export type SessionStartReason = "startup" | "reload" | "new" | "resume" | "fork";
export type SessionStartEvent = {
    reason: SessionStartReason;
    previousSessionFile?: string;
};
export type SessionShutdownEvent = {
    reason: string;
    targetSessionFile?: string;
};
/** A custom session entry, as built by sessionManager.appendCustomEntry(customType, data). */
export type CustomEntry = {
    type?: string;
    customType?: string;
    data?: unknown;
    id?: string;
};
export type EntryAppendedEvent = {
    entry: CustomEntry;
};
export type TurnEndEvent = Record<string, never>;
/** Themed rendering primitives handed to a widget callback. */
export interface Theme {
    fg(color: string, text: string): string;
    bold(text: string): string;
}
/** Minimal TUI handle passed to the widget factory. */
export interface TuiApi {
    width?: number;
    requestRender?(): void;
}
/** A widget component: `render(width)` returns the text to draw. pi's layout calls this
 *  with the available column width (Container.render(width) → child.render(width)); every
 *  returned line MUST fit within it or the TUI aborts doRender. `invalidate` is called on
 *  theme change so the factory can re-capture. */
export interface WidgetComponent {
    render(width?: number): string[];
    invalidate?(): void;
}
/** The widget factory registered via setWidget — returns a component, NOT a raw string. */
export type WidgetFactory = (tui: TuiApi, theme: Theme) => WidgetComponent;
/** The UI surface (present only in a TUI session). Captured from a hook's ctx. */
export interface UIContext {
    setWidget(key: string, factory: WidgetFactory | undefined, options?: {
        placement?: "aboveEditor" | "belowEditor" | string;
    }): void;
    setStatus(key: string, text: string | undefined): void;
    setFooter(render: ((tui: TuiApi, theme: Theme, footerData?: unknown) => string) | undefined): void;
    notify?(message: string, level?: "info" | "warn" | "error"): void;
}
export interface ExtensionContext {
    cwd: string;
    mode: "tui" | "rpc" | "json" | "print";
    hasUI: boolean;
    signal?: AbortSignal;
    ui?: UIContext;
}
export type AutocompleteItem = {
    value: string;
    label?: string;
};
export type CommandSpec = {
    description: string;
    handler: (args: string, ctx: ExtensionContext) => void | Promise<void>;
    getArgumentCompletions?: (prefix: string) => AutocompleteItem[] | null;
};
type BusHandler = (data: unknown) => void;
export interface ExtensionAPI {
    on(event: "session_start", handler: (event: SessionStartEvent, ctx: ExtensionContext) => void | Promise<void>): void;
    on(event: "session_shutdown", handler: (event: SessionShutdownEvent, ctx: ExtensionContext) => void | Promise<void>): void;
    on(event: "entry_appended", handler: (event: EntryAppendedEvent, ctx: ExtensionContext) => void | Promise<void>): void;
    on(event: "turn_end", handler: (event: TurnEndEvent, ctx: ExtensionContext) => void | Promise<void>): void;
    /** In-process pub/sub bus (subagents:* etc.). Handler gets only data, no ctx. */
    events: {
        on(channel: string, handler: BusHandler): () => void;
        emit(channel: string, data?: unknown): void;
    };
    /** Persist a custom session entry; emits `entry_appended` (also forwarded over RPC). */
    appendEntry(customType: string, data?: unknown): string;
    /** Register a slash command (e.g. `/plan`). */
    registerCommand(name: string, spec: CommandSpec): void;
}
export {};