Fix empty display_name for Lichess autocomplete results

_slim_profile's "username" field falls back to data.get("id") since
autocomplete's raw JSON only has "id", not "username" — but "display_name"
never had the same fallback, so it was always "" for every autocomplete
candidate. That made the resolver's cheap name-only first pass
(_resolve_lichess_by_autocomplete, which ranks all candidates before
fetching full profiles for just the top 2) score every candidate against
_name_score(name, ""), i.e. effectively unranked/random order rather than
name-similarity-driven.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Author: jlhe97

lookup/lichess.py

@@ -163,7 +163,13 @@ def _slim_profile(data: dict) -> dict:
     profile = data.get("profile") or {}
     return {
         "username": data.get("id") or data.get("username", ""),
-        "display_name": data.get("username", ""),
+        # Autocomplete's raw JSON only has "id" (lowercase-normalized), not
+        # "username" — falling back the same way "username" above does
+        # keeps display_name non-empty for autocomplete-only results
+        # instead of "", which made _name_score(name, "") score every
+        # candidate identically (effectively random ranking) in the
+        # resolver's cheap name-only first pass.
+        "display_name": data.get("username") or data.get("id", ""),
         "title": data.get("title"),
         "ratings": {
             k: perfs[k]["rating"]

tests/test_lookup.py

@@ -103,6 +103,14 @@ def test_extracts_username(self):
         assert p["username"] == "gmkasparov"
         assert p["display_name"] == "GMKasparov"
 
+    def test_display_name_falls_back_to_id_for_autocomplete_only_data(self):
+        # /api/player/autocomplete's raw entries only ever have "id", never
+        # "username" — display_name must not go empty here, or every
+        # autocomplete candidate scores identically (effectively unranked)
+        # in the resolver's cheap name-only first pass.
+        p = _slim_profile({"id": "kasparov1", "title": None, "perfs": {}})
+        assert p["display_name"] == "kasparov1"
+
     def test_extracts_title(self):
         assert _slim_profile(LICHESS_USER)["title"] == "GM"