/**
 * Utility for extracting incomplete message state from historical messages
 * Used to continue building messages across realtime connections
 */
import type { ProcessedMessage } from '../types';
import type { InitializeExtras } from '../stream/chat-stream-reducer';
/**
 * What the realtime accumulator needs to RESUME an unfinished turn.
 *
 * DERIVED, not restated: this is exactly the reducer's `InitializeExtras`
 * minus `escalatedApprovals` (which only the live stream can produce — it has
 * no historical representation to extract). Hosts pass the result straight
 * into `reducer.initializeWithState(messages, extras)`, so the two must not
 * drift; a structural coincidence is not a contract.
 */
export type IncompleteMessageState = Omit<InitializeExtras, 'escalatedApprovals'>;
/**
 * Extract incomplete message state from the last historical assistant message
 * Used to initialize realtime chunk processor when continuing an incomplete message
 */
export declare function extractIncompleteMessageState(lastMessage: ProcessedMessage | undefined): IncompleteMessageState | undefined;
/**
 * THREAD-level generalization of `extractIncompleteMessageState`: given a
 * processed thread, look at the TRAILING RUN of consecutive assistant
 * messages (not just the very last row), flatten it to one segment list, and
 * ask the single-message extractor whether that tail is unfinished.
 *
 * Why the run and not the last row: the backend can split one logical turn
 * across several assistant messages (a preamble bubble, then the approval
 * card, then the continuation). The unfinished artifact — a pending approval,
 * an EXECUTING_TOOL with no result, an open compaction — can therefore sit in
 * an EARLIER bubble of the same trailing run, and a last-row-only check
 * reports "complete" while the turn is very much still in flight.
 *
 * SSOT for every "is the tail incomplete?" question — the NATS adapter (which
 * used to inline the single-row check) and hosts replaying a stored thread
 * both call this instead of re-deriving the walk.
 *
 * A trailing non-assistant row (user / error) means the last turn closed →
 * `undefined`.
 */
export declare function extractIncompleteTailState(messages: readonly ProcessedMessage[] | undefined): IncompleteMessageState | undefined;
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