# Contributor handoff — swc-project/swc

> Canonical page: https://codevetter.com/unpack/swc/agent-handoff

# Contributor handoff — swc-project/swc

Scanned commit 3c46139b86b27a7b3fefcf7b19ca07a63de9db0a (2026-10-02). Generated by codevetter codevetter 1.15.0 on 2026-10-02.

Source inspection; upstream code and tests were not executed.

Begin with the public API and the smallest corresponding binding/compiler/configuration files, then follow the exact input and output branches. Preserve pass ordering, source-context ownership, generated artifacts, and feature-dependent behavior. Tests and CI were inspected, not executed, and this brief provides bounded onboarding evidence rather than a whole-repository audit. The commands below describe repository verification expectations for separately authorized implementation work.
- For Node compiler changes, read index.ts, the relevant native operation module, Compiler::process_js_with_custom_pass, and Options/config construction together; raw text, raw AST, and context-bearing AST inputs take different paths. — [packages/core/src/index.ts#L295-326](https://github.com/swc-project/swc/blob/3c46139b86b27a7b3fefcf7b19ca07a63de9db0a/packages/core/src/index.ts#L295-L326) [bindings/binding_core_node/src/transform.rs#L42-76](https://github.com/swc-project/swc/blob/3c46139b86b27a7b3fefcf7b19ca07a63de9db0a/bindings/binding_core_node/src/transform.rs#L42-L76) [crates/swc/src/lib.rs#L953-978](https://github.com/swc-project/swc/blob/3c46139b86b27a7b3fefcf7b19ca07a63de9db0a/crates/swc/src/lib.rs#L953-L978) [crates/swc/src/lib.rs#L875-910](https://github.com/swc-project/swc/blob/3c46139b86b27a7b3fefcf7b19ca07a63de9db0a/crates/swc/src/lib.rs#L875-L910)
- Root conventions prefer documented English code, typed enums, small files, structured tracing, and borrowed strings when creating Atoms; inspect local source conventions before changing a pass or binding. — [AGENTS.md#L11-29](https://github.com/swc-project/swc/blob/3c46139b86b27a7b3fefcf7b19ca07a63de9db0a/AGENTS.md#L11-L29)
- Generated Rust visitors must be changed through code generation; cargo codegen is a configured alias, and helper generation supports --check against packages/helpers/esm and generated Rust helpers. — [crates/swc_ecma_visit/src/generated.rs#L1-3](https://github.com/swc-project/swc/blob/3c46139b86b27a7b3fefcf7b19ca07a63de9db0a/crates/swc_ecma_visit/src/generated.rs#L1-L3) [.cargo/config.toml#L4-8](https://github.com/swc-project/swc/blob/3c46139b86b27a7b3fefcf7b19ca07a63de9db0a/.cargo/config.toml#L4-L8) [tools/generate-code/src/main.rs#L70-80](https://github.com/swc-project/swc/blob/3c46139b86b27a7b3fefcf7b19ca07a63de9db0a/tools/generate-code/src/main.rs#L70-L80)
- Use existing fixture suites: swc and swc_ecma_parser document their roots and UPDATE=1 commands, followed by the same crate tests without UPDATE; root instructions prohibit removing or modifying existing tests when fixing them. — [crates/swc/AGENTS.md#L1-5](https://github.com/swc-project/swc/blob/3c46139b86b27a7b3fefcf7b19ca07a63de9db0a/crates/swc/AGENTS.md#L1-L5) [crates/swc_ecma_parser/AGENTS.md#L1-5](https://github.com/swc-project/swc/blob/3c46139b86b27a7b3fefcf7b19ca07a63de9db0a/crates/swc_ecma_parser/AGENTS.md#L1-L5) [AGENTS.md#L44-58](https://github.com/swc-project/swc/blob/3c46139b86b27a7b3fefcf7b19ca07a63de9db0a/AGENTS.md#L44-L58)
