Route text requests by region

Use a regional Phaseo endpoint to keep provider execution and provider data handling within the EU or US routes documented by Phaseo. You can use regional routing with Chat Completions, Responses, and Messages without changing your model IDs or API keys.

Regional routing is not currently an end-to-end data residency guarantee. Phaseo restricts provider selection and uses a Cloudflare placement hint near the selected region, but shared account, billing, cache, and operational systems may process data outside that region.

Choose an endpoint

Region	Base URL	Behavior
European Union	`https://eu.api.phaseo.app/v1`	Requires EU execution and data-region provider routes
United States	`https://us.api.phaseo.app/v1`	Requires US execution and data-region provider routes
Global	`https://api.phaseo.app/v1`	Uses the standard global routing policy

The regional hostname is the policy boundary. A request cannot override it with a conflicting required_execution_region or required_data_region value.

Use the Phaseo SDK

Set region when creating the client. Every supported request made by that client uses the corresponding regional base URL.

import { Phaseo } from "@phaseo/sdk";

const phaseo = new Phaseo({
  apiKey: process.env.PHASEO_API_KEY!,
  region: "eu",
});

const response = await phaseo.responses.create({
  model: "openai/gpt-5-mini",
  input: "Summarize this note in one sentence.",
});

console.log(response.output_text);

import os
from phaseo import Phaseo

phaseo = Phaseo(
    api_key=os.environ["PHASEO_API_KEY"],
    region="eu",
)

response = phaseo.responses.create({
    "model": "openai/gpt-5-mini",
    "input": "Summarize this note in one sentence.",
})

print(response.get("output_text"))

Use "us" for US routing. Omit region, or use "global", for global routing. The SDK rejects configurations that combine region with a custom baseUrl or base_url, because the two options would select competing hosts.

Use Chat Completions

curl https://eu.api.phaseo.app/v1/chat/completions \
  -H "Authorization: Bearer $PHASEO_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-5-mini",
    "messages": [
      {"role": "user", "content": "Write a two-line status update."}
    ]
  }'

Use Responses

curl https://eu.api.phaseo.app/v1/responses \
  -H "Authorization: Bearer $PHASEO_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-5-mini",
    "input": "Extract the three most important actions from this note."
  }'

Use Messages

The Messages endpoint accepts the Anthropic request format while retaining the same regional provider restriction.

curl https://us.api.phaseo.app/v1/messages \
  -H "Authorization: Bearer $PHASEO_API_KEY" \
  -H "Content-Type: application/json" \
  -H "anthropic-version: 2023-06-01" \
  -d '{
    "model": "anthropic/claude-sonnet-4.6",
    "max_tokens": 256,
    "messages": [
      {"role": "user", "content": "Summarize this incident report."}
    ]
  }'

Supported request features

Regional routing currently supports:

Text input and text output
Streaming and non-streaming responses
System and developer instructions
Client-defined function tools and custom tools
Tool results containing text
Structured text and JSON output, when supported by the model
Presets, provider ordering, fallbacks, and pricing limits that do not conflict with the regional policy

The regional endpoints reject:

Images, audio, video, documents, files, and attachments
Non-text output modalities
Provider-hosted tools such as web search, file search, code execution, computer use, and image generation
Image, audio, video, embedding, moderation, batch, file, webhook, and realtime endpoints

Function tools are allowed because the tool executes in your application. A provider-hosted tool is blocked because its execution location may not match the regional policy.

Discover models available in a region

Call /v1/models through the same regional hostname you use for generation:

curl https://eu.api.phaseo.app/v1/models \
  -H "Authorization: Bearer $PHASEO_API_KEY"

The response contains only models with an active provider route whose declared execution and data regions both include the selected region. It advertises only Chat Completions, Responses, and Messages, with text input and output. Each offer includes its regional metadata:

{
  "provider": { "id": "example-eu", "name": "Example EU" },
  "residency": {
    "execution_regions": ["eu"],
    "data_regions": ["eu"]
  }
}

Model availability can differ between the EU, US, and global endpoints. Always discover models through the endpoint your application will call.

Verify the selected gateway

Regional responses include:

X-Phaseo-Gateway-Region: eu

Use this header to confirm that the request reached the expected Phaseo deployment. Request details record the required execution region, required data region, selected provider, and the provider’s declared regional metadata.

The header identifies the regional Phaseo policy that handled the request. It is not evidence of guaranteed Cloudflare execution residency.

Failure behavior

Regional routing fails closed. Phaseo never silently retries the request through a provider outside the hostname’s region.

Error	Meaning	What to do
`regional_endpoint_not_supported`	The path is not available on regional Workers	Use one of the three supported text endpoints or the global API
`regional_non_text_content`	The request contains media, a file, or an attachment	Remove non-text content or use the global API
`regional_non_text_output`	The request asks for a non-text response	Request text output or use the global API
`regional_hosted_tool_not_supported`	A provider-hosted tool was requested	Use a client-defined function tool or the global API
`deployment_region_conflict`	The request or preset specifies another region	Remove the conflicting setting
No available provider route	No healthy provider satisfies the model and regional policy	Choose another model returned by the regional `/v1/models` endpoint

What regional routing covers

For an accepted generation request, Phaseo requires the selected provider route to declare both:

Model execution in the selected region
Prompt and completion data handling in the selected region

Phaseo applies these requirements after presets and dynamic routing rules are merged, so those features cannot weaken the hostname policy. If no provider matches, the request stops before upstream model execution.

Current limitations

This initial release does not guarantee that the complete request lifecycle stays inside the selected region:

Cloudflare Workers placement hints choose a location near the configured cloud region, but do not create a compliance boundary.
Phaseo account, authentication, billing, and request metadata use shared Supabase infrastructure.
Cloudflare KV and Worker invocation logs are not region-bound.
Provider subrequests are constrained by the selected provider endpoint, not by Cloudflare’s placement setting.
Support and operational access are not restricted to personnel in the selected region.

Phaseo will only describe the feature as end-to-end data residency after the gateway, storage, logging, provider, and operational paths are covered by enforceable regional controls.

Overview

Models & Routing

Features

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Reliability & Operations

Platform & Research

Migration Guides

Community

Route text requests by region

Choose an endpoint

Use the Phaseo SDK

Use Chat Completions

Use Responses

Use Messages

Supported request features

Discover models available in a region

Verify the selected gateway

Failure behavior

What regional routing covers

Current limitations

​Choose an endpoint

​Use the Phaseo SDK

​Use Chat Completions

​Use Responses

​Use Messages

​Supported request features

​Discover models available in a region

​Verify the selected gateway

​Failure behavior

​What regional routing covers

​Current limitations

​Related guides

Choose an endpoint

Use the Phaseo SDK

Use Chat Completions

Use Responses

Use Messages

Supported request features

Discover models available in a region

Verify the selected gateway

Failure behavior

What regional routing covers

Current limitations

Related guides