## Summary `GrammarProcessor.__init__` declared the keyword-only `checker` parameter before the positional parameters (`arch`, `target_arch`, `platforms`) that `BaseProcessor.__init__` accepts positionally. That makes the override incompatible with the base class signature (Liskov Substitution Principle) and fails the `ty` type check run by `make lint`: ``` error[invalid-method-override]: Invalid override of method `__init__` --> craft_grammar/_processor.py:61:9 info: parameter `checker` is keyword-only but must also accept positional arguments ``` This fix moves `checker` after the shared positional parameters so the override matches `BaseProcessor.__init__`. The public keyword-only calling convention is unchanged, so there is no behavioural or API break. Pre-existing failure on `main`, unrelated to the Starbase sync; split out so the Starbase merge diff stays reviewable. ## Test plan - [x] `uv run pytest tests/unit` passes - [x] `uv tool run ty check --python .venv craft_grammar tests` passes - [x] pre-commit hooks (ruff check, ruff format) pass