refactor: refine signoff logic and docs

- update README with AIGITCOMMIT_SIGNOFF env var details
- refine should_signoff comments in repository and utils
- update env var list in utils to remove GIT_AUTO_SIGNOFF

Signed-off-by: mingcheng <[email protected]>

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

@@ -6,6 +6,35 @@ log() {
     printf '%s\n' "$1" >&2
 }
 
+is_truthy() {
+    case "$1" in
+        1 | true | TRUE | yes | YES | on | ON)
+            return 0
+            ;;
+        *)
+            return 1
+            ;;
+    esac
+}
+
+should_signoff() {
+    if is_truthy "${AIGITCOMMIT_SIGNOFF:-}"; then
+        return 0
+    fi
+
+    config=$(git config --bool aigitcommit.signoff 2>/dev/null || true)
+    case "$config" in
+        true)
+            return 0
+            ;;
+        false)
+            return 1
+            ;;
+    esac
+
+    return 0
+}
+
 COMMIT_MSG_FILE=${1:-}
 COMMIT_MSG_TYPE=${2:-}
 
@@ -44,7 +73,12 @@ trap cleanup EXIT INT TERM
 
 log "Generating commit message with aigitcommit..."
 
-if ! aigitcommit "$REPO_ROOT" --save "$TEMP_FILE" >/dev/null 2>&1; then
+SIGNOFF_FLAG=""
+if should_signoff; then
+    SIGNOFF_FLAG="--signoff"
+fi
+
+if ! aigitcommit "$REPO_ROOT" ${SIGNOFF_FLAG:+$SIGNOFF_FLAG} --save "$TEMP_FILE" >/dev/null 2>&1; then
     log "Error: aigitcommit failed to generate commit message."
     exit 1
 fi

src/git/repository.rs

@@ -243,7 +243,8 @@ impl Repository {
     }
 
     /// Check if commit should be signed off
-    /// Returns true if either CLI flag is set or AIGITCOMMIT_SIGNOFF environment variable is true
+    /// 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";

src/utils.rs

@@ -38,7 +38,7 @@ pub fn get_env_bool(key: &str) -> bool {
 }
 
 /// Check if commit should be signed off
-/// Returns true if either CLI flag is set or AIGITCOMMIT_SIGNOFF environment variable is true
+/// 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()
 }
@@ -116,7 +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));