moonbit-agent-skills: Instructions file for Codex

Working in this repository (agent instructions)

This repository publishes two MoonBit product skills (skills/moonbit-language, skills/moonbit-toolchain) plus a repository-maintenance skill (skills/moonbit-agent-skills-maintainer). The core promise is: every claim is verified against a pinned MoonBit toolchain, every upstream release item has an explicit decision and a discoverable product route, every official language topic is routed or explicitly outside the product boundary, and all three contracts are machine-checked. When editing here, that promise is the thing you must not break.

Rules

1. Repository tooling is TypeScript. Repository-owned executable tooling, validators, generators, eval runners, and tests must be TypeScript run directly by Node.js 24. Do not add Python or shell implementations. Shell is allowed only for documented command examples and CI run blocks that invoke external tools.
2. No unverified content. A fact enters a skill only with a runnable proof: an mbt check block in a .mbt.md reference (executed by tooling/run_checked_docs.ts), a fixture under verification/fixtures/ (executed by tooling/run_fixtures.ts), or a command-manifest entry (executed by tooling/verify_commands.ts). If you cannot verify it, label it documented (with source URL) or leave it out.
3. One owner per fact. Language semantics belong to moonbit-language; project operation belongs to moonbit-toolchain. Cross-links are one line; never copy explanations across skills (tooling/check_duplication.ts enforces this).
4. Always follow the official latest version. The repository's single authoritative state is the exact current latest channel published at https://cli.moonbitlang.com/version.json, with both documentation surfaces pinned to the current moonbitlang/moonbit-docs main commit. Never hold the skills on an older compiler while waiting for a monthly website article. Never hand-edit moon, moonc, or moonrun version strings: re-pin with vp run snapshot-toolchain --date YYYY-MM-DD, regenerate both language and toolchain surfaces from current docs, re-run all verification, re-stamp fixtures (vp run run-fixtures --stamp --date ...), and update skill frontmatter to match. tooling/check_versions.ts checks internal consistency and tooling/verify_latest_upstream.ts makes CI fail as soon as any official latest source moves.
5. Proposals are not features. Anything sourced from moonbit-evolution or a release-note "planned" section must be labeled proposal, never shown as current syntax.
6. Skill descriptions are an interface. If you touch a frontmatter description, re-run the activation eval (evals/activation/run_activation.ts) or state explicitly that routing is unrevalidated.
7. Each installable skill has per-client activation surfaces — keep all of them in sync. A product skill ships three: the frontmatter description (open-spec catalog, all clients), user-invocable: false (Claude Code extension, hides the manual / entry), and agents/openai.yaml (Codex: display name, short description, default prompt, allow_implicit_invocation: true). When renaming a product skill, changing its scope/description, or adding a new product skill, update the Codex sidecar in the same change (tooling/validate_skills.ts enforces its presence).
8. Release articles are supplemental, not a version gate. For every MoonBit website release article that exists, use the internal moonbit-agent-skills-maintainer workflow to generate verification/releases/<release>/source.json from the pinned moonbitlang/website Markdown and close every source ID in coverage.json. Never hand-author or filter that inventory. A compiler or toolchain version may ship before its website article; in that case, update immediately from the official latest toolchain, full current language surface, upstream docs, and executable probes. tooling/verify_release_sources.ts checks published article inventories and tooling/check_release_coverage.ts blocks missing, duplicate, unsupported, or unproved decisions. The current coverage status means the newest published website article, not the product version. Every actionable decision in that article also needs a discoverability route whose reference path and exact search terms occur together on one line in the owning skill's Feature index.
9. Baseline completeness is separate from release completeness. verification/language-surface/source.json is mechanically generated from the pinned moonbitlang/moonbit-docs language tree by recursively following root and nested toctrees, pinned glob expansions, {include} pages, and H2-H4 headings. Every item includes a section-body fingerprint. Close every source ID exactly once in schema-v2 coverage.json as routed or out-of-scope, record the reviewed fingerprint, and put every routed official topic name in its target reference; never add pending, a hand-written page whitelist, or a broad route that claims content the reference does not contain. Official docs discover topics but do not verify semantics: every routed fact still needs checked documentation, a fixture, or an explicit Documented, not executed source. Run both language-surface checks for language-scope or documentation-pin changes.
10. Toolchain docs are a separate closed surface. verification/toolchain-surface/source.json mechanically inventories every Markdown document below next/toolchain/ at the pinned docs commit and fingerprints every H1-H4 section body. Close each source ID exactly once in coverage.json, recording its current fingerprint and either a product route or an explicit out-of-scope reason. A changed body, new heading, or new file must fail CI until reviewed. Official docs discover claims; executable command-manifest evidence or an explicit Documented, not executed label is still required before a fact enters the skill.
11. Deprecations prove both sides. Enable warnings that are off by default, add --deny-warn, prove the old form is caught, and prove the replacement passes under the same warning settings. Inspect upstream warning configuration before treating a green test as evidence that its syntax is current.
12. Repository-maintenance skills stay internal. Set metadata.internal: true so default listing, interactive selection, and installs without an explicit skill selector omit them. Do not use --skill "*" in public install instructions because an explicit selector opts into internal skills. The two product skills are the only public install surface.
13. Eval breadth comes before repetition. Count distinct user cases, not condition cells. A case may have at most two materially different user-facing angles, and each angle may run at most twice. Start every content case with one paired none versus ours run on Claude Code's sonnet alias; on this repository's verified local setup the assistant execution model must be deepseek-v4-pro, not deepseek-v4-flash. Repeat the DeepSeek pair only when ours fails or the pair is unstable. Use Kimi/K3 only when ours still fails on the second DeepSeek run, and report that fallback separately rather than pooling providers. Do not automatically cross-product angles, repetitions, and clients.
14. Every new or updated eval report has a simple user-facing result. Put it before the technical analysis and keep it even when a detailed report follows. Give every distinct task its own row named after the concrete work the agent had to complete, state the total number of distinct tasks, show percentages for the two conditions side by side, identify the observed model, and give the primary finding in one sentence. Name the comparison exactly (No skills, Historical skill, or the specific removed route), never just Baseline. Always show final task success, including ties and regressions; skill activation and reference reads are secondary evidence and must not replace it. Keep exact counts, internal task IDs, claim IDs, condition names, repetitions, cells, graders, token breakdowns, and statistical analysis in the technical section. Never call cells or repetitions tasks.
15. A skill directory change needs a new installed identity. Increment that skill's metadata.skill-version, set metadata.updated-date to the change date, and keep the public README status synchronized. Use SemVer: patch for corrections or metadata, minor for compatible new coverage, and major for an incompatible rename or scope change. validate-skills checks the metadata format and README projection.