feat: add message-ai-attribution to check commits for AI attribution only

Each commit is checked with commit-check --message-ai-attribution: the
AI rules (CC013 to CC017) without the format rules. It takes the place
of message, which defaults to true, so it needs no other input.

Author: shenxianpeng

README.md

@@ -80,6 +80,7 @@ runners need a few tools — see [Good to know](#good-to-know).
 | `author-name` | `false` | Check each commit's author name |
 | `author-email` | `false` | Check each commit's author email |
 | `pr-title` | `false` | Check the pull request title against Conventional Commits — the one that matters for squash merges. Pull request events only |
+| `message-ai-attribution` | `false` | Check every commit against the AI rules of `cchk.toml` (`ai_attribution`) only, author included, without the format rules. Takes the place of `message` |
 | `pr-body-ai-attribution` | `false` | Check the pull request description against the AI rules of `cchk.toml` (`ai_attribution`) only. Pull request events only |
 | `ai-label` | `false` | Label the pull request when an AI tool wrote any of it (a commit, the description, or an agent's app that opened it): `true` for `ai-assisted`, or the label's name. Labels are only added, never removed. Needs `pull-requests: write`; skipped on fork pull requests under `pull_request` |
 | `pr-comments` | `false` | Post the report as a pull request comment, edited in place on later runs. Needs `pull-requests: write`; skipped on fork pull requests |

action.yml

@@ -37,6 +37,10 @@ inputs:
     description: check pull request title following conventional commits
     required: false
     default: false
+  message-ai-attribution:
+    description: check each commit against the AI attribution rules (ai_attribution in cchk.toml) only, without the format rules; overrides message
+    required: false
+    default: false
   pr-body-ai-attribution:
     description: check the pull request description against the AI attribution rules (ai_attribution in cchk.toml)
     required: false
@@ -118,6 +122,7 @@ runs:
         JOB_SUMMARY: ${{ inputs.job-summary }}
         PR_COMMENTS: ${{ inputs.pr-comments }}
         PR_TITLE: ${{ inputs.pr-title }}
+        MESSAGE_AI_ATTRIBUTION: ${{ inputs.message-ai-attribution }}
         PR_BODY_AI_ATTRIBUTION: ${{ inputs.pr-body-ai-attribution }}
         AI_LABEL: ${{ inputs.ai-label }}
         GITHUB_TOKEN: ${{ github.token }}

main.py

@@ -88,6 +88,20 @@ def _reconfigure_io() -> None:
 PR_COMMENTS_ENABLED = env_flag("PR_COMMENTS")
 PR_TITLE_ENABLED = env_flag("PR_TITLE")
 PR_BODY_AI_ATTRIBUTION_ENABLED = env_flag("PR_BODY_AI_ATTRIBUTION")
+MESSAGE_AI_ATTRIBUTION_ENABLED = env_flag("MESSAGE_AI_ATTRIBUTION")
+
+
+def message_check_args() -> list[str]:
+    """The CLI flag each commit message is checked with.
+
+    ``message-ai-attribution: true`` narrows the check to the AI rules (CC013
+    to CC017), whatever ``message`` says: ``message`` defaults to true, so
+    asking for the AI rules alone must not need it turned off as well.
+    """
+    if MESSAGE_AI_ATTRIBUTION_ENABLED:
+        return ["--message-ai-attribution"]
+    return ["--message"]
+
 
 #: The label ``ai-label: true`` puts on a pull request that an AI tool wrote.
 DEFAULT_AI_LABEL = "ai-assisted"
@@ -255,6 +269,7 @@ def log_env_vars():
         "PR_COMMENTS",
         "PR_TITLE",
         "PR_BODY_AI_ATTRIBUTION",
+        "MESSAGE_AI_ATTRIBUTION",
         "AI_LABEL",
     ):
         value = os.getenv(name, "false")
@@ -790,7 +805,7 @@ def run_pr_message_checks(pr_commits: list[Commit]) -> list[ScopeResult]:
             names = ("GIT_AUTHOR_NAME", "GIT_AUTHOR_EMAIL")
             env = {key: value for key, value in zip(names, author) if value} or None
         results.append(
-            check_scope(label, ["--message"], input_text=msg, sha=sha, env=env)
+            check_scope(label, message_check_args(), input_text=msg, sha=sha, env=env)
         )
     return results
 
@@ -817,7 +832,7 @@ def run_other_checks(args: list[str], rev: str | None = None) -> list[ScopeResul
 def build_check_args() -> list[str]:
     """Map enabled validation switches to commit-check CLI arguments."""
     flags = [
-        ("--message", MESSAGE_ENABLED),
+        ("--message", MESSAGE_ENABLED or MESSAGE_AI_ATTRIBUTION_ENABLED),
         ("--branch", BRANCH_ENABLED),
         ("--author-name", AUTHOR_NAME_ENABLED),
         ("--author-email", AUTHOR_EMAIL_ENABLED),
@@ -833,7 +848,8 @@ def run_commit_check() -> tuple[int, list[ScopeResult]]:
       2. PR description, AI rules only (when ``pr-body-ai-attribution: true`` and in a PR
          event; with only ``ai-label`` set it is read for the label, and no
          scope is reported)
-      3. Individual PR commit messages (when ``message: true`` and in a PR event)
+      3. Individual PR commit messages (when ``message: true`` and in a PR event;
+         AI rules only with ``message-ai-attribution: true``)
       4. All remaining checks (branch, author name/email, etc.)
 
