Context Compactor

context-compactor

Tells you when to /clear vs keep, what to dump to a memory file before clearing, and how to re-seed the next session efficiently.

When to activate

Trigger phrases: context full, running low, should I clear, compact this, lots of files read, /compact.

Auto-trigger at 70% of the context window if Claude Code exposes that metric. Warn at 85%, force-suggest at 95%.

Decision tree

Is the current task done?
├── YES → Suggest /clear. Save anything durable to a vault note first.
└── NO → 
    Is most context now stale (reading files we won't touch again)?
    ├── YES → Suggest dumping current state to a session brief, then /clear, then re-seed.
    └── NO → Stay. The model still needs this context.

The "session brief" pattern

Before clearing, write a hand-off document at .proteus/sessions/<date>-<topic>.md:

# Session brief: <topic>

## What I was doing
<2-3 sentences>

## What's done
- <thing 1>
- <thing 2>

## Where I am right now
<the next concrete action>

## Files I touched
- path/file.py — <one-line change summary>
- ...

## Decisions made
- <decision> — (see ADR-NNNN if recorded)

## Open questions
- <q>

Then run /clear. Re-seed the next session by pasting the brief or by saying "read .proteus/sessions/-.md and continue."

Process

1. Detect context pressure (token count vs window size)
2. Categorize what's in context:
   • Active code (keep)
   • Stale file reads (drop)
   • Verbose tool outputs (drop)
   • Decisions / current task state (preserve as brief)
3. Generate the session brief
4. Ask: "Save brief and clear? (y / no / brief-only / clear-only)"
5. On approval: write brief, then /clear

Inputs

• Current context token usage
• Tool call history (to find stale reads)
• The user's stated task

Outputs

• Session brief file (at .proteus/sessions/)
• /clear invocation (if approved)
• Re-seed instructions for next session

Slash command

/compact — start the flow regardless of context pressure.

Why this skill

Cherny's data: 80% of "Claude got dumb" complaints trace to bloated context. Compacting is the single highest-impact session hygiene practice.