Do some utterly disgusting MC library munging to deal with contacts coming out of sync

app/radio_sync.py

@@ -116,6 +116,30 @@ async def sync_and_offload_contacts(mc: MeshCore) -> dict:
                 remove_result = await mc.commands.remove_contact(contact_data)
                 if remove_result.type == EventType.OK:
                     removed += 1
+
+                    # LIBRARY INTERNAL FIXUP: The MeshCore library's
+                    # commands.remove_contact() sends the remove command over
+                    # the wire but does NOT update the library's in-memory
+                    # contact cache (mc._contacts). This is a gap in the
+                    # library — there's no public API to clear a single
+                    # contact from the cache, and the library only refreshes
+                    # it on a full get_contacts() call.
+                    #
+                    # Why this matters: sync_recent_contacts_to_radio() uses
+                    # mc.get_contact_by_key_prefix() to check whether a
+                    # contact is already loaded on the radio. That method
+                    # searches mc._contacts. If we don't evict the removed
+                    # contact from the cache here, get_contact_by_key_prefix()
+                    # will still find it and skip the add_contact() call —
+                    # meaning contacts never get loaded back onto the radio
+                    # after offload. The result: no DM ACKs, degraded routing
+                    # for potentially minutes until the next periodic sync
+                    # refreshes the cache from the (now-empty) radio.
+                    #
+                    # We access mc._contacts directly because the library
+                    # exposes it as a read-only property (mc.contacts) with
+                    # no removal API. The dict is keyed by public_key string.
+                    mc._contacts.pop(public_key, None)
                 else:
                     logger.warning(
                         "Failed to remove contact %s: %s", public_key[:12], remove_result.payload

tests/test_radio_sync.py

@@ -555,6 +555,79 @@ class TestSyncAndOffloadContacts:
         assert contact is not None
         assert contact.on_radio is False
 
+    @pytest.mark.asyncio
+    async def test_evicts_removed_contacts_from_library_cache(self, test_db):
+        """Successfully removed contacts are evicted from mc._contacts.
+
+        The MeshCore library's remove_contact() command does not update the
+        library's in-memory _contacts cache. If we don't evict manually,
+        sync_recent_contacts_to_radio() will find stale entries via
+        get_contact_by_key_prefix() and skip re-adding contacts to the radio.
+        """
+        from app.radio_sync import sync_and_offload_contacts
+
+        contact_payload = {
+            KEY_A: {"adv_name": "Alice", "type": 1, "flags": 0},
+            KEY_B: {"adv_name": "Bob", "type": 1, "flags": 0},
+        }
+
+        mock_get_result = MagicMock()
+        mock_get_result.type = EventType.NEW_CONTACT
+        mock_get_result.payload = contact_payload
+
+        mock_remove_result = MagicMock()
+        mock_remove_result.type = EventType.OK
+
+        mock_mc = MagicMock()
+        mock_mc.commands.get_contacts = AsyncMock(return_value=mock_get_result)
+        mock_mc.commands.remove_contact = AsyncMock(return_value=mock_remove_result)
+        # Seed the library's in-memory cache with the same contacts —
+        # simulating what happens after get_contacts() populates it.
+        mock_mc._contacts = {
+            KEY_A: {"public_key": KEY_A, "adv_name": "Alice"},
+            KEY_B: {"public_key": KEY_B, "adv_name": "Bob"},
+        }
+
+        await sync_and_offload_contacts(mock_mc)
+
+        # Both contacts should have been evicted from the library cache
+        assert KEY_A not in mock_mc._contacts
+        assert KEY_B not in mock_mc._contacts
+        assert mock_mc._contacts == {}
+
+    @pytest.mark.asyncio
+    async def test_failed_remove_does_not_evict_from_library_cache(self, test_db):
+        """Contacts that fail to remove from radio stay in mc._contacts.
+
+        We only evict from the cache on successful removal — if the radio
+        still has the contact, the cache should reflect that.
+        """
+        from app.radio_sync import sync_and_offload_contacts
+
+        contact_payload = {
+            KEY_A: {"adv_name": "Alice", "type": 1, "flags": 0},
+        }
+
+        mock_get_result = MagicMock()
+        mock_get_result.type = EventType.NEW_CONTACT
+        mock_get_result.payload = contact_payload
+
+        mock_fail_result = MagicMock()
+        mock_fail_result.type = EventType.ERROR
+        mock_fail_result.payload = {"error": "busy"}
+
+        mock_mc = MagicMock()
+        mock_mc.commands.get_contacts = AsyncMock(return_value=mock_get_result)
+        mock_mc.commands.remove_contact = AsyncMock(return_value=mock_fail_result)
+        mock_mc._contacts = {
+            KEY_A: {"public_key": KEY_A, "adv_name": "Alice"},
+        }
+
+        await sync_and_offload_contacts(mock_mc)
+
+        # Contact should still be in the cache since removal failed
+        assert KEY_A in mock_mc._contacts
+
 
 class TestSyncAndOffloadChannels:
     """Test sync_and_offload_channels: pull channels from radio, save to DB, clear from radio."""