Compact Guard

compact-guard — survive /compact

Fixes: #24686, #26061

What this prevents

"After context compaction occurs during plan mode execution, Claude Code fails to re-read or reference the existing plan." — issue #24686

"Plan mode state lost after context compression." — issue #26061

You're 30 turns into a careful refactor. /compact runs (manually or because you hit the auto-compact threshold). The summarizer condenses everything, including the plan you were halfway through. Claude wakes up on the other side without the plan, and you have to re-prompt from scratch.

compact-guard snapshots the plan before compaction touches it, then re-injects the snapshot as context immediately after, so the post-compact turn starts knowing the current task, active todos, files touched, and the most recent plan.

How it works (zero manual work for the user)

/compact (manual)  or  auto-compact at threshold
        │
        ▼
   PreCompact hook fires
        │
        ▼
Read transcript → extract:
  • Most recent user message     (the current task)
  • Latest TodoWrite todos       (pending + in_progress only)
  • Files edited this session    (Edit / Write / MultiEdit)
  • Last assistant text block    (likely the working plan)
        │
        ▼
Write .papercuts/compact-snapshots/<timestamp>.md
(keeps 5 most recent — oldest pruned)


Compaction runs. The summarizer eats most of the context.


Next session start with source="compact"
        │
        ▼
   SessionStart hook fires
        │
        ▼
Read the latest snapshot → print to stdout
Claude Code auto-injects stdout as additional context

When you (the model) should invoke this skill manually

• User runs /claude-papercuts:compact-guard
• User asks "what was I doing before the compact?"
• User asks to see the latest pre-compact snapshot
• User says they lost their plan / their todos / their work after a compact ran

Manual invocation procedure

When asked to show compact-guard state:

1. Check if .papercuts/compact-snapshots/ exists in the project root.
2. If not, tell the user no compaction has happened yet in this project — the directory will populate on the first PreCompact. Then stop.
3. Otherwise, list the snapshots (sorted newest first). Tell the user:
   • How many snapshots are stored
   • The timestamp of each
4. If asked for a specific snapshot, cat it to the user verbatim. The format is plain markdown — don't summarize.
5. Never modify or delete snapshots automatically. If the user asks you to clean them up, ask for explicit confirmation first.

Snapshot format

Each snapshot is a markdown file in .papercuts/compact-snapshots/<UTC-timestamp>.md:

# compact-guard snapshot

- **When:** 2026-05-16 09:14 UTC
- **Trigger:** auto-compact
- **Session:** abc123def456

## Current task (last user message)
> <the most recent user prompt>

## Active todos
- [in_progress] <todo content>
- [pending] <todo content>

## Files edited this session
- `src/middleware/auth.ts`
- `src/__tests__/auth.test.ts`

## Last assistant message (plan / summary)

<the last assistant text block — usually the working plan, capped at 1500 chars>

Sections that have nothing useful are omitted. Total snapshot file is uncapped because it's read on demand, not auto-injected into the system prompt.

What this skill does NOT do

• It does not block compaction. PreCompact runs read-only and exits 0.
• It does not modify the transcript. The snapshot is a separate file.
• It does not deduplicate snapshots. Five most-recent are kept, in case you want to inspect a series of compactions.
• It does not survive across projects. Snapshots live in .papercuts/compact-snapshots/ relative to the project's cwd.
• It does not inject context on /clear, /resume, or startup — only post-compact. Use amnesia-fix for cross-session continuity.

Privacy

Snapshots are written to a local file in your project's .papercuts/ directory. No network calls. Add .papercuts/ to your .gitignore if not already.

Deprecation plan

If Anthropic ships a compact-resilient plan-mode (per issues #24686 and #26061), this skill becomes a no-op and gets deprecated in the next monthly release with the date.