fix(openconditions): preserve invalid Unicode contract

Author: Medformatik

packages/openconditions-contrib-client/src/conformance.test.ts

@@ -54,6 +54,10 @@ describe("cross-repo conformance", () => {
   it("canonicalClaimBytes matches the pinned RFC 8785 hex", () => {
     expect(toHex(canonicalClaimBytes(FIXED_CLAIM))).toBe(PINNED_CLAIM_HEX);
   });
+
+  it("rejects invalid Unicode through the public TypeError contract", () => {
+    expect(() => canonicalClaimBytes({ note: "\ud800" })).toThrow(TypeError);
+  });
 });
 
 describe("round-trip signing", () => {

packages/openconditions-contrib-client/src/jcs.ts

@@ -15,8 +15,8 @@ const encoder = new TextEncoder();
  * `canonicalize` package (the JCS reference implementation, EXACT version
  * @openconditions/contrib-core uses); nothing here is hand-rolled.
  *
- * @throws TypeError when the value contains a non-finite number, is nested too
- *   deeply to canonicalize, or is not JSON-serializable at all
+ * @throws TypeError when the value contains a non-finite number or lone
+ *   surrogate, is nested too deeply to canonicalize, or is not JSON-serializable at all
  *   (undefined, function, symbol); Error on a circular reference.
  */
 export function canonicalClaimBytes(claim: unknown): Uint8Array<ArrayBuffer> {
@@ -30,6 +30,9 @@ export function canonicalClaimBytes(claim: unknown): Uint8Array<ArrayBuffer> {
     if (err instanceof Error && /NaN|Infinity/.test(err.message)) {
       throw new TypeError("canonicalClaimBytes: non-finite number in value");
     }
+    if (err instanceof Error && /Lone surrogate/.test(err.message)) {
+      throw new TypeError("canonicalClaimBytes: lone surrogate in value");
+    }
     throw err;
   }
   if (text === undefined) {