/**
 * `fmt` runtime semantics — string interpolation / template.
 *
 * Operational semantics:
 *   1. Parse the `template=` body into literal quasis + interpolation
 *      expressions (reusing KERN's template-literal parser).
 *   2. Evaluate each interpolation left-to-right over the portable scalar
 *      domain, exactly once.
 *   3. Format each value via KERN-canonical formatting (string = exact;
 *      finite integer = base-10; bool = "true"/"false"; null = "null") and
 *      concatenate with the literal quasis.
 *   4. Bind the result to `name` and emit one observable assignment event
 *      `{op:"assign", target:name, value}`. Complete normally.
 *
 * Portability domain:
 *   - `name` is a simple, non-reserved identifier, not already bound.
 *   - Interpolated values are portable scalars; bool and null are admitted
 *     ONLY as the canonical strings "true"/"false"/"null" — never raw host
 *     formatting (Python `str(True)`="True", `str(None)`="None" diverge).
 *     The Python emitter routes every interpolation through `_kern_fmt` to
 *     match TS template-literal coercion; this contract proves that parity.
 *
 * Exclusions (out of domain — fail preconditions):
 *   Floats / non-integers (TS `1.0`->"1" vs Python "1.0"); bigint; objects /
 *   arrays; undefined; escape sequences in the literal text (whose cooked
 *   runtime value would have to be replicated here); the `return=true`
 *   position form (no observable binding to compare).
 */
import { type NodeContract } from './index.js';
export declare const fmtContract: NodeContract;
/** Idempotent registration. Test cleanup that clears the registry must re-call. */
export declare function registerFmtContract(): void;
/** Reset registration flag — only for test cleanup that clears the registry. */
export declare function _resetFmtContractForTest(): void;