Checkpoints Skill

Checkpoints let multi-phase commands survive session interruptions. When a phase completes, the command writes a checkpoint file. When the command is re-invoked, it reads the checkpoint and resumes from the first incomplete phase.

Context Pre-flight

Before starting a multi-phase command, check context usage:

• At 60% context: Warn the user. Suggest running /compact to free space, or finishing the current phase, committing the checkpoint, and starting a fresh session.
• At 80% context: Warn the user. Suggest running /virtual-team:handoff to generate a handoff document before context runs out, so the next session can resume cleanly.

Checkpoints exist precisely for this scenario — running out of context mid-work is expected, not exceptional. The command proceeds either way, but the user knows checkpoints will protect their progress.

File Location and Naming

Checkpoint files live in docs/checkpoints/:

docs/checkpoints/<command>-<ID>.md

Where:

• <command> is the command name: debug, epic, feature, implement, plan
• <ID> is the item identifier the command is working on (e.g., FEAT-003, EPIC-001, BUG-012, the plan filename slug)

Examples:

docs/checkpoints/feature-FEAT-003.md
docs/checkpoints/implement-2026-02-12-notifications.md
docs/checkpoints/debug-BUG-012.md
docs/checkpoints/epic-EPIC-001.md
docs/checkpoints/plan-FEAT-007.md

If the item has no formal ID (e.g., a debug session started from a symptom description), derive a short slug from the context (e.g., debug-login-timeout).

Checkpoint File Format

---
command: <command>
item: <ID or description>
branch: <git branch name>
started: <ISO 8601 timestamp>
updated: <ISO 8601 timestamp>
status: in_progress
current_phase: 2
total_phases: 5
---

# Checkpoint: <command> — <item>

## Phases

| # | Phase | Status | Completed |
|---|---|---|---|
| 0 | Decision Sync | done | 2026-02-27T10:15:00Z |
| 1 | Capture | done | 2026-02-27T10:32:00Z |
| 2 | Product Analysis | in_progress | — |
| 3 | Technical Routing | pending | — |
| 4 | Agreements | pending | — |
| 5 | Document | pending | — |

## Current Phase Detail

<!-- Granular sub-tasks within the active phase only.
     Cleared when the phase completes. -->

- [x] Gathered user interview notes from docs/research/
- [x] Identified three competitor approaches
- [ ] Draft market positioning summary
- [ ] Validate assumptions with user persona matrix

## Current State

<!-- Brief description of where things stand — what was the last thing completed,
     what's next, any decisions made or blockers encountered. Keep this short
     but specific enough to resume without re-reading everything. -->

## Key Decisions

<!-- Capture decisions made during completed phases that affect later phases.
     This prevents re-asking the user questions they already answered. -->

- [Phase 0] Synced with hub decisions ADR-NNN and ADR-NNN
- [Phase 1] Scope confirmed: notifications for orders only, not marketing

## Artifacts Produced

<!-- List files created or modified by completed phases. This tells the
     resuming session what already exists and doesn't need to be recreated. -->

- `docs/epics/EPIC-001-notifications.md` (draft, through Phase 1)
- `docs/decisions/2026-02-27-notification-transport.md`

## Key Context

<!-- References to documents and context the resuming session should re-read.
     Populated on creation, stays fixed throughout. -->

- Feature: `docs/features/FEAT-003-notifications.md`
- Plan: `docs/plans/2026-02-12-notifications.md`
- Branch: `feat/CTR-12`
- Stack: Node.js + React (from stack.md)

Phase Definitions by Command

Each command defines its own phases in its command file. The checkpoint tracks progress through those phases — it does not redefine them.

When writing a checkpoint, copy the phase names from the command's definition. Do not invent or rename phases here.

Protocol

On Command Start (Step 0)

Every checkpointed command runs this before anything else:

1. If --fresh was passed:
   • Delete docs/checkpoints/<command>-*.md matching the current item
   • Proceed as if no checkpoint exists
2. Check for existing checkpoint:
   • Look for docs/checkpoints/<command>-<ID>.md
   • If found, read it and show a resume summary:

     Resuming from checkpoint: docs/checkpoints/<command>-<ID>.md
     Last updated: <timestamp>
     Completed: Phase 0 (Decision Sync), Phase 1 (Capture)
     Resuming at: Phase 2 (Product Analysis)

   • Skip to the first phase with status pending or in_progress
   • Re-read any artifacts listed in the checkpoint to restore context
3. If no checkpoint exists:
   • Proceed normally from the beginning

After Each Phase Completes

1. Update the checkpoint file:
   • Set the completed phase status to done with a timestamp
   • Set the next phase status to in_progress (if there is one)
   • Update the updated timestamp in frontmatter
   • Update Current State with a brief summary
   • Add any decisions to Key Decisions
   • Add any created files to Artifacts Produced
   • Clear Current Phase Detail sub-tasks (the next phase starts with a fresh list)
2. Write the file using the Write tool — always overwrite the full file (not Edit), since multiple sections change each time.
3. Commit the checkpoint:

   git add docs/checkpoints/<command>-<ID>.md
   git commit -m "checkpoint: <command> <ID> — phase <N> complete"

On Successful Completion

When all phases are done:

1. Delete the checkpoint file: rm docs/checkpoints/<command>-<ID>.md
2. Bundle the deletion into the final commit (e.g., the backlog update commit in /virtual-team:implement)
3. If the command doesn't produce a final commit, use: git rm + git commit -m "checkpoint: <command> <ID> — complete, removing checkpoint"

On Failure or Interruption

If a phase fails (verification doesn't pass, blocker found):

1. Update the checkpoint with the failure state in Current State
2. Leave the phase as in_progress (not done)
3. Commit the failure state:

   git add docs/checkpoints/<command>-<ID>.md
   git commit -m "checkpoint: <command> <ID> — phase <N> failed"

4. The next session will resume at the failed phase with context about what went wrong

If the session is interrupted (context limit, user closes terminal):

• The last committed checkpoint is the recovery point
• This is why checkpoints are committed after each phase, not at the end — partial progress is preserved

Directory Management

• Create docs/checkpoints/ if it doesn't exist (with .gitkeep)
• Checkpoints are committed. They live in git so they survive across sessions, worktrees, and machines.
• Never add docs/checkpoints/ to .gitignore — checkpoint reliability depends on git persistence.

Guidelines

1. Write checkpoints after phases, not during. A phase is either done or not — no partial phase checkpoints.
2. Keep Current State concise. Two to three sentences max. The resuming session will re-read artifacts for detail.
3. Capture decisions, not discussion. Key Decisions records what was decided, not the deliberation.
4. Always delete on success. Stale checkpoints cause confusion. Clean up.
5. Checkpoints are committed. Every checkpoint write is followed by a git commit. This is the reliability guarantee — without it, checkpoints don't survive session boundaries.
6. Don't checkpoint trivial commands. Only the five multi-phase commands use checkpoints. Single-step commands like /virtual-team:commit or /virtual-team:review don't need them.
7. Sub-tasks are ephemeral. Current Phase Detail tracks granular items within the active phase only. When the phase completes, sub-tasks are cleared — they've served their purpose.
8. Completed phases are trusted. When resuming, do NOT re-verify or re-implement completed phases. Trust the checkpoint. If something is wrong, the user can --fresh to start over.
9. One checkpoint per command+ID pair. If /virtual-team:implement FEAT-007 is run, there's one checkpoint file. Running it again resumes. Running /virtual-team:implement FEAT-008 creates a separate checkpoint.