The first of the widevine / playready config keys in a cdm entry sets which device loads first and which DRM system licenses a track that offers the two. An entry that lists playready first changes from Widevine to PlayReady.
A remote client that passes --cdm, has a cdm entry for the service that named the loaded device, or sets server_cdm: false now declines the server CDM at session create, and warns when the server keeps it. A service option listed in SERVER_DEVICE_OPTIONS keeps the server CDM.
Opt-in decrypt_segments runs mp4decrypt --fragments-info per segment on a thread pool as segments land (DASH, single-init HLS), then decrypts the init alone; hides the post-download decrypt step with byte-identical output.