fix(sdk): replace z.coerce.bigint with pipe-based coercion for JSON schema compat (#8595)

Author: Xaroz

.changeset/bright-lizards-glow.md

@@ -0,0 +1,5 @@
+---
+'@hyperlane-xyz/sdk': patch
+---
+
+Replaced z.coerce.bigint().positive() with pipe-based coercion in TokenMetadataSchema scale field to fix zod-to-json-schema compatibility in the registry build.

typescript/sdk/src/token/types.ts

@@ -33,6 +33,33 @@ export const contractVersionMatchesDependency = (version: string) => {
 
 export const VERSION_ERROR_MESSAGE = `Contract version must match the @hyperlane-xyz/core dependency version (${CONTRACTS_PACKAGE_VERSION})`;
 
+/**
+ * Coerces bigint or string to bigint with positivity check.
+ * Needed because bigints are serialised as strings in JSON/YAML
+ * and must be converted back on parse. Uses .refine() instead of
+ * .positive() to avoid bigint values in zod-to-json-schema output.
+ */
+const PositiveBigIntFromString = z
+  .union([
+    z.bigint(),
+    z
+      .string()
+      .refine(
+        (s) => {
+          try {
+            BigInt(s);
+            return true;
+          } catch {
+            return false;
+          }
+        },
+        { message: 'Must be a bigint-compatible string' },
+      )
+      .transform((s) => BigInt(s)),
+  ])
+  .pipe(z.bigint())
+  .refine((n) => n > 0n, { message: 'Must be positive' });
+
 export const TokenMetadataSchema = z.object({
   name: z.string(),
   symbol: z.string(),
@@ -45,8 +72,8 @@ export const TokenMetadataSchema = z.object({
         denominator: z.number().int().gt(0),
       }),
       z.object({
-        numerator: z.coerce.bigint().positive(),
-        denominator: z.coerce.bigint().positive(),
+        numerator: PositiveBigIntFromString,
+        denominator: PositiveBigIntFromString,
       }),
     ])
     .optional(),