- Tests and CI here were inspected, not executed; authorized implementation verification normally initializes submodules, runs touched-crate cargo tests, cargo fmt/clippy, and core build:dev plus pnpm test when Node integration changes. — [AGENTS.md#L44-49](https://github.com/swc-project/swc/blob/3c46139b86b27a7b3fefcf7b19ca07a63de9db0a/AGENTS.md#L44-L49) [AGENTS.md#L60-73](https://github.com/swc-project/swc/blob/3c46139b86b27a7b3fefcf7b19ca07a63de9db0a/AGENTS.md#L60-L73) [packages/core/package.json#L59-61](https://github.com/swc-project/swc/blob/3c46139b86b27a7b3fefcf7b19ca07a63de9db0a/packages/core/package.json#L59-L61) [.github/workflows/CI.yml#L557-565](https://github.com/swc-project/swc/blob/3c46139b86b27a7b3fefcf7b19ca07a63de9db0a/.github/workflows/CI.yml#L557-L565)
- Resolve toolchain drift before running checks: README states MSRV 1.73, agent rules prohibit nightly-only production features, .cargo/config.toml contains -Zshare-generics, and parser conformance tests use unstable libtest. — [README.md#L35-48](https://github.com/swc-project/swc/blob/3c46139b86b27a7b3fefcf7b19ca07a63de9db0a/README.md#L35-L48) [AGENTS.md#L75-78](https://github.com/swc-project/swc/blob/3c46139b86b27a7b3fefcf7b19ca07a63de9db0a/AGENTS.md#L75-L78) [.cargo/config.toml#L10-22](https://github.com/swc-project/swc/blob/3c46139b86b27a7b3fefcf7b19ca07a63de9db0a/.cargo/config.toml#L10-L22) [crates/swc_ecma_parser/tests/test262.rs#L1-18](https://github.com/swc-project/swc/blob/3c46139b86b27a7b3fefcf7b19ca07a63de9db0a/crates/swc_ecma_parser/tests/test262.rs#L1-L18)
- For carrier changes, preserve final stripped raw bytes, target allowlisting, private payload/integrity sections, and verification before loading; documented checks include native Node contracts and cargo tests for swc_native_addon, its packer, and binding_native_addon. — [crates/swc_native_addon/README.md#L11-50](https://github.com/swc-project/swc/blob/3c46139b86b27a7b3fefcf7b19ca07a63de9db0a/crates/swc_native_addon/README.md#L11-L50) [docs/native-addon-carriers.md#L161-177](https://github.com/swc-project/swc/blob/3c46139b86b27a7b3fefcf7b19ca07a63de9db0a/docs/native-addon-carriers.md#L161-L177)
- Check runtime parity explicitly: native defaults enable swc_v1/plugins, @swc/wasm async interfaces do not perform actual async work, WASM plugin transforms may be skipped, and CLI watch requires an output file or directory. — [bindings/binding_core_node/Cargo.toml#L15-23](https://github.com/swc-project/swc/blob/3c46139b86b27a7b3fefcf7b19ca07a63de9db0a/bindings/binding_core_node/Cargo.toml#L15-L23) [bindings/binding_core_wasm/src/lib.rs#L27-35](https://github.com/swc-project/swc/blob/3c46139b86b27a7b3fefcf7b19ca07a63de9db0a/bindings/binding_core_wasm/src/lib.rs#L27-L35) [crates/swc/src/config/mod.rs#L881-900](https://github.com/swc-project/swc/blob/3c46139b86b27a7b3fefcf7b19ca07a63de9db0a/crates/swc/src/config/mod.rs#L881-L900) [crates/swc_cli_impl/src/commands/compile.rs#L1201-1210](https://github.com/swc-project/swc/blob/3c46139b86b27a7b3fefcf7b19ca07a63de9db0a/crates/swc_cli_impl/src/commands/compile.rs#L1201-L1210)

Every claim links to its cited files at the pinned commit. Citations identify source evidence; they do not establish runtime correctness. Independent CodeVetter scan — not reviewed by upstream maintainers.

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