Phase 2.

tests/integration/README.md

@@ -1,11 +1,28 @@
 # Integration tests
 
-Planned integration coverage:
-- deterministic offline render;
-- repeated engine initialization and shutdown;
-- graph replacement while processing;
-- project save/load round trip;
-- backend disconnect/reconnect;
-- MIDI panic and transport stop.
+`make test` is hardware/server independent: offline render tests, concurrent
+plan-replacement stress, and (when JACK headers are present) JACK ABI fault
+injection. The fake links against installed declarations without linking
+libjack. It does not claim to reproduce JACK scheduling; the separate
+threaded stress test exercises publication/reclamation.
 
-Do not mark these tests as passing until they exist and run.
+`make test-jack` explicitly runs a five-second live JACK loopback test. Requires
+an existing JACK or PipeWire JACK-compatible server; does not start a server,
+change its sample rate/block size, or connect physical outputs. Source output
+is connected only to the test's capture client, then disconnected and removed.
+It checks finite/bounded captured samples at two gains, active plan replacement,
+status and ten restart cycles. For a longer run:
+
+```sh
+make build/test_jack
+./build/test_jack 30
+```
+
+On the inspected system the 30-second test passed at 48000 Hz (initial 1024
+frames): 704 engine blocks, 716 probe blocks, both gains observed, zero xruns,
+and ten restart cycles. This is a limited software-loopback result, not an
+endurance or physical-device qualification. No live server termination or global
+format change is performed on the shared server. Those paths, missing server,
+port/callback setup failure, activation/deactivation/close failure, null buffers,
+invalid configuration, oversize buffers, and reopen are tested with injected
+JACK callbacks/results in `tests/unit/test_backend.c`.