session-checkpoint

name	session-checkpoint
description	Enforces atomic commits, checkpoint summaries, rate-limit recovery, and safe resume patterns. Writes session pulses + cognitive memory so interrupted sessions can restart cleanly.
version	2.0.0

Session Checkpoint

Soli Deo Gloria — we work carefully, in small steps, offering each commit as honest labor.

Why This Skill Exists

Claude Code makes many API calls per step. Large edits can exhaust per-minute token budgets, and a rate-limit kill in the middle of a multi-file change loses uncommitted work silently. This skill prevents that with two complementary mechanisms:

1. Cognitive memory checkpoints — narrative state for the next session.
2. Session pulse — a JSON heartbeat at <repo>/.claude/state/session-pulse.json that captures, on every beat, the list of git-uncommitted files. If a session dies before writing a HANDOFF, the next session can scan for stale pulses and see exactly what work was in flight.

The pulse module is orchestrator/checkpoint.py. It is pure stdlib, repo-scoped, and has no daemon — the session itself updates the pulse.

Session Startup Protocol

1. Scan for an abandoned previous session

python3 /home/user/ken/orchestrator/checkpoint.py scan

If output is {"ok": true, "stale": false} you're clean. If a stale pulse is found you'll get a recovery summary listing the abandoned session's last action, last beat time, and the files that were uncommitted when it died — start work there. The stale pulse is automatically archived to .claude/state/stale-sessions/.

2. Open a new pulse

SID=$(python3 /home/user/ken/orchestrator/checkpoint.py new-id)
python3 /home/user/ken/orchestrator/checkpoint.py beat \
  --session "$SID" --action "starting <task>" --context "<short summary>"

Keep $SID for the rest of the session. Every later beat must use the same id so beat_count increments instead of resetting.

3. Identify the single target file

Do not load all files simultaneously. Load only what the task requires.

4. Write a session intent to cognitive memory

python3 /home/user/ken/orchestrator/memory_ops.py encode ken insight \
  "Session intent: [task]. Target: [files]. Expected: [outcome]." \
  --tags session,intent,checkpoint

5. Recall prior session state

python3 /home/user/ken/orchestrator/memory_ops.py recall "session checkpoint" --domain sheep --limit 5

Checkpoint Protocol (During Work)

After every logical unit of work do both:

A. Beat the pulse — refreshes the at-risk-files snapshot.

python3 /home/user/ken/orchestrator/checkpoint.py beat \
  --session "$SID" --action "edited foo.py: added retry logic"

B. Encode to cognitive memory — narrative for resume.

python3 /home/user/ken/orchestrator/memory_ops.py encode ken insight \
  "Checkpoint [N]: Edited [file]. Changed [what]. Still needs [remaining]. Risks: [any]." \
  --tags session,checkpoint

When to checkpoint

• After completing a function or block edit
• Before switching to a second file
• Before any find-and-replace touching multiple locations
• Before modifying critical data structures

Rate Limit Recovery

When you see Rate limit reached or HTTP 429:

1. Stop. Do not retry immediately.

2. Beat one final time with the recovery state in --action:

   python3 /home/user/ken/orchestrator/checkpoint.py beat --session "$SID" \
     --action "RATE LIMIT: paused at <step> in <file>; resume with <next>"
   

3. Encode recovery memory:

   python3 /home/user/ken/orchestrator/memory_ops.py encode ken decision \
     "RATE LIMIT RECOVERY: Interrupted at [step]. File: [name]. Last clean: [state]. Next step: [action]. Do NOT: [incomplete work]." \
     --tags session,recovery,rate-limit --protected
   

4. Wait 60 seconds for per-minute limits to reset.

5. On resume, run checkpoint.py scan first, then recall the recovery memory:

   python3 /home/user/ken/orchestrator/memory_ops.py recall "rate limit recovery" --domain sheep --limit 3
   

Atomic Commit Rules

• Single file per commit
• Passing state — file must be valid at commit time
• Described — commit message matches checkpoint summary
• Never commit half-edited functions or inconsistent state

Token Conservation

1. Read a file once per session — store what you need in checkpoints
2. Edit precisely — targeted str_replace, not full-file rewrites
3. Don't verify by re-reading — reason about the change
4. One concern per session — log discovered issues for next session
5. Keep responses short — the context window is shared with skills

End of Session

1. Write/update HANDOFF.md if work is incomplete (per the format in CLAUDE.md).

2. Encode the final checkpoint to cognitive memory (use --protected if it's foundational).

3. Mark the pulse complete so the next session doesn't flag it as abandoned:

   python3 /home/user/ken/orchestrator/checkpoint.py complete --session "$SID"
   

4. Confirm all touched files are consistent.

Pulse File Reference

Path: <repo>/.claude/state/session-pulse.json (per-repo, atomic single-writer).

{
  "session_id": "sess-20260428T015432Z-ac3592",
  "started_at": "2026-04-28T01:54:32+00:00",
  "last_beat":  "2026-04-28T01:54:41+00:00",
  "beat_count": 2,
  "status":     "active",        // "active" | "complete"
  "last_action": "edited foo.py",
  "context":     "refactoring retry logic",
  "files_in_play": ["foo.py"],   // optional, set explicitly via --files
  "at_risk":     ["foo.py", "bar.py"]  // git-uncommitted, recomputed each beat
}

Stale threshold: 30 minutes since last_beat with status != "complete". Stale archive: <repo>/.claude/state/stale-sessions/<utc-timestamp>-<session-id>.json.

CLI Reference

Command	Purpose
checkpoint.py new-id	Generate a fresh session id.
checkpoint.py beat --session ID --action TEXT [--context TEXT] [--files A B]	Record a heartbeat; refreshes at-risk file list.
checkpoint.py status [--json]	Show current pulse + at-risk files.
checkpoint.py scan [--stale-minutes N] [--json]	If pulse is stale-and-not-complete, archive it and print recovery summary.
checkpoint.py recover [--json]	Print recovery summary for the latest pulse.
checkpoint.py complete [--session ID]	Mark current pulse complete (graceful end).