Context Compactor Skill

Analyze and compact documents that affect context window size. Reduce token usage while preserving essential information.

Activation Triggers

Manual only — never auto-activate.

• /compact-context — run full analysis
• "コンテキストを整理して", "compact context", "reduce context size"

Target Files

Workflow

Phase 1: Measure

1. Count lines and estimate tokens for each target file
2. Present a summary table with file sizes
3. Identify the largest contributors to context

Phase 2: Analyze

For each target file, detect:

• Redundancy: Content duplicated across files (e.g., CLAUDE.md vs skills, memory vs CLAUDE.md)
• Obsolescence: Outdated information (completed tasks, old decisions, superseded patterns)
• Verbosity: Content that can be expressed more concisely without losing meaning
• Language inefficiency: Japanese text in technical/process docs where English would use fewer tokens

Phase 3: Propose

Present findings as a structured table:

| File | Current | Est. After | Reduction | Changes |
|------|---------|-----------|-----------|---------|
| ... | ... | ... | ... | Brief description |

For each file with proposed changes, show:

• What will be removed/compacted (with reasoning)
• What will be preserved (and why)

Wait for user approval before proceeding.

Phase 4: Execute (after approval)

• Apply approved changes only
• Show before/after line counts
• Suggest committing if in a git repo

Analysis Rules

MUST preserve

• User-specified behavioral instructions (personality, output style, preferences)
• Active project conventions and standards
• Security-related rules and constraints
• Information that exists nowhere else (sole source of truth)

Safe to compact

• Duplicated content (keep in the most appropriate location)
• Verbose explanations of standard practices (LLMs already know these)
• Completed/obsolete memory entries
• Boilerplate sections repeated across files

Requires user judgment

• Content the user may consider important even if technically redundant
• Trade-offs between token savings and clarity
• Whether to convert Japanese → English for token efficiency

Important Notes

• Never delete without showing what will be removed
• Preserve meaning even when reducing words
• When in doubt, keep — false deletion is worse than slight verbosity
• This skill does NOT auto-activate — context growth is normal and expected