Replace unreliable PduCount pagination tokens with ShortEventId throughout
the relations and messages endpoints. ShortEventId provides stable, unique
identifiers that persist across server restarts and database operations.
Key improvements:
- Add token parsing helpers that try ShortEventId first, fall back to
PduCount for backwards compatibility
- Include thread root event when paginating backwards to thread start
- Fix off-by-one error in get_relations that was returning the starting
event in results
- Only return next_batch/prev_batch tokens when more events are available,
preventing clients from making unnecessary requests at thread boundaries
- Ensure consistent token format between /relations, /messages, and /sync
endpoints for interoperability
This fixes duplicate events when scrolling at thread boundaries and ensures
the thread root message is visible when viewing a thread, matching expected
client behaviour.
Ensures access tokens are unique across both user and appservice tables to
prevent authentication ambiguity and potential security issues.
Changes:
- On startup, automatically logout any user devices using tokens that
conflict with appservice tokens (resolves in favour of appservices)
and log a warning with affected user/device details
- When creating new user tokens, check for conflicts with appservice tokens
and generate a new token if a collision would occur
- When registering new appservices, reject registration if the token is
already in use by a user device
- Use futures::select_ok to race token lookups concurrently for better
performance (adapted from tuwunel commit 066097a8)
This fix-forward approach resolves existing token collisions on startup
whilst preventing new ones from being created, without breaking existing
valid authentications.
The find_token optimisation is adapted from tuwunel (matrix-construct/tuwunel)
commit 066097a8: "Optimize user and appservice token queries" by Jason Volk.
Fixes#813: Application services were unable to work because their sender_localpart
user was never created in the database, preventing authentication.
This fix ensures the appservice user account is created when:
- The server starts up and loads existing appservices from the database
- A new appservice is registered via the admin command
Additionally, if an appservice user has been accidentally deactivated, it will be
automatically reactivated when the appservice starts.
The solution centralises all appservice startup logic into a single `start_appservice`
helper method, eliminating code duplication between the registration and startup paths.
