# Hermes Gauge

> Hermes Gauge is a free, open-source (MIT) plugin for Hermes Agent by Nous Research. It measures how full the agent's context is, shows it as a fuel gauge against the usable window of the model, and warns before the agent forgets. It never compacts and never opens the next session on its own. Built by SIDELIGHT (Switzerland) for the Hermes Agent Plugin Hackathon 2026.

## What it does

- Reads the context of a Hermes session continuously and shows it as a gauge (for example "Context 21.3% OK, 55,865 / 262,144 effective tokens").
- Scores against the usable window, not the announced one. On flash, nano and lite models the factor is 0.25: an announced 1,000,000 tokens is about 250,000 usable.
- Two tunable thresholds: WATCH and FULL.
- Warns before the agent forgets the start of the conversation (context rot) and recommends the next step. Compaction and the session cycle stay with Hermes.
- Every reading states its window source: detected, configured, fallback or unresolved. Estimates are marked with "≈". The percentage never exceeds 100% and is never stale.
- Local only: peak history is stored in SQLite, nothing is sent anywhere. Measurement is passive, after the reply, with no second poller.

## Install

```
hermes plugins install SidelightAi/hermes-gauge --enable
```

Requires Hermes Agent (https://github.com/NousResearch/hermes-agent). Current version: 0.5.0. License: MIT.

## Key facts

- Name: Hermes Gauge (repository: hermes-gauge)
- Type: Hermes Agent plugin, context monitoring
- Price: free, open source (MIT)
- Author: SIDELIGHT, https://www.sidelight.ch
- Languages of the site: English, French

## Pages

- [Hermes Gauge (English)](https://hermes-gauge.sidelight.ch/): landing page, demo, proof, install steps, FAQ
- [Hermes Gauge (Français)](https://hermes-gauge.sidelight.ch/fr/): même page en français
- [Source code and documentation](https://github.com/SidelightAi/hermes-gauge): GitHub repository
- [Walkthrough video, 1 min 28 s](https://www.youtube.com/watch?v=eweaNpiojWM): "Your Hermes Agent Forgot — Fix It Now (1 Plugin)"

## FAQ

- Does it slow the agent down? No. The measurement is passive, after the reply.
- Does it work with every model? The window is detected per model. If it cannot be detected, the gauge says so.
- Does the data leave the machine? No. Local SQLite. Nothing is sent.
- Can I turn it off? Yes. No hook blocks the agent.

## Optional

- [SIDELIGHT on X](https://x.com/Sidelight_ai)
- [SIDELIGHT on YouTube](https://www.youtube.com/@Sidelight_ai)
- [Contact](https://www.sidelight.ch/contact)