Problems with beaker.hyperdrive.writeFile and beaker.peersockets when inside an <iframe>

[sentamalin]

Inside of an <iframe> in an application like Beakermentions:

• beaker.hyperdrive.readFile - Endpoint in <iframe> can read .webmention files and successfully checks if mentions exist before adding or deleting (when sending/deleting mentions) or just returning all mentions (when getting mentions)
• beaker.hyperdrive.writeFile - Fails with an Uncaught Exception error; no other information is given in the console
• beaker.peersockets - I don't know if anything's going on with it. No peers are being logged in the console as leaving or joining, even when peer join/leave events are logged in the console when an endpoint is opened in a new tab

Effectively, this means that applications can ask endpoints to get mentions, and can know if a mention will succeed, but no write operations can happen, and no peers are successfully asked. It's unclear what's exactly causing this behavior--me, or Beaker Browser. I will assume it's something I'm doing wrong for now, but with no information I'm a bit stuck.