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.
curl -O https://raw.githubusercontent.com/ymm-oss/fsl/main/AGENTS.mdgit clone --depth 1 https://github.com/ymm-oss/fslWrote 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.
[](https://agentmods.dev/instructions/ymm-oss/fsl/agents-md)<a href="https://agentmods.dev/instructions/ymm-oss/fsl/agents-md"><img src="https://agentmods.dev/badge/instructions/ymm-oss/fsl/agents-md/github.svg" alt="Measured on agentmods" height="20"></a>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.
<a href="https://agentmods.dev/instructions/ymm-oss/fsl/agents-md"><img src="https://agentmods.dev/badge/instructions/ymm-oss/fsl/agents-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.01685 | $0.01685 |
| Opus 5.5 | $0.00674 | $0.00674 |
| Sonnet 5.5 | $0.00337 | $0.00337 |
| Haiku 4.5 | $0.00169 | $0.00169 |
Grade A, and why
fsl AGENTS.md 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 1mo 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.
How it starts
The opening of the file, as written. The whole thing — 135 lines — stays where its author put it; the contents beside it link to each section on GitHub.
FSL repository contract
Authority and scope
fslc is the verifier for FSL. The native Rust workspace under rust/ is the
authoritative implementation and distribution surface, including fslc-lsp.
src/fslc/ is a frozen Python compatibility reference; add product behavior
there only when a compatibility change explicitly requires it.
Resolve evidence in this order:
docs/manual/LANGUAGE.md, accepteddocs/design/DESIGN-*.md, tests, and CI contracts.- Native Rust implementation and public Kernel/JSON contracts.
- Observable frozen-Python behavior where parity applies.
- Proposals, task notes, conversations, and agent memory.
Stop on a conflict instead of silently choosing a source. Keep durable decisions in accepted contracts or executable tests, not temporary reports.
Work discipline
- Start with
git status --short, named paths/issues/symbols, andrg. Read the smallest useful ranges; widen only when evidence requires it. - Preserve unrelated user changes. Use a dedicated branch/worktree for non-trivial work. Do not inspect secrets, unrelated user data, generated trees, vendor/build output, snapshots, or full logs without a task-specific reason.
- Make the smallest coherent diff. Do not perform opportunistic refactors, dependency upgrades, formatting sweeps, or unrelated cleanup.
skills/holds distributable canonical skills; repository-internal workflow skills go in.claude/skillsor.codex/skills..claude/skills/fsl*and.agents/skills/fsl*stay symlinks to the distributable ones.- For bounded implementation, bug-fix, test, or refactor work, use
$focused-change. It routes soundness-sensitive FSL work to the complete repository contract only when needed. - Use
$task-startbefore substantial Codex work and$checkpointbefore compaction, handoff, independent review, or ending the task. - Delegate broad read-heavy exploration to
evidence_explorerand independent final review toindependent_reviewer. Keep iterative implementation in the main thread unless writes can be isolated.
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.
- 1mo ago Changed · +4 tokens per session d24850548e1e
- 1mo ago Changed · -95 lines · -2,026 tokens per session 69f688320348
- 1mo ago Changed · +13 lines · +293 tokens per session 84934a139759
- 1mo ago Changed · +6 lines · +127 tokens per session 130105147fa3
- 2mo ago First seen · 211 lines · 3,287 tokens per session scan A 032d485ce147
fsl AGENTS.md is an instructions file published in the GitHub repository ymm-oss/fsl (35 stars, last pushed today), licensed Apache-2.0. It adds 1,685 tokens to every session, about $0.0067 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.
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