meshcore/fix: short name should be 1st 4 hex digits of public key (#679)

data/mesh_ingestor/providers/meshcore.py

@@ -34,7 +34,9 @@ Connection type is detected automatically from the target string:
 
 Node identities are derived from the first four bytes (eight hex characters)
 of each contact's 32-byte public key, formatted as ``!xxxxxxxx`` to match
-the canonical node-ID schema used across the system.
+the canonical node-ID schema used across the system.  Ingested
+``user.shortName`` is the first four hex digits of that key (two bytes),
+not the advertised name.
 """
 
 from __future__ import annotations
@@ -118,6 +120,25 @@ def _meshcore_node_id(public_key_hex: str | None) -> str | None:
     return "!" + public_key_hex[:8].lower()
 
 
+def _meshcore_short_name(public_key_hex: str | None) -> str:
+    """Return the first four hex digits of a MeshCore public key as short name.
+
+    Meshtastic-style ``shortName`` fields are four characters wide; MeshCore
+    ingest uses the leading two bytes of the 32-byte public key in lowercase
+    hex so the label is stable and unique per key prefix.
+
+    Parameters:
+        public_key_hex: Full public key as a hex string from the MeshCore API.
+
+    Returns:
+        Four lowercase hex characters, or an empty string when the key is
+        missing or shorter than four hex digits.
+    """
+    if not public_key_hex or len(public_key_hex) < 4:
+        return ""
+    return public_key_hex[:4].lower()
+
+
 def _pubkey_prefix_to_node_id(contacts: dict, pubkey_prefix: str) -> str | None:
     """Look up a canonical node ID by six-byte public-key prefix.
 
@@ -153,7 +174,7 @@ def _contact_to_node_dict(contact: dict) -> dict:
         "lastHeard": contact.get("last_advert"),
         "user": {
             "longName": name,
-            "shortName": name[:4] if name else "",
+            "shortName": _meshcore_short_name(pub_key),
             "publicKey": pub_key,
         },
     }
@@ -180,7 +201,7 @@ def _self_info_to_node_dict(self_info: dict) -> dict:
         "lastHeard": int(time.time()),
         "user": {
             "longName": name,
-            "shortName": name[:4] if name else "",
+            "shortName": _meshcore_short_name(pub_key),
             "publicKey": pub_key,
         },
     }

tests/test_provider_unit.py

@@ -39,6 +39,7 @@ from data.mesh_ingestor.providers.meshcore import (  # noqa: E402 - path setup
     _make_connection,
     _make_event_handlers,
     _meshcore_node_id,
+    _meshcore_short_name,
     _process_contact_update,
     _process_contacts,
     _process_self_info,
@@ -434,6 +435,7 @@ def test_meshcore_node_snapshot_items_with_contacts(monkeypatch):
     node_id, node_dict = items[0]
     assert node_id == "!aabbccdd"
     assert node_dict["user"]["longName"] == "Alice"
+    assert node_dict["user"]["shortName"] == "aabb"
     iface.close()
 
 
@@ -537,6 +539,18 @@ def test_meshcore_node_id_none_on_empty():
     assert _meshcore_node_id(None) is None  # type: ignore[arg-type]
 
 
+def test_meshcore_short_name_first_four_hex_digits():
+    """_meshcore_short_name returns the first four hex chars, lowercased."""
+    assert _meshcore_short_name("AABBccdd" + "00" * 28) == "aabb"
+
+
+def test_meshcore_short_name_empty_when_too_short():
+    """_meshcore_short_name returns '' when the key has fewer than four hex digits."""
+    assert _meshcore_short_name("") == ""
+    assert _meshcore_short_name("abc") == ""
+    assert _meshcore_short_name(None) == ""  # type: ignore[arg-type]
+
+
 # ---------------------------------------------------------------------------
 # _pubkey_prefix_to_node_id
 # ---------------------------------------------------------------------------
@@ -576,7 +590,7 @@ def test_contact_to_node_dict_basic_fields():
     node = _contact_to_node_dict(contact)
     assert node["lastHeard"] == 1700000000
     assert node["user"]["longName"] == "Alice"
-    assert node["user"]["shortName"] == "Alic"
+    assert node["user"]["shortName"] == "aabb"
     assert node["user"]["publicKey"] == contact["public_key"]
 
 
@@ -616,7 +630,7 @@ def test_self_info_to_node_dict_basic_fields():
     self_info = {"name": "MyNode", "public_key": "bb" * 32}
     node = _self_info_to_node_dict(self_info)
     assert node["user"]["longName"] == "MyNode"
-    assert node["user"]["shortName"] == "MyNo"
+    assert node["user"]["shortName"] == "bbbb"
     assert node["user"]["publicKey"] == "bb" * 32
     assert isinstance(node["lastHeard"], int)
 
@@ -649,6 +663,7 @@ def test_interface_update_and_snapshot_contacts():
     node_id, node_dict = snapshot[0]
     assert node_id == "!aabbccdd"
     assert node_dict["user"]["longName"] == "Bob"
+    assert node_dict["user"]["shortName"] == "aabb"
 
 
 def test_interface_lookup_node_id_by_prefix():