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Synapse

COMMS
Velocity5.0

Open-source Matrix homeserver for secure decentralized real-time messaging

element.io ↗

Synapse holds its biweekly cadence, grinding through Matrix spec MSCs

matrixhomeserversliding-syncfederationspec-compliancemaintenance
◆Current state
Synapse is the reference Matrix homeserver, shipping on a steady two-week release train. Recent work centers on Simplified Sliding Sync (MSC4186), sticky events, cancellable delayed events, and a preview-URL capabilities API, alongside a run of federation and to-device stability fixes. This is maintenance-heavy engineering: paired rc/stable releases, a mid-May CVE security patch in 1.152.1, and Debian 12 packaging now being retired.
◆Where it's heading
The arc is incremental spec conformance, not new direction. Sliding Sync and appservice/ephemeral-event plumbing are maturing toward Matrix 1.15 requirements, with repeated fix-and-stabilize cycles (one Sliding Sync change was reverted for performance and re-landed). Expect continued MSC pickups and hardening rather than architectural change.
◆Prediction
The next release likely stabilizes more Sliding Sync and sticky-event behavior and continues trimming legacy packaging, arriving as another rc-then-stable pair within roughly two weeks.

◆Recent moves

  1. 2d ago

    Sticky events over Sliding Sync; appservice EDUs stabilized

    The 1.156.0 stable release exposes MSC4354 sticky events over Simplified Sliding Sync and stabilizes sending ephemeral events to application services (MSC2409), plus restricted-room summary data required by Matrix 1.15. Consistent with the trajectory of steady spec pickups rather than a directional shift.

    View source ↗
  2. 9d ago

    Release candidate for 1.156.0

    The release candidate for 1.156.0; the stable release that followed reported no significant changes on top of it. Same feature set as the paired stable entry.

    View source ↗
  3. 23d ago

    Federation to-device fixes; drops Debian 12 packaging

    The 1.155.0 stable release folds in bugfixes for outgoing federation (bounding to-device EDU size) and restricted-room joins, and announces the end of Debian 12 Bookworm packaging. Routine stability-and-housekeeping work in the maintenance cadence.

    View source ↗
  4. 1mo ago

    Release candidate for 1.155.0

    The release candidate carrying the 1.155.0 federation and Sliding Sync bugfixes ahead of the stable cut. Duplicate of the paired stable entry.

    View source ↗
  5. 1mo ago

    MSC4452 preview-URL capabilities API

    The 1.154.0 stable release adds the MSC4452 preview-URL capabilities API, letting servers advertise and gate URL-preview behavior, plus a Sliding Sync avatar fix. Another incremental spec surface, gated behind an experimental flag.

    View source ↗
  6. 1mo ago

    Release candidate for 1.154.0

    The release candidate for 1.154.0, introducing the MSC4452 preview-URL capability and Sliding Sync fixes later shipped in the stable release. Duplicate of the paired stable entry.

    View source ↗