[plan-attest] SHA-256: %s... (stored in %s)\n" "${short_hash}" "${attestation_file}"
printf "[plan-attest] Hooks will block injection if the file is modified without re-running this command.\n"
;;
esac
exit 0