This file will be renamed to
2026-reliable-channel-api-developer-preview
Resources Required for 2026H1:
- 2 Delivery engineers
- 1 Chat engineer for integration
The Chat — Foundations milestone does not include the Scalable Data Sync protocol. This milestone delivers dedicated work to fully leverage SDS to:
- Identify and retrieve missed messages
- Track, acknowledge, and resend unacknowledged messages
The Reliable Channel API delivers a simple API that enables those features, as well as:
- SDS-Repair, an extension to SDS that reduces reliance on Store services and improves receiver anonymity from the original SDS protocol.
This milestone focuses on forming the API and delivering a pre-configured SDS experience. Segmentation and rate limit manager will be delivered in the General Availability milestone.
FURPS
- Reliable Channel API: F1, F2, F3, F4, F5, F6, F7, F8, F9, U1, U2, U3, U4, R1, R3
Risks
| Risk | (Accept, Own, Mitigation) |
|---|---|
| SDS maturity | SDS protocol has not been extensively tested in production. May require tuning of parameters to avoid network saturation. |
| SDS-Repair network overhead | SDS-R can quickly saturate the network with repair requests if parameters are not carefully tuned. Linear backoff should become exponential. |
Deliverables
Deliver Reliable Channel API
Owner: Delivery Team
Feature: Reliable Channel API
FURPS:
- F1. All messages sent in a channel are eventually received by all participants.
- F2. Senders are notified when messages are acknowledged by other participants.
- F3. Missing messages are automatically detected.
- F4. Missing messages are automatically retrieved via store hash queries.
- F5. Messages are causally ordered using Lamport timestamps.
- F6. Outbound messages that are not acknowledged are automatically resent.
- F7. API delegates message encryption and decryption to consumer-provided implementations.
- F8. When encryption is applied, the SDS envelope is encrypted.
- U1. Sane defaults with pre-configured parameters for common scenarios.
- U2. Single cohesive interface wrapping SDS and store queries for missing messages.
- U3. Event-driven model exposing message lifecycle through intuitive events.
- U4. The API is agnostic to the encryption mechanism used.
Note: No segmentation or rate limit manager in this milestone. SDS messages cached locally.
Implement SDS Repair
Owner: Delivery Team
Feature: Reliable Channel API
FURPS:
- F9. Missing messages re-emission is requested from other channel participants
Use Reliable Channels in Logos Chat
Owner: Chat Team
Feature: Reliable Channel API
FURPS:
- U2. Single cohesive interface wrapping SDS, store queries, segmentation, and rate limits.