strategic-compact

SKILL.md

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

Tool count alone is a weak proxy for window pressure: a few large file reads or MCP responses can fill the window in very few calls, while many tiny calls can cross 50 with a near-empty window. The context-size signal fires when it actually matters.

Hook Setup

Installed as a plugin? No setup is needed. The plugin's hooks/hooks.json already registers suggest-compact.js (hook id pre:edit-write:suggest-compact, active in the standard and strict hook profiles). Do not copy the block below into ~/.claude/settings.json — ~/.claude/scripts/ does not exist on plugin installs, and duplicating a plugin hook causes double execution.

If installed manually (./install.sh), add to your ~/.claude/settings.json:

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

COMPACT_STATE_TTL_DAYS — Days before stale per-session state files in the temp dir are swept (default: 14)

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

Token Optimization Patterns

Trigger-Table Lazy Loading

Instead of loading full skill content at session start, use a trigger table that maps keywords to skill paths. Skills load only when triggered, reducing baseline context by 50%+:

Trigger
Skill
Load When

"test", "tdd", "coverage"
tdd-workflow
User mentions testing

"security", "auth", "xss"
security-review
Security-related work

"deploy", "ci/cd"
deployment-patterns
Deployment context

Context Composition Awareness

Monitor what's consuming your context window:

CLAUDE.md files — Always loaded, keep lean

Loaded skills — Each skill adds 1-5K tokens

Conversation history — Grows with each exchange

Tool results — File reads, search results add bulk

Duplicate Instruction Detection

Common sources of duplicate context:

Same rules in both ~/.claude/rules/ and project .claude/rules/

Skills that repeat CLAUDE.md instructions

Multiple skills covering overlapping domains

Context Optimization Tools

token-optimizer MCP — Automated 95%+ token reduction via content deduplication

context-mode — Context virtualization (315KB to 5.4KB demonstrated)

Related

The Longform Guide — Token optimization section

Memory persistence hooks — For state that survives compaction

continuous-learning skill — Extracts patterns before session ends