test(channels): add 9 cases for matchesChatID

Covers: empty config, missing key, empty value, exact match,
no match, multiple IDs one match / no match, whitespace
trim, and trailing comma edge case.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

workspace-server/internal/handlers/channels_test.go

@@ -848,3 +848,62 @@ func TestChannelHandler_Webhook_Discord_ValidSig_PingAccepted(t *testing.T) {
 		t.Fatalf("unmet sqlmock expectations: %v", err)
 	}
 }
+
+// ==================== matchesChatID (pure helper) ====================
+
+func TestMatchesChatID_EmptyConfig(t *testing.T) {
+	if matchesChatID(map[string]interface{}{}, "12345") {
+		t.Error("empty config should return false")
+	}
+}
+
+func TestMatchesChatID_MissingChatIDKey(t *testing.T) {
+	if matchesChatID(map[string]interface{}{"foo": "bar"}, "12345") {
+		t.Error("missing chat_id key should return false")
+	}
+}
+
+func TestMatchesChatID_EmptyChatIDValue(t *testing.T) {
+	if matchesChatID(map[string]interface{}{"chat_id": ""}, "12345") {
+		t.Error("empty chat_id value should return false")
+	}
+}
+
+func TestMatchesChatID_ExactMatch(t *testing.T) {
+	if !matchesChatID(map[string]interface{}{"chat_id": "12345"}, "12345") {
+		t.Error("exact match should return true")
+	}
+}
+
+func TestMatchesChatID_NoMatch(t *testing.T) {
+	if matchesChatID(map[string]interface{}{"chat_id": "12345"}, "67890") {
+		t.Error("no match should return false")
+	}
+}
+
+func TestMatchesChatID_MultipleIDsOneMatch(t *testing.T) {
+	if !matchesChatID(map[string]interface{}{"chat_id": "111,222,333"}, "222") {
+		t.Error("middle ID should match")
+	}
+}
+
+func TestMatchesChatID_MultipleIDsNoMatch(t *testing.T) {
+	if matchesChatID(map[string]interface{}{"chat_id": "111,222,333"}, "444") {
+		t.Error("none of multiple IDs match → false")
+	}
+}
+
+func TestMatchesChatID_WhitespaceTrimmed(t *testing.T) {
+	if !matchesChatID(map[string]interface{}{"chat_id": " 111 , 222 , 333 "}, "222") {
+		t.Error("whitespace around ID should be trimmed before match")
+	}
+	if matchesChatID(map[string]interface{}{"chat_id": " 111 , 222 , 333 "}, " 222 ") {
+		t.Error("search string is not trimmed; no match expected")
+	}
+}
+
+func TestMatchesChatID_TrailingComma(t *testing.T) {
+	if !matchesChatID(map[string]interface{}{"chat_id": "12345,"}, "12345") {
+		t.Error("single ID with trailing comma should still match")
+	}
+}