Code review:

- Expose a nullable descriptor
- Log the JSON element kind instead of the raw, network-sourced value.
- drop birthday happy-path tests duplicated by UpdateMetadataTest

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip01Core/metadata/BirthdayTolerantSerializer.kt

@@ -23,6 +23,7 @@ package com.vitorpamplona.quartz.nip01Core.metadata
 import com.vitorpamplona.quartz.utils.Log
 import kotlinx.serialization.KSerializer
 import kotlinx.serialization.descriptors.SerialDescriptor
+import kotlinx.serialization.descriptors.nullable
 import kotlinx.serialization.encoding.Decoder
 import kotlinx.serialization.encoding.Encoder
 import kotlinx.serialization.json.JsonDecoder
@@ -48,7 +49,9 @@ import kotlinx.serialization.json.JsonObject
 object BirthdayTolerantSerializer : KSerializer<Birthday?> {
     private val delegate = Birthday.serializer()
 
-    override val descriptor: SerialDescriptor = delegate.descriptor
+    // Nullable serializer ⇒ nullable descriptor, so the framework's metadata stays
+    // honest even on code paths that consult it (e.g. coerceInputValues).
+    override val descriptor: SerialDescriptor = delegate.descriptor.nullable
 
     override fun deserialize(decoder: Decoder): Birthday? {
         require(decoder is JsonDecoder) { "This serializer can only be used with Json format" }
@@ -56,8 +59,9 @@ object BirthdayTolerantSerializer : KSerializer<Birthday?> {
         val element = decoder.decodeJsonElement()
         if (element !is JsonObject) {
             // Non-spec birthday (e.g. Ditto's "10-24" string). Ignore it rather than
-            // failing the whole profile parse.
-            Log.w("BirthdayTolerantSerializer") { "Ignoring non-object birthday: $element" }
+            // failing the whole profile parse. Log the JSON kind only, not the raw
+            // (untrusted, network-sourced) value.
+            Log.w("BirthdayTolerantSerializer") { "Ignoring non-object birthday (${element::class.simpleName})" }
             return null
         }
 

quartz/src/commonTest/kotlin/com/vitorpamplona/quartz/nip01Core/metadata/BirthdayTolerantSerializerTest.kt

@@ -75,41 +75,12 @@ class BirthdayTolerantSerializerTest {
         }
     }
 
-    @Test
-    fun specObjectBirthdayStillParses() {
-        val meta = metaWith("""{"name":"A","birthday":{"year":1990,"month":6,"day":15}}""").contactMetaData()
-        assertIs<UserMetadata>(meta)
-        val birthday = meta.birthday
-        assertIs<Birthday>(birthday)
-        assertEquals(1990, birthday.year)
-        assertEquals(6, birthday.month)
-        assertEquals(15, birthday.day)
-    }
-
-    @Test
-    fun partialObjectBirthdayStillParses() {
-        val meta = metaWith("""{"name":"A","birthday":{"month":6,"day":15}}""").contactMetaData()
-        assertIs<UserMetadata>(meta)
-        val birthday = meta.birthday
-        assertIs<Birthday>(birthday)
-        assertNull(birthday.year)
-        assertEquals(6, birthday.month)
-        assertEquals(15, birthday.day)
-    }
-
-    @Test
-    fun objectBirthdayRoundTrips() {
-        val meta = metaWith("""{"name":"A","birthday":{"year":1990,"month":6,"day":15}}""").contactMetaData()
-        assertIs<UserMetadata>(meta)
-        val serialized = JsonMapper.toJson(meta)
-        val reparsed = JsonMapper.fromJson<UserMetadata>(serialized)
-        val birthday = reparsed.birthday
-        assertIs<Birthday>(birthday)
-        assertEquals(1990, birthday.year)
-        assertEquals(6, birthday.month)
-        assertEquals(15, birthday.day)
-    }
-
+    /**
+     * End-to-end check that a dropped birthday does not leak back into the
+     * serialized profile. The omission itself is the decoder's default-null
+     * suppression (encodeDefaults stays false on JsonMapper), not the serializer —
+     * this just pins the real-world JsonMapper output.
+     */
     @Test
     fun nullBirthdayIsOmittedOnSerialization() {
         val meta = metaWith("""{"name":"A","birthday":"10-24"}""").contactMetaData()