> ## 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 If a page is wrong or out of date, report it with the MCP `submit_feedback` tool.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.

# Files

> Use the C# SDK for file upload, metadata, and file-content retrieval.

**Methods**: `client.UploadFile()`, `client.ListFiles()`, `client.RetrieveFile()`, `client.RetrieveFileContent()`.

### Example

```csharp theme={null}
var client = new Phaseo(apiKey: apiKey);

var uploaded = await client.UploadFile(new Dictionary<string, object>
{
    ["purpose"] = "batch",
    ["file"] = "data:application/json;base64,eyJ0ZXN0Ijp0cnVlfQ=="
});

var file = await client.RetrieveFile("file_123");
var content = await client.RetrieveFileContent("file_123");
```

> [!NOTE]
>
> `ListFiles()` is wired through the SDK, but `GET /files` currently returns `file_list_not_supported_with_shared_gateway_key`
> on the shared gateway key. Persist uploaded file ids and retrieve them directly instead.


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