> ## Documentation Index
> Fetch the complete documentation index at: https://docs.vendo.run/llms.txt
> Use this file to discover all available pages before exploring further.

# Prompt assembly: how Vendo builds the agent system prompt

> The fixed five-step order Vendo uses to assemble the agent system prompt each turn, from operating prompt through brief, directions, catalog, and host.

The agent assembles its system prompt fresh for each turn:

1. Vendo's operating prompt.
2. The host product brief from `.vendo/brief.md`.
3. Company directions returned by `guard.directions(ctx)`.
4. Catalog and theme summary when the venue can render trees.
5. Host instructions.

Directions are policy data. Put them in `.vendo/policy.json` or pass them in
`PolicyConfig`; there is no second directions channel or merge rule.

The apps generation engine has its own specialized prompts for tree emission
and code edits. It receives the component catalog, theme, optional
`.vendo/design-rules.md`, and format limits. It can use the same model as the
agent or a different AI SDK `LanguageModel`.

Memory is deferred and has no reserved v0 seam.