/**
 * Token Estimation Utilities
 *
 * Provides character-based token estimation with per-provider adjustment
 * multipliers. Uses the same approach as Continue (gpt-tokenizer baseline
 * + provider multipliers) but without requiring a tokenizer dependency.
 *
 * Multiplier sources: Continue project's getAdjustedTokenCount.ts
 * - Anthropic: 1.23x (Anthropic tokenizer produces ~23% more tokens)
 * - Google (AI Studio / Vertex): 1.18x
 * - Mistral/Codestral: 1.26x
 * - OpenAI/GPT: 1.0x (baseline)
 */
import type { ChatMessage } from "../types/index.js";
/** Characters per token for English text */
export declare const CHARS_PER_TOKEN = 4;
/** Characters per token for code */
export declare const CODE_CHARS_PER_TOKEN = 3;
/**
 * Safety margin: additive fraction of baseTokens added to the provider-adjusted estimate.
 * Using additive margin prevents compounding with provider multipliers.
 *
 * Old behavior: baseTokens * providerMultiplier * 1.15  (compounding)
 *   e.g. Anthropic: baseTokens * 1.23 * 1.15 = baseTokens * 1.4145
 * New behavior: baseTokens * providerMultiplier + baseTokens * 0.05  (additive)
 *   e.g. Anthropic: baseTokens * 1.23 + baseTokens * 0.05 = baseTokens * 1.28
 */
export declare const TOKEN_SAFETY_MARGIN_ADDITIVE = 0.05;
/** @deprecated Use TOKEN_SAFETY_MARGIN_ADDITIVE instead. Kept for backward compatibility. */
export declare const TOKEN_SAFETY_MARGIN = 1.15;
/** Message framing overhead in tokens (role + delimiters) */
export declare const TOKENS_PER_MESSAGE = 4;
/** Conversation-level overhead in tokens */
export declare const TOKENS_PER_CONVERSATION = 24;
/** Image token estimate (flat) */
export declare const IMAGE_TOKEN_ESTIMATE = 1024;
/**
 * Get the token multiplier for a given provider.
 */
export declare function getProviderMultiplier(provider?: string): number;
/**
 * Estimate token count for a string.
 *
 * @param text - Input text
 * @param provider - Optional provider for multiplier adjustment
 * @param isCode - Whether the text is code (uses CODE_CHARS_PER_TOKEN)
 * @returns Estimated token count
 */
export declare function estimateTokens(text: string, provider?: string, isCode?: boolean): number;
/**
 * Serialize an arbitrary value for estimation. Never throws: `JSON.stringify`
 * raises RangeError once a value exceeds V8's max string length, and a tool
 * argument blob is exactly the shape that gets there. A payload that large is
 * charged at the fallback size rather than aborting the estimate (and with it
 * the whole turn).
 */
/**
 * Serialize a value for token estimation. The fallback is deliberately huge:
 * an estimator that cannot measure a value must over-report, so a budget guard
 * fires rather than waving through content it failed to size.
 */
export declare function serializeForEstimate(value: unknown): string;
/**
 * Estimate token count for a single ChatMessage.
 * Includes message framing overhead.
 *
 * Counts `content` AND `args`. A `tool_call` is persisted with an EMPTY
 * `content` and its entire payload in `args` (see flushPendingToolData),
 * so a content-only estimate scored a 39 KB Write call at ~28 tokens against a
 * real cost near 9,750 — the budget checker, the compaction trigger and the
 * summarization threshold were all blind to the single largest source of
 * context growth in an agentic session.
 *
 * `result` is deliberately NOT counted: `result.result` is re-hydrated FROM
 * `content` at read time (redisConversationMemoryManager), so counting both
 * double-bills the same bytes. Only `result.error`, which has no counterpart in
 * `content`, is included.
 */
export declare function estimateMessageTokens(message: ChatMessage | {
    role: string;
    content: unknown;
}, provider?: string): number;
/**
 * Estimate total token count for an array of messages.
 * Includes conversation-level overhead.
 */
export declare function estimateMessagesTokens(messages: Array<ChatMessage | {
    role: string;
    content: unknown;
}>, provider?: string): number;
/**
 * Truncate text to fit within a token budget.
 * Tries to cut at sentence or word boundaries.
 *
 * @param text - Input text
 * @param maxTokens - Maximum tokens allowed
 * @param provider - Optional provider for multiplier
 * @returns Truncated text with "..." suffix if truncated
 */
export declare function truncateToTokenBudget(text: string, maxTokens: number, provider?: string): {
    text: string;
    truncated: boolean;
};