| name | add-language-feature |
| description | Scaffold and verify a new native Rust FSL language feature while keeping syntax, lowering, symbolic/concrete semantics, docs, skill reference, tests, and changelog coupled. |
Add a native FSL language feature
The Rust workspace is authoritative. Before editing, classify the feature as surface-only lowering,
typed Kernel behavior, evaluator semantics, CLI/report behavior, or public Kernel contract.
Coupled checklist
rust/fsl-syntax: tokens, parsing, AST, and locations when syntax changes.rust/fsl-core: validation, types, name resolution, dialect lowering, and Kernel projection.rust/fsl-runtime: concrete Monitor/BFS behavior for evaluable semantics.rust/fsl-verifier: symbolic BMC/induction/refinement/liveness behavior.rust/fsl-tools or rust/fslc: report/command/envelope behavior when applicable.rust/fsl-wasm: only when Worker-visible behavior or shared envelopes require it.- Focused positive, negative, and boundary regression evidence.
docs/LANGUAGE.md, skills/fsl/reference.md, relevant docs/DESIGN-*.md, docs map, and
CHANGELOG.md [Unreleased].- Schemas/conformance vectors when the public Kernel contract changes.
Do not update src/fslc by default. Record the explicit compatibility or LSP contract before changing
the frozen Python reference.
Verification
- Iterate with the native CLI:
cargo run --manifest-path rust/Cargo.toml -p fslc-rust --bin fslc -- check <case> and the smallest relevant
verify command.
- Run focused syntax/core/runtime/verifier tests for the changed seam.
- Check symbolic/concrete/BFS agreement and a false-negative case.
- Run induction, mutation, vacuity, refinement, replay, or browser evidence when the contract calls for
it.
- Run formatting and Clippy, then wider workspace and compatibility gates in proportion to impact.
- Invoke the soundness and coupled-change reviewers before completion.
Never widen an allowlist, hollow a spec, or hand-edit a generated artifact to make the gate pass.
