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opal: Skill for Claude Code

.claude/skills/codegen-sync/SKILL.md

codegen-sync is a skill for Claude Code from matteing/opal. It costs 50 tokens per session (360 once invoked), scanned A, original, MIT.

A check that keeps TypeScript client types synchronized with protocol definitions written in Elixir. Code generation automatically creates the TypeScript files from those Elixir definitions.

In plain words
What is it for?
Regenerating and checking SDK types after changing Elixir structs, protocol messages, RPC types, or tool schemas, then reviewing the generated changes.
Why use it?
It prevents the TypeScript client and the Elixir side from describing different message or data shapes, which can cause build or CI failures.

Skill for Claude Code

Written for Claude Code: installed under .claude/.

This is matteing/opal's own configuration. It tells Claude Code how to work on opal itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything opal configures →

not rated 62repo 2mo ago A scan SkillSpector: pass 50 tokens original MIT
View source ↗ matteing/opal
Reuse

Borrowing it

Nothing to install: this file belongs to matteing/opal. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/matteing/opal/main/.claude/skills/codegen-sync/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/matteing/opal

Made for: Claude Code.

Wrote this? Show the measurements

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Per session 50 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 360 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 5.1 $0.00050 $0.00360
Opus 5.5 $0.00020 $0.00144
Sonnet 5.5 $0.00010 $0.00072
Haiku 4.5 $0.00005 $0.00036

Measured 2mo ago against content hash ee5b36c253df, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

codegen-sync 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 2mo ago.

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.

.claude/skills/codegen-sync/SKILL.md · 39 lines

What it actually says

Codegen Sync Skill

This project uses code generation to keep TypeScript SDK types in sync with Elixir protocol definitions. When Elixir types change, the TypeScript side must be regenerated.

When to act

  • After modifying any Elixir structs, message types, or RPC definitions in lib/opal/.
  • After adding or changing tool schemas in lib/opal/tool/.
  • When CI fails with a codegen drift error.
  • When the user asks to sync or regenerate types.

Commands

# Run codegen (Elixir -> TypeScript)
mix run scripts/codegen_ts.exs

# Verify codegen is up to date (what CI runs)
mix run scripts/codegen_ts.exs --check

Workflow

  1. After modifying Elixir protocol types, run mix run scripts/codegen_ts.exs.
  2. Review the generated diff in cli/src/sdk/ to verify correctness.
  3. Include the regenerated files in the same commit as the Elixir changes.

Rules

  1. Never hand-edit generated files. Always regenerate from the Elixir source.
  2. If codegen output looks wrong, fix the Elixir definitions or the codegen script (scripts/codegen_ts.exs), not the output.
  3. Always commit codegen output alongside the source changes — never in a separate commit.
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. 2mo ago First seen · 39 lines · 50 tokens per session scan A ee5b36c253df

Subscribe to this mod's changes

codegen-sync is a skill published in the GitHub repository matteing/opal (62 stars, last pushed 2mo ago), licensed MIT. It adds 50 tokens to every session and 360 once invoked, about $0.0002 per session on Opus 5.5. 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.

LLMLanguagesTypeScriptagentsaiai-agentsclielixir
Related

codegen-sync compared with skills from other repositories

codegen-sync next to 6 skills from other repositories
ModTypeStarsLast pushLicenceScanTokensWorks with
codegen-syncmatteing/opalSkill622mo agoMITA50Claude Code
typescriptgenkit-ai/genkitSkill6.6kyesterdayApache-2.0A20Claude Code, Codex
buncode-yeongyu/senpiSkill511yesterdayMITA237Claude Code, Codex
js-conventionsmetarhia/metaskillsSkill607d agoMITA120Claude Code, Codex
error-handlingmetarhia/metaskillsSkill607d agoMITA70Claude Code, Codex
typescript-developmentsammcj/agentic-codingSkill1682d agoApache-2.0A17Claude Code, Codex
js-gofmetarhia/metaskillsSkill607d agoMITA0Claude Code, Codex