Request Normalizer Capability

The request normalizer capability rewrites a request payload before it enters the execution path into a shape that later host stages can handle more easily. It is commonly used to fill defaults, fix provider-specific payloads, or implement lightweight request rewrites.

Capability Field

{
  "capabilities": {
    "request_normalizer": true
  }
}

Source references:

• sdk/pluginapi/types.go: RequestNormalizer, RequestTransformRequest, PayloadResponse
• sdk/pluginabi/types.go: request.normalize
• internal/pluginhost/adapters.go: NormalizeRequest, callRequestNormalizer

Example references:

• examples/plugin/request-normalizer/go/main.go
• examples/plugin/codex-service-tier/go/main.go
• examples/plugin/codex-service-tier/README.md
• examples/plugin/simple/go/main.go: MethodRequestNormalize

Methods

Method	Purpose
request.normalize	Returns a new request body based on format, model, and stream flag.

Request

{
  "FromFormat": "chat-completions",
  "ToFormat": "codex",
  "Model": "gpt-5.5",
  "Stream": false,
  "Body": "base64-request-body"
}

Response

{
  "Body": "base64-normalized-body"
}

Example: Codex Service Tier

examples/plugin/codex-service-tier is a request normalizer example closer to real usage. It reads the fast field from plugin configuration and modifies Codex requests when all of these conditions match:

• ToFormat is codex
• Model is gpt-5.5
• fast is true

Configuration example:

plugins:
  configs:
    codex-service-tier:
      enabled: true
      priority: 1
      fast: true

Development Notes

• Request normalization should stay narrow and predictable. It should not take on executor responsibilities.
• An empty Body prevents the host from applying an effective rewrite. Return the original Body when the original content should be kept.
• Plugin-owned configuration is passed to plugin.register and plugin.reconfigure through config_yaml; parse and cache it there.