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Mandelbrot

Mandelbrot is a GNOME-native Matrix messaging client, forked from Fractal to move faster on the modern Matrix feature set. It is built in Rust on GTK 4, Libadwaita, and the matrix-rust-sdk.

Why a fork?​

Fractal is an excellent, actively maintained client, but some features are outside its current scope. Mandelbrot keeps full compatibility with everything Fractal does — E2EE with cross-signing and verification, rich messaging, moderation, multi-account — and adds the modern Matrix feature set on top.

Features beyond Fractal​

  • Native voice & video calls (experimental) — MatrixRTC built in natively (no embedded browser): join calls from the room header, GNOME-native call view with participant grid and auto-hiding controls, a return-to-call bar, and incoming-call notifications using the freedesktop portal v2 call.incoming category (great on Phosh, landing in GNOME Shell). Calls are end-to-end encrypted with automatic key rotation, and crash-safe membership cleanup via MSC4140 delayed events. Requires a homeserver with a LiveKit focus (e.g. matrix.org). The implementation's conformance suite — ported from matrix-js-sdk — runs in CI, plus a live interop test harness.
  • Simplified sliding sync (MSC4186) — instant room list on supported homeservers (Synapse ≥ 1.114), with automatic fallback to classic sync elsewhere.
  • QR code login (MSC4108) — "Sign in with QR code" on the login screen, and "Link New Device…" in Account Settings → Sessions (OAuth 2.0 homeservers).
  • Threads (MSC3440) — a "N replies in thread" button opens an adaptive thread panel with its own composer, thread-scoped replies/edits/reactions, and per-thread drafts.
  • Polls (MSC3381) — create disclosed or undisclosed polls from the composer menu, vote, watch live results, and end polls from the context menu.
  • Voice messages (MSC3245) — record with the composer's microphone button (live level meter), send as Ogg Opus with waveform metadata.

Full feature documentation: docs/FEATURES.md.

Installation​

flatpak remote-add --user --if-not-exists tuna-os https://tunaos.org/flatpak/tuna-os.flatpakrepo
flatpak install --user tuna-os org.tunaos.mandelbrot

Mandelbrot runs on the GNOME 50 runtime, so you also need the Flathub remote (or another source for org.gnome.Platform//50).

Added the tuna-os remote before it moved to tunaos.org? --if-not-exists keeps your old one and the install will say nothing matches. Fix it with flatpak remote-modify --user tuna-os --url=oci+https://tunaos.org/flatpak.

Reporting issues​

Please report issues with core messaging that also reproduce in Fractal to the Fractal issue tracker, and Mandelbrot-specific issues (calls, sliding sync, QR login…) to the Mandelbrot repo.

Source​