@@ -378,7 +378,7 @@ describe('DPoP server validation scenario', () => {
 
   it('anchors iat probes to the server clock (no false failure under skew)', async () => {
     // The server's clock is 30s behind the framework. Without anchoring, the
-    // stale probe (now−301s by the framework clock) looks only ~271s old to the
+    // stale probe (now−303s by the framework clock) looks only ~273s old to the
     // server → inside ±5 min → wrongly accepted → the iat check would FAIL a
     // conformant server. Anchoring to the server's Date header keeps it rejected.
     const checks = await new DPoPServerValidationScenario().run(
 
@@ -266,7 +266,11 @@ algorithms, the 401 challenge format, token audience validation under DPoP, and
     // value into every subsequent proof — including the negatives — so a server
     // that checks the nonce first still evaluates the injected defect rather
     // than merely re-challenging. Refreshing (vs capturing once) keeps this
-    // correct against servers that rotate or single-use their nonces.
+    // correct against servers that ROTATE their nonce (each response carries the
+    // next one). A strict single-use server that re-arms the nonce only via a
+    // use_dpop_nonce challenge (not on ordinary rejections, which §8.2 doesn't
+    // require) can still push alternate negatives to untestable — acceptable, as
+    // those are correctly reported not-testable rather than mis-scored.
     let heldNonce: string | undefined;
 
     const send = async (