diff --git a/main.py b/main.py
index 77b34c2..57387bd 100644
--- a/main.py
+++ b/main.py
@@ -23,6 +23,7 @@ import yaml
 
 # ── Subsystem imports ─────────────────────────────────────────────────────────
 from src.system.audio import AudioConfig, AudioSystem, JackAudioClient, _jack_is_running
+from src.system.defaults import ensure_defaults_exist
 from src.dsp.pipeline import AudioPipeline
 from src.dsp.nam_host import NAMHost
 from src.dsp.ir_loader import IRLoader
@@ -109,6 +110,9 @@ class PedalApp:
         logger.info("═══════ Pi Multi-FX Pedal — Booting ═══════")
 
         try:
+            # ── 0. Ensure default IRs, NAM models, and directories ──
+            ensure_defaults_exist()
+
             # ── 1. Audio config + system ──────────────────────────
             acfg = self._config["audio"]
             audio_mode = acfg.get("mode", "mono")
@@ -171,6 +175,9 @@ class PedalApp:
                 installed = self.presets.install_factory_presets(overwrite=False)
                 if installed:
                     logger.info("Installed %d factory preset(s)", installed)
+                ir_installed = self.presets.install_factory_irs(overwrite=False)
+                if ir_installed:
+                    logger.info("Installed %d factory cab IR(s)", ir_installed)
 
             # Restore last active preset
             restored = self.presets.restore_state()
@@ -262,9 +269,11 @@ class PedalApp:
 
         # CC → registered parameter handlers (per preset mapping)
         # We register a general CC handler that looks up the current
-        # preset's MIDI mappings dynamically
+        # preset's MIDI mappings dynamically.
+        # The lambda captures cc_num so the callback knows which CC
+        # number triggered it (register_cc only passes value + channel).
         for cc in range(128):
-            self.midi.register_cc(cc, self._on_midi_cc)
+            self.midi.register_cc(cc, lambda val, ch, cc_num=cc: self._on_midi_cc(val, cc_num, ch))
 
         # MIDI Learn completion
         self.midi.set_midi_learn_callback(self._on_midi_learn)
@@ -279,21 +288,28 @@ class PedalApp:
         except Exception as e:
             logger.warning("MIDI PC to (ch=%d, pg=%d) failed: %s", channel, program, e)
 
-    def _on_midi_cc(self, value: int, channel: int) -> None:
+    def _on_midi_cc(self, value: int, cc_number: int, channel: int) -> None:
         """MIDI CC → live parameter update.
 
         Maps expression pedal (CC 11) to master volume by default.
         Full MIDI-mapped parameter control is resolved via the preset's
         MIDI mappings per param_key.
+
+        Args:
+            value: CC value (0-127).
+            cc_number: The CC number (0-127) that triggered this callback.
+            channel: MIDI channel (0-15) the message arrived on.
         """
-        if not self.presets or not self.pipeline:
+        # Map expression pedal (CC 11) to master volume regardless of
+        # preset state — global mapping.
+        if cc_number == 11:
+            if self.pipeline:
+                normalized = value / 127.0
+                self.pipeline._master_volume = normalized
+                logger.debug("MIDI CC 11 → master volume: %.2f", normalized)
             return
 
-        # Map expression pedal (CC 11) to master volume
-        if channel == 11:
-            normalized = value / 127.0
-            self.pipeline._master_volume = normalized
-            logger.debug("MIDI CC 11 → master volume: %.2f", normalized)
+        if not self.presets or not self.pipeline:
             return
 
         # Look up preset's MIDI mappings for other CC numbers
@@ -304,13 +320,11 @@ class PedalApp:
         except Exception:
             return
 
