fix(signal): read groupV2.id in envelope, fall back to legacy groupInfo

Port from qwibitai/nanoclaw#1962: modern Signal V2-only groups surface on
dataMessage.groupV2.id, not groupInfo.groupId. signal-cli versions differ
in which field they expose for V2 groups — some forward the underlying
libsignal envelope verbatim (groupV2), others normalize everything into
groupInfo. Without a groupV2 read, V2-only groups appear as DMs because
groupInfo is undefined and the adapter misroutes them to the sender's
DM session.

Reads groupV2.id first, falls back to groupInfo.groupId. Also hardens
chat_name extraction against non-dict groupInfo payloads (crashed with
AttributeError under malformed envelopes).

6 new tests cover V2 routing, V1 legacy compatibility, V2-preferred
precedence, no-group DM path, allowlist enforcement, and malformed
payloads.

gateway/platforms/signal.py

@@ -460,9 +460,19 @@ class SignalAdapter(BasePlatformAdapter):
         if not data_message:
             return
 
-        # Check for group message
+        # Check for group message.
+        # Modern Signal groups surface on dataMessage.groupV2.id; legacy V1
+        # groups still arrive under dataMessage.groupInfo.groupId. signal-cli
+        # versions differ in which field they expose for V2 groups — some
+        # forward the underlying libsignal envelope verbatim (groupV2), others
+        # normalize everything into groupInfo. Read groupV2 first and fall
+        # back to groupInfo so V2-only groups aren't misrouted as DMs.
         group_info = data_message.get("groupInfo")
-        group_id = group_info.get("groupId") if group_info else None
+        group_v2 = data_message.get("groupV2")
+        group_id = (
+            (group_v2.get("id") if isinstance(group_v2, dict) else None)
+            or (group_info.get("groupId") if isinstance(group_info, dict) else None)
+        )
         is_group = bool(group_id)
 
         # Group message filtering — derived from SIGNAL_GROUP_ALLOWED_USERS:
@@ -515,7 +525,7 @@ class SignalAdapter(BasePlatformAdapter):
         # Build session source
         source = self.build_source(
             chat_id=chat_id,
-            chat_name=group_info.get("groupName") if group_info else sender_name,
+            chat_name=(group_info.get("groupName") if isinstance(group_info, dict) else None) or sender_name,
             chat_type=chat_type,
             user_id=sender,
             user_name=sender_name or sender,

tests/gateway/test_signal.py

@@ -997,3 +997,162 @@ class TestSignalTypingBackoff:
 
