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 If a page is wrong or out of date, report it with the MCP `submit_feedback` tool.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

# Usage

> Run tool loops, human review, retries, and resumable agents with the Go Agent SDK.

## Prepare the runtime

The Agent SDK does not yet have a public Go module version. Follow the [source installation instructions](https://phaseo.app/docs/v1/sdk-reference/go/agent-sdk-installation.md).

## Quickstart

```go theme={null}
package main

import (
  "context"
  "fmt"

  phaseoagent "github.com/phaseoteam/Phaseo/packages/sdk/agent-sdk-go"
)

func main() {
  client, err := phaseoagent.CreateGatewayAgentClient(phaseoagent.GatewayAgentClientOptions{})
  if err != nil {
    panic(err)
  }

  agent := phaseoagent.CreateAgent(phaseoagent.AgentDefinition{
    ID:           "quickstart-agent",
    Model:        "openai/gpt-5.4-nano",
    Instructions: "Answer concisely and helpfully.",
  })

  result, err := agent.Run(context.Background(), phaseoagent.RunOptions{
    Input:  "Give me one fun fact about cURL.",
    Client: client,
  })
  if err != nil {
    panic(err)
  }

  fmt.Println(result.Output)
}
```

## What it ships

* `CreateAgent(...)`
* `DefineTool(...)`
* `CreateGatewayAgentClient(...)`
* a bounded tool loop over the Phaseo `responses` API

## Advanced runtime

Go supports validators and approvals, HITL and manual tools, progress, recoverable errors, replayable channels, stop helpers, dynamic turns, persisted `NextTurnParams`, normalized usage/cost, and `StateAccessor`.

## Streaming and cancellation

`Agent.Stream(...)` and `Agent.ContinueStream(...)` consume the gateway's Responses SSE stream. Read `Text()` or `Events()` more than once when separate consumers need replay, and call `Cancel()` to cancel the request context. Completed steps retain request IDs, provider metadata, finish reasons, warnings, usage, and cost.

## Related

* [Agent SDK overview](https://phaseo.app/docs/v1/sdk-reference/agent-sdk/overview.md)
* [TypeScript Agent SDK](https://phaseo.app/docs/v1/sdk-reference/typescript/agent-sdk.md)


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