-        # Iterate preset mappings and find which one matches this CC.
-        # The MIDIHandler dispatches per-cc-number callbacks but doesn't
-        # pass the CC number — we infer it from the mapping.
+        # Iterate preset mappings and find which one matches this CC number
         for param_key, mapping in preset.midi_mappings.items():
-            if mapping.cc_number == channel:
+            if mapping.cc_number == cc_number:
                 normalized = value / 127.0
-                logger.debug("MIDI CC %d → %s = %.2f", channel, param_key, normalized)
+                logger.debug("MIDI CC %d → %s = %.2f", cc_number, param_key, normalized)
                 break
 
     def _on_midi_learn(self, mapping: object) -> None:
diff --git a/tests/test_midi_integration.py b/tests/test_midi_integration.py
new file mode 100644
index 0000000..5e8a763
--- /dev/null
+++ b/tests/test_midi_integration.py
@@ -0,0 +1,485 @@
+"""Integration tests for MIDI controller — PC, CC, expression pedal.
+
+Tests the full chain from MIDI handler → PedalApp callbacks →
+preset manager → pipeline parameter control.
+"""
+from __future__ import annotations
+
+from typing import Any
+
+import pytest
+
+from midi.handler import (
+    MIDIHandler,
+    MIDIEvent,
+    CC_EXPRESSION,
+    RT_CLOCK,
+    RT_START,
+    RT_STOP,
+    CONTROL_CHANGE,
+    PROGRAM_CHANGE,
+    NOTE_ON,
+)
+from presets.manager import PresetManager
+from presets.types import FXBlock, FXType, MIDIMapping, Preset
+
+
+# ═══════════════════════════════════════════════════════════════════
+# Fixtures
+# ═══════════════════════════════════════════════════════════════════
+
+
+class MockPipeline:
+    """Minimal mock of AudioPipeline for testing MIDI integration."""
+
+    def __init__(self) -> None:
+        self._master_volume = 0.8
+        self._bypassed = False
+        self._loaded_preset: Preset | None = None
+
+    def load_preset(self, preset: Preset) -> None:
+        self._loaded_preset = preset
+
+
+@pytest.fixture
+def preset_manager(tmp_path: Any) -> PresetManager:
+    """PresetManager with a temp directory."""
+    pm = PresetManager(preset_dir=str(tmp_path / "presets"))
+    return pm
+
+
+@pytest.fixture
+def mock_pipeline() -> MockPipeline:
+    return MockPipeline()
+
+
+@pytest.fixture
+def handler() -> MIDIHandler:
+    """MIDIHandler with no hardware interfaces."""
+    h = MIDIHandler()
+    return h
+
+
+# ═══════════════════════════════════════════════════════════════════
+# CC callback lambda tests (the bugfix)
+# ═══════════════════════════════════════════════════════════════════
+
+
+class TestCCLambdaClosure:
+    """Verify that register_cc closures capture the CC number correctly.
+
+    This was the root cause bug: _on_midi_cc received the MIDI channel
+    instead of the CC number, breaking expression pedal and preset mappings.
+    """
+
+    def test_lambda_captures_cc_number(self, handler: MIDIHandler) -> None:
+        """Each registered CC callback should know its CC number."""
+        results: list[int] = []
+
+        # Simulate what PedalApp._wire_midi_callbacks does
+        for cc in range(128):
+            handler.register_cc(cc, lambda val, ch, cc_num=cc: results.append(cc_num))
+
+        # Fire a few CCs through dispatch
+        handler.dispatch(MIDIEvent(type="cc", cc_number=0, cc_value=64))
+        handler.dispatch(MIDIEvent(type="cc", cc_number=11, cc_value=100))
+        handler.dispatch(MIDIEvent(type="cc", cc_number=74, cc_value=50))
+        handler.dispatch(MIDIEvent(type="cc", cc_number=127, cc_value=127))
+
+        assert results == [0, 11, 74, 127]
+
+    def test_expression_pedal_identified_correctly(self, handler: MIDIHandler) -> None:
+        """Expression pedal (CC #11) should be distinguishable from other CCs."""
+        results: list[tuple[int, int, int]] = []
+
+        # Register callbacks like PedalApp does
+        for cc in range(128):
+            handler.register_cc(
+                cc, lambda val, ch, cc_num=cc: results.append((val, cc_num, ch))
+            )
+
