/**
 * Key canonicalization + dev guards for `useData`.
 *
 * A key does three jobs at once — reactive trigger, cache/SSR identity, and
 * fetcher input — so identity must be canonical: tuples serialize to JSON
 * (`['user', 7]` → `'["user",7]"`), which also keeps them disjoint from
 * plain string keys used by other producers in the shared SSR blob (a
 * canonical tuple always starts with `[`).
 *
 * Pure module: no web globals, no blob access (that lives in ./restore.ts).
 */
/** All skip values — including '' so `str && tuple` getters type cleanly. */
export type Falsy = null | undefined | false | '';
/** Tuple elements are JSON primitives only — identity is canonical JSON. */
export type KeyTuple = readonly (string | number | boolean | null)[];
export type KeyValue = string | KeyTuple;
/**
 * A server-fn reference usable AS a key (rfc-server §6.2, #452): any
 * callable carrying the build-stamped stable key (`<stableId>/<name>`).
 * Structural — runtime-core never imports `@sigx/server`; the brand is the
 * stamped property. As a key it canonicalizes to the key STRING in place
 * (`useData(getVotes)` → `'["<stableId>/getVotes"]'`), so a mutation's
 * fn-ref `invalidates` pattern matches by tuple prefix.
 */
export interface ServerFnDataRef<A extends KeyTuple = KeyTuple, R = unknown> {
    (...args: A): R | Promise<R>;
    /** Build-stamped stable key (`<stableId>/<name>`). */
    __sigxKey: string;
}
/** Brand check — a function whose `__sigxKey` is a non-empty string. */
export declare function isServerFnDataRef(value: unknown): value is ServerFnDataRef;
/** Per-cell dedup flags for the soft key warnings (warn once per cell). */
export interface KeyWarnFlags {
    emptyString?: boolean;
    emptyTuple?: boolean;
    negZero?: boolean;
}
/**
 * Resolve a key result to its canonical string identity, or `null` when the
 * read should be skipped (state `'idle'`, fetcher not run).
 *
 * Dev guards (stripped in production):
 * - `''` ⇒ skip + warn (almost always an interpolation bug)
 * - empty tuple ⇒ skip + warn
 * - non-primitive tuple element ⇒ throw
 * - non-finite number ⇒ throw (NaN/±Infinity JSON to `null` — identity collision)
 * - `-0` ⇒ warn (canonicalizes to `0`)
 */
export declare function resolveKeyResult(raw: KeyValue | Falsy, warns?: KeyWarnFlags): string | null;
/**
 * Classify `useData`'s first argument. A static tuple is rejected by design:
 * a tuple exists to carry parameters, and parameters that change belong in a
 * reactive getter — a static tuple can never change.
 */
export declare function assertKeyArgShape(first: unknown): 'static' | 'getter';
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