Jackson 3 migration – polymorphic use case differences in `readerFor` and `writerFor` expected?

^{Originally posted by **soc** July 14, 2026}
I have some code that makes use of various Jackson features including
- `@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, property = "type")`,
- `@JsonSubTypes({ @JsonSubTypes.Type(value = LinkSettings.Action.class, name = "action"), ... })`, and
- `@JsonTypeName`

to (de)serialize a `sealed interface LinkSettings` whose subtypes are records nested in that very interface as well as another sealed interface (`sealed interface Action`).

I have tests that serialize values of this type with

```
String serialized = jsonMapper.writerFor(LinkSettings.class).writeValueAsString(linkSettings);
```
working on Jackson 2.22.0.

When I migrate to Jackson 3.2.1, the serialization tests start failing, as the configured type name of the sealed interface appears to be ignored, and the type is traversed all to the bottom of the hierarchy (`record OpenWindow` being one the impls of `Action`):

```
expected: "action"
but was: "LinkSettings$Action$OpenWindow"
```

I was able to "fix" this by removing the `writerFor` call (that imo was already questionable before):

```
String serialized = jsonMapper.writeValueAsString(linkSettings)
```

Now I hit the same issue with deserialization, but there I cannot replace

```
jsonMapper.readerFor(LinkSettings.class).readValue(linkSettings);
```
with

```
jsonMapper.readValue(linkSettings);
```

Is this expected, or a symptom of a misconfiguration/misuse of annotations?
Or is this a bug and I should try to create a reproduction for it?