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fix(sync): resolve $ME and $LAZY state keys in sliding sync required_state #1690

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Reaster wants to merge 2 commits from Reaster/continuwuity:Sync--$ME-and-$LAZY into main

Reaster commented

2026-04-20 12:54:33 +00:00

First-time contributor

Summary

collect_required_state in src/api/client/sync/v5.rs currently only
expands the * wildcard when building a sliding sync response. The
$ME and $LAZY sentinel values defined by MSC3575 are passed
through as literal state keys, so the subsequent room_state_get
lookups always miss.

This breaks clients built on the Matrix Rust SDK (most notably
Element X iOS / Android), which rely on $ME to fetch the current
user's push rules during sync. When the lookup fails the client falls
back to silent notifications.

Closes #1661. Related: #1533, #1424,
element-hq/element-x-ios#5132.

Changes

collect_required_state now also takes sender_user and the
room's timeline_pdus.
$ME → replaced by sender_user.as_str() before the state lookup.
$LAZY (only meaningful for m.room.member) → expanded to the
member events of every user that sent a timeline event plus the
target of every m.room.member event in the timeline, matching the
behaviour of Synapse and Tuwunel.
The literal "$LAZY" key is no longer looked up directly; it would
always return Err.
A small fetched set de-duplicates events so an explicit member
key combined with $LAZY, or with an earlier * expansion, does
not push the same event twice.
$LAZY is skipped when m.room.member has already been wildcard-
expanded in the same request.

The control flow was reshaped from if / else if to a match on the
state key for readability, but the * branch and the default branch
behave exactly as before.

Non-goals

The lazy_members: true boolean from the RoomSubscription schema
is still not implemented. Only the $LAZY sentinel in
required_state is handled here. Left for a follow-up.

Testing

Local build via docker compose build conduwuit against the
bundled Dockerfile.
Manually verified with Element X iOS that push rules are now
delivered on initial sync and that notifications produce sound /
vibration again.
Existing sliding sync flows (wildcard expansion, explicit state
keys) are unchanged — covered by the existing Complement suite.

Reference

The resolution logic mirrors Tuwunel's
src/api/client/sync/v5/rooms.rs (lines ~150-260),
adapted to continuwuity's non-stream loop style.

Changelog entry — add file changelog.d/<PR_NUMBER>.bugfix (replace number after MR created):

Resolve $ME and $LAZY sentinels in sliding sync required_state, fixing push-rule loading for Element X and other Matrix Rust SDK
clients.

## Summary `collect_required_state` in `src/api/client/sync/v5.rs` currently only expands the `*` wildcard when building a sliding sync response. The `$ME` and `$LAZY` sentinel values defined by [MSC3575] are passed through as literal state keys, so the subsequent `room_state_get` lookups always miss. This breaks clients built on the Matrix Rust SDK (most notably Element X iOS / Android), which rely on `$ME` to fetch the current user's push rules during sync. When the lookup fails the client falls back to silent notifications. Closes #1661. Related: #1533, #1424, element-hq/element-x-ios#5132. ## Changes - `collect_required_state` now also takes `sender_user` and the room's `timeline_pdus`. - `$ME` → replaced by `sender_user.as_str()` before the state lookup. - `$LAZY` (only meaningful for `m.room.member`) → expanded to the member events of every user that sent a timeline event plus the target of every `m.room.member` event in the timeline, matching the behaviour of Synapse and Tuwunel. - The literal `"$LAZY"` key is no longer looked up directly; it would always return `Err`. - A small `fetched` set de-duplicates events so an explicit member key combined with `$LAZY`, or with an earlier `*` expansion, does not push the same event twice. - `$LAZY` is skipped when `m.room.member` has already been wildcard- expanded in the same request. The control flow was reshaped from `if / else if` to a `match` on the state key for readability, but the `*` branch and the default branch behave exactly as before. ## Non-goals - The `lazy_members: true` boolean from the `RoomSubscription` schema is still not implemented. Only the `$LAZY` sentinel in `required_state` is handled here. Left for a follow-up. ## Testing - Local build via `docker compose build conduwuit` against the bundled Dockerfile. - Manually verified with Element X iOS that push rules are now delivered on initial sync and that notifications produce sound / vibration again. - Existing sliding sync flows (wildcard expansion, explicit state keys) are unchanged — covered by the existing Complement suite. ## Reference The resolution logic mirrors Tuwunel's [`src/api/client/sync/v5/rooms.rs`][tuwunel] (lines ~150-260), adapted to continuwuity's non-stream loop style. [MSC3575]: https://github.com/matrix-org/matrix-spec-proposals/blob/main/proposals/3575-sync.md [tuwunel]: https://github.com/matrix-construct/tuwunel/blob/main/src/api/client/sync/v5/rooms.rs Changelog entry — add file changelog.d/<PR_NUMBER>.bugfix (replace number after MR created): Resolve `$ME` and `$LAZY` sentinels in sliding sync `required_state`, fixing push-rule loading for Element X and other Matrix Rust SDK clients.

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Henry-Hiles commented

2026-05-10 01:36:59 +00:00

Member

RE #1661, I don't think this is wanted, as its not in current SSS spec, and therefore not a Continuwuity issue. Feel free to leave a comment if I am incorrect, just cleaning stuff up.

Henry-Hiles closed this pull request

2026-05-10 01:36:59 +00:00