Event Hooks
Event Hooks
Start with meaning, then move to detail.
This lesson explains Event Hooks as part of using Hermes through messaging channels. You will learn what it does, when it matters, and the smallest safe test that proves it works.
If you are new, do not memorize names. Focus on three questions: what problem does this solve, what access does it need, and how can you verify the result?
For practice, inspect the first example, identify its effects, run it on test data, and compare the result with the source claim.
For advanced readers, inspect Gateway Event Hooks, Creating a Hook, HOOK.yaml, then verify failure modes and version compatibility.
Prepare the channel account and understand allowlists and secret storage.
A clear outcome before you read.
- Understand Event Hooks without assumed prior knowledge.
- Separate the source description from what still needs testing in your environment.
- Read the first command and identify its inputs and outputs before copying it.
Short definitions before the details.
- Gateway
- The process that connects Hermes to channels such as Telegram or Discord and routes messages.
- Session & memory
- A session holds conversation context, while memory keeps selected facts that should persist.
Run custom code at key lifecycle points — log activity, send alerts, post to webhooks
What does the source say, and in what order?
- 01Gateway Event Hooks
Start here to understand the core idea or structure.
- 02Creating a Hook
Read this after the foundation, then connect it to the previous step.
- 03HOOK.yaml
Read this after the foundation, then connect it to the previous step.
- 04handler.py
Read this after the foundation, then connect it to the previous step.
- 05Available Events
Read this after the foundation, then connect it to the previous step.
- 06Wildcard Matching
Read this after the foundation, then connect it to the previous step.
- 07Examples
Read this after the foundation, then connect it to the previous step.
- 08Telegram Alert on Long Tasks
Read this after the foundation, then connect it to the previous step.
- 09Command Usage Logger
Read this after the foundation, then connect it to the previous step.
- 10Session Start Webhook
Finish here to verify the result and special cases.
Copy only after you understand the effect.
~/.hermes/hooks/
└── my-hook/
├── HOOK.yaml # Declares which events to listen for
└── handler.py # Python handler functionname: my-hook
description: Log all agent activity to a file
events:
- agent:start
- agent:end
- agent:step**Handler rules:**
- Must be named `handle`
- Receives `event_type` (string) and `context` (dict)
- Can be `async def` or regular `def` — both work
- Errors are caught and logged, never crashing the agent
### Available Events
| Event | When it fires | Context keys |
|-------|---------------|--------------|
| `gateway:startup` | Gateway process starts | `platforms` (list of active platform names) |
| `session:start` | New messaging session created | `platform`, `user_id`, `session_id`, `session_key` |
| `session:end` | Session ended (before reset) | `platform`, `user_id`, `session_key` |
| `sRead the first command and identify its inputs and outputs before copying it.
Match every command to your installed Hermes version, review the files and accounts it can reach, and use non-sensitive data for the first test. If this explanation differs from the source, the official source wins.