> For the complete documentation index, see [llms.txt](https://docs.fastn.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.fastn.ai/reference.md).

# Reference

- [Workflow runtime API](https://docs.fastn.ai/reference/workflow-runtime.md): What a workflow can reach at runtime: ctx, multi-tenant headers, connectors, unified APIs, database, state, secrets and configs.
- [HTTP API](https://docs.fastn.ai/reference/api.md): Calling workflows and unified endpoints over HTTP.
- [Errors and failure states](https://docs.fastn.ai/reference/errors.md): What each failure state means, where fastn shows you the detail, and what to do about it.
- [fastn for AI agents](https://docs.fastn.ai/reference/ai-agents.md): A single dense page for LLMs and coding agents: the model, the runtime surface, the endpoints, and the things that are easy to get wrong.
- [FAQs](https://docs.fastn.ai/reference/faqs.md): Short answers to the questions that come up most.
- [Glossary](https://docs.fastn.ai/reference/glossary.md): Alphabetized definitions of every term used across the Fastn platform and documentation.


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