Decryption keys should be resent also from the sender client if needed and appropriate

[ell1e]

Steps to reproduce

1. Get a message to a device that is currently offline and then have that device somehow break itself before getting the message, as element sometimes likes to do (endless spinner hang for example that forces data wipe)
2. Log in to a new device via element web that wasn't logged in before, make sure to properly use your recovery key to get it marked as trusted
3. The backup hydrated device apparently will be ignored even if it was/is enabled by some other element desktop web device
4. You'll get an unfixable This device is requesting decryption keys from your other devices. and Unable to decrypt message since the other device broke itself and the backup hydrated one doesn't seem to be understood or queried by element web (but let's pretend that one just wasn't enabled either), even if the person sending you the message is currently online and the sender's client trusts your new client to the same level via a user-wide fingerprint

Outcome

What did you expect?

If none of my devices is available, the sender client should resend the decryption keys instead (or the entire message in whatever newly decrypted way) only if the trust level is the same

What happened instead?

I just get This device is requesting decryption keys from your other devices. and Unable to decrypt message. Note how it doesn't say "from your other device or the sender." which is what I think it should.

Operating system

Linux

Browser information

Firefox 111.0b8

URL for webapp

https://app.element.io

Application version

No response

Homeserver

Element version: 1.11.24 Olm version: 3.2.12

Will you send logs?

No

[t3chguy]

If none of my devices is available, the sender client should resend the decryption keys instead (or the entire message in whatever newly decrypted way) only if the trust level is the same

Currently Element clients only resend the keys if the device asking for it was sent them in the first place (but they got lost) - never if that device didn't exist at the time that megolm session was generated

[richvdh]

We used to request keys from the sender but it was disabled because the results were untrustworthy so we would not trust them (matrix-org/matrix-js-sdk#2982). Such a mechanism would be too easy to abuse.