Anchor generated attachments to assistant messages

Deliverables now inherit the active assistant draft message ID so clients can render them beside the reply that produced them.

tests/test_pheby.py

@@ -28,6 +28,7 @@ if str(_PLUGIN_DIR) not in sys.path:
 
 from pheby import protocol as proto  # noqa: E402
 from pheby.attachments import AttachmentStore, constant_time_equals  # noqa: E402
+from pheby.adapter import PhebyAdapter  # noqa: E402
 from pheby.config import load_config  # noqa: E402
 from pheby.conversations import ConversationRouter  # noqa: E402
 from pheby.server import PhebyServer  # noqa: E402
@@ -344,6 +345,13 @@ class TestConversations:
 # Attachments
 # ═══════════════════════════════════════════════════════════════════════════
 class TestAttachments:
+    def test_adapter_anchors_deliverable_to_active_assistant_draft(self):
+        adapter = object.__new__(PhebyAdapter)
+        adapter._drafts = {"conv": {"message_id": "draft-run-1", "text": ""}}
+
+        assert adapter._active_assistant_message_id("conv") == "draft-run-1"
+        assert adapter._active_assistant_message_id("unknown") is None
+
     @pytest.mark.asyncio
     async def test_register_describe_download_path(self, tmp_path):
         src = Path(tmp_path) / "report.pdf"