/**
 * Provider-neutral protocol representation.
 *
 * Provider codecs decode into this representation before application logic
 * consumes the payload. Extensions are deliberately typed and namespaced:
 * provider-specific data must never be smuggled into a provider-neutral field.
 */
export type ExtensionField<Namespace extends string = string, Value = unknown> = Readonly<{
    namespace: Namespace;
    value: Value;
}>;
export type Citation = Readonly<{
    url: string;
    title?: string;
    startIndex?: number;
    endIndex?: number;
    extensions?: readonly ExtensionField[];
}>;
export type AnthropicReasoningExtension = ExtensionField<"anthropic.reasoning", Readonly<{
    index: number;
    phase?: "start" | "delta" | "signature" | "stop" | "block";
    signature?: string;
    redacted?: boolean;
}>>;
export type GoogleReasoningExtension = ExtensionField<"google.reasoning", Readonly<{
    index: number;
    thoughtSignature: string;
}>>;
export type ResponsesReasoningExtension = ExtensionField<"openai.responses.reasoning", Readonly<{
    id?: string;
    summary?: unknown;
    content?: unknown;
}>>;
export type Reasoning = Readonly<{
    text?: string;
    summary?: string;
    encryptedContent?: string;
    extensions?: readonly (AnthropicReasoningExtension | GoogleReasoningExtension | ResponsesReasoningExtension | ExtensionField)[];
}>;
export type ToolCall = Readonly<{
    id: string;
    name: string;
    arguments: unknown;
    execution: "client" | "server";
    extensions?: readonly ExtensionField[];
}>;
export type ToolCallAssemblyExtension = ExtensionField<"routekit.tool-call-assembly", Readonly<{
    index?: number;
    providerIndex?: number;
}>>;
export type ToolResult = Readonly<{
    toolCallId?: string;
    content: string;
    isError: boolean;
    citations: readonly Citation[];
    extensions?: readonly ExtensionField[];
}>;
export type ContentPart = Readonly<{
    type: "text";
    text: string;
    citations?: readonly Citation[];
}> | Readonly<{
    type: "image";
    url: string;
    mediaType?: string;
}> | Readonly<{
    type: "reasoning";
    reasoning: Reasoning;
}> | Readonly<{
    type: "tool_call";
    call: ToolCall;
}> | Readonly<{
    type: "tool_result";
    result: ToolResult;
}>;
export type ConversationMessage = Readonly<{
    role: "system" | "developer" | "user" | "assistant" | "tool";
    content: readonly ContentPart[];
    extensions?: readonly ExtensionField[];
}>;
export type Conversation = Readonly<{
    messages: readonly ConversationMessage[];
    extensions?: readonly ExtensionField[];
}>;
export type Usage = Readonly<{
    inputTokens?: number;
    outputTokens?: number;
    totalTokens?: number;
    cachedInputTokens?: number;
    extensions?: readonly ExtensionField[];
}>;
export type OpenAiUsageExtension = ExtensionField<"openai.chat.usage-details", Readonly<{
    promptTokens?: Readonly<Record<string, unknown>>;
    completionTokens?: Readonly<Record<string, unknown>>;
}>>;
export declare function extensionValue<Namespace extends string, Value>(extensions: readonly ExtensionField[] | undefined, namespace: Namespace): Value | undefined;
export declare function conversationFromOpenAiMessages(messages: readonly Readonly<{
    role?: string;
    content?: unknown;
    tool_call_id?: string;
}>[]): Conversation;
export declare function conversationText(message: ConversationMessage): string;