[PATCH v2] scripts/checkpatch: add Assisted-by: tag validation

[Harry Wentland <harry.wentland@amd.com>]

The coding-assistants.rst documentation defines the Assisted-by: tag
format for AI-assisted contributions as:

  Assisted-by: AGENT_NAME:MODEL_VERSION [TOOL1] [TOOL2]

This format does not use an email address, so checkpatch currently
reports a false positive about an invalid email when encountering this
tag.

Add Assisted-by: to the recognized signature tags and standard signature
list. When an Assisted-by: tag is found, validate it instead of checking
for an email address.

Examples of passing tags:
- Claude:claude-3-opus coccinelle sparse
- FOO:BAR.baz
- Copilot Github:claude-3-opus
- GitHub Copilot:Claude Opus 4.6
- My Cool Agent:v1.2.3 coccinelle sparse

Examples of tags triggering the new warning:
- Claude coccinelle sparse
- JustAName
- :missing-agent

Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Assisted-by: Claude:claude-opus-4.6
Co-developed-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Harry Wentland <harry.wentland@amd.com>
---
 scripts/checkpatch.pl | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index e56374662ff7..b8d961d77ff4 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -641,6 +641,7 @@ our $signature_tags = qr{(?xi:
 	Reviewed-by:|
 	Reported-by:|
 	Suggested-by:|
+	Assisted-by:|
 	To:|
 	Cc:
 )};
@@ -737,7 +738,7 @@ sub find_standard_signature {
 	my ($sign_off) = @_;
 	my @standard_signature_tags = (
 		'Signed-off-by:', 'Co-developed-by:', 'Acked-by:', 'Tested-by:',
-		'Reviewed-by:', 'Reported-by:', 'Suggested-by:'
+		'Reviewed-by:', 'Reported-by:', 'Suggested-by:', 'Assisted-by:'
 	);
 	foreach my $signature (@standard_signature_tags) {
 		return $signature if (get_edit_distance($sign_off, $signature) <= 2);
@@ -3105,6 +3106,15 @@ sub process {
 				}
 			}
 
+# Assisted-by: uses format AGENT_NAME:MODEL_VERSION [TOOL1] [TOOL2] instead of email
+			if ($sign_off =~ /^assisted-by:$/i) {
+				if ($email !~ /^[^:]+:\S+(\s+\S+)*$/) {
+					WARN("BAD_ASSISTED_BY",
+					     "Assisted-by: should use format: 'Assisted-by: AGENT_NAME:MODEL_VERSION [TOOL1] [TOOL2]'\n" . $herecurr);
+				}
+				next;
+			}
+
 			my ($email_name, $name_comment, $email_address, $comment) = parse_email($email);
 			my $suggested_email = format_email(($email_name, $name_comment, $email_address, $comment));
 			if ($suggested_email eq "") {
-- 
2.53.0