Add Co-Authored-By trailer and commit message pattern detection

utils.go → detection.go

@@ -1,14 +1,15 @@
 package main
 
 import (
+	"regexp"
 	"strings"
 )
 
 var knownAgentCommitters = map[string]string{
 	"209825114+claude[bot]@users.noreply.github.com":					"Claude",
 	"215619710+anthropic-claude[bot]@users.noreply.github.com":			"Claude (Anthropic)",
 	"208546643+claude-code-action[bot]@users.noreply.github.com": 		"Claude Code Action",
-	"198982749+Copilot@users.noreply.github.com": 						"GitHub Copilot (agent)",
+	"198982749+copilot@users.noreply.github.com": 						"GitHub Copilot (agent)",
 	"167198135+copilot[bot]@users.noreply.github.com": 					"GitHub Copilot (chat)",
 	"206951365+cursor[bot]@users.noreply.github.com": 					"Cursor",
 	"215057067+openai-codex[bot]@users.noreply.github.com": 			"OpenAI Codex",
@@ -26,7 +27,61 @@ var knownAgentCommitters = map[string]string{
 // Check if a given committer email is a known AI agent, returns the agent name and a boolean for success
 func IdentifyAgentCommitterEmail(email string) (string, bool) {
 	cleanEmail := strings.ToLower(strings.TrimSpace(email))
-	
+
 	name, exists := knownAgentCommitters[cleanEmail]
 	return name, exists
+}
+
+var knownCoAuthorEmails = map[string]string{
+	"noreply@anthropic.com": "Claude Code",
+	"cursoragent@cursor.com": "Cursor",
+	"noreply@aider.chat":    "Aider",
+}
+
+var coAuthorPattern = regexp.MustCompile(`(?im)^co-authored-by:\s*[^<]*<([^>]+)>`)
+
+// IdentifyCoAuthorTrailers parses a commit message for Co-Authored-By trailers
+// and returns the names of any matched AI tools.
+func IdentifyCoAuthorTrailers(message string) []string {
+	matches := coAuthorPattern.FindAllStringSubmatch(message, -1)
+	var tools []string
+	seen := map[string]bool{}
+	for _, match := range matches {
+		email := strings.ToLower(strings.TrimSpace(match[1]))
+		if name, ok := knownCoAuthorEmails[email]; ok && !seen[name] {
+			tools = append(tools, name)
+			seen[name] = true
+		}
+	}
+	return tools
+}
+
+var commitMessagePatterns = []struct {
+	check func(string) bool
+	name  string
+}{
+	{
+		check: func(msg string) bool {
+			return strings.HasPrefix(strings.ToLower(msg), "aider:")
+		},
+		name: "Aider",
+	},
+	{
+		check: func(msg string) bool {
+			return strings.Contains(msg, "Generated with Claude Code")
+		},
+		name: "Claude Code",
+	},
+}
+
+// IdentifyCommitMessagePatterns checks a commit message for known AI tool
+// signatures and returns matched tool names.
+func IdentifyCommitMessagePatterns(message string) []string {
+	var tools []string
+	for _, p := range commitMessagePatterns {
+		if p.check(message) {
+			tools = append(tools, p.name)
+		}
+	}
+	return tools
 }

