add check_names.py: detect and fix mod folder name mismatches

Compares @Mod folder names in downloads/ against server canonical
names. Uses meta.cpp steam_id as primary lookup (most reliable),
falls back to normalized name. Reports OK / MISMATCH / NOT_ON_SERVER
per folder.

--fix mode renames mismatched folders and updates arma_dir junctions
in one pass so the full pipeline can run cleanly afterward.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

test_suite.py

@@ -1059,7 +1059,93 @@ test("all exported symbols are callable or types", _test_exports_are_callable)
 
 
 # ---------------------------------------------------------------------------
-# 9. Integration: parse → compare → reporter (offline)
+# 9. check_names helpers
+# ---------------------------------------------------------------------------
+
+group("check_names helpers")
+
+from check_names import _server_name_from_url, _read_local_steam_id, _lookup_server_name
+
+
+def _test_server_name_from_url():
+    assert_eq(_server_name_from_url("https://x.com/mods/@ace/"), "@ace")
+    assert_eq(_server_name_from_url("https://x.com/mods/@cba_a3"), "@cba_a3")
+
+
+def _test_read_local_steam_id_present():
+    with tempfile.TemporaryDirectory() as d:
+        d = Path(d)
+        (d / "meta.cpp").write_text('publishedid = 463939057;\nname = "ACE3";', encoding="utf-8")
+        assert_eq(_read_local_steam_id(d), "463939057")
+
+
+def _test_read_local_steam_id_missing():
+    with tempfile.TemporaryDirectory() as d:
+        assert _read_local_steam_id(Path(d)) is None
+
+
+def _test_read_local_steam_id_no_id_in_file():
+    with tempfile.TemporaryDirectory() as d:
+        d = Path(d)
+        (d / "meta.cpp").write_text('name = "LocalMod";\n', encoding="utf-8")
+        assert _read_local_steam_id(d) is None
+
+
+def _test_lookup_server_name_by_steam_id():
+    index = {
+        "by_steam_id": {"463939057": "https://x.com/@ace3/"},
+        "by_name": {},
+    }
+    with tempfile.TemporaryDirectory() as d:
+        d = Path(d)
+        (d / "meta.cpp").write_text("publishedid = 463939057;", encoding="utf-8")
+        result = _lookup_server_name("@ACE3", d, index)
+    assert_eq(result, "@ace3")
+
+
+def _test_lookup_server_name_by_name_fallback():
+    index = {
+        "by_steam_id": {},
+        "by_name": {"cbaa3": "https://x.com/@cba_a3/"},
+    }
+    with tempfile.TemporaryDirectory() as d:
+        # No meta.cpp — name fallback
+        result = _lookup_server_name("@CBA_A3", Path(d), index)
+    assert_eq(result, "@cba_a3")
+
+
+def _test_lookup_server_name_steam_id_beats_name():
+    """steam_id lookup must take priority over name fallback."""
+    index = {
+        "by_steam_id": {"111": "https://x.com/@correct/"},
+        "by_name": {"mymod": "https://x.com/@wrong/"},
+    }
+    with tempfile.TemporaryDirectory() as d:
+        d = Path(d)
+        (d / "meta.cpp").write_text("publishedid = 111;", encoding="utf-8")
+        result = _lookup_server_name("@MyMod", d, index)
+    assert_eq(result, "@correct")
+
+
+def _test_lookup_server_name_not_found():
+    index = {"by_steam_id": {}, "by_name": {}}
+    with tempfile.TemporaryDirectory() as d:
+        result = _lookup_server_name("@Unknown", Path(d), index)
+    assert result is None
+
+
+test("_server_name_from_url: extracts name from URL", _test_server_name_from_url)
+test("_read_local_steam_id: reads meta.cpp", _test_read_local_steam_id_present)
+test("_read_local_steam_id: no meta.cpp -> None", _test_read_local_steam_id_missing)
+test("_read_local_steam_id: meta.cpp without id -> None", _test_read_local_steam_id_no_id_in_file)
+test("_lookup_server_name: matches by steam_id", _test_lookup_server_name_by_steam_id)
+test("_lookup_server_name: falls back to name", _test_lookup_server_name_by_name_fallback)
+test("_lookup_server_name: steam_id beats name fallback", _test_lookup_server_name_steam_id_beats_name)
+test("_lookup_server_name: not found -> None", _test_lookup_server_name_not_found)
+
+
+# ---------------------------------------------------------------------------
+# 10. Integration: parse → compare → reporter (offline)
 # ---------------------------------------------------------------------------
 
 group("integration: parse → compare → reporter (offline)")