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+# httpware 0.9.1 — `MsgspecDecoder` stops claiming containers it can't decode
+
+**Patch release with one behavior change.** When `MsgspecDecoder` is the only decoder registered (an msgspec-only install, or an explicit `decoders=[MsgspecDecoder()]`), a `response_model=` of `list[SomePydanticModel]`, `dict[str, SomePydanticModel]`, `SomePydanticModel | None`, or any container parameterized by a type msgspec can't natively decode now raises `MissingDecoderError` *before* a request is sent — instead of sending the request and failing at decode with `DecodeError`.
+
+## The gap
+
+`MsgspecDecoder.can_decode` answers the client's pre-flight question "can you decode this type?" — and on a `False` from every registered decoder, the client raises `MissingDecoderError` without touching the network. msgspec builds a `json.Decoder` for almost any type via a generic `CustomType` fallback, so `can_decode` used `msgspec.inspect.type_info` to detect and reject that fallback. But it inspected only the **top-level** node: `type_info(list[PUser])` is a `ListType` whose `item_type` is the `CustomType`, so the top-level check passed, the decoder built, and `can_decode` returned `True`. The pre-flight was bypassed, a real HTTP request went out, and `decode` then raised a validation error (surfaced as `DecodeError`). The false-positive was cached per instance, so every later request of that shape repeated the wasted round-trip.
+
+Under the default pydantic-first `decoders=[PydanticDecoder(), MsgspecDecoder()]`, this was masked — pydantic claims `list[PUser]` first. The bug only bit msgspec-only configurations.
+
+## The fix
+
+`can_decode` now walks the full `type_info` tree and rejects if a `CustomType` appears **anywhere** in it, via a recursive helper that visits every nested element type (`list`/`dict`/`set`/`tuple`/`Optional`/`Union`, arbitrarily nested). The walk stops at `Struct`/dataclass field boundaries automatically, so genuine msgspec targets like `list[SomeStruct]` stay accepted and self-referential structs can't loop.
+
+No public-API change: the `ResponseDecoder` protocol and `can_decode`'s signature are unchanged. Only the set of types `MsgspecDecoder` claims is corrected.