Precedence and effective settings
Defaults are Solidity, optimizer enabled with 200 runs, `via_ir = false`, `warnings_as_errors = false`, and output selection `default`. Named `source`, `language`, and `options` override positional values; `compiler_version` overrides `compiler`; `output` overrides `output_selection`.
- Omitting `append_cbor` does not send false.
- The current service merges `options.settings` after named settings, so it can change effective optimizer, EVM, IR, metadata, or output settings.
- The current service replaces `<stdin>` with `options.sources` when supplied.
- Solidity compiler selection is forwarded. Vyper selection is not; inspect returned `compiler_version`.