arc-compacting

arc-compacting

Guide compaction decisions at logical workflow boundaries instead of letting auto-compaction fire mid-task. Compact at the right time to preserve context quality without losing critical state.

Core principle: Compact between phases (when state is persisted to files), not during phases (when context holds un-persisted decisions).

When to Use

Use this skill when:

• The compact-suggester hook fires a threshold notification
• You're transitioning between workflow phases (brainstorming → planning → implementation)
• A long session is accumulating stale context
• You've just saved deliverables to files and context is bulky

Decision Guide

Phase Transition	Compact?	Why
Exploration → planning	Yes	Research context is bulky; plan is the distilled output
Planning → implementation	Yes	DAG/tasks are in files; free up context for code
Implementation → testing	Maybe	Keep if tests reference recent code changes
Debugging → next feature	Yes	Debug traces pollute context for unrelated work
Mid-implementation	No	Losing variable names, file paths, partial state is costly
After failed approach	Yes	Clear dead-end reasoning before new approach
After arc-brainstorming produces design doc	Yes	Design is saved to file; compact before refining
After arc-planning produces dag.yaml	Yes	DAG persists; free context for implementation

What Survives vs What's Lost

Persists After Compact	Lost After Compact
CLAUDE.md + rules (auto-loaded)	Intermediate reasoning
Tasks (TodoWrite)	File contents previously read
Memory files	Conversation context
Git state (commits, branches)	Tool call history
dag.yaml, .arcforge-epic	Verbal preferences given this session
Skill definitions (auto-loaded)	Session-specific observations

Best Practices

Before Compacting

1. Write before compacting — save decisions to files or memory
   • Design decisions → docs/plans/ or memory
   • Task progress → update dag.yaml or TodoWrite
   • Observations → memory files
2. Run /diary if the session was substantial — captures session insights before they're lost
3. Check for un-committed work — ensure valuable changes are committed

During Compact

Use a focused compact command to orient the post-compact session:

/compact Focus on implementing [next task] using arc-agent-driven

The summary text becomes the seed for the compressed context. Make it actionable.

After Compact

• Run arcforge reboot to recover DAG context quickly
• Re-read any files you'll need for the next phase
• The agent will have CLAUDE.md, rules, and memory — but not conversation history

Integration

Works with:

• compact-suggester hook — triggers threshold notifications that reference this skill
• pre-compact hook — auto-triggers diary capture before compaction
• arc-agent-driven — compact between task batches, not mid-task
• arc-planning — compact after DAG is written to disk

Red Flags:

• Compacting while holding un-persisted design decisions
• Compacting mid-implementation when partial state is in context only
• Ignoring compact suggestions past 75+ tool calls (context quality degrades)
• Compacting without saving observations to memory first