fix(weld): merge colliding lang files by key

src/smithed/weld/merging/handler.py

@@ -20,7 +20,7 @@ class since several methods based on each file are passing similar parameters wi
 from importlib import resources
 from typing import Iterator, Literal, cast, overload
 
-from beet import Context, JsonFile, NamespaceFile
+from beet import Context, JsonFile, Language, NamespaceFile
 from beet.contrib.format_json import get_formatter
 from beet.contrib.vanilla import Vanilla
 from pydantic import ValidationError
@@ -76,6 +76,10 @@ def __call__(self, pack: Pack, path: str, current: JsonFile, conflict: JsonFile,
         physical_file = json_file_type, path
 
         logger.debug(f"Registering conflict: {path!r}")
+        if json_file_type is Language:
+            current.data.update(conflict.data)
+            return True
+
         if physical_file in self.overrides[pack]:
             logger.debug("Skipping due to override")
             return True

tests/test_overlay_merging.py

@@ -2,7 +2,7 @@
 
 from copy import deepcopy
 
-from beet import DataPack, Function, LootTable, Predicate
+from beet import DataPack, Function, Language, LootTable, Predicate, ResourcePack
 import pytest
 
 from smithed.weld import run_weld
@@ -172,3 +172,16 @@ def test_override_skips_queued_rules_only_for_its_physical_file(
             predicate = _file_at_format(ctx.data, Predicate, path, pack_format)
             assert [pool["name"] for pool in loot.data["pools"]] == ["override"]
             assert [pool["name"] for pool in predicate.data["pools"]] == expected
+
+
+def test_language_files_merge_by_key_in_pack_order(monkeypatch):
+    first, second = ResourcePack(), ResourcePack()
+    first[Language]["minecraft:en_us"] = Language({"a": "first", "b": "first"})
+    second[Language]["minecraft:en_us"] = Language({"b": "second", "c": "second"})
+
+    with _weld_sources(monkeypatch, {"first": first, "second": second}) as ctx:
+        assert ctx.assets[Language]["minecraft:en_us"].data == {
+            "a": "first",
+            "b": "second",
+            "c": "second",
+        }