Use git hooks for commit attribution

Co-authored-by: Codex <noreply@openai.com>

codex-rs/core/src/commit_attribution.rs

@@ -1,17 +1,54 @@
-const DEFAULT_ATTRIBUTION_VALUE: &str = "Codex <noreply@openai.com>";
+use std::collections::HashMap;
+use std::fs;
+#[cfg(unix)]
+use std::os::unix::fs::PermissionsExt;
+use std::path::Path;
+use std::path::PathBuf;
 
-fn build_commit_message_trailer(config_attribution: Option<&str>) -> Option<String> {
-    let value = resolve_attribution_value(config_attribution)?;
-    Some(format!("Co-authored-by: {value}"))
+use crate::config::Config;
+
+const DEFAULT_ATTRIBUTION_VALUE: &str = "Codex <noreply@openai.com>";
+const PREPARE_COMMIT_MSG_HOOK_NAME: &str = "prepare-commit-msg";
+
+pub(crate) fn configure_git_hooks_env_for_config(
+    env: &mut HashMap<String, String>,
+    config: &Config,
+) {
+    configure_git_hooks_env(
+        env,
+        config.codex_home.as_path(),
+        config.commit_attribution.as_deref(),
+    );
 }
 
-pub(crate) fn commit_message_trailer_instruction(
+pub(crate) fn configure_git_hooks_env(
+    env: &mut HashMap<String, String>,
+    codex_home: &Path,
     config_attribution: Option<&str>,
-) -> Option<String> {
-    let trailer = build_commit_message_trailer(config_attribution)?;
-    Some(format!(
-        "When you write or edit a git commit message, ensure the message ends with this trailer exactly once:\n{trailer}\n\nRules:\n- Keep existing trailers and append this trailer at the end if missing.\n- Do not duplicate this trailer if it already exists.\n- Keep one blank line between the commit body and trailer block."
-    ))
+) {
+    let Some(value) = resolve_attribution_value(config_attribution) else {
+        return;
+    };
+
+    let Ok(hooks_path) = ensure_codex_hook_scripts(codex_home, &value) else {
+        return;
+    };
+
+    set_git_runtime_config(env, "core.hooksPath", hooks_path.to_string_lossy().as_ref());
+}
+
+pub(crate) fn injected_git_config_env(env: &HashMap<String, String>) -> Vec<(String, String)> {
+    let mut pairs = env
+        .iter()
+        .filter(|(key, _)| {
+            *key == "GIT_CONFIG_COUNT"
+                || key.starts_with("GIT_CONFIG_KEY_")
+                || key.starts_with("GIT_CONFIG_VALUE_")
+        })
+        .map(|(key, value)| (key.clone(), value.clone()))
+        .collect::<Vec<_>>();
+    pairs.sort_unstable_by(|(left, _), (right, _)| left.cmp(right));
+    pairs
 }
 
 fn resolve_attribution_value(config_attribution: Option<&str>) -> Option<String> {
@@ -28,6 +65,55 @@ fn resolve_attribution_value(config_attribution: Option<&str>) -> Option<String>
     }
 }
 
+fn ensure_codex_hook_scripts(codex_home: &Path, value: &str) -> std::io::Result<PathBuf> {
+    let hooks_dir = codex_home.join("hooks").join("commit-attribution");
+    fs::create_dir_all(&hooks_dir)?;
+
+    let script = build_hook_script(value);
+    let hook_path = hooks_dir.join(PREPARE_COMMIT_MSG_HOOK_NAME);
+    let should_write = match fs::read_to_string(&hook_path) {
+        Ok(existing) => existing != script,
+        Err(_) => true,
+    };
+
+    if should_write {
+        fs::write(&hook_path, script.as_bytes())?;
+    }
+
+    #[cfg(unix)]
+    {
+        let mut perms = fs::metadata(&hook_path)?.permissions();
+        perms.set_mode(0o755);
+        fs::set_permissions(&hook_path, perms)?;
+    }
+
+    Ok(hooks_dir)
+}
+
+fn build_hook_script(value: &str) -> String {
+    let escaped_value = value.replace('\'', "'\"'\"'");
+    format!(
+        "#!/usr/bin/env bash\nset -euo pipefail\n\nmsg_file=\"${{1:-}}\"\nif [[ -n \"$msg_file\" && -f \"$msg_file\" ]]; then\n  git interpret-trailers \\\n    --in-place \\\n    --if-exists doNothing \\\n    --if-missing add \\\n    --trailer 'Co-authored-by={escaped_value}' \\\n    \"$msg_file\" || true\nfi\n\nunset GIT_CONFIG_COUNT\nwhile IFS='=' read -r name _; do\n  case \"$name\" in\n    GIT_CONFIG_KEY_*|GIT_CONFIG_VALUE_*) unset \"$name\" ;;\n  esac\ndone < <(env)\n\nexisting_hooks_path=\"$(git config --path core.hooksPath 2>/dev/null || true)\"\nif [[ -z \"$existing_hooks_path\" ]]; then\n  git_dir=\"$(git rev-parse --git-common-dir 2>/dev/null || git rev-parse --git-dir 2>/dev/null || true)\"\n  if [[ -n \"$git_dir\" ]]; then\n    existing_hooks_path=\"$git_dir/hooks\"\n  fi\nfi\n\nif [[ -n \"$existing_hooks_path\" ]]; then\n  existing_hook=\"$existing_hooks_path/{PREPARE_COMMIT_MSG_HOOK_NAME}\"\n  if [[ -x \"$existing_hook\" && \"$existing_hook\" != \"$0\" ]]; then\n    \"$existing_hook\" \"$@\"\n  fi\nfi\n"
+    )
+}
+
+fn set_git_runtime_config(env: &mut HashMap<String, String>, key: &str, value: &str) {
+    let mut index = env
+        .get("GIT_CONFIG_COUNT")
+        .and_then(|count| count.parse::<usize>().ok())
+        .unwrap_or(0);
+
+    while env.contains_key(&format!("GIT_CONFIG_KEY_{index}"))
+        || env.contains_key(&format!("GIT_CONFIG_VALUE_{index}"))
+    {
+        index += 1;
+    }
+
+    env.insert(format!("GIT_CONFIG_KEY_{index}"), key.to_string());
+    env.insert(format!("GIT_CONFIG_VALUE_{index}"), value.to_string());
+    env.insert("GIT_CONFIG_COUNT".to_string(), (index + 1).to_string());
+}
+
 #[cfg(test)]
 #[path = "commit_attribution_tests.rs"]
 mod tests;