API for deleting user & room account_data (SPEC-431)

[matrixbot]

Submitted by @​matthew:matrix.org
We seem to have deliberately avoided to specify a DELETE for account_data. Unsure why (possibly to simplify the /sync responses when it disappears?), but it's not ideal that as a result empty account_data objects start to stack up where people try to delete them

(Imported from https://matrix.org/jira/browse/SPEC-431)

[matrixbot]

Jira watchers: @richvdh

[matrixbot]

Yeah. We'll need synapse to support it first, of course...

-- @richvdh

[bmarty]

possibly to simplify the /sync responses when it disappears?

Right, this point has to be handled, maybe by adding a new section in the sync response with deleted account data...

This feature should be useful, now that we store arbitrary type in the account data, for 4S. When resetting 4S, the account data cannot be fully cleared.

[ShadowJonathan]

Encountered this when trying to delete m.tag room account data items, it'd be very useful as it allows room/account data to be fully CRUD

[foresto]

I have old, disused account_data piling up in at least one account as secret storage keys are changed. This slows down development work, as I have to read through more and more uncollected garbage in order to see the effects of various client actions.

Finally being able to clear these out would be helpful.