Feature Request: Context Usage Threshold Hooks (Handoff Capsules)

We request the ability to define hooks that trigger at certain context usage thresholds.

Use Case

The primary goal is to receive a callback when context is critically low (e.g., 10% remaining). This triggers a workflow to:

1. Prompt the agent to record a 'handoff capsule' on the current bead(s).
2. Provide options to either:

• Reprime the agent after compaction (using the fresh handoff info).
• Kill the agent and hand off the bead to a new instance.

Benefit

This enables more robust long-running sessions and better state management/continuity during context exhaustion events, allowing for smarter handling than simple truncation or aggressive summarization.