Phase 2.

README.md

@@ -17,10 +17,14 @@ This repository is a starter scaffold, not a production DAW. It currently provid
 - a mono graph model with port validation, cycle rejection and topological ordering;
 - compiled offline plans with preallocated buffers, sine oscillator, gain, meter and output nodes;
 - C tests for deterministic rendering, routing, validation and lifecycle;
+- an optional JACK-compatible mono backend with start/stop, routing and status;
+- safe control/audio plan handoff and concurrent replacement tests;
 - an optional FLTK GUI shell;
 - architecture, format, GUI, roadmap, and decision documents.
 
-Real audio-device integration, recording, MIDI, plugin hosting, project persistence, and the actual sequencer UI are not implemented yet.
+The JACK backend has passed software-loopback testing; physical-device playback
+is unverified. Recording, MIDI, plugin hosting, project persistence, and the
+actual sequencer UI are not implemented yet.
 
 ## Build
 
@@ -47,7 +51,11 @@ Run the GUI:
 ./build/xtc
 ```
 
-The current GUI is only a shell and does not yet produce sound. The core's offline graph test is the first executable audio-processing milestone.
+The current GUI is only a shell and is not connected to the backend yet.
+With JACK development files and an existing JACK-compatible server, run the
+isolated software-loopback test with `make test-jack`. It connects only test
+clients. See [engine documentation](docs/AUDIO_ENGINE.md) for configuration,
+routing, ownership and recovery.
 
 Clean generated files: