feat(signoff): add auto sign-off for commits

- implement should_signoff in prepare-commit-msg hook for env and config checks
- update README with AIGITCOMMIT_SIGNOFF env var and git config options
- add should_signoff method to Repository for centralized sign-off logic
- refactor utils should_signoff to use repository and update save_to_file interface
- enhance main.rs sign-off detection and file save error handling

Signed-off-by: mingcheng <mingcheng@apache.org>

Author: mingcheng

README.md

@@ -26,7 +26,7 @@ It inspects your diffs, summarizes the intent of your changes, and produces clea
 - Easy-to-use command-line interface with sensible defaults and confirm prompts (can be skipped with `--yes`).
 - Uses libgit2 via the `git2` crate, avoiding external git commands for improved security and performance.
 - Supports multiple OpenAI-compatible models and configurable API base, token, and proxy settings.
-- Optional auto sign-off of commits when `GIT_AUTO_SIGNOFF=true`.
+- Optional auto sign-off of commits when `AIGITCOMMIT_SIGNOFF=true` or `git config --bool aigitcommit.signoff true`.
 - Proxy support: HTTP and SOCKS5 (set via `OPENAI_API_PROXY`).
 
 
@@ -128,7 +128,16 @@ Before using AIGitCommit, export the following environment variables (for exampl
 - `OPENAI_API_BASE`: The API base URL (useful for alternative providers or local proxies).
 - `OPENAI_MODEL_NAME`: The model name to query (e.g., a GPT-compatible model).
 - `OPENAI_API_PROXY`: Optional. Proxy address for network access (e.g., `http://127.0.0.1:1080` or `socks://127.0.0.1:1086`).
-- `GIT_AUTO_SIGNOFF`: Optional. Set to `true` to append a Signed-off-by line to commits.
+- `AIGITCOMMIT_SIGNOFF`: Optional. Set to `true` (or any truthy value) to append a Signed-off-by line to commits.
+
+You can also enable sign-off via Git configuration:
+
+```bash
+git config aigitcommit.signoff true       # repository only
+git config --global aigitcommit.signoff true
+```
+
+The Git configuration takes precedence over the environment variable.
 
 ### Check the configuration
 

hooks/prepare-commit-msg

@@ -1,58 +1,56 @@
 #!/bin/sh
 
-set -eu
-
-log() {
-    printf '%s\n' "$1" >&2
-}
-
-COMMIT_MSG_FILE=${1:-}
-COMMIT_MSG_TYPE=${2:-}
-
-if [ -z "$COMMIT_MSG_FILE" ] || [ ! -f "$COMMIT_MSG_FILE" ]; then
-    log "Error: commit message file missing."
+# This script is a Git hook that generates a commit message using the `aigitcommit` command.
+# It is triggered before the commit message editor is opened.
+# Usage: Place this script in the `.git/hooks/` directory of your repository and make it executable.
+COMMIT_MSG_FILE=$1
+COMMIT_MSG_TYPE=$2
+REPO_ROOT=$(git rev-parse --show-toplevel)
+
+# Check the repository root directory is valid
+# The `git rev-parse --show-toplevel` command returns the absolute path to the root of the repository
+# If the command fails, it means we are not in a Git repository
+if [ ! -d "$REPO_ROOT" ]; then
+    echo "Error: Repository root not found."
     exit 1
 fi
 
-if ! REPO_ROOT=$(git rev-parse --show-toplevel 2>/dev/null); then
-    log "Error: repository root not found."
-    exit 1
+# Check if aigitcommit is installed
+if ! type aigitcommit >/dev/null 2>&1; then
+    echo "Error: aigitcommit is not installed. Please install it first."
+    exit 0
 fi
 
-if ! command -v aigitcommit >/dev/null 2>&1; then
-    log "Warning: aigitcommit not installed; skipping hook."
+# Only run for interactive commits without a pre-populated message
+if [ -n "$COMMIT_MSG_TYPE" ]; then
     exit 0
 fi
 
-case "$COMMIT_MSG_TYPE" in
-    ""|"message") ;;
-    *) exit 0 ;;
-esac
-
-if git diff --cached --quiet --exit-code; then
-    log "Warning: no staged changes detected; aborting commit."
-    exit 1
+# Skip if the commit message already contains non-comment content
+if grep -Eq '^[[:space:]]*[^#[:space:]]' "$COMMIT_MSG_FILE"; then
+    exit 0
 fi
 
-TEMP_FILE=$(mktemp) || exit 1
-
-cleanup() {
-    rm -f "$TEMP_FILE"
-}
-
-trap cleanup EXIT INT TERM
+# Get only the diff of what has already been staged
+GIT_DIFF_OUTPUT=$(git diff --cached)
 
