test(whatsapp): add group trigger filtering tests

Covers the four cases introduced by the group_trigger fix:
- mention_only: group message without mention is dropped
- mention_only: group message with mentioned:true is forwarded
- mention_only: group message with non-empty mentions array is forwarded
- mention_only: DMs are always forwarded regardless of config
- prefix: matching prefix is forwarded with prefix stripped
- prefix: non-matching message is dropped
- no config: permissive default forwards everything

https://claude.ai/code/session_01PfpBofWnnVaNf7uyBEJA4T

pkg/channels/whatsapp/whatsapp_command_test.go

@@ -9,6 +9,32 @@ import (
 	"github.com/sipeed/picoclaw/pkg/config"
 )
 
+func newTestChannel(gt config.GroupTriggerConfig) (*WhatsAppChannel, *bus.MessageBus) {
+	messageBus := bus.NewMessageBus()
+	cfg := config.WhatsAppConfig{GroupTrigger: gt}
+	ch := &WhatsAppChannel{
+		BaseChannel: channels.NewBaseChannel("whatsapp", cfg, messageBus, nil,
+			channels.WithGroupTrigger(cfg.GroupTrigger),
+		),
+		ctx: context.Background(),
+	}
+	return ch, messageBus
+}
+
+// drainInbound returns the next non-observe-only message from the bus, if any.
+// ObserveOnly messages (recorded by ObserveGroupMessage) are not counted as "forwarded".
+func drainInbound(mb *bus.MessageBus) (bus.InboundMessage, bool) {
+	select {
+	case msg := <-mb.InboundChan():
+		if msg.ObserveOnly {
+			return bus.InboundMessage{}, false
+		}
+		return msg, true
+	default:
+		return bus.InboundMessage{}, false
+	}
+}
+
 func TestHandleIncomingMessage_DoesNotConsumeGenericCommandsLocally(t *testing.T) {
 	messageBus := bus.NewMessageBus()
 	ch := &WhatsAppChannel{
@@ -35,3 +61,110 @@ func TestHandleIncomingMessage_DoesNotConsumeGenericCommandsLocally(t *testing.T
 		t.Fatalf("content=%q", inbound.Content)
 	}
 }
+
+// TestGroupTrigger_MentionOnly verifies that with mention_only:true the bot
+// ignores group messages unless the bridge signals a mention.
+func TestGroupTrigger_MentionOnly(t *testing.T) {
+	gt := config.GroupTriggerConfig{MentionOnly: true}
+
+	t.Run("group message without mention is dropped", func(t *testing.T) {
+		ch, mb := newTestChannel(gt)
+		ch.handleIncomingMessage(map[string]any{
+			"from":    "user1",
+			"chat":    "group1",
+			"content": "hello everyone",
+		})
+		if _, ok := drainInbound(mb); ok {
+			t.Fatal("expected message to be dropped, but it was forwarded")
+		}
+	})
+
+	t.Run("group message with mentioned:true is forwarded", func(t *testing.T) {
+		ch, mb := newTestChannel(gt)
+		ch.handleIncomingMessage(map[string]any{
+			"from":      "user1",
+			"chat":      "group1",
+			"content":   "hey bot",
+			"mentioned": true,
+		})
+		msg, ok := drainInbound(mb)
+		if !ok {
+			t.Fatal("expected message to be forwarded, but it was dropped")
+		}
+		if msg.Content != "hey bot" {
+			t.Fatalf("content=%q", msg.Content)
+		}
+	})
+
+	t.Run("group message with non-empty mentions array is forwarded", func(t *testing.T) {
+		ch, mb := newTestChannel(gt)
+		ch.handleIncomingMessage(map[string]any{
+			"from":     "user1",
+			"chat":     "group1",
+			"content":  "hey bot",
+			"mentions": []any{"botjid@s.whatsapp.net"},
+		})
+		if _, ok := drainInbound(mb); !ok {
+			t.Fatal("expected message to be forwarded, but it was dropped")
+		}
+	})
+
+	t.Run("DM is always forwarded regardless of mention_only", func(t *testing.T) {
+		ch, mb := newTestChannel(gt)
+		ch.handleIncomingMessage(map[string]any{
+			"from":    "user1",
+			"chat":    "user1", // chat == sender → DM
+			"content": "private message",
+		})
+		if _, ok := drainInbound(mb); !ok {
+			t.Fatal("expected DM to be forwarded, but it was dropped")
+		}
+	})
+}
+
+// TestGroupTrigger_Prefix verifies prefix-based group trigger filtering.
+func TestGroupTrigger_Prefix(t *testing.T) {
+	gt := config.GroupTriggerConfig{Prefixes: []string{"/ask"}}
+
+	t.Run("group message with matching prefix is forwarded and prefix stripped", func(t *testing.T) {
+		ch, mb := newTestChannel(gt)
+		ch.handleIncomingMessage(map[string]any{
+			"from":    "user1",
+			"chat":    "group1",
+			"content": "/ask what time is it",
+		})
+		msg, ok := drainInbound(mb)
+		if !ok {
+			t.Fatal("expected message to be forwarded")
+		}
+		if msg.Content != "what time is it" {
+			t.Fatalf("content=%q, want %q", msg.Content, "what time is it")
+		}
+	})
+
+	t.Run("group message without prefix is dropped", func(t *testing.T) {
+		ch, mb := newTestChannel(gt)
+		ch.handleIncomingMessage(map[string]any{
+			"from":    "user1",
+			"chat":    "group1",
+			"content": "hello",
+		})
+		if _, ok := drainInbound(mb); ok {
+			t.Fatal("expected message to be dropped")
+		}
+	})
+}
+
+// TestGroupTrigger_NoConfig verifies that without any group_trigger config the
+// bot responds to all group messages (permissive default).
+func TestGroupTrigger_NoConfig(t *testing.T) {
+	ch, mb := newTestChannel(config.GroupTriggerConfig{})
+	ch.handleIncomingMessage(map[string]any{
+		"from":    "user1",
+		"chat":    "group1",
+		"content": "any message",
+	})
+	if _, ok := drainInbound(mb); !ok {
+		t.Fatal("expected message to be forwarded with no group_trigger config")
+	}
+}