         assert "+155****4567" not in adapter._typing_failures
         assert "+155****4567" not in adapter._typing_skip_until
+
+
+# ---------------------------------------------------------------------------
+# Envelope handling — group routing (legacy groupInfo vs modern groupV2)
+# ---------------------------------------------------------------------------
+
+class TestSignalGroupV2Routing:
+    """Regression coverage for groupV2 envelope handling.
+
+    signal-cli's JSON-RPC ``subscribeReceive`` envelope shape has drifted across
+    versions: some forward the underlying libsignal V2 envelope as
+    ``dataMessage.groupV2.id`` while older / normalized paths still use
+    ``dataMessage.groupInfo.groupId``. The adapter must read groupV2 first and
+    fall back to groupInfo so V2-only groups aren't misrouted as DMs.
+
+    Ported from qwibitai/nanoclaw#1962 (V2 adapter improvements).
+    """
+
+    def _base_envelope(self, data_message: dict) -> dict:
+        return {
+            "envelope": {
+                "sourceNumber": "+15559998888",
+                "sourceUuid": "uuid-sender",
+                "sourceName": "Alice",
+                "timestamp": 1700000000000,
+                "dataMessage": data_message,
+            }
+        }
+
+    @pytest.mark.asyncio
+    async def test_group_v2_id_routes_as_group(self, monkeypatch):
+        adapter = _make_signal_adapter(monkeypatch, group_allowed="*")
+        captured = []
+
+        async def _capture(event):
+            captured.append(event)
+
+        adapter.handle_message = _capture
+
+        env = self._base_envelope({
+            "message": "hello v2",
+            "groupV2": {"id": "v2group=="},
+        })
+
+        await adapter._handle_envelope(env)
+
+        assert len(captured) == 1
+        assert captured[0].source.chat_id == "group:v2group=="
+        assert captured[0].source.chat_type == "group"
+        assert captured[0].text == "hello v2"
+
+    @pytest.mark.asyncio
+    async def test_legacy_group_info_still_works(self, monkeypatch):
+        adapter = _make_signal_adapter(monkeypatch, group_allowed="*")
+        captured = []
+
+        async def _capture(event):
+            captured.append(event)
+
+        adapter.handle_message = _capture
+
+        env = self._base_envelope({
+            "message": "hello v1",
+            "groupInfo": {"groupId": "legacy=="},
+        })
+
+        await adapter._handle_envelope(env)
+
+        assert len(captured) == 1
+        assert captured[0].source.chat_id == "group:legacy=="
+        assert captured[0].source.chat_type == "group"
+
+    @pytest.mark.asyncio
+    async def test_group_v2_preferred_over_group_info(self, monkeypatch):
+        """When both fields are present, groupV2 wins — it's the authoritative V2 id."""
+        adapter = _make_signal_adapter(monkeypatch, group_allowed="*")
+        captured = []
+
+        async def _capture(event):
+            captured.append(event)
+
+        adapter.handle_message = _capture
+
+        env = self._base_envelope({
+            "message": "hello",
+            "groupV2": {"id": "v2=="},
+            "groupInfo": {"groupId": "v1=="},
+        })
+
+        await adapter._handle_envelope(env)
+
+        assert len(captured) == 1
+        assert captured[0].source.chat_id == "group:v2=="
+
+    @pytest.mark.asyncio
+    async def test_no_group_fields_routes_as_dm(self, monkeypatch):
+        adapter = _make_signal_adapter(monkeypatch)
+        captured = []
+
+        async def _capture(event):
+            captured.append(event)
+
+        adapter.handle_message = _capture
+
+        env = self._base_envelope({"message": "direct message"})
+
+        await adapter._handle_envelope(env)
+
+        assert len(captured) == 1
+        assert captured[0].source.chat_type == "dm"
+        assert captured[0].source.chat_id == "+15559998888"
+
+    @pytest.mark.asyncio
+    async def test_group_v2_respects_allowlist(self, monkeypatch):
+        """V2 group ids flow through the same SIGNAL_GROUP_ALLOWED_USERS filter."""
+        adapter = _make_signal_adapter(monkeypatch, group_allowed="allowed-v2==")
+        captured = []
+
+        async def _capture(event):
+            captured.append(event)
+
+        adapter.handle_message = _capture
+
+        # Blocked group (not in allowlist)
+        await adapter._handle_envelope(self._base_envelope({
+            "message": "blocked",
+            "groupV2": {"id": "blocked-v2=="},
+        }))
+        assert len(captured) == 0
+
+        # Allowed group
+        await adapter._handle_envelope(self._base_envelope({
+            "message": "allowed",
+            "groupV2": {"id": "allowed-v2=="},
+        }))
+        assert len(captured) == 1
+        assert captured[0].source.chat_id == "group:allowed-v2=="
+
+    @pytest.mark.asyncio
+    async def test_malformed_group_fields_fall_through_to_dm(self, monkeypatch):
+        """Non-dict groupV2 / groupInfo shouldn't crash — treat as DM."""
+        adapter = _make_signal_adapter(monkeypatch)
+        captured = []
+
+        async def _capture(event):
+            captured.append(event)
+
+        adapter.handle_message = _capture
+
+        env = self._base_envelope({
+            "message": "malformed",
+            "groupV2": "not-a-dict",
+            "groupInfo": 42,
+        })
+
+        await adapter._handle_envelope(env)
+
+        assert len(captured) == 1
+        assert captured[0].source.chat_type == "dm"