> ## Documentation Index
> Fetch the complete documentation index at: https://arizeai-433a7140.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# 05.08.2026: OTLP Project Routing via HTTP Header

> Route OTLP traces to a named Phoenix project by setting the x-project-name HTTP header — no resource attribute required.

**Available in arize-phoenix 15.5.0+**

Phoenix now reads the `x-project-name` HTTP header on incoming OTLP trace exports and routes all spans in the request to that project. The header takes precedence over the `openinference.project.name` resource attribute, so tools like the OpenTelemetry Collector, Openclaw, and Daytona can route traces to the right project without modifying the instrumented application.

## Setting the header

**OpenTelemetry Collector**

```yaml theme={null}
exporters:
  otlphttp:
    endpoint: http://localhost:6006
    headers:
      x-project-name: my-project
```

**Environment variable**

```bash theme={null}
OTEL_EXPORTER_OTLP_HEADERS="x-project-name=my-project"
```

## Precedence rules

| Source                                          | Priority |
| ----------------------------------------------- | -------- |
| `x-project-name` HTTP header                    | Highest  |
| `openinference.project.name` resource attribute | Second   |
| Server default project                          | Fallback |

Every span in the request goes to the same project when the header is set, regardless of what individual spans report in their resource attributes.

## Bug fix: built-in evaluator preserved on dataset evaluator delete

**Available in arize-phoenix 15.5.1+**

Deleting a dataset evaluator link no longer removes the underlying evaluator — it stays available for other datasets.