feat: add batch and intent validation utilities

src/validation.ts

@@ -0,0 +1,18 @@
+import type { DVPIntent } from "./types";
+import { MAX_BATCH_SIZE } from "./constants";
+
+export function validateBatchSize(intents: DVPIntent[]): void {
+  if (intents.length === 0) throw new Error("Empty batch");
+  if (intents.length > MAX_BATCH_SIZE) throw new Error(`Batch size ${intents.length} exceeds max ${MAX_BATCH_SIZE}`);
+}
+
+export function validateIntentDeadline(intent: DVPIntent): void {
+  const now = BigInt(Math.floor(Date.now() / 1000));
+  if (intent.deadline <= now) throw new Error("Intent deadline has passed");
+}
+
+export function validateIntentPair(intent: DVPIntent): void {
+  if (intent.buyer === intent.seller) throw new Error("Buyer and seller must be different");
+  if (intent.amount === 0n) throw new Error("Amount must be non-zero");
+  if (intent.price === 0n) throw new Error("Price must be non-zero");
+}