/** True when the name contains an ASCII `A`-`Z`, i.e. is not already the wire spelling. */
export declare function hasUpperAscii(name: string): boolean;
/** True when every name in the record is already the lowercase wire spelling. */
export declare function headerKeysAllLowercase(record: Readonly<Record<string, unknown>>): boolean;
/** Record the {@link LOWERCASE_HEADER_KEYS} proof on a record the caller has just verified. */
export declare function markLowercaseHeaderKeys(record: Record<string, string | readonly string[]>): void;
/** True when this record carries the proof - never a claim the reader has to re-check. */
export declare function hasLowercaseHeaderKeysMark(record: Readonly<Record<string, unknown>>): boolean;
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