fix(meshcore): force full contact re-fetch on DM resolve miss

_resolve_contact relied on ensure_contacts(), which is a no-op once the
lib's contact mirror is populated — so firmware-side auto-added senders
never synced in and every reply dropped with "could not resolve contact".
On a prefix-lookup miss, force get_contacts(lastmod=0) to pull the full
roster from the radio, then retry the lookup. Lets AIDA reply to anyone
the firmware has (auto-added or previously heard) even when the cached
mirror is stale.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

work/meshai/transport/meshcore_transport.py

@@ -121,22 +121,49 @@ class MeshCoreTransport(MeshTransport):
     def _resolve_contact(self, dest: str):
         """Resolve a pubkey prefix (or key) to the full MeshCore contact dict.
 
-        Refreshes the roster first (ensure_contacts) so the lib can upgrade the
-        6-byte prefix to the full 32-byte key. Returns None if the contact can't
-        be resolved.
+        Fast path: if the lib's cached contact mirror already has a match for
+        *dest*, return it immediately with no serial round-trip.
+
+        On a cache miss, force a full contact re-fetch directly from the
+        firmware (``get_contacts(lastmod=0)``).  ``lastmod=0`` fetches ALL
+        contacts, bypassing the no-op cache guard in ``ensure_contacts()``
+        (which skips the fetch once ``self._contacts`` is already populated).
+        This pulls in any contacts the firmware has auto-added since the last
+        sync (e.g. the sender of an inbound DM).  The lib merges the result
+        into its ``_contacts`` cache automatically via its CONTACTS/NEXT_CONTACT
+        event handler, so a subsequent ``get_contact_by_key_prefix`` will find
+        the freshly-learned entry.
+
+        Returns None if the firmware genuinely has no such contact.
         """
         if self._mc is None:
             return None
-        ensure = getattr(self._mc, "ensure_contacts", None)
-        if ensure is not None:
-            try:
-                self._run_coro(ensure(), timeout=15)
-            except Exception:
-                logger.debug("MeshCore: ensure_contacts (resolve) failed", exc_info=True)
+        # Fast path: contact already in the lib's cached mirror.
+        try:
+            contact = self._mc.get_contact_by_key_prefix(dest)
+            if contact is not None:
+                return contact
+        except Exception:
+            logger.debug(
+                "MeshCore: get_contact_by_key_prefix (fast path) failed for %s", dest, exc_info=True
+            )
+            return None
+        # Miss: force a full re-fetch so the firmware's auto-added contacts
+        # (including the sender of the inbound DM we're about to reply to)
+        # are merged into the lib's cache before we retry.
+        try:
+            self._run_coro(self._mc.commands.get_contacts(lastmod=0), timeout=15)
+        except Exception:
+            logger.debug(
+                "MeshCore: get_contacts(lastmod=0) refetch failed for %s", dest, exc_info=True
+            )
+        # Retry with the freshly merged roster.
         try:
             return self._mc.get_contact_by_key_prefix(dest)
         except Exception:
-            logger.debug("MeshCore: get_contact_by_key_prefix failed for %s", dest, exc_info=True)
+            logger.debug(
+                "MeshCore: get_contact_by_key_prefix (retry) failed for %s", dest, exc_info=True
+            )
             return None
 
     def _establish_direct_path(self, contact: dict, dst: str) -> None:

work/tests/test_meshcore_transport.py

@@ -911,3 +911,40 @@ class TestAutoAddContacts:
             t._on_new_contact(event)  # must not raise
         finally:
             _cleanup(t)
+
+
+# ---------------------------------------------------------------------------
+# 13. _resolve_contact — cache-miss refetch behavior
+# ---------------------------------------------------------------------------
+
+class TestResolveContact:
+    """_resolve_contact: fast path (hit) and miss → refetch → retry behavior."""
+
+    _FAKE_CONTACT = {"public_key": "a" * 64, "adv_name": "RemoteNode", "out_path_len": -1}
+
+    def test_miss_triggers_refetch_and_returns_contact_on_retry(self):
+        """On a cache miss, get_contacts(lastmod=0) is called exactly once and
+        the contact returned on the subsequent retry is passed back to the caller."""
+        t, mc, _ = _transport_with_mock_mc()
+        try:
+            # First call returns None (miss); second call (after refetch) finds it.
+            mc.get_contact_by_key_prefix.side_effect = [None, self._FAKE_CONTACT]
+            mc.commands.get_contacts = AsyncMock(return_value=None)
+            result = t._resolve_contact("7d4e07237294")
+            assert result == self._FAKE_CONTACT
+            mc.commands.get_contacts.assert_awaited_once_with(lastmod=0)
+        finally:
+            _cleanup(t)
+
+    def test_hit_skips_refetch(self):
+        """When the first lookup returns a contact, get_contacts is NOT called
+        (fast path — no unnecessary serial round-trip to the radio)."""
+        t, mc, _ = _transport_with_mock_mc()
+        try:
+            mc.get_contact_by_key_prefix.return_value = self._FAKE_CONTACT
+            mc.commands.get_contacts = AsyncMock(return_value=None)
+            result = t._resolve_contact("7d4e07237294")
+            assert result == self._FAKE_CONTACT
+            mc.commands.get_contacts.assert_not_awaited()
+        finally:
+            _cleanup(t)