checkpoint

<skill id="checkpoint">

<purpose>

The small resumable manifest. A handoff transfers a whole session; a checkpoint records

bounded progress INSIDE a long-running task so work can continue after a context reset

with a fresh, minimal context instead of an inherited transcript.

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.

</purpose>

<flow>

1. Gather provenance:

   git branch --show-current && git rev-parse HEAD && git status --short

1. Write _meta/checkpoints/{task}-{timestamp}.json per

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).

1. Validate — MANDATORY:

   "${CLAUDE_PLUGIN_ROOT:-.}/orchestration/manifest/kernel-manifest" validate _meta/checkpoints/{file}.json

1. 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.

</flow>

<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>

</skill>