Compatibility Scope

This page is the canonical entry point for Mattermost compatibility expectations.

Compatibility Commitment

RustChat prioritizes compatibility with Mattermost mobile and desktop clients on /api/v4/* and /api/v4/websocket.

Current Headline Coverage

Scope	Coverage	Last Audited
Mobile-critical endpoints	39/41 (95.1%)	2026-03-17

Known gaps:

• POST /api/v4/emoji
• POST /api/v4/posts/search

Protected Compatibility Surface

Changes in these paths should be treated as compatibility-sensitive:

• backend/src/api/v4/
• backend/src/mattermost_compat/
• backend/compat/
• backend/src/realtime/

Verification Expectations

When compatibility-sensitive changes are made:

# Compatibility workflow
cd backend
cargo test --no-fail-fast -- --nocapture

Also review compatibility guidance in:

• Development Compatibility Guide
• Reference Compatibility Matrix