---

name: context-sentinel description: "Monitors session context and automatically manages model switching based on a cascading protocol. Use as part of a heartbeat or cron job to maintain session health and optimize token usage." version: 1.0.0

Context Sentinel

This skill provides a script to automate the "Cascading Model Protocol," ensuring the agent gracefully degrades from high-cost models to high-context models as the session grows.

Protocol Summary

1. Opus 4.6: Use until 80% context, then switch to Opus 4.5.
2. Opus 4.5: Use until 80% context, then switch to Gemini 2.5 Pro.
3. Gemini Pro: Use until 80% context, then trigger a handoff.

This skill operationalizes the logic defined in MEMORY.md.

How to Use

This skill is designed to be run periodically, either via a cron job or as part of the main agent's HEARTBEAT.md checklist.

Workflow

1. Execute the script: Run the check_context.ps1 script to get the current session status and determine the required action.

   powershell -File scripts/check_context.ps1
   

2. Evaluate the output: The script will return one of three possible string commands:

   • SWITCH_TO:<model_id>
   • HANDOFF_NOW
   • STATUS_OK

3. Take Action: Based on the output, execute the appropriate agent command.

   • If SWITCH_TO:<model_id>, run session_status with the new model ID:

     session_status model=<model_id>
     

   • If HANDOFF_NOW, trigger the handoff process by writing to the handoff file. This is typically done by running a specific, pre-defined prompt or script.

   • If STATUS_OK, no action is needed.

Example Usage in HEARTBEAT.md

You can replace the manual checks in your HEARTBEAT.md with a call to this skill's script.

Old HEARTBEAT.md:

## Cascading Model Protocol (Check Every Heartbeat)
1.  **Check Status:** Get current model and context %.
2.  **Opus 4.6:** If model is `Opus 4.6` and context > 80% -> Switch to `Opus 4.5`.
...

New HEARTBEAT.md using this skill:

## Context Sentinel (Check Every Heartbeat)
1. Run `powershell -File skills/context-sentinel/scripts/check_context.ps1`.
2. Evaluate the output and take action (`SWITCH_TO`, `HANDOFF_NOW`, or `STATUS_OK`).

This makes the logic reusable and keeps the HEARTBEAT.md file clean and focused on execution.