import type { ChatHistoryEntry } from './chat-runtime-adapters.js';
export declare const PROACTIVE_COMPACTION_RATIO = 0.75;
export declare const RECENT_TURNS_KEPT = 4;
/**
 * Rough token estimate for a prompt. The model budgets in `context-builder`
 * are expressed in BYTES, so callers compare bytes-to-bytes; this helper exists
 * for callers/tests that want a token-ish number (≈ bytes / 4 for English text).
 */
export declare function estimateTokens(text: string): number;
/** Byte size of a string (the unit `getContextBudgetForModel` returns). */
export declare function estimateBytes(text: string): number;
/**
 * Decide whether the outgoing prompt should be compacted before sending.
 * Compares the estimated prompt byte size against the model's byte budget and
 * trips once the prompt crosses PROACTIVE_COMPACTION_RATIO of that budget.
 */
export declare function shouldCompactProactively(promptBytes: number, budgetBytes: number): boolean;
/**
 * True when CLI stderr / output signals a context-overflow ("prompt too long")
 * failure that compaction-and-retry can recover from. Deliberately permissive —
 * the precise wording varies by CLI version, so prefer false positives (a
 * harmless extra compaction) over missing a real overflow.
 */
export declare function isContextOverflowError(text: string | null | undefined): boolean;
/**
 * Build a concise, dependency-free digest of the conversation. Preserves the
 * thread's load-bearing state verbatim: the first user goal, any task ids, and
 * any explicit decisions, plus short per-turn takeaways. This avoids a separate
 * LLM summarization call (latency/cost/another failure mode); an LLM summary is
 * a possible future refinement noted in the issue.
 *
 * @param activeTaskId optionally pin the active task id (e.g. from the workflow)
 */
export declare function summarizeHistory(history: ChatHistoryEntry[], activeTaskId?: string): string;
export type CompactionResult = {
    /** Whether compaction actually changed the history. */
    compacted: boolean;
    /** The deterministic summary block (empty when not compacted). */
    summary: string;
    /**
     * The compacted history to send to the model: a single synthetic assistant
     * "summary" turn followed by the most recent verbatim turns. When not
     * compacted this is the original history unchanged.
     */
    history: ChatHistoryEntry[];
};
/**
 * Collapse older history into a summary turn, keeping the most recent
 * `recentTurns` verbatim. Returns the original history untouched when it is
 * already short enough to keep all turns verbatim.
 */
export declare function compactHistory(history: ChatHistoryEntry[], options?: {
    recentTurns?: number;
    activeTaskId?: string;
}): CompactionResult;
/**
 * Render a history list as the "Prior conversation" text block injected into the
 * outgoing prompt. Mirrors the formatting used by the /send handler so the
 * proactive path can measure and compact the exact text that would be sent.
 */
export declare function renderHistoryBlock(history: ChatHistoryEntry[]): string;