compiler-port

A workflow for moving a compiler pass from TypeScript to Rust. A compiler pass is one processing stage that transforms or analyzes program code.

In plain words
What is it for?
Finding a pass in the React Compiler pipeline, locating its TypeScript implementation, mapping it to the correct Rust crate, implementing the port, and fixing test failures.
Why use it?
It verifies that the requested pass exists and is supported before implementation begins. It also gathers the relevant source and Rust-crate context, then uses testing and review to catch porting mistakes.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/react/react/compiler-port
Any agent
npx skills add react/react --skill compiler-port
Clone the repo
git clone --depth 1 https://github.com/react/react

Made for: Claude Code, Codex.

Per session 35 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,147 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00035 $0.01147
Opus 5 $0.00017 $0.00574
Sonnet 5 $0.00007 $0.00229
Haiku 4.5 $0.00003 $0.00115

Measured yesterday against content hash 15c953f2bde9, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

compiler-port scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

compiler/.claude/skills/compiler-port/SKILL.md · 102 lines

How it starts

The opening of the file, as written. The whole thing — 102 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Port Compiler Pass

Port a compiler pass from TypeScript to Rust end-to-end.

Arguments:

  • $ARGUMENTS: Pass name exactly as it appears in Pipeline.ts log entries (e.g., PruneMaybeThrows, SSA, ConstantPropagation)

Step 0: Validate pass name

  1. Read compiler/packages/babel-plugin-react-compiler/src/Entrypoint/Pipeline.ts
  2. Search for name: '$ARGUMENTS' in log entries
  3. If not found, list all available pass names from the log({...name: '...'}) calls and stop
  4. Check the kind field of the matching log entry:
    • If kind: 'ast', report that test-rust-port only supports hir and reactive kind passes currently and stop
    • If kind: 'hir' or kind: 'reactive', proceed

Step 1: Determine TS source files and Rust crate

  1. Follow the import in Pipeline.ts to find the actual TypeScript file(s) for the pass
  2. Map the TS folder to a Rust crate using this mapping:
TypeScript Path Rust Crate
src/HIR/ (excluding BuildHIR.ts, HIRBuilder.ts) react_compiler_hir
src/HIR/BuildHIR.ts, src/HIR/HIRBuilder.ts react_compiler_lowering
src/Babel/, src/Entrypoint/ react_compiler
src/CompilerError.ts react_compiler_diagnostics
src/ReactiveScopes/ react_compiler_reactive_scopes
src/<Name>/ react_compiler_<name> (1:1, e.g., src/Optimization/ -> react_compiler_optimization)
  1. Check if the pass is already ported:
    • Check if the corresponding Rust file exists in the target crate
    • Check if compiler/crates/react_compiler/src/entrypoint/pipeline.rs already calls it
    • If both are true, report the pass is already ported and stop

Step 2: Gather context

Read the following files (all reads happen in main context):

  1. Architecture guide: compiler/docs/rust-port/rust-port-architecture.md
  2. Pass documentation: Check compiler/packages/babel-plugin-react-compiler/docs/passes/ for docs about this pass
  3. TypeScript source: All TypeScript source files for the pass + any helpers imported from the same folder
  4. Rust pipeline: compiler/crates/react_compiler/src/entrypoint/pipeline.rs
  5. Rust HIR types: Key type files in compiler/crates/react_compiler_hir/src/ (especially hir.rs, environment.rs)
  6. Rust reactive types: For reactive passes, also read compiler/crates/react_compiler_hir/src/reactive_function.rs
  7. Target crate: If the target crate already exists, read its Cargo.toml, src/lib.rs, and existing files to understand the current structure

Read the full file on GitHub · 102 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 102 lines · 35 tokens per session scan A 15c953f2bde9

Subscribe to this mod's changes

compiler-port is a skill published in the GitHub repository react/react (248,328 stars, last pushed 4d ago), licensed MIT. It adds 35 tokens to every session and 1,147 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.