detection_test.go

@@ -0,0 +1,202 @@
+package main
+
+import (
+	"slices"
+	"testing"
+)
+
+func TestIdentifyAgentCommitterEmailAllKnown(t *testing.T) {
+	for email, expectedName := range knownAgentCommitters {
+		name, exists := IdentifyAgentCommitterEmail(email)
+		if !exists || name != expectedName {
+			t.Errorf("IdentifyAgentCommitterEmail(%q) = %q, %v, want %q, true", email, name, exists, expectedName)
+		}
+	}
+}
+
+func TestIdentifyAgentCommitterEmailMixedCase(t *testing.T) {
+	cases := []struct {
+		input    string
+		wantName string
+	}{
+		{"198982749+Copilot@users.noreply.github.com", "GitHub Copilot (agent)"},
+		{"209825114+CLAUDE[BOT]@USERS.NOREPLY.GITHUB.COM", "Claude"},
+		{"136622811+CodeRabbitAI[bot]@users.noreply.github.com", "CodeRabbit"},
+	}
+
+	for _, tc := range cases {
+		name, exists := IdentifyAgentCommitterEmail(tc.input)
+		if !exists || name != tc.wantName {
+			t.Errorf("IdentifyAgentCommitterEmail(%q) = %q, %v, want %q, true", tc.input, name, exists, tc.wantName)
+		}
+	}
+}
+
+func TestIdentifyAgentCommitterEmailWhitespace(t *testing.T) {
+	cases := []string{
+		"  209825114+claude[bot]@users.noreply.github.com",
+		"209825114+claude[bot]@users.noreply.github.com  ",
+		"  209825114+claude[bot]@users.noreply.github.com  ",
+	}
+
+	for _, email := range cases {
+		name, exists := IdentifyAgentCommitterEmail(email)
+		if !exists || name != "Claude" {
+			t.Errorf("IdentifyAgentCommitterEmail(%q) = %q, %v, want %q, true", email, name, exists, "Claude")
+		}
+	}
+}
+
+func TestIdentifyAgentCommitterEmailNotFound(t *testing.T) {
+	cases := []string{
+		"user@example.com",
+		"",
+		"  ",
+		"claude@anthropic.com",
+		"not-a-bot@users.noreply.github.com",
+	}
+
+	for _, email := range cases {
+		name, exists := IdentifyAgentCommitterEmail(email)
+		if exists || name != "" {
+			t.Errorf("IdentifyAgentCommitterEmail(%q) = %q, %v, want \"\", false", email, name, exists)
+		}
+	}
+}
+
+func TestIdentifyCoAuthorTrailers(t *testing.T) {
+	tests := []struct {
+		name    string
+		message string
+		want    []string
+	}{
+		{
+			name:    "Claude trailer with Opus model",
+			message: "fix: update handler\n\nCo-Authored-By: Claude Opus 4 <noreply@anthropic.com>",
+			want:    []string{"Claude Code"},
+		},
+		{
+			name:    "Claude trailer with Sonnet model",
+			message: "fix: update handler\n\nCo-Authored-By: Claude Sonnet 4 <noreply@anthropic.com>",
+			want:    []string{"Claude Code"},
+		},
+		{
+			name:    "Cursor trailer",
+			message: "refactor: extract method\n\nCo-Authored-By: Cursor <cursoragent@cursor.com>",
+			want:    []string{"Cursor"},
+		},
+		{
+			name:    "Aider trailer with model name",
+			message: "feat: add endpoint\n\nCo-Authored-By: aider (gpt-4o) <noreply@aider.chat>",
+			want:    []string{"Aider"},
+		},
+		{
+			name:    "Aider trailer with different model",
+			message: "feat: add endpoint\n\nCo-Authored-By: aider (claude-3.5-sonnet) <noreply@aider.chat>",
+			want:    []string{"Aider"},
+		},
+		{
+			name:    "multiple trailers with Claude and human",
+			message: "fix: bug\n\nCo-Authored-By: Claude Opus 4 <noreply@anthropic.com>\nCo-Authored-By: Alice <alice@example.com>",
+			want:    []string{"Claude Code"},
+		},
+		{
+			name:    "multiple AI trailers",
+			message: "fix: bug\n\nCo-Authored-By: Claude Opus 4 <noreply@anthropic.com>\nCo-Authored-By: aider (gpt-4o) <noreply@aider.chat>",
+			want:    []string{"Claude Code", "Aider"},
+		},
+		{
+			name:    "case variation",
+			message: "fix: thing\n\nco-authored-by: Claude <noreply@anthropic.com>",
+			want:    []string{"Claude Code"},
+		},
+		{
+			name:    "CO-AUTHORED-BY uppercase",
+			message: "fix: thing\n\nCO-AUTHORED-BY: Claude <noreply@anthropic.com>",
+			want:    []string{"Claude Code"},
+		},
+		{
+			name:    "no trailers",
+			message: "just a normal commit message",
+			want:    nil,
+		},
+		{
+			name:    "human co-author only",
+			message: "pair programming\n\nCo-Authored-By: Bob <bob@company.com>",
+			want:    nil,
+		},
+		{
+			name:    "empty message",
+			message: "",
+			want:    nil,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := IdentifyCoAuthorTrailers(tt.message)
+			if !slices.Equal(got, tt.want) {
+				t.Errorf("IdentifyCoAuthorTrailers() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestIdentifyCommitMessagePatterns(t *testing.T) {
+	tests := []struct {
+		name    string
+		message string
+		want    []string
+	}{
+		{
+			name:    "aider prefix",
+			message: "aider: fix the login bug",
+			want:    []string{"Aider"},
+		},
+		{
+			name:    "aider prefix uppercase",
+			message: "Aider: refactor auth module",
+			want:    []string{"Aider"},
+		},
+		{
+			name:    "Claude Code footer",
+			message: "Add user validation\n\nGenerated with Claude Code",
+			want:    []string{"Claude Code"},
+		},
+		{
+			name:    "Claude Code footer with link",
+			message: "Add validation\n\nGenerated with Claude Code\nhttps://claude.ai",
+			want:    []string{"Claude Code"},
+		},
+		{
+			name:    "no patterns",
+			message: "normal commit message with no AI signatures",
+			want:    nil,
+		},
+		{
+			name:    "aider in middle of message not prefix",
+			message: "fix the aider: integration test",
+			want:    nil,
+		},
+		{
+			name:    "aider as substring of a word",
+			message: "raider: fix the tests",
+			want:    nil,
+		},
+		{
+			name:    "empty message",
+			message: "",
+			want:    nil,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := IdentifyCommitMessagePatterns(tt.message)
+			if !slices.Equal(got, tt.want) {
+				t.Errorf("IdentifyCommitMessagePatterns() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+