Routing and fallbacks

These are advanced options the pre.dev AI API supports on top of the standard chat completion fields. This page lists them and how they interact with billing.

Fallback models

Send models instead of a single model. The gateway tries each in order and the response reports which one answered.

{
  "models": ["anthropic/claude-sonnet-5", "openai/gpt-5.6-luna", "deepseek/deepseek-v4.1-flash"],
  "route": "fallback",
  "messages": [{ "role": "user", "content": "Summarize the plot of Dune in two sentences." }]
}

You pay for the model that actually served the call, at its own price. Read model in the response, or the by_model rows in usage, to see where traffic landed.

Provider preferences

The provider object controls which providers serve a model:

Key	Purpose
`order`	Providers to try first
`sort`	Sort candidates by `price`, `throughput`, or `latency`
`ignore`, `only`	Exclude or restrict providers
`max_price`	Per-token price ceiling
`data_collection`	Allow or deny providers that retain data

{
  "model": "deepseek/deepseek-v4.1-flash",
  "provider": { "sort": "throughput", "data_collection": "deny" },
  "messages": [{ "role": "user", "content": "ping" }]
}

usage.cost reflects the chosen provider’s price, so max_price bounds your credit spend per token. The :nitro variant is shorthand for throughput sorting.

Reasoning

reasoning (an object) and reasoning_effort (a string) request thinking on models that support it. Reasoning tokens are output tokens for billing.

{
  "model": "anthropic/claude-sonnet-5",
  "reasoning": { "effort": "medium" },
  "messages": [{ "role": "user", "content": "Is 9973 prime? Show your reasoning briefly." }]
}

Plugins and web search

plugins accepts web, file-parser, response-healing, and context-compression. web_search_options tunes the web plugin. Plugin costs are included in usage.cost.

{
  "model": "openai/gpt-5.6-luna",
  "plugins": [{ "id": "web" }],
  "web_search_options": { "search_context_size": "low" },
  "messages": [{ "role": "user", "content": "What changed in the latest Node.js LTS release?" }]
}

Other pass-through fields

Field	Purpose
`transforms`	Prompt transforms such as middle-out compression
`prediction`	Predicted outputs
`verbosity`	Response length hint
`session_id`	Group related requests under one session
`user`	End-user identifier; the gateway prefixes it with a workspace hash

If you send user, keep it stable per end user so abuse reports can be attributed. The gateway sets it when absent.

Get started

Guides

API reference

Routing and fallbacks

Fallback models

Provider preferences

Reasoning

Plugins and web search

Other pass-through fields

​Fallback models

​Provider preferences

​Reasoning

​Plugins and web search

​Other pass-through fields

Fallback models

Provider preferences

Reasoning

Plugins and web search

Other pass-through fields