zed doesn't try to detect CSV, Parquet, JSON, or ZST inputs, but for file inputs, it should.

It doesn't because zio/detector.NewReaderWithOpts wraps its io.Reader parameter with Track and Recorder, which don't implement io.ReadSeeker and so aren't compatible with zio/parquetio.NewReader or zio/zstio.NewReader. But if the io.Reader parameter does implement io.ReadSeeker, NewReaderWithOpts can try Parquet, JSON, and ZST first, using Seek to rewind for the next format after each try.