[parked] Sliding Sync (MSC3575 / simplified MSC4186) — server GA, client side judged not safe to roll out #206

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2026-09-17T23:25:32-04:00

jared commented

2026-09-17 23:25:32 -04:00

Migrated from LOTUS_TODO.md on 2026-09-17 (the file is now reference-only).

[PARKED] Sliding Sync — MSC3575 / simplified MSC4186 (evaluated 2026-07, 3 research passes). Server side is GA (simplified_msc3575), but the client side is not viable for a safe rollout: matrix-js-sdk's SlidingSync/SlidingSyncSdk are _internal_/@experimental (Element shipped labs-only, never GA in ~2 yrs, moved to the Rust SDK); presence isn't delivered over sliding sync (regresses Lotus presence badges/rings/status); no upstream Cinny impl to follow; and Cinny's whole nav (sidebar/spaces/DM/unread) is derived from the full local room set (allRoomsAtom ← mx.getRooms()), so ~14 subsystems (4 core) need re-architecting to a server-windowed list. ~10% confidence a full rollout wouldn't break/regress (missing rooms/messages/unread = worst failure class). Revisit only if we adopt the Rust SDK or accounts grow large enough that startup latency is a real complaint; an off-by-default experimental spike is possible but not recommended. Full assessment: git plan history.

_Migrated from `LOTUS_TODO.md` on 2026-09-17 (the file is now reference-only)._ **[PARKED] Sliding Sync — MSC3575 / simplified MSC4186** (evaluated 2026-07, 3 research passes). Server side is GA (`simplified_msc3575`), but the **client** side is not viable for a safe rollout: matrix-js-sdk's `SlidingSync`/`SlidingSyncSdk` are `_internal_`/`@experimental` (Element shipped labs-only, never GA in ~2 yrs, moved to the Rust SDK); **presence isn't delivered over sliding sync** (regresses Lotus presence badges/rings/status); **no upstream Cinny impl** to follow; and Cinny's whole nav (sidebar/spaces/DM/unread) is derived from the **full local room set** (`allRoomsAtom` ← `mx.getRooms()`), so ~14 subsystems (4 core) need re-architecting to a server-windowed list. ~10% confidence a full rollout wouldn't break/regress (missing rooms/messages/unread = worst failure class). **Revisit only if we adopt the Rust SDK or accounts grow large enough that startup latency is a real complaint; an off-by-default experimental spike is possible but not recommended.** Full assessment: git plan history.

jared added the priority: low performance research labels 2026-09-17 23:25:32 -04:00

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Reference: LotusGuild/cinny#206