/**
 * defineFact — sugar for context-style Injections (data, not behavior).
 *
 * Use for developer-supplied facts the LLM should see in addition to
 * user messages and tool results. Examples: user profile, env info,
 * computed conversation summary, cached config, current time. Distinct
 * from Skills (LLM-activated guidance) and Steering (always-on rules)
 * in INTENT — they share the engine.
 *
 * Produces an `Injection` with:
 *   - flavor: `'fact'`
 *   - trigger: configurable (default `'always'`)
 *   - inject: targets `systemPrompt` OR `messages` (consumer chooses)
 *
 * @example
 *   const userProfile = defineFact({
 *     id: 'user-profile',
 *     data: `Name: ${user.name}, Plan: ${user.plan}, Joined: ${user.joinedAt}`,
 *   });
 *
 *   const turnTime = defineFact({
 *     id: 'turn-time',
 *     data: `Current time: ${new Date().toISOString()}`,
 *     slot: 'messages',
 *     role: 'system',
 *   });
 */
import type { ContextRole } from '../../../events/types.js';
import type { Injection, InjectionContext } from '../types.js';
import type { CachePolicy } from '../../../cache/types.js';
export interface DefineFactOptions {
    readonly id: string;
    readonly description?: string;
    /** The fact (data string) to inject. */
    readonly data: string;
    /**
     * Which slot to land in. Default `'system-prompt'` (most common —
     * facts the model should always have in mind).
     * `'messages'` for facts that should appear inline with the
     * conversation history (use sparingly — increases token cost).
     */
    readonly slot?: 'system-prompt' | 'messages';
    /** When `slot: 'messages'`, the role to use. Default `'system'`. */
    readonly role?: ContextRole;
    /**
     * Trigger control. Defaults to always-on. For conditional facts
     * (e.g., "only show user profile after iteration 3"), pass a
     * predicate via `activeWhen`.
     */
    readonly activeWhen?: (ctx: InjectionContext) => boolean;
    /**
     * Cache policy for this fact injection. Defaults to `'always'` —
     * facts are typically static data the LLM should always have in mind.
     * Override with `'never'` for facts containing volatile content
     * (e.g., a `Current time:` fact); use `{ until }` for time-bounded
     * facts.
     */
    readonly cache?: CachePolicy;
}
export declare function defineFact(opts: DefineFactOptions): Injection;