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

> ## Agent Instructions
> Phaseo Gateway base URL: https://api.phaseo.app/v1. Send `Authorization: Bearer $PHASEO_API_KEY` with every request.
> Model IDs look like `provider/model`, for example `openai/gpt-6-astra`. Do not guess IDs: list them with `GET /v1/models` or check https://phaseo.app/models. `phaseo/free` routes to an available free model and needs no wallet balance.
> For new text integrations prefer `POST /v1/responses`. `POST /v1/chat/completions` (OpenAI format) and `POST /v1/messages` (Anthropic format) suit existing code.
> The full API contract is https://phaseo.app/docs/openapi/v1/openapi.yaml. Official SDKs: `@phaseo/sdk` (TypeScript) and `phaseo` (Python), plus Go, C#, PHP, Ruby and Rust.
> Search these docs over MCP at https://phaseo.app/docs/mcp, and install Phaseo skills with `npx skills add https://phaseo.app/docs`. If a page is wrong or out of date, report it with the MCP `submit_feedback` tool.
> Manage Phaseo accounts with the `phaseo` CLI (`npm install -g @phaseo/cli`, then `phaseo login` or `phaseo login --device-code`), the `/v1` Management API or the MCP server at `https://mcp.phaseo.app/mcp?access=manage`. Do not send users to the dashboard for account tasks. A person is still needed for sign-up, approving a sign-in, paying the first top-up on the checkout link that `phaseo credits add` returns when no card is saved, confirming each saved-card top-up from the emailed link, and account security (password, MFA, passkeys). Create API keys with `phaseo keys create --name <name> --json`; never guess one. Credit top-ups need `phaseo login --scopes billing:write` first. Task map: https://phaseo.app/docs/v1/developers/manage-from-an-agent.md.

# Chat completions

> Call /chat/completions with the Ruby SDK.

**Methods**: `client.generate_text(...)`, `client.create_chat_completion(...)`.

### Example

```ruby theme={null}
require 'phaseo_sdk'

client = PhaseoSdk::Phaseo.new(api_key: ENV.fetch("PHASEO_API_KEY"))

response = client.create_chat_completion(
  "model" => "openai/gpt-4o-mini",
  messages: [
    { "role" => "user", "content" => "Write a limerick about lighthouses." }
  ],
  "temperature" => 0.5
)
```

### Key parameters

* `model` (required): Target model id.
* `messages` (required): Ordered messages with roles `user`/`system`/`assistant`/`tool`; content as strings.
* Sampling: `temperature` (0–2), `top_p` (0–1), `top_k` (>=1), `seed` (int, optional).
* Length/penalties: `max_output_tokens` (int), `presence_penalty` and `frequency_penalty` (-2 to 2), `stop` (string|string\[]).
* Tools: `tools` (definitions), `tool_choice` (auto/none/specific tool), `max_tool_calls` (int), `parallel_tool_calls` (bool).
* Logprobs: `logprobs` (bool), `top_logprobs` (0–20).
* Output: `response_format` (json/text), `metadata` (object passthrough), `stream` (bool), `service_tier`.
* Gateway extras: `usage` (bool to request usage), `meta` (bool to include meta block).

### Returns

`ChatCompletionsResponse`


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