feat: add .commit-guard.toml config file support

README.md

@@ -80,6 +80,25 @@ Available checks:
 * `signed-off` - `Signed-off-by:` trailer exists
 * `signature` - Verify GPG or SSH signature
 
+### Configuration file
+
+Place `.commit-guard.toml` in your project root (or any parent directory) to
+set defaults for `enable` and `disable`. commit-guard searches upward from the
+working directory and uses the first file found.
+
+```toml
+# .commit-guard.toml
+disable = ["signature", "body"]
+```
+
+```toml
+# .commit-guard.toml
+enable = ["subject", "imperative"]
+```
+
+CLI flags (`--enable`, `--disable`) take full precedence and ignore the config
+file entirely when provided.
+
 ### Checking a range of commits
 
 ```bash

src/git_commit_guard/__init__.py

@@ -7,6 +7,7 @@
 from pathlib import Path
 
 import nltk
+import tomllib
 from nltk.corpus import wordnet
 
 TYPES = frozenset(
@@ -51,6 +52,23 @@ class Check(StrEnum):
 ALL_CHECKS = frozenset(Check.__members__.values())
 
 
+def _load_config(start=None):
+    start = start or Path.cwd()
+    for directory in [start, *start.parents]:
+        config_path = directory / ".commit-guard.toml"
+        if config_path.exists():
+            with config_path.open("rb") as f:
+                return tomllib.load(f)
+    return {}
+
+
+def _parse_config_checks(config, key):
+    try:
+        return [Check(v) for v in config.get(key, [])]
+    except ValueError as e:
+        sys.exit(f".commit-guard.toml: {e}")
+
+
 class Level(StrEnum):
     ERROR = "error"
     WARN = "warn"
@@ -220,12 +238,20 @@ def _parse_args():
         help=f"skip these checks ({checks_list})",
     )
     args = parser.parse_args()
+    config = _load_config()
 
-    enabled = (
-        frozenset(_parse_checks(parser, args.enable)) if args.enable else ALL_CHECKS
-    )
-    if args.disable:
-        enabled = enabled - frozenset(_parse_checks(parser, args.disable))
+    if args.enable or args.disable:
+        enabled = (
+            frozenset(_parse_checks(parser, args.enable)) if args.enable else ALL_CHECKS
+        )
+        if args.disable:
+            enabled = enabled - frozenset(_parse_checks(parser, args.disable))
+    elif config.get("enable"):
+        enabled = frozenset(_parse_config_checks(config, "enable"))
+    elif config.get("disable"):
+        enabled = ALL_CHECKS - frozenset(_parse_config_checks(config, "disable"))
+    else:
+        enabled = ALL_CHECKS
 
     if args.message_file:
         rev = None

tests/test_git_commit_guard.py

@@ -8,7 +8,9 @@
     _download_if_missing,
     _ensure_nltk_data,
     _get_message,
+    _load_config,
     _parse_checks,
+    _parse_config_checks,
     _report,
     _strip_comments,
     check_body,
@@ -331,6 +333,41 @@ def test_other_git_error(self):
             _get_message("abc")
 
 
+class TestLoadConfig:
+    def test_returns_empty_when_no_file(self, tmp_path):
+        assert _load_config(tmp_path) == {}
+
+    def test_loads_file_in_start_dir(self, tmp_path):
+        (tmp_path / ".commit-guard.toml").write_text('disable = ["signature"]\n')
+        assert _load_config(tmp_path) == {"disable": ["signature"]}
+
+    def test_loads_file_from_parent(self, tmp_path):
+        (tmp_path / ".commit-guard.toml").write_text('disable = ["body"]\n')
+        subdir = tmp_path / "sub"
+        subdir.mkdir()
+        assert _load_config(subdir) == {"disable": ["body"]}
+
+    def test_first_found_wins(self, tmp_path):
+        (tmp_path / ".commit-guard.toml").write_text('disable = ["body"]\n')
+        subdir = tmp_path / "sub"
+        subdir.mkdir()
+        (subdir / ".commit-guard.toml").write_text('disable = ["signature"]\n')
+        assert _load_config(subdir) == {"disable": ["signature"]}
+
+
+class TestParseConfigChecks:
+    def test_disable_list(self):
+        checks = _parse_config_checks({"disable": ["signature", "body"]}, "disable")
+        assert len(checks) == 2  # noqa: PLR2004
+
+    def test_missing_key_returns_empty(self):
+        assert _parse_config_checks({}, "disable") == []
+
+    def test_invalid_check_name_exits(self):
+        with pytest.raises(SystemExit, match=r"\.commit-guard\.toml"):
+            _parse_config_checks({"disable": ["bogus"]}, "disable")
+
+
 class TestParseChecks:
     def test_invalid_check_name(self):
         parser = ArgumentParser()
@@ -462,3 +499,37 @@ def test_invalid_check_name_exits(self, tmp_path):
             pytest.raises(SystemExit),
         ):
             main()
+
+    def test_config_disable_applied(self, tmp_path):
+        f = tmp_path / "msg"
+        f.write_text(_VALID_MSG)
+        disabled = {"disable": ["signature", "body", "signed-off", "imperative"]}
+        with (
+            patch("sys.argv", ["cg", "--message-file", str(f)]),
+            patch("git_commit_guard._load_config", return_value=disabled),
+        ):
+            assert main() == 0
+
+    def test_config_enable_applied(self, tmp_path):
+        f = tmp_path / "msg"
+        f.write_text(_VALID_MSG)
+        with (
+            patch("sys.argv", ["cg", "--message-file", str(f)]),
+            patch(
+                "git_commit_guard._load_config",
+                return_value={"enable": ["subject"]},
+            ),
+        ):
+            assert main() == 0
+
+    def test_cli_overrides_config(self, tmp_path):
+        f = tmp_path / "msg"
+        f.write_text(_VALID_MSG)
+        with (
+            patch("sys.argv", ["cg", "--message-file", str(f), "--enable", "subject"]),
+            patch(
+                "git_commit_guard._load_config",
+                return_value={"disable": ["subject"]},
+            ),
+        ):
+            assert main() == 0