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#!/bin/sh
# Reject pushes that include commits which:
# * lack a good signature, or
# * have a committer different from this repo's user.name / user.email, or
# * have an author that looks like a coding agent (Copilot, Claude,
# Codex, ChatGPT, Cursor, Aider, Devin, ...) -- I want my name on
# anything I push, even when an agent helped write it. Use
# `git commit --amend --reset-author` after agent-assisted work.
#
# Activated via core.hooksPath in ~/.config/git/config so it applies to
# every repo unless that repo overrides hooksPath itself (this dotfiles
# repo does, pointing at .githooks/ which delegates here).
#
# Bypass for one push: git push --no-verify
set -eu
zero=$(git hash-object --stdin </dev/null | tr '0-9a-f' '0')
expected_name=$(git config user.name || true)
expected_email=$(git config user.email || true)
if [ -z "$expected_name" ] || [ -z "$expected_email" ]; then
printf 'pre-push: user.name or user.email is unset; refusing.\n' >&2
exit 1
fi
# %G? signature status codes from git-log:
# G good signature
# U good, unknown validity (e.g. trust level not set)
# X good but expired signature
# Y good but key is expiring
# R good but key has been revoked
# B bad signature
# E signature cannot be checked (e.g. missing key)
# N no signature
# We accept G/U/X/Y and reject anything else.
ok='G U X Y'
# Case-insensitive substrings that disqualify an author. Matched against
# "<name> <email>" lowercased. Plain substring matching (index()) is
# used in the awk below to dodge regex-escaping pitfalls. Keep this list
# narrow on purpose: false positives are worse than misses (a slipped
# commit can be amended and force-pushed; a noisy hook gets disabled).
agent_subs='copilot claude codex chatgpt cursor aider devin [bot] @openai. @anthropic.'
fail=0
while read -r _local_ref local_sha remote_ref remote_sha; do
# Branch deletion: nothing to verify on our side.
[ "$local_sha" = "$zero" ] && continue
if [ "$remote_sha" = "$zero" ]; then
# New branch: verify the commits unique to this push, excluding
# anything already reachable from any remote-tracking ref.
set -- "$local_sha" --not --remotes
else
set -- "${remote_sha}..${local_sha}"
fi
# One pass: per-commit emit
# SHA \t %G? \t cn \t ce \t an \t ae \t co-authored-by-list \t subject
# Co-authored-by trailers are joined with 0x1f (unit separator) which
# cannot appear in identity strings. Tabs aren't valid in identity
# fields either, so awk -F'\t' parses unambiguously.
bad=$(git rev-list \
--format='%H%x09%G?%x09%cn%x09%ce%x09%an%x09%ae%x09%(trailers:key=Co-authored-by,valueonly,unfold,separator=%x1f)%x09%s' \
--no-commit-header "$@" |
awk -F'\t' \
-v ok="$ok" \
-v en="$expected_name" \
-v ee="$expected_email" \
-v agent_subs="$agent_subs" '
BEGIN {
split(ok, a, " "); for (i in a) good[a[i]] = 1
n_subs = split(agent_subs, subs, " ")
}
function is_agent(s, i) {
for (i = 1; i <= n_subs; i++) if (index(s, subs[i])) return 1
return 0
}
{
reasons = ""
if (!($2 in good)) reasons = reasons " [sig=" $2 "]"
if ($3 != en || $4 != ee) {
reasons = reasons " [committer=" $3 " <" $4 ">]"
}
if (is_agent(tolower($5 " " $6))) {
reasons = reasons " [agent-author=" $5 " <" $6 ">]"
}
if ($7 != "") {
n_co = split($7, coauthors, "\037")
for (i = 1; i <= n_co; i++) {
if (coauthors[i] != "" && is_agent(tolower(coauthors[i]))) {
reasons = reasons " [agent-coauthor=" coauthors[i] "]"
}
}
}
if (reasons != "") print $1 reasons " " $8
}
')
if [ -n "$bad" ]; then
if [ "$fail" -eq 0 ]; then
printf '\nrefusing to push: bad commits found\n' >&2
printf '(expected committer: %s <%s>)\n' \
"$expected_name" "$expected_email" >&2
fi
printf '\non %s:\n%s\n' "$remote_ref" "$bad" >&2
fail=1
fi
done
if [ "$fail" -ne 0 ]; then
printf '\nfix sig + committer:\n' >&2
printf ' git rebase --exec "git commit --amend --no-edit -S" <base>\n' >&2
printf 'fix author (re-stamp yourself as author, keep agent out):\n' >&2
printf ' git rebase --exec "git commit --amend --no-edit --reset-author -S" <base>\n' >&2
printf 'bypass:\n git push --no-verify\n\n' >&2
exit 1
fi
exit 0
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