/**
 * Pluggable embedding backends.
 *
 * Privacy-by-default: workspace source is only ever sent to explicitly
 * configured LOCAL (loopback) backends. Remote OpenAI-compatible embedding is
 * disabled unless explicitly enabled by policy. A deterministic fixture backend
 * provides the no-paid-dependency test path.
 */
import type { EmbeddingBackend, EmbeddingRequest, EmbeddingResult } from "./types.js";
export type EmbeddingMode = "disabled" | "fixture" | "local" | "remote";
export interface EmbeddingConfig {
    mode: EmbeddingMode;
    modelId?: string;
    dimensions?: number;
    maximumInputTokens?: number;
    endpoint?: string;
    apiKey?: string;
    purpose?: string;
    allowed?: boolean;
}
export declare const DEFAULT_DIMENSIONS = 32;
export declare const DEFAULT_MAX_TOKENS = 2048;
/** Deterministic fixture embedder: stable hashed bag-of-ngrams vector. */
export declare class FixtureEmbeddingBackend implements EmbeddingBackend {
    backendId: string;
    modelId: string;
    dimensions: number;
    maximumInputTokens: number;
    local: boolean;
    constructor(modelId?: string, dimensions?: number);
    embed(request: EmbeddingRequest): Promise<EmbeddingResult>;
    /** Deterministic unit-norm vector derived from token hashes (ngram coverage). */
    vectorFor(text: string): number[];
}
/** Drag a seed-based deterministic vector (for test stability across runs). */
export declare function deterministicSeed(): string;
/** Local loopback OpenAI-compatible embedding backend. */
export declare class LocalEmbeddingBackend implements EmbeddingBackend {
    backendId: string;
    modelId: string;
    dimensions: number;
    maximumInputTokens: number;
    local: boolean;
    private endpoint;
    private apiKey?;
    constructor(config: {
        endpoint: string;
        modelId: string;
        dimensions: number;
        maximumInputTokens?: number;
        apiKey?: string;
    });
    assertLoopback(): void;
    embed(request: EmbeddingRequest): Promise<EmbeddingResult>;
}
/** A disabled backend that always throws — retrieval degrades to lexical/symbolic. */
export declare class DisabledEmbeddingBackend implements EmbeddingBackend {
    backendId: string;
    modelId: string;
    dimensions: number;
    maximumInputTokens: number;
    local: boolean;
    embed(): Promise<EmbeddingResult>;
}
/** Resolve config into an active backend. */
export declare function resolveEmbeddingBackend(config?: EmbeddingConfig): EmbeddingBackend;
/** Impacts an accurate per-chunk token estimate (rough, deterministic bound). */
export declare function estimateTokens(text: string): number;
/** Deterministic token-aware truncation of embedding text. */
export declare function truncateForEmbedding(text: string, maxTokens: number): string;
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