export interface RuntimeContextOptions {
    now?: Date;
    timezone?: string | null;
    /**
     * Delegation depth of the agent this prompt is built for. 0 = the top-level
     * (user-facing) agent, 1 = a sub-agent spawned by the top-level agent, and so
     * on. Threaded through so a spawned sub-agent knows how deep it sits and
     * whether it is still allowed to delegate further. Omitted (or 0) for the
     * top-level chat. See `MAX_SUBAGENT_DELEGATION_DEPTH`.
     */
    delegationDepth?: number;
}
/**
 * Default hard cap on sub-agent delegation depth. The top-level agent is depth
 * 0 and may spawn sub-agents (depth 1); those may spawn once more (depth 2);
 * a spawn that would create a depth-3 sub-agent is refused. Borrowed from the
 * "sub-agents must not infinitely spawn sub-agents" runaway/cost safety rail.
 *
 * Override at deploy time via `AGENT_NATIVE_MAX_SUBAGENT_DEPTH` (see
 * `resolveMaxSubagentDelegationDepth`).
 */
export declare const MAX_SUBAGENT_DELEGATION_DEPTH = 2;
/** Env var name that overrides the default sub-agent delegation-depth cap. */
export declare const MAX_SUBAGENT_DELEGATION_DEPTH_ENV = "AGENT_NATIVE_MAX_SUBAGENT_DEPTH";
/**
 * Resolve the effective maximum sub-agent delegation depth.
 *
 * Reads `AGENT_NATIVE_MAX_SUBAGENT_DEPTH` and, when it parses to a finite
 * non-negative integer, clamps it to `[0, MAX_SUBAGENT_DELEGATION_DEPTH_CEILING]`.
 * Any invalid value (non-numeric, negative, NaN, Infinity, fractional) falls
 * back to `MAX_SUBAGENT_DELEGATION_DEPTH` so a typo can never silently disable
 * the guardrail. `0` is a valid override meaning "no sub-agents may be spawned".
 */
export declare function resolveMaxSubagentDelegationDepth(env?: Record<string, string | undefined>): number;
export declare function isValidTimezone(timezone: string): boolean;
export declare function formatDateTime(date: Date, timezone: string): string;
export declare function formatDate(date: Date, timezone: string): string;
/**
 * Build the stable, day-granular runtime-context block embedded in the
 * SYSTEM prompt.
 *
 * This block is part of the cached prompt prefix, so it must stay byte-for-
 * byte identical across requests within the same calendar day — anything
 * with sub-day granularity (a millisecond/second timestamp) here would
 * invalidate the Anthropic prompt cache on every single turn, since the
 * cache matches prefixes and this block sits near the start of the system
 * prompt. Precise current time is injected separately, per-turn, into the
 * USER message instead (see `buildCurrentTimeUserContext` below) so the
 * model can still answer "what time is it" accurately without destabilizing
 * the cached prefix.
 */
export declare function buildRuntimeContextPrompt(options?: RuntimeContextOptions): string;
export interface CurrentTimeContextOptions {
    now?: Date;
    timezone?: string | null;
}
/**
 * Build the precise, per-turn current-time block injected into the USER
 * message (not the system prompt). Millisecond-precision time changes every
 * request, so it must never live in the cached system-prompt prefix — see
 * `buildRuntimeContextPrompt`. This follows the same volatile-context pattern
 * as the current-screen/current-url/selection blocks in production-agent.ts.
 */
export declare function buildCurrentTimeUserContext(options?: CurrentTimeContextOptions): string;
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