/**
 * density-filter — sentence-level compression with FNV-1a deduplication.
 *
 * Used for user-prompt compression (userPromptHook) and sdk-context
 * compression (sdkContextHook) where no query context is available.
 * Selects sentences by length-based score within a token budget.
 */
export declare function estimateTokens(text: string): number;
/**
 * Density-filter text to the target token budget.
 *
 * Scores sentences by length (longer = higher score, capped at 40 tokens).
 * Deduplicates by FNV-1a hash. Reconstructs in original document order.
 *
 * @param text            Input text to compress.
 * @param targetReduction Fraction to remove (0–1). E.g. 0.22 removes ~22%.
 * @returns Compressed text, or original if nothing could be filtered.
 */
export declare function densityFilterText(text: string, targetReduction: number): string;
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