/**
 * Hashing helpers. Conversation identity matches OpenRouter's own
 * fingerprinting (sha256 over system prompt + first non-system message),
 * so our `session_id` groups the same traffic their logs do.
 */

export function sha256Hex(input: string): string {
	return new Bun.CryptoHasher("sha256").update(input).digest("hex");
}

/** First 32 hex chars of sha256(systemText NUL firstNonSystemText). */
export function conversationKeyOf(systemText: string, firstNonSystemText: string): string {
	return sha256Hex(systemText + " " + firstNonSystemText).slice(0, 32);
}