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.
npx agentmods add skills/ariaxhan/kernel-claude/checkpointnpx skills add ariaxhan/kernel-claude --skill checkpointgit clone --depth 1 https://github.com/ariaxhan/kernel-claudeWhat 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 | $0.00034 | $0.00689 |
| Opus 5 | $0.00017 | $0.00345 |
| Sonnet 5 | $0.00007 | $0.00138 |
| Haiku 4.5 | $0.00003 | $0.00069 |
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 3d 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
When to fire (EXP-L21: attention efficiency decays to ~11% late-session; a reset from a checkpoint restores the flat ~50-70k load-bearing line):
- a long task crosses a natural boundary (a commit lands, a phase completes)
- context is about to compact, or the session is degrading (anchor-drift, I0.13)
- the manifest's execution.checkpoints list says so
Checkpoint vs handoff: same task + same session continuation → checkpoint. Ending the session / transferring to a future session with decisions and policy → handoff.
-
Write
_meta/checkpoints/{task}-{timestamp}.jsonper schemas/kernel.checkpoint.v1.schema.json:- task: goal + handoff_ref/contract_ref if they exist
- steps_completed: each with EVIDENCE (commit sha, test output, command result), never intent. Receipts describe intent; files describe reality.
- current_outputs: files produced so far
- provenance.dirty_tree_sha256: when dirty, sha256 of
git diff --binary HEAD - pending_steps: what remains, in order
- resume: position (exact place in the work), entrypoint (skill to re-enter), next_operation (the LITERAL first action — "retarget tests/run-tests.sh lines ~1250 registration tests", not "continue the migration")
- context (optional): required selectors + budget if the resume should be bounded
Quote every sha/commit string (all-digit shas parse as integers and fail validation).
-
Validate — MANDATORY:
"${CLAUDE_PLUGIN_ROOT:-.}/orchestration/manifest/kernel-manifest" validate _meta/checkpoints/{file}.json -
Record:
agentdb write-end '{"skill":"checkpoint","saved_to":"_meta/checkpoints/{file}.json","position":"..."}'
Resume path: /kernel:ingest discovers the newest manifest automatically
(kernel-manifest latest — checkpoints and handoffs share discovery), or accepts an
explicit path.
<hard_stops>
- steps_completed without evidence → not a checkpoint, a hope. Add evidence or move the step to pending_steps.
- unvalidated json → does not exist. Validate before reporting done. </hard_stops>
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.
- 3d ago First seen · 75 lines · 34 tokens per session scan A ac40162296b1
checkpoint is a skill published in the GitHub repository ariaxhan/kernel-claude (12 stars, last pushed 3d ago), licensed MIT. It adds 34 tokens to every session and 689 once invoked, about $0.0002 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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