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

> ## Agent Instructions
> Setting up Context.dev for a user? Follow https://docs.context.dev/agent-quickstart.md. MCP clients sign in with OAuth and need no API key; application code reads CONTEXT_DEV_API_KEY.

# Sources and deadlines

> Use source URLs, partial answers, and research time limits correctly.

`sources` lists URLs that supplied search results or readable page content, in first-seen order. It is not a field-by-field citation map. Pages that could not be read are excluded.

## Freshness

Ultra reads pages fresh. Fast can reuse a page read from the last minute. Source publication dates and the evidence’s own age still matter when asking about current facts.

## Deadlines and partial answers

`timeoutOpts.milliseconds` can shorten research but cannot extend the mode’s 30- or 50-second budget. It accepts 1,000–300,000 ms. Set the client timeout longer than the request deadline.

With `behavior: "return-partial"`, a valid answer from the evidence collected so far may be returned with `partial: true`. If no usable answer can be formed, the request fails. Treat absent or null facts as unresolved.

## Failures

Correct invalid tasks or answer shapes after 400. Handle 408 by reducing the task or allowing more time within the mode budget; retry transient 5xx failures with backoff. Use [rate-limit headers](/optimization/rate-limits) after 429.

[Zero data retention](/optimization/zero-data-retention) is available when enabled for the organization. Save `request_id` for support without storing content your application does not need.