zat 0.4.2+ decodes finite 64-bit floats, so after the zat bump a float record stopped failing at decode and was emitted to subscribers as a JSON number. upstream decodes the float too but cbor.ToJSON rejects it as outside the atproto data model (atmos cbor/json.go), and stream on zat 0.4.0 never emitted one. writeCborValue now returns WriteFailed for floats, which lands in the existing encode-error path. the hot-tail test goes back to its original 64-bit float fixture, and a wire test pins the rejection; both fail without the change. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>