Strategic Compact Skill

Suggests manual /compact at strategic points in your workflow rather than relying on arbitrary auto-compaction.

When to Activate

Running long sessions that approach context limits (200K+ tokens)
Working on multi-phase tasks (research → plan → implement → test)
Switching between unrelated tasks within the same session
After completing a major milestone and starting new work
When responses slow down or become less coherent (context pressure)

Why Strategic Compaction?

Auto-compaction triggers at arbitrary points:

Often mid-task, losing important context
No awareness of logical task boundaries
Can interrupt complex multi-step operations

Strategic compaction at logical boundaries:

After exploration, before execution — Compact research context, keep implementation plan
After completing a milestone — Fresh start for next phase
Before major context shifts — Clear exploration context before different task

How It Works

The suggest-compact.js script runs on PreToolUse (Edit/Write) and combines two signals:

Context size (primary) — Reads the latest usage record from the session transcript (transcript_path in the hook payload) and sums input_tokens + cache_read_input_tokens + cache_creation_input_tokens (the true context size of the turn). Suggests /compact at a window-scaled threshold — 160k tokens on a 200k window, 250k on a 1M window (detected from a [1m] model marker, or inferred when observed tokens already exceed 200k) — and re-reminds after every additional 60k tokens of context growth
Tool-call count (secondary) — Counts tool invocations in session; suggests at a configurable threshold (default: 50 calls), then every 25 calls after

Hook Setup

Add to your ~/.claude/settings.json:

{
  "hooks": {
    "PreToolUse": [
      {
        "matcher": "Edit",
        "hooks": [{ "type": "command", "command": "node ~/.claude/skills/strategic-compact/suggest-compact.js" }]
      },
      {
        "matcher": "Write",
        "hooks": [{ "type": "command", "command": "node ~/.claude/skills/strategic-compact/suggest-compact.js" }]
      }
    ]
  }
}

Configuration

Environment variables:

COMPACT_THRESHOLD — Tool calls before first suggestion (default: 50)
COMPACT_CONTEXT_THRESHOLD — Context tokens before the context-size suggestion (default: 160000 on a 200k window, 250000 on a 1M window; 0 disables the context signal)
COMPACT_CONTEXT_INTERVAL — Additional context tokens before the suggestion repeats (default: 60000)

Compaction Decision Guide

Use this table to decide when to compact:

Phase Transition	Compact?	Why
Research → Planning	Yes	Research context is bulky; plan is the distilled output
Planning → Implementation	Yes	Plan is in TodoWrite or a file; free up context for code
Implementation → Testing	Maybe	Keep if tests reference recent code; compact if switching focus
Debugging → Next feature	Yes	Debug traces pollute context for unrelated work
Mid-implementation	No	Losing variable names, file paths, and partial state is costly
After a failed approach	Yes	Clear the dead-end reasoning before trying a new approach

What Survives Compaction

Understanding what persists helps you compact with confidence:

Persists	Lost
CLAUDE.md instructions	Intermediate reasoning and analysis
TodoWrite task list	File contents you previously read
Memory files (`~/.claude/memory/`)	Multi-step conversation context
Git state (commits, branches)	Tool call history and counts
Files on disk	Nuanced user preferences stated verbally

Best Practices

Compact after planning — Once plan is finalized in TodoWrite, compact to start fresh
Compact after debugging — Clear error-resolution context before continuing
Don't compact mid-implementation — Preserve context for related changes
Read the suggestion — The hook tells you when, you decide if
Write before compacting — Save important context to files or memory before compacting
Use /compact with a summary — Add a custom message: /compact Focus on implementing auth middleware next

The Longform Guide — Token optimization section
Memory persistence hooks — For state that survives compaction
continuous-learning skill — Extracts patterns before session ends

strategic-compact