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 If a page is wrong or out of date, report it with the MCP `submit_feedback` tool.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

# Dynamic turns

> Change the model, instructions, tools, and sampling settings between Go agent turns.

Dynamic turn callbacks let routing react to run state without rebuilding the agent. They run before each model request and receive the current turn context.

```go theme={null}
agent := phaseoagent.CreateAgent(phaseoagent.AgentDefinition{
  ID: "support-agent",
  DynamicModel: func(turn phaseoagent.TurnContext) string {
    if turn.Run.StepCount > 3 { return "openai/gpt-5.4" }
    return "openai/gpt-5.4-nano"
  },
  DynamicInstructions: func(turn phaseoagent.TurnContext) string {
    return fmt.Sprintf("Resolve the request. Current context: %v", turn.Context)
  },
})
```

You can also configure dynamic tools and per-turn `Temperature`, `MaxOutputTokens`, and `TopP` values.

## Let a tool influence the next turn

Set `NextTurn` on a tool to change the immediately following model request. These overrides are stored in paused state, so they survive an approval checkpoint, and expire after the next turn.

Use dynamic callbacks for policy that should be recalculated every turn. Use `NextTurn` for a tool-specific handoff such as switching models after repository inspection.


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