diff --git a/internal/channel/adapters/telegram/config.go b/internal/channel/adapters/telegram/config.go
index d77e2feb..9e807476 100644
--- a/internal/channel/adapters/telegram/config.go
+++ b/internal/channel/adapters/telegram/config.go
@@ -146,15 +146,26 @@ func normalizeTarget(raw string) string {
 	if strings.HasPrefix(value, "@") {
 		return value
 	}
-	isNumeric := true
-	for _, r := range value {
-		if r < '0' || r > '9' {
-			isNumeric = false
-			break
-		}
-	}
-	if isNumeric {
+	if isTelegramChatID(value) {
 		return value
 	}
 	return "@" + value
 }
+
+// isTelegramChatID returns true when s looks like a Telegram numeric chat ID,
+// which may be negative (e.g. supergroup IDs like -1002280927535).
+func isTelegramChatID(s string) bool {
+	digits := s
+	if strings.HasPrefix(digits, "-") {
+		digits = digits[1:]
+	}
+	if len(digits) == 0 {
+		return false
+	}
+	for _, r := range digits {
+		if r < '0' || r > '9' {
+			return false
+		}
+	}
+	return true
+}
diff --git a/internal/channel/adapters/telegram/config_test.go b/internal/channel/adapters/telegram/config_test.go
index 3a314592..2aa041da 100644
--- a/internal/channel/adapters/telegram/config_test.go
+++ b/internal/channel/adapters/telegram/config_test.go
@@ -85,4 +85,10 @@ func TestNormalizeTarget(t *testing.T) {
 	if got := normalizeTarget("@alice"); got != "@alice" {
 		t.Fatalf("unexpected normalized target: %s", got)
 	}
+	if got := normalizeTarget("123456789"); got != "123456789" {
+		t.Fatalf("positive chat ID mangled: %s", got)
+	}
+	if got := normalizeTarget("-1002280927535"); got != "-1002280927535" {
+		t.Fatalf("negative supergroup chat ID mangled: %s", got)
+	}
 }