import type { ModelMessage } from './model.js';
import type { SessionEntry } from './types.js';
export interface ContextBudget {
    estimatedTokens: number;
    contextWindowTokens?: number;
    reserveTokens: number;
    compactAtTokens?: number;
    shouldCompact: boolean;
    keepRecentTokens?: number;
}
export interface ContextBudgetOptions {
    contextWindowTokens?: number;
    compactAtTokens?: number;
    reserveTokens?: number;
    keepRecentTokens?: number;
}
export declare function estimateTextTokens(text: string): number;
export declare function estimateModelMessagesTokens(messages: ModelMessage[]): number;
export declare function estimateSessionEntryTokens(entry: SessionEntry): number;
export declare function estimateSessionEntriesTokens(entries: SessionEntry[]): number;
/**
 * Compute model-aware compaction defaults. Reserve is capped at the model's
 * max output because reserving more than the model can emit in one turn
 * wastes context; the preserved tail stays flat because recent-context
 * fidelity depends on the active work, not on the model's total window size.
 */
export declare function deriveCompactionDefaults(input: {
    contextWindowTokens: number;
    maxOutputTokens?: number;
}): {
    reserveTokens: number;
    keepRecentTokens: number;
};
export declare function evaluateContextBudget(messages: ModelMessage[], options?: ContextBudgetOptions): ContextBudget;
export declare function isContextOverflowError(error: unknown): boolean;
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