/**
 * Signal type schema — single source of truth.
 *
 * Closed enum: the six canonical signal types.
 * assertSignalType is the agent-mitigation lever — prevents LLMs
 * from fabricating signal types.
 */
export declare const SIGNAL_TYPES: readonly ["action_item", "commitment", "decision", "key_point", "risk", "summary"];
export type SignalType = (typeof SIGNAL_TYPES)[number];
export declare class InvalidSignalTypeError extends Error {
    readonly name = "InvalidSignalTypeError";
    constructor(value: unknown);
}
export declare function isSignalType(value: unknown): value is SignalType;
export declare function assertSignalType(value: unknown): asserts value is SignalType;
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