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/skills/checkpoint/SKILL.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/skills/ymm-oss/fsl/checkpoint)<a href="https://agentmods.dev/skills/ymm-oss/fsl/checkpoint"><img src="https://agentmods.dev/badge/skills/ymm-oss/fsl/checkpoint/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/skills/ymm-oss/fsl/checkpoint"><img src="https://agentmods.dev/badge/skills/ymm-oss/fsl/checkpoint.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 | $0.00027 | $0.00267 |
| Opus 5.5 | $0.00011 | $0.00107 |
| Sonnet 5.5 | $0.00005 | $0.00053 |
| Haiku 4.5 | $0.00003 | $0.00027 |
Grade A, and why
checkpoint 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.
What it actually says
Checkpoint an FSL task
Use this skill at a meaningful boundary, before /compact, before /clear, and before handing work to another agent or person.
- Re-read
tasks/active.md,git status --short, and the relevant diff. - Verify changed files and observed command output instead of relying on conversation history.
- Preserve the goal, authority surface, current state, decisions, invariants, evidence, changed files, failed approaches, verification results, discovered follow-ups, remaining work, and one concrete next action.
- Remove narration, raw logs, superseded hypotheses, and machine-specific absolute paths.
- Do not claim a test or check passed unless its output was observed in this worktree.
- Reconcile every discovered soundness defect: it must be fixed in scope, linked to an existing or
newly created issue, or marked
authorization requiredwith an explicit user request. Do not mark the task complete while such a finding exists only in chat, review output, or agent memory.
The result must let a fresh Codex session continue safely without reconstructing the conversation.
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 2mo ago First seen · 22 lines · 27 tokens per session scan A a7b32af416d6
checkpoint is a skill published in the GitHub repository ymm-oss/fsl (35 stars, last pushed today), licensed Apache-2.0. It adds 27 tokens to every session and 267 once invoked, about $0.0001 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.
Other skills, from other repositories
mem0-test-integration
Verify a Mem0 integration produced by /mem0-integrate. Runs in the same workspace on the same branch (loose coupling) — installs dependencies, runs the repo's native test suite, then exercises a real end-to-end smoke flow against the user's API key. Produces a scorecard. TRIGGER when: user has just run /mem0-integrate…
mem0-integrate
Integrate Mem0 into an existing repository using a goal-driven, TDD pipeline. Detects the repo's language automatically and asks the user to pick between Mem0 Platform (managed) and Mem0 Open Source (self-hosted). Writes failing tests before any implementation. Produces a local feature branch plus .mem0-integration/…
prep-repo
Prepare an existing project for GitHub or public release with scope-appropriate checks for sensitive data, documentation, installation, tests and release artifacts. Separate release blockers from polish, preserve existing authorization, and verify the published result only when publishing is requested. Not for…
pypi-release
This skill should be used when releasing tunacode-cli to PyPI. It keeps the existing local release checks, then hands the actual PyPI upload to a GitHub Actions workflow that uses the repository's PYPIAPITOKEN secret.
migrate-rename
Evolutionary file renaming with wrapper files, plus the terse MOVED-stub standard for whole folder/file moves. Enables renames without hard breaks — references are organically updated through usage.
reissverschluss-merge
Reißverschluss-Verfahren (englisch: zipper merge) für sehr konfliktreiche Merges: Wenn zwei divergente Branches oder ein PR und sein Zielbranch BEIDE wertvolle, unvereinbar erscheinende Änderungen tragen, wird nicht pauschal eine Seite gewählt, sondern Abschnitt für Abschnitt verglichen, per Entscheidungstabelle…