[Arathorn]

there's already a standardised export format for message keys (although EX doesn't let you load/save it yet, mainly because online backup already solves most use cases): https://spec.matrix.org/v1.12/client-server-api/#key-export-.... If you enable backup on your clients then EX at least will merge the missing keys to/from the backup. Meanwhile, the original problem of missing keys were probably unfortunately just due to bugs - although as per https://matrix.org/blog/2024/10/29/matrix-2.0-is-here/#4-inv... we've done a huge amount of work to improve this now, and they should be really unusual now (at least when due to bugs, rather than permissions or data loss or similar).

Separately, talking of standardised key formats: one of the team did a skunkworks hack last Friday to experiment with a standardized file-format for user public keys - a kind of basic key transparency ledger for Matrix, to help with bulk-verification within orgs.