     Outside of a PR event all enabled checks are handed to the CLI at once.
@@ -861,7 +877,7 @@ def run_commit_check() -> tuple[int, list[ScopeResult]]:
                 PR_BODY_AI_TOOLS[:] = scope.ai_tools
 
     # ---- 3. Commit message checks -----------------------------------------
-    if MESSAGE_ENABLED:
+    if MESSAGE_ENABLED or MESSAGE_AI_ATTRIBUTION_ENABLED:
         pr_commits = get_pr_commit_messages()
         if pr_commits:
             # In PR context: check each commit individually to avoid
@@ -879,7 +895,9 @@ def run_commit_check() -> tuple[int, list[ScopeResult]]:
     # ---- 4. Remaining checks (branch, author, etc.) -----------------------
     # Outside a PR, check the HEAD commit message directly.
     if "--message" in args:
-        results.append(check_scope("Commit message", ["--message"], sha=head_sha()))
+        results.append(
+            check_scope("Commit message", message_check_args(), sha=head_sha())
+        )
         args = [a for a in args if a != "--message"]
     rev = None
     if is_pr_event() and any(flag in AUTHOR_FLAGS for flag in args):

main_test.py

@@ -154,6 +154,7 @@ def test_every_input_is_logged_as_a_debug_command(self):
                 "::debug::PR_COMMENTS=false",
                 "::debug::PR_TITLE=false",
                 "::debug::PR_BODY_AI_ATTRIBUTION=false",
+                "::debug::MESSAGE_AI_ATTRIBUTION=false",
                 "::debug::AI_LABEL=false",
             ],
         )
@@ -421,6 +422,21 @@ def test_a_commit_in_the_clone_carries_its_own_author(self):
         self.assertEqual(env["GIT_AUTHOR_NAME"], "Renovate Bot")
         self.assertEqual(env["GIT_AUTHOR_EMAIL"], "bot@renovateapp.com")
 
+    def test_message_ai_attribution_checks_only_the_ai_rules(self):
+        """The commit still goes in with its author, so CC017 judges it."""
+        self.local_author.return_value = ("Jane Dev", "jane@example.com")
+        mock_result = MagicMock(returncode=0, stdout=json_output(make_check("message")))
+        with (
+            patch("main.MESSAGE_AI_ATTRIBUTION_ENABLED", True),
+            patch("main.subprocess.run", return_value=mock_result) as mock_run,
+        ):
+            main.run_pr_message_checks([(SHA_A, "WIP")])
+        self.assertEqual(
+            mock_run.call_args[0][0],
+            ["commit-check", "--format", "json", "--message-ai-attribution"],
+        )
+        self.assertEqual(mock_run.call_args[1]["env"]["GIT_AUTHOR_NAME"], "Jane Dev")
+
     def test_a_blank_author_field_is_left_to_git(self):
         self.local_author.return_value = ("Renovate Bot", "")
         mock_result = MagicMock(returncode=0, stdout=json_output(make_check("message")))
@@ -960,6 +976,43 @@ def test_non_pr_message_check_uses_commit_message_scope(self):
         # HEAD is the commit that was checked, so the scope names it too.
         mock_scope.assert_called_once_with("Commit message", ["--message"], sha=SHA_A)
 
+    def test_message_ai_attribution_alone_checks_each_commit(self):
+        """With message: false the commits are still checked, for AI only."""
+        with (
+            patch("main.MESSAGE_ENABLED", False),
+            patch("main.MESSAGE_AI_ATTRIBUTION_ENABLED", True),
+            patch("main.BRANCH_ENABLED", False),
+            patch("main.AUTHOR_NAME_ENABLED", False),
+            patch("main.AUTHOR_EMAIL_ENABLED", False),
+            patch("main.get_pr_commit_messages", return_value=[(SHA_A, "WIP")]),
+            patch("main.run_pr_message_checks", return_value=[pass_scope()]) as mock_pr,
+            patch("main.run_other_checks", return_value=[]) as mock_other,
+        ):
+            rc, _results = main.run_commit_check()
+        self.assertEqual(rc, 0)
+        mock_pr.assert_called_once_with([(SHA_A, "WIP")])
+        mock_other.assert_called_once_with([], rev=None)
+
+    def test_message_ai_attribution_narrows_the_head_check(self):
+        """Outside a PR, HEAD is checked for AI only, even with message: true."""
+        with (
+            patch("main.MESSAGE_ENABLED", True),
+            patch("main.MESSAGE_AI_ATTRIBUTION_ENABLED", True),
+            patch("main.BRANCH_ENABLED", False),
+            patch("main.AUTHOR_NAME_ENABLED", False),
+            patch("main.AUTHOR_EMAIL_ENABLED", False),
+            patch("main.get_pr_commit_messages", return_value=[]),
+            patch("main.head_sha", return_value=SHA_A),
+            patch(
+                "main.check_scope", return_value=pass_scope("Commit message")
+            ) as mock_scope,
+            patch("main.run_other_checks", return_value=[]),
+        ):
+            main.run_commit_check()
+        mock_scope.assert_called_once_with(
+            "Commit message", ["--message-ai-attribution"], sha=SHA_A
+        )
+
     def test_message_flag_removed_before_other_checks_in_pr(self):
         captured_args = []