engine

type ChatRequest struct {
	Model        string
	System       string
	Messages     []Message
	Tools        []ToolSpec
	MaxSteps     int
	MaxOutTokens int
}

type EventType string

type Message struct {
	Role    Role   `json:"role"`
	Content string `json:"content"`
	// ToolCalls is set on assistant messages that called tools.
	ToolCalls []ToolCall `json:"toolCalls,omitempty"`
	// ToolCallID + Name identify a tool-result message.
	ToolCallID string `json:"toolCallId,omitempty"`
	Name       string `json:"name,omitempty"`
}

type ModelInfo struct {
	ID            string `json:"id"`
	ContextWindow int    `json:"contextWindow,omitempty"`
}

type Provider interface {
	// Models lists the provider's available models (for the switcher/validation).
	Models(ctx context.Context) ([]ModelInfo, error)
	// Stream runs one turn, invoking exec for tool calls and emitting events on
	// the returned channel until it closes with a done (or error) event.
	Stream(ctx context.Context, req ChatRequest, exec ToolExecutor) (<-chan StreamEvent, error)
}

type Role string

type StreamEvent struct {
	Type     EventType      `json:"type"`
	Text     string         `json:"text,omitempty"`
	ToolName string         `json:"toolName,omitempty"`
	ToolID   string         `json:"toolId,omitempty"`
	Input    map[string]any `json:"input,omitempty"`
	Output   any            `json:"output,omitempty"`
	Err      string         `json:"err,omitempty"`
	Usage    *Usage         `json:"usage,omitempty"`
	// Subagent, when set, marks a tool event as nested work performed by a
	// subagent (the UI prefixes it and styles it distinctly).
	Subagent  string `json:"subagent,omitempty"`
	Truncated bool   `json:"truncated,omitempty"`
}

type ToolCall struct {
	ID    string         `json:"id"`
	Name  string         `json:"name"`
	Input map[string]any `json:"input"`
}

type ToolExecutor interface {
	Execute(ctx context.Context, call ToolCall) (any, error)
}

type ToolSpec struct {
	Name        string         `json:"name"`
	Description string         `json:"description"`
	Parameters  map[string]any `json:"parameters"`
}

type Usage struct {
	InputTokens  int `json:"inputTokens"`
	OutputTokens int `json:"outputTokens"`
}