Mycel vs Temporal
A durable execution engine, and a harness for AI work, are different layers.
What Temporal is good at
Temporal is the best durable workflow engine there is. If you need a long-running process to survive process death, resume exactly where it stopped, and do that at enormous scale, it is the correct answer and has been for years.
The actual difference
Temporal makes your code durable. Mycel makes an AI agent's actions safe. Temporal has no opinion about model calls, approval gates, sandboxes or credential isolation — nor should it, that isn't its layer. Mycel has strong opinions about all four and comparatively simple durability. You could build Mycel's trust boundary on top of Temporal; you could not build Temporal's durability on top of Mycel.
Side by side
| Temporal | Mycel | |
|---|---|---|
| Layer | Durable execution | Agent harness + trust boundary |
| Human approval | You build it | Built in, on by default |
| Credential isolation | Not its concern | The core design constraint |
| Sandboxed agent | No | Local, Docker or Daytona |
| Durability | Best in class | Postgres queue, leases, replay |
| Setup | A cluster | One binary + Postgres |
Choose Temporal
- The workflows are deterministic code, not model calls
- You need exactly-once semantics across a distributed system
- You already run it and the AI part is a small piece of a larger process
Choose Mycel
- The work is done by an agent and a human has to approve what it sends
- Credentials must never reach the model
- You want a service business, not a workflow engine to build one with
Other comparisons: LangGraph, Zapier & n8n, CrewAI & AutoGen, Building it yourself