-log "Generating commit message with aigitcommit..."
-
-if ! aigitcommit "$REPO_ROOT" --save "$TEMP_FILE" >/dev/null 2>&1; then
-    log "Error: aigitcommit failed to generate commit message."
+# Check if there are any staged changes to commit
+if [ -z "$GIT_DIFF_OUTPUT" ]; then
+    echo "No staged changes detected. Aborting."
     exit 1
 fi
 
-if [ -s "$COMMIT_MSG_FILE" ]; then
-    printf '\n' >>"$TEMP_FILE"
-    cat "$COMMIT_MSG_FILE" >>"$TEMP_FILE"
+# Generate a temporary file for the commit message
+TEMP_FILE=$(mktemp)
+
+# Execute aigitcommit to generate the commit message and append existing content
+echo "Generating commit message by using AIGitCommit..."
+echo "This may take a few seconds..."
+aigitcommit $REPO_ROOT --save $TEMP_FILE >/dev/null 2>&1
+if [ $? -ne 0 ]; then
+    echo "Error: aigitcommit failed to generate commit message."
+    rm -f $TEMP_FILE
+    exit 1
 fi
 
-mv -f "$TEMP_FILE" "$COMMIT_MSG_FILE"
-trap - EXIT INT TERM
+cat $COMMIT_MSG_FILE >>$TEMP_FILE && mv -f $TEMP_FILE $COMMIT_MSG_FILE

src/git/repository.rs

@@ -9,7 +9,7 @@
  * File Created: 2025-10-16 15:07:05
  *
  * Modified By: mingcheng <mingcheng@apache.org>
- * Last Modified: 2025-11-06 15:00:29
+ * Last Modified: 2025-11-07 11:09:51
  */
 
 use git2::{Oid, Repository as _Repo, RepositoryOpenFlags, Signature};
@@ -19,7 +19,7 @@ use std::fmt::{Display, Formatter};
 use tracing::{trace, warn};
 
 use crate::git::message::GitMessage;
-use crate::utils::get_env;
+use crate::utils::{self, get_env};
 
 /// Author information from git configuration
 pub struct Author {
@@ -242,6 +242,24 @@ impl Repository {
         Ok(result)
     }
 
+    /// Check if commit should be signed off
+    /// Returns true when git config `aigitcommit.signoff` is enabled or the
+    /// `AIGITCOMMIT_SIGNOFF` environment variable evaluates to true
+    pub fn should_signoff(&self) -> bool {
+        // Define the config key for signoff
+        const SIGNOFF_KEY: &str = "aigitcommit.signoff";
+
+        // Check git config first
+        if let Ok(config) = self.repository.config() {
+            let signoff = config.get_bool(SIGNOFF_KEY).unwrap_or(false);
+            trace!("✍️ git config signoff: {}", signoff);
+            return signoff;
+        }
+
+        // Fall back to environment variable
+        utils::get_env_bool("AIGITCOMMIT_SIGNOFF")
+    }
+
     /// Get the list of filenames to exclude from diffs
     fn get_excluded_files() -> Vec<&'static str> {
         vec![

src/main.rs

@@ -1,15 +1,15 @@
-/*
- * Copyright (c) 2025 Hangzhou Guanwaii Technology Co,.Ltd.
+/*!
+ * Copyright (c) 2025 Hangzhou Guanwaii Technology Co., Ltd.
  *
  * This source code is licensed under the MIT License,
  * which is located in the LICENSE file in the source tree's root directory.
  *
  * File: main.rs
- * Author: mingcheng (mingcheng@apache.org)
+ * Author: mingcheng <mingcheng@apache.org>
  * File Created: 2025-03-01 17:17:30
  *
- * Modified By: mingcheng (mingcheng@apache.org)
- * Last Modified: 2025-09-26 15:45:37
+ * Modified By: mingcheng <mingcheng@apache.org>
+ * Last Modified: 2025-11-07 11:37:33
  */
 
 use aigitcommit::built_info::{PKG_NAME, PKG_VERSION};
@@ -26,7 +26,7 @@ use clap::Parser;
 use std::error::Error;
 use std::fs;
 use std::io::Write;
-use tracing::{Level, debug, trace};
+use tracing::{Level, debug, error, info, trace};
 
 use aigitcommit::utils::{
     OutputFormat, check_env_variables, format_openai_error, get_env, save_to_file, should_signoff,
@@ -143,7 +143,7 @@ async fn main() -> std::result::Result<(), Box<dyn Error>> {
         .ok_or("Invalid response format: expected title and content separated by double newline")?;
 
     // Detect auto signoff from environment variable or CLI flag
-    let need_signoff = should_signoff(cli.signoff);
+    let need_signoff = should_signoff(&repository, cli.signoff);
 
     let message: GitMessage = GitMessage::new(&repository, title, content, need_signoff)?;
 
@@ -163,11 +163,11 @@ async fn main() -> std::result::Result<(), Box<dyn Error>> {
 
