export declare const BACKENDS_ENV = "AGENTPRISM_BACKENDS";
/** How to spawn (and optionally pre-configure) one custom ACP backend. */
export interface CustomBackendConfig {
    /** The ACP server executable (absolute path or on PATH). */
    command: string;
    /** Arguments for the command. Default []. */
    args?: string[];
    /** Extra environment for the subprocess, merged OVER the inherited process.env. */
    env?: Record<string, string>;
    /** Static `_meta` sent on every session/new for this backend (backend-level defaults).
     *  Per-call RunOptions.meta merges over these; backend-computed keys win over both. */
    sessionMeta?: Record<string, unknown>;
    /** agentCapabilities._meta namespace + bare `_meta` keys this custom agent negotiates.
     *  Undefined means the backend's custom `_meta`, if any, is never gated. */
    customCapabilities?: {
        readonly namespace: string;
        readonly gatedKeys: readonly string[];
    };
    /** Enable client-hosted StructuredOutput MCP tool injection when schema runs negotiate HTTP MCP.
     *  Default true; set false for custom agents that should use only the generic prompt/_meta path. */
    structuredOutputTool?: boolean;
}
/** A validated registry entry: the (lowercased) name plus its config. */
export interface RegisteredBackend extends CustomBackendConfig {
    name: string;
}
export type BackendRegistry = ReadonlyMap<string, RegisteredBackend>;
/**
 * Resolve the custom-backend registry: env-declared backends first, programmatic `backends`
 * merged over them (option wins per name). Throws on malformed JSON, invalid names/configs, or
 * malformed configs — a misconfigured registry should fail LOUDLY at construction, not silently
 * misroute at run time. A name matching a built-in is valid and takes routing priority.
 */
export declare function resolveBackendRegistry(option?: Record<string, CustomBackendConfig>, env?: NodeJS.ProcessEnv): BackendRegistry;
/**
 * Layer a RUN-SCOPED registry (an approved script-declared `meta.backends`, arriving via
 * RunOptions.backends) UNDER the host registry: run entries are validated with the same rules
 * and a host-registered name always wins on conflict — a script can never hijack a name the
 * operator configured. Returns the host registry unchanged when the run declares nothing.
 */
export declare function registryWithRunBackends(host: BackendRegistry, run?: Record<string, CustomBackendConfig>): BackendRegistry;
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