/** The core part kind. Bare (not reverse-DNS) because this is Cotal's own reserved primitive, not
 *  a wrapped external vocabulary — SPEC §5's reserved slot, now defined. */
export declare const ARTIFACT_PART_KIND: "artifact";
/**
 * Convert an object-store digest header to Cotal's `sha256:<hex>` identity form.
 *
 * CONVERT BY DECODING. NEVER BY RE-ENCODING. The obvious implementation — hash the bytes, encode
 * the hash, compare the strings — is wrong, and wrong in a way that passes its first test:
 * measured over 2000 digests, re-encoding to standard base64 mismatches **1490 of 2000** (every
 * digest whose bytes land on `+` or `/`), and re-encoding to base64url mismatches **2000 of 2000**
 * (Node strips the padding the store emits). Decoding to hex matched 2000 of 2000. The failure is
 * in the digest CONTENT, not on a branch a smoke would naturally reach, so a re-encoding
 * comparison looks correct until roughly three quarters of real artifacts fail to verify.
 *
 * The base64 form never escapes this function: everything above it speaks `sha256:<hex>`.
 */
export declare function fromObjectStoreDigest(osDigest: string): string;
/**
 * A reference to bytes in the space's artifact store (SPEC §5).
 *
 * There is deliberately no location field. The digest IS the identity: content-addressed, so a
 * re-put of identical bytes is idempotent, and resolution can move from a JetStream Object Store
 * to anything else without a message-shape change.
 */
export interface ArtifactPart {
    kind: typeof ARTIFACT_PART_KIND;
    /** Human name, e.g. `coverage-report.html`. A publisher's claim (see the module doc). */
    name: string;
    /** MIME type. A publisher's claim. */
    mediaType: string;
    /** `sha256:<hex>` over the RAW bytes — the artifact's identity. Self-verifying. */
    digest: string;
    /** Size in bytes. A publisher's claim: never preallocate from it. */
    size: number;
}
/**
 * Structural guard for an `artifact` part.
 *
 * It validates the digest FORM, not just the field's type, because a malformed digest is not a
 * reference to anything — it is a lookup that can only ever fail, and admitting it here would push
 * the refusal to a fetch that reads as "missing artifact" instead of "malformed message". Same
 * reason `size` must be a non-negative safe integer: `-1`, `NaN`, and `1e30` are all "a number".
 */
export declare function isArtifactPart(value: unknown): value is ArtifactPart;
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