checkpoint

A handoff tool for recording the current state of a long coding session in a STATE.md file so work can continue in a fresh session.

In plain words
What is it for?
Use it before clearing or changing sessions, when a task has become lengthy, or when the user asks for a checkpoint.
Why use it?
It preserves the decisions, progress, and next steps needed to resume without relying on a long conversation history.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/tradebaas/groundwork/checkpoint
Any agent
npx skills add Tradebaas/Groundwork --skill checkpoint
Clone the repo
git clone --depth 1 https://github.com/Tradebaas/Groundwork

Made for: Claude Code, Codex.

Per session 110 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,444 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00110 $0.01444
Opus 5 $0.00055 $0.00722
Sonnet 5 $0.00022 $0.00289
Haiku 4.5 $0.00011 $0.00144

Measured 2d ago against content hash 4b1794248620, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

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 2d 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.

.agents/skills/checkpoint/SKILL.md · 93 lines

How it starts

The opening of the file, as written. The whole thing — 93 lines — stays where its author put it; the contents beside it link to each section on GitHub.

checkpoint: reset the context, keep the thread

Long sessions get expensive: every turn re-sends the whole history. A checkpoint writes down just enough for a fresh session to pick up exactly where this one stopped, so you can clear the context (/clear in Claude Code; every tool has its own fresh-session command) and continue at a fraction of the token cost. The fresh session already reads STATE.md first (AGENTS.md session protocol, step 1), so the handoff has one home: STATE.md. Do not create a second document.

This is the light sibling of handover. handover transfers the project to a stranger at a milestone and runs a full audit. checkpoint just parks the current train of work so you can resume it yourself in a clean session. If the work is actually being handed to someone else or a milestone is closing, use handover instead.

When to fire

  • Roughly 15% of the context window is spent in this session, or the session is long and every turn feels heavy. Fire before the harness auto-summarizes, so the handoff is yours and accurate, not a lossy machine summary.
  • The user asks for it, or is about to clear the context.
  • Do not fire for a two-message session: there is nothing to save and the checkpoint itself costs tokens.

The 15% mark is the activation point: propose the checkpoint there by default. Stretching past it to at most ~40% is the user's call, and only when finishing the current unit of work first is clearly better than parking it. Past ~40%, always checkpoint: advise it urgently, before quality degrades and the handoff turns lossy. Suggest, do not force, and never clear the context on the user's behalf. A tool that supports lifecycle hooks can surface this reminder automatically once context crosses the threshold; such a hook only ever suggests.

The method (do it from context you already have; do not re-read the repo)

The whole point is to spend few tokens. Write from what is already in this conversation. Only open a file if a fact is genuinely missing.

Read the full file on GitHub · 93 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. 2d ago First seen · 93 lines · 0 tokens per session scan A 4b1794248620

Subscribe to this mod's changes

checkpoint is a skill published in the GitHub repository Tradebaas/Groundwork (2 stars, last pushed 6d ago), licensed MIT. It adds 110 tokens to every session and 1,444 once invoked, about $0.0006 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 2026-08-31.

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