Function check_encode_policy_admission 

pub fn check_encode_policy_admission<E, D>(
    enc: E,
    dec: D,
    pixels: PixelSlice<'_>,
    metadata: Metadata,
    initial: EncodePolicy,
    request: EncodePolicy,
    accepted: bool,
    expected: &Metadata,
) -> Conformance
where
    E: EncoderConfig + 'static,
    D: DecoderConfig,
    <E::Job as EncodeJob>::Enc: Encoder<Error = E::Error> + Send,
    <E::Job as EncodeJob>::AnimationFrameEnc: AnimationFrameEncoder,

Verify checked encode-policy admission and rejection atomicity. initial must be supported; request must match accepted. Decode observations must equal expected metadata, making preservation and denial explicit instead of treating a successful setter as proof of delivery. metadata is the unfiltered input. Color/fidelity observations remain codec-specific.