fix: ListTask's statusTimestampAfter only accept ISO 8601 format (#640)

Fixes #639 🦕

Signed-off-by: Jeff Mesnil <jmesnil@ibm.com>

Author: jmesnil

spec-grpc/src/main/java/io/a2a/grpc/utils/JSONRPCUtils.java

@@ -489,7 +489,7 @@ private static JsonProcessingException convertProtoBufExceptionToJsonProcessingE
         }
 
         // Extract field name if present in error message - check common prefixes
-        String[] prefixes = {"Cannot find field: ", "Invalid value for", "Invalid enum value:"};
+        String[] prefixes = {"Cannot find field: ", "Invalid value for", "Invalid enum value:", "Failed to parse"};
         for (String prefix : prefixes) {
             if (message.contains(prefix)) {
                 return new InvalidParamsJsonMappingException(ERROR_MESSAGE.formatted(message.substring(message.indexOf(prefix) + prefix.length())), id);

spec-grpc/src/test/java/io/a2a/grpc/utils/JSONRPCUtilsTest.java

@@ -7,6 +7,7 @@
 import static org.junit.jupiter.api.Assertions.assertInstanceOf;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.fail;
 
 import com.google.gson.JsonSyntaxException;
 import io.a2a.jsonrpc.common.json.InvalidParamsJsonMappingException;
@@ -143,6 +144,42 @@ public void testParseInvalidProtoStructure_ThrowsInvalidParamsJsonMappingExcepti
         assertEquals(ERROR_MESSAGE.formatted("invalid_field in message a2a.v1.CreateTaskPushNotificationConfigRequest"), exception.getMessage());
     }
 
+    @Test
+    public void testParseNumericalTimestampThrowsInvalidParamsJsonMappingException() {
+        String valideRequest = """
+            {
+              "jsonrpc": "2.0",
+              "method": "ListTasks",
+              "id": "1",
+              "params": {
+                "statusTimestampAfter": "2023-10-27T10:00:00Z"
+              }
+            }
+            """;
+        String invalidRequest = """
+            {
+              "jsonrpc": "2.0",
+              "method": "ListTasks",
+              "id": "2",
+              "params": {
+                "statusTimestampAfter": "1"
+              }
+            }
+            """;
+
+        try {
+            A2ARequest<?> request = JSONRPCUtils.parseRequestBody(valideRequest, null);
+            assertEquals(1, request.getId());
+        } catch (JsonProcessingException e) {
+            fail(e);
+        }
+        InvalidParamsJsonMappingException exception = assertThrows(
+                InvalidParamsJsonMappingException.class,
+                () -> JSONRPCUtils.parseRequestBody(invalidRequest, null)
+        );
+        assertEquals(2, exception.getId());
+    }
+
     @Test
     public void testParseMissingField_ThrowsInvalidParamsError() throws JsonMappingException {
         String missingRoleMessage=  """

transport/rest/src/main/java/io/a2a/transport/rest/handler/RestHandler.java

@@ -268,25 +268,12 @@ public HTTPRestResponse listTasks(@Nullable String contextId, @Nullable String s
             paramsBuilder.tenant(tenant);
             if (statusTimestampAfter != null) {
                 try {
-                    // Try parsing as Unix milliseconds first (integer)
-                    long millis = Long.parseLong(statusTimestampAfter);
-                    if (millis < 0L) {
-                        Map<String, Object> errorData = new HashMap<>();
-                        errorData.put("parameter", "statusTimestampAfter");
-                        errorData.put("reason", "Must be a non-negative timestamp value, got: " + millis);
-                        throw new InvalidParamsError(null, "Invalid params", errorData);
-                    }
-                    paramsBuilder.statusTimestampAfter(Instant.ofEpochMilli(millis));
-                } catch (NumberFormatException nfe) {
-                    // Fall back to ISO-8601 format
-                    try {
-                        paramsBuilder.statusTimestampAfter(Instant.parse(statusTimestampAfter));
-                    } catch (DateTimeParseException e) {
-                        Map<String, Object> errorData = new HashMap<>();
-                        errorData.put("parameter", "lastUpdatedAfter");
-                        errorData.put("reason", "Must be valid Unix milliseconds or ISO-8601 timestamp");
-                        throw new InvalidParamsError(null, "Invalid params", errorData);
-                    }
+                    paramsBuilder.statusTimestampAfter(Instant.parse(statusTimestampAfter));
+                } catch (DateTimeParseException e) {
+                    Map<String, Object> errorData = new HashMap<>();
+                    errorData.put("parameter", "statusTimestampAfter");
+                    errorData.put("reason", "Must be an ISO-8601 timestamp");
+                    throw new InvalidParamsError(null, "Invalid params", errorData);
                 }
             }
             if (includeArtifacts != null) {

transport/rest/src/test/java/io/a2a/transport/rest/handler/RestHandlerTest.java

@@ -887,16 +887,12 @@ public void testListTasksNegativeTimestampReturns422() {
     @Test
     public void testListTasksUnixMillisecondsTimestamp() {
         RestHandler handler = new RestHandler(CARD, requestHandler, internalExecutor);
-        taskStore.save(MINIMAL_TASK, false);
 
-        // Unix milliseconds timestamp should be accepted
-        String timestampMillis = String.valueOf(System.currentTimeMillis() - 10000);
+        // Unix milliseconds timestamp are no longer accepted
         RestHandler.HTTPRestResponse response = handler.listTasks(null, null, null, null,
-                null, timestampMillis, null, "", callContext);
+                null, "1234567", null, "", callContext);
 
-        Assertions.assertEquals(200, response.getStatusCode());
-        Assertions.assertEquals("application/json", response.getContentType());
-        Assertions.assertTrue(response.getBody().contains("tasks"));
+        Assertions.assertEquals(422, response.getStatusCode());
     }
 
     @Test