Feature request: Allow skills to trigger /compact programmatically

Summary

Skills (SKILL.md) currently have no way to programmatically trigger the built-in /compact command. This means a skill that saves a snapshot and wants to compact the context must ask the user to manually type /compact — breaking the single-command UX.

Use Case

I maintain AuraKit, a Claude Code skill with 33 modes. We have an /aura-compact command that:

1. Saves a snapshot of the current work state to .aura/snapshots/current.md
2. Should trigger /compact to reduce context

Step 2 is currently impossible. We've tried:

• echo '/compact' | claude --resume — starts a new process, doesn't affect current session
• export CLAUDE_AUTOCOMPACT_PCT_OVERRIDE=1 — only affects Bash child process, not parent harness
• PowerShell SendKeys — unreliable, platform-specific hack

None of these work because /compact is handled by the harness, and skills/AI have no API to trigger it.

Proposed Solution

One of these would solve the problem:

Option A: Add a compact field to skill/hook output JSON:

{ "compact": true }

When the harness sees this from a skill or hook, it triggers compaction after the current turn.

Option B: Add a triggerCompact() function accessible from hooks:

// In a PostToolUse or Stop hook
const { triggerCompact } = require('claude-code-hooks');
triggerCompact(); // Signals harness to compact after this hook

Option C: Allow the Skill tool to invoke built-in commands:

skill: "compact"  // Currently blocked: "Do not use this tool for built-in CLI commands"

Environment

• Claude Code v2.1.84
• Windows 11
• AuraKit v6.2.1

Impact

This affects any skill that wants to offer a "save + compact" workflow. The current workaround (asking users to manually type /compact) breaks the seamless automation that skills are supposed to provide.