Phase 1-4: Audio stack, mixer engine, MIDI, and network API

P2-R1: ALSA + JACK2 low-latency config (scripts, quirks, tuning)
P2-R2: Carla integration (build scripts, 8ch rack config, NAM LV2 support)
P2-R3: Plugin manager, categories, blacklist, NAM model support
P3-R1: Mixer DSP engine (channel strip, routing matrix, bus mgr, automation)
P4-R1: MIDI engine (learn mode, clock sync, HID discovery, mapping store)
P4-R2: Network API (OSC server, FastAPI REST, WebSocket, auth, rate limiter)
P5-R1: Touchscreen UI evaluation + main entry point
docs: Audio stack, Carla integration, MIDI support, UI evaluation
tests: Full test suite (292 passing)

tests/test_mapping_store.py

@@ -0,0 +1,173 @@
+"""Tests for mapping persistence."""
+
+import json
+import tempfile
+from pathlib import Path
+
+import pytest
+from src.midi.types import MIDIMapping, MIDIMessageType, ParameterType
+from src.midi.mapping_store import (
+    mapping_to_dict,
+    mapping_from_dict,
+    save_mappings,
+    load_mappings,
+    list_sessions,
+    delete_session,
+    DEFAULT_MAPPINGS_DIR,
+    DEFAULT_SESSION_NAME,
+)
+
+
+class TestSerialisation:
+    def test_roundtrip_cc_mapping(self):
+        original = MIDIMapping(
+            msg_type=MIDIMessageType.CONTROL_CHANGE,
+            channel=0,
+            controller=7,
+            param_type=ParameterType.VOLUME,
+            param_channel=0,
+            invert=True,
+            curve="logarithmic",
+            label="CH0 Vol",
+        )
+        d = mapping_to_dict(original)
+        restored = mapping_from_dict(d)
+
+        assert restored.msg_type == original.msg_type
+        assert restored.channel == original.channel
+        assert restored.controller == original.controller
+        assert restored.param_type == original.param_type
+        assert restored.param_channel == original.param_channel
+        assert restored.invert == original.invert
+        assert restored.curve == original.curve
+        assert restored.label == original.label
+
+    def test_roundtrip_nrpn_mapping(self):
+        original = MIDIMapping(
+            msg_type=MIDIMessageType.CONTROL_CHANGE,
+            channel=1,
+            is_nrpn=True,
+            nrpn_number=258,
+            param_type=ParameterType.COMP_THRESHOLD,
+            param_channel=3,
+        )
+        d = mapping_to_dict(original)
+        restored = mapping_from_dict(d)
+
+        assert restored.is_nrpn
+        assert restored.nrpn_number == 258
+
+    def test_roundtrip_with_device(self):
+        original = MIDIMapping(
+            controller=10,
+            source_device="X-Touch",
+        )
+        d = mapping_to_dict(original)
+        restored = mapping_from_dict(d)
+
+        assert restored.source_device == "X-Touch"
+
+    def test_roundtrip_disabled(self):
+        original = MIDIMapping(enabled=False)
+        d = mapping_to_dict(original)
+        restored = mapping_from_dict(d)
+        assert not restored.enabled
+
+    def test_dict_format_has_expected_keys(self):
+        m = MIDIMapping()
+        d = mapping_to_dict(m)
+
+        assert "midi" in d
+        assert "target" in d
+        assert "value" in d
+        assert "meta" in d
+        assert d["midi"]["type"] == "CONTROL_CHANGE"
+        assert d["target"]["parameter"] == "volume"
+
+
+class TestFileIO:
+    @pytest.fixture(autouse=True)
+    def temp_dir(self, monkeypatch):
+        """Redirect mappings to a temp directory."""
+        td = tempfile.mkdtemp(prefix="rpi-mixer-test-")
+        monkeypatch.setattr(
+            "src.midi.mapping_store.DEFAULT_MAPPINGS_DIR",
+            Path(td),
+        )
+        yield td
+        # Cleanup
+        import shutil
+        shutil.rmtree(td, ignore_errors=True)
+
+    def test_save_and_load(self):
+        mappings = [
+            MIDIMapping(
+                msg_type=MIDIMessageType.CONTROL_CHANGE,
+                channel=0,
+                controller=7,
+                param_type=ParameterType.VOLUME,
+                param_channel=0,
+                label="CH0 Vol",
+            ),
+            MIDIMapping(
+                msg_type=MIDIMessageType.CONTROL_CHANGE,
+                channel=0,
+                controller=10,
+                param_type=ParameterType.PAN,
+                param_channel=0,
+                label="CH0 Pan",
+            ),
+        ]
+
+        path = save_mappings(mappings, DEFAULT_SESSION_NAME)
+        assert path.exists()
+
+        loaded = load_mappings(DEFAULT_SESSION_NAME)
+        assert len(loaded) == 2
+        assert loaded[0].controller == 7
+        assert loaded[1].controller == 10
+        assert loaded[0].label == "CH0 Vol"
+        assert loaded[1].label == "CH0 Pan"
+
+    def test_missing_session_returns_empty(self):
+        loaded = load_mappings("nonexistent-session")
+        assert loaded == []
+
+    def test_list_sessions(self, temp_dir):
+        save_mappings([MIDIMapping()], "session-a")
+        save_mappings([MIDIMapping()], "session-b")
+
+        sessions = list_sessions()
+        assert "session-a" in sessions
+        assert "session-b" in sessions
+
+    def test_delete_session(self):
+        save_mappings([MIDIMapping()], "to-delete")
+        assert delete_session("to-delete")
+        assert load_mappings("to-delete") == []
+
+    def test_delete_nonexistent_session(self):
+        assert not delete_session("never-existed")
+
+    def test_save_empty_mappings(self):
+        path = save_mappings([], DEFAULT_SESSION_NAME)
+        assert path.exists()
+
+        loaded = load_mappings(DEFAULT_SESSION_NAME)
+        assert loaded == []
+
+    def test_json_is_valid(self):
+        """Saved JSON should be parseable by standard json module."""
+        mappings = [
+            MIDIMapping(controller=7, param_type=ParameterType.VOLUME, param_channel=0),
+            MIDIMapping(controller=10, param_type=ParameterType.PAN, param_channel=1, invert=True),
+        ]
+        path = save_mappings(mappings, DEFAULT_SESSION_NAME)
+
+        with open(path) as fh:
+            doc = json.load(fh)
+
+        assert doc["version"] == 1
+        assert len(doc["mappings"]) == 2
+        assert doc["mappings"][0]["target"]["parameter"] == "volume"
+        assert doc["mappings"][1]["value"]["invert"] is True