/**
 * Continuous assistant response text tracking via event hook.
 *
 * Listens for `message.updated` and `message.part.updated` events from
 * the OpenCode `event` hook to build a live cache of the latest assistant
 * response text per session. Eliminates the need to poll `getSessionMessages()`
 * in `handleSessionIdle()` for last-message fallback.
 *
 * The cache is bounded to 5 entries (FIFO eviction) to prevent unbounded
 * memory growth over long plugin lifetimes.
 *
 * @module session-tracker/capture/last-message-capture
 */
/**
 * Continuously tracks the latest assistant response text from
 * `message.updated` / `message.part.updated` events.
 *
 * Maintains a bounded FIFO cache keyed by `messageID` with at most
 * 5 entries. Provides lookup by sessionID for `handleSessionIdle()`.
 *
 * The optional `onLastMessageUpdate` callback allows wiring to
 * `SessionWriter.updateFrontmatter()` for continuous `.md` frontmatter
 * updates as text streams in.
 */
export declare class LastMessageCapture {
    /** Bounded cache: messageID → { sessionID, lastText }. */
    private messages;
    /** FIFO insertion order tracking for bounded eviction. */
    private insertionOrder;
    /** Maximum number of message entries before FIFO eviction. */
    private readonly maxEntries;
    /** Optional callback invoked when a non-empty text update arrives. */
    private readonly onLastMessageUpdate?;
    /**
     * @param deps - Optional dependencies.
     * @param deps.onLastMessageUpdate - Callback invoked when a non-empty
     *   assistant text part is captured. Receives the sessionID and the
     *   full text. Useful for wiring to `SessionWriter.updateFrontmatter()`.
     */
    constructor(deps?: {
        onLastMessageUpdate?: (sessionID: string, text: string) => void;
    });
    /**
     * Handles an event from the OpenCode `event` hook pipeline.
     *
     * Processes:
     * - `message.updated` — registers a new message entry when the role is
     *   `"assistant"`, using `event.properties.info.id` as the key.
     * - `message.part.updated` — updates the tracked `lastText` for an
     *   existing message when the part type is `"text"`. Invokes the
     *   `onLastMessageUpdate` callback when the accumulated text is non-empty.
     *
     * All other event types are silently ignored.
     *
     * @param event - Raw event payload from the OpenCode event hook.
     */
    handleEvent(event: Record<string, unknown>): void;
    /**
     * Processes a `message.updated` event.
     *
     * Extracts the role, messageID, and sessionID from the event properties.
     * If the role is `"assistant"`, registers the messageID in the bounded
     * cache with an empty `lastText` (accumulated later via part updates).
     *
     * @param event - The raw event payload.
     */
    private handleMessageUpdated;
    /**
     * Processes a `message.part.updated` event.
     *
     * Extracts the `messageID` and part data from the event. If the part
     * type is `"text"` and the messageID is already tracked in the cache,
     * appends the new text to the existing `lastText`. Invokes the
     * `onLastMessageUpdate` callback when the accumulated text is non-empty.
     *
     * @param event - The raw event payload.
     */
    private handleMessagePartUpdated;
    /**
     * Retrieves the latest tracked assistant text for a given session.
     *
     * Iterates through tracked entries in insertion order (most recent last)
     * and returns the first matching non-empty combined text (including formatted thinking).
     * Returns `undefined` if no assistant text has been tracked for this session.
     *
     * @param sessionID - The session identifier to look up.
     * @returns The latest assistant text, or `undefined` if not found.
     */
    getLastMessage(sessionID: string): string | undefined;
    /**
     * Removes all tracked message entries for a given session.
     *
     * Called when a session terminates (session.deleted, session.error) to
     * free cache space and prevent stale text from being returned for
     * recycled session IDs.
     *
     * @param sessionID - The session identifier to clear.
     */
    clearSession(sessionID: string): void;
}
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