fix: Fix appointment time serialization issue with Jackson.

src/main/java/com/ironhack/application/dto/request/BookAppointmentRequest.java

@@ -3,9 +3,14 @@
 import java.time.OffsetDateTime;
 import java.util.UUID;
 
+import com.ironhack.infra.config.jackson.FlexibleOffsetDateTimeDeserializer;
 import jakarta.validation.constraints.NotNull;
+import tools.jackson.databind.annotation.JsonDeserialize;
 
 public record BookAppointmentRequest(
         @NotNull(message = "Patient ID is required") UUID patientId,
         @NotNull(message = "Doctor ID is required") UUID doctorId,
-        @NotNull(message = "Appointment time is required") OffsetDateTime appointmentTime) {}
+
+        @NotNull(message = "Appointment time is required")
+        @JsonDeserialize(using = FlexibleOffsetDateTimeDeserializer.class)
+        OffsetDateTime appointmentTime) {}

src/main/java/com/ironhack/infra/config/jackson/FlexibleOffsetDateTimeDeserializer.java

@@ -0,0 +1,39 @@
+package com.ironhack.infra.config.jackson;
+
+import java.time.DateTimeException;
+import java.time.LocalDateTime;
+import java.time.OffsetDateTime;
+import java.time.ZoneId;
+import java.time.format.DateTimeFormatter;
+import java.time.format.DateTimeParseException;
+
+import tools.jackson.core.JacksonException;
+import tools.jackson.core.JsonParser;
+import tools.jackson.databind.DeserializationContext;
+import tools.jackson.databind.ValueDeserializer;
+
+/**
+ * Accepts standard {@link OffsetDateTime} strings, or a local ISO-8601 datetime
+ * (e.g. {@code 2026-05-21T13:00}) using the JVM default zone.
+ */
+public class FlexibleOffsetDateTimeDeserializer extends ValueDeserializer<OffsetDateTime> {
+    @Override
+    public OffsetDateTime deserialize(JsonParser p, DeserializationContext ctxt) throws JacksonException {
+        String text = p.getValueAsString();
+        if (text == null || text.isBlank()) {
+            return null;
+        }
+        text = text.trim();
+        try {
+            return OffsetDateTime.parse(text);
+        } catch (DateTimeParseException ignored) {
+            // fall through
+        }
+        try {
+            LocalDateTime local = LocalDateTime.parse(text, DateTimeFormatter.ISO_LOCAL_DATE_TIME);
+            return local.atZone(ZoneId.systemDefault()).toOffsetDateTime();
+        } catch (DateTimeException e) {
+            throw ctxt.weirdStringException(text, OffsetDateTime.class, e.getMessage());
+        }
+    }
+}

src/test/java/com/ironhack/infra/adapter/input/AppointmentRestAdapterTest.java

@@ -85,6 +85,24 @@ void shouldBookAppointmentSuccessfully() throws Exception {
                 .andExpect(jsonPath("$.data.status").value("SCHEDULED"));
     }
 
+    @Test
+    @DisplayName("Should book appointment when appointment time is local ISO-8601 without offset")
+    void shouldBookAppointmentWithLocalIsoDateTime() throws Exception {
+        String body = """
+                {
+                  "patientId": "%s",
+                  "doctorId": "%s",
+                  "appointmentTime": "2099-01-15T14:30"
+                }
+                """.formatted(patientId, doctorId);
+
+        mockMvc.perform(post("/v1/appointments")
+                        .contentType(MediaType.APPLICATION_JSON)
+                        .content(body))
+                .andExpect(status().isCreated())
+                .andExpect(jsonPath("$.data.status").value("SCHEDULED"));
+    }
+
     @Test
     @DisplayName("Should return 400 when booking appointment with past time")
     void shouldReturnBadRequestWhenAppointmentTimeInPast() throws Exception {