fsl: Agent for Claude Code

.claude/agents/fsl-coupled-change-reviewer.md

fsl-coupled-change-reviewer is an agent for Claude Code from ymm-oss/fsl. It costs 58 tokens per session (547 once invoked), scanned A, original, Apache-2.0.

A read-only review agent for Rust FSL changes and their related files. It checks whether code changes are matched by the required tests, documentation, skills, generated files, and changelog entries.

In plain words
What is it for?
Use it after changing FSL syntax, lowering, semantics, the verifier, runtime, CLI, worker, kernel contracts, solver behavior, or corpus specifications.
Why use it?
Changes to a language, runtime, command-line tool, or public interface can affect many parts of a project. This review helps identify dependent work that was missed.

Agent for Claude Code

Written for Claude Code: installed under .claude/. Also seen: model in frontmatter.

This is ymm-oss/fsl's own configuration. It tells Claude Code how to work on fsl 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 fsl configures →

View source ↗ ymm-oss/fsl
Reuse

Borrowing it

Nothing to install: this file belongs to ymm-oss/fsl. 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/ymm-oss/fsl/main/.claude/agents/fsl-coupled-change-reviewer.md
Clone the repo
git clone --depth 1 https://github.com/ymm-oss/fsl

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

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README.md
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Your own site
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Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

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Your own site · 80×15
<a href="https://agentmods.dev/agents/ymm-oss/fsl/fsl-coupled-change-reviewer"><img src="https://agentmods.dev/badge/agents/ymm-oss/fsl/fsl-coupled-change-reviewer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 58 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 547 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.
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 $0.00058 $0.00547
Opus 5 $0.00029 $0.00273
Sonnet 5 $0.00012 $0.00109
Haiku 4.5 $0.00006 $0.00055

Measured 5d ago against content hash 8bc84d677a7b, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

fsl-coupled-change-reviewer 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 5d 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/agents/fsl-coupled-change-reviewer.md · 37 lines

How it starts

The opening of the file, as written. The whole thing — 37 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Audit the current diff against the rule that an FSL contract change moves all dependent artifacts together. Inspect staged and unstaged changes; do not modify them.

Coupling map

  1. Syntax or surface grammar in rust/fsl-syntax requires the corresponding lowering/model work, regression cases, docs/LANGUAGE.md, docs/LANGUAGE.ja.md, skills/fsl/references/, an accepted docs/DESIGN-*.md, and a new changelog.d/<id>-<slug>.<category>.md fragment (see changelog.d/README.md) -- not a direct CHANGELOG.md edit, which is aggregated from fragments only at release time. A new declaration, binder, or reference form additionally requires rust/fsl-lsp/src/index.rs and a targeted role/scope test.
  2. Typed semantics in rust/fsl-core or symbolic behavior in rust/fsl-verifier requires matching rust/fsl-runtime behavior when concretely evaluable, plus agreement/false-negative evidence.
  3. Solver changes require the relevant backend tests and preservation of runtime solver independence.
  4. CLI/Worker changes require native/Worker envelope, exit-code, raw-output, and replay contracts.
  5. Public Kernel changes require schemas, exporters/consumers, conformance vectors, agreement tests, docs/DESIGN-kernel-contract.md, language/reference docs, and a changelog.d/<id>-<slug>.<category>.md fragment (see changelog.d/README.md) -- not a direct CHANGELOG.md edit.
  6. Changes under specs/ or examples/ require native check/verify and non-vacuity evidence. Generated compatibility artifacts may change only through their owning generator.
  7. New source files require the repository SPDX header.
  8. The frozen Python implementation should remain untouched unless the diff states a compatibility or LSP reason and includes focused evidence.

Output

Return a concise checklist. Mark each applicable rule satisfied or MISSING, naming exact files or tests required. Note unrelated bundled changes. End with coupled-change complete or N gaps.

Read the full file on GitHub · 37 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. 5d ago Changed · +2 lines 8bc84d677a7b
  2. 10d ago First seen · 35 lines · 58 tokens per session scan A 60236103af78

Subscribe to this mod's changes

fsl-coupled-change-reviewer is an agent published in the GitHub repository ymm-oss/fsl (23 stars, last pushed yesterday), licensed Apache-2.0. It adds 58 tokens to every session and 547 once invoked, about $0.0003 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.

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