     // directly commit the changes to the repository if the --commit option is enabled
     if cli.commit {
-        trace!("commit option is enabled, will commit the changes to the repository");
+        trace!("commit option is enabled, will commit the changes directly to the repository");
 
         if cli.yes || {
             cliclack::intro(format!("{PKG_NAME} v{PKG_VERSION}"))?;
-            cliclack::confirm("Are you sure to commit with those changes?").interact()?
+            cliclack::confirm("Are you sure to commit with generated message below?").interact()?
         } {
             match repository.commit(&message) {
                 Ok(oid) => {
@@ -185,10 +185,16 @@ async fn main() -> std::result::Result<(), Box<dyn Error>> {
     // If the --save option is enabled, save the commit message to a file
     if !cli.save.is_empty() {
         trace!("save option is enabled, will save the commit message to a file");
-        debug!("the save file path is {:?}", &cli.save);
 
-        save_to_file(&cli.save, &result)?;
-        writeln!(std::io::stdout(), "commit message saved to {}", cli.save)?;
+        // Save the commit message to the specified file
+        match save_to_file(&cli.save, &message) {
+            Ok(f) => {
+                info!("commit message saved to file: {:?}", f);
+            }
+            Err(e) => {
+                error!("failed to save commit message to file: {}", e);
+            }
+        }
     }
 
     Ok(())

src/utils.rs

@@ -9,14 +9,15 @@
  * File Created: 2025-10-21 11:34:11
  *
  * Modified By: mingcheng <mingcheng@apache.org>
- * Last Modified: 2025-11-06 12:24:04
+ * Last Modified: 2025-11-07 11:22:27
  */
 
 use std::env;
 use std::io::Write;
 use tracing::debug;
 
 use crate::git::message::GitMessage;
+use crate::git::repository::Repository;
 
 /// Get environment variable with default value fallback
 pub fn get_env(key: &str, default: &str) -> String {
@@ -37,16 +38,9 @@ pub fn get_env_bool(key: &str) -> bool {
 }
 
 /// Check if commit should be signed off
-/// Returns true if either CLI flag is set or GIT_AUTO_SIGNOFF environment variable is true
-pub fn should_signoff(cli_signoff: bool) -> bool {
-    let result = cli_signoff || get_env_bool("GIT_AUTO_SIGNOFF");
-    log::trace!(
-        "should_signoff: cli_signoff={}, GIT_AUTO_SIGNOFF={}, result={}",
-        cli_signoff,
-        get_env_bool("GIT_AUTO_SIGNOFF"),
-        result
-    );
-    result
+/// Returns true if either CLI flag is set or repository/git config/env enable sign-off
+pub fn should_signoff(repository: &Repository, cli_signoff: bool) -> bool {
+    cli_signoff || repository.should_signoff()
 }
 
 /// Output format for commit messages
@@ -122,7 +116,7 @@ pub fn check_env_variables() {
         "OPENAI_API_PROXY",
         "OPENAI_API_TIMEOUT",
         "OPENAI_API_MAX_TOKENS",
-        "GIT_AUTO_SIGNOFF",
+        "AIGITCOMMIT_SIGNOFF",
     ]
     .iter()
     .for_each(|v| check_and_print_env(v));
@@ -146,12 +140,15 @@ pub fn format_openai_error(error: async_openai::error::OpenAIError) -> String {
 }
 
 /// Save content to a file
-pub fn save_to_file(path: &str, content: &str) -> Result<(), Box<dyn std::error::Error>> {
+pub fn save_to_file(
+    path: &str,
+    content: &dyn std::fmt::Display,
+) -> Result<(), Box<dyn std::error::Error>> {
     use std::fs::File;
     use std::io::Write;
 
     let mut file = File::create(path)?;
-    file.write_all(content.as_bytes())?;
+    file.write_all(content.to_string().as_bytes())?;
     file.flush()?;
     Ok(())
 }
@@ -188,32 +185,4 @@ Signed-off-by: mingcheng <mingcheng@apache.org>
         let result = get_env("NONEXISTENT_VAR_XYZ", "default_value");
         assert_eq!(result, "default_value");
     }
-
-    #[test]
-    fn test_should_signoff() {
-        // Test with CLI flag true
-        assert!(should_signoff(true));
-
-        // Test with CLI flag false and no env var
-        unsafe {
-            std::env::remove_var("GIT_AUTO_SIGNOFF");
-        }
-        assert!(!should_signoff(false));
-
-        // Test with CLI flag false but env var true
-        unsafe {
-            std::env::set_var("GIT_AUTO_SIGNOFF", "1");
-        }
-        assert!(should_signoff(false));
-
-        unsafe {
-            std::env::set_var("GIT_AUTO_SIGNOFF", "true");
-        }
-        assert!(should_signoff(false));
-
-        // Clean up
-        unsafe {
-            std::env::remove_var("GIT_AUTO_SIGNOFF");
-        }
-    }
 }