+        # Send expression pedal CC on MIDI channel 0
+        handler.dispatch(
+            MIDIEvent(type="cc", cc_number=CC_EXPRESSION, cc_value=64, channel=0)
+        )
+
+        assert len(results) == 1
+        val, cc_num, ch = results[0]
+        assert cc_num == CC_EXPRESSION  # Should be 11, not the MIDI channel
+        assert val == 64
+        assert ch == 0
+
+    def test_midi_channel_preserved(self, handler: MIDIHandler) -> None:
+        """MIDI channel should still be passed correctly."""
+        results: list[tuple[int, int, int]] = []
+
+        for cc in range(128):
+            handler.register_cc(
+                cc, lambda val, ch, cc_num=cc: results.append((val, cc_num, ch))
+            )
+
+        # CC#7 on MIDI channel 5
+        handler.dispatch(MIDIEvent(type="cc", cc_number=7, cc_value=100, channel=5))
+
+        assert len(results) == 1
+        val, cc_num, ch = results[0]
+        assert cc_num == 7
+        assert val == 100
+        assert ch == 5
+
+
+# ═══════════════════════════════════════════════════════════════════
+# PedalApp callback tests
+# ═══════════════════════════════════════════════════════════════════
+
+
+class TestPedalAppMIDICallbacks:
+    """Test the PedalApp-level MIDI callback logic in isolation."""
+
+    def test_on_midi_pc_selects_preset(
+        self, preset_manager: PresetManager, mock_pipeline: MockPipeline
+    ) -> None:
+        """Simulate PedalApp._on_midi_pc — PC message should select a preset."""
+        from main import PedalApp
+
+        # Create a preset to select
+        preset = Preset(name="Test", bank=1, program=2)
+        preset_manager.save(preset)
+
+        # Simulate PedalApp callback by calling preset_manager.midi_pc directly
+        # (same as PedalApp._on_midi_pc does)
+        result = preset_manager.midi_pc(channel=1, program=2)
+
+        assert result.name == "Test"
+        assert result.bank == 1
+        assert result.program == 2
+        assert preset_manager.current_bank == 1
+        assert preset_manager.current_program == 2
+
+    def test_on_midi_pc_creates_blank_on_empty_slot(
+        self, preset_manager: PresetManager, mock_pipeline: MockPipeline
+    ) -> None:
+        """Selecting an empty slot via PC should create a blank preset."""
+        result = preset_manager.midi_pc(channel=2, program=0)
+
+        assert result is not None
+        assert result.bank == 2
+        assert result.program == 0
+        assert result.name == "New Bank 2 #0"
+
+    def test_expression_pedal_sets_master_volume(
+        self, mock_pipeline: MockPipeline
+    ) -> None:
+        """CC#11 = expression pedal → master volume update."""
+        # Simulate PedalApp._on_midi_cc with our fixed signature
+        from main import PedalApp
+
+        app = PedalApp.__new__(PedalApp)
+        app.pipeline = mock_pipeline
+        app.presets = None  # Not needed for expression pedal path
+
+        # Call with CC#11 = expression pedal
+        app._on_midi_cc(value=64, cc_number=11, channel=0)
+
+        # Master volume should be 64/127 ≈ 0.504
+        assert mock_pipeline._master_volume == pytest.approx(64.0 / 127.0)
+
+    def test_expression_pedal_full_sweep(
+        self, mock_pipeline: MockPipeline
+    ) -> None:
+        """Full expression pedal sweep from heel to toe."""
+        from main import PedalApp
+
+        app = PedalApp.__new__(PedalApp)
+        app.pipeline = mock_pipeline
+        app.presets = None
+
+        values = [0, 32, 64, 96, 127]
+        expected = [0.0, 32 / 127, 64 / 127, 96 / 127, 127 / 127]
+
+        for val, exp in zip(values, expected):
+            app._on_midi_cc(value=val, cc_number=11, channel=0)
+            assert mock_pipeline._master_volume == pytest.approx(exp)
+
+    def test_cc_updates_preset_mapping(
+        self, preset_manager: PresetManager, mock_pipeline: MockPipeline
+    ) -> None:
+        """CC should update a parameter mapped in the preset's MIDI mappings."""
+        from main import PedalApp
+
+        # Create a preset with a MIDI mapping for delay feedback on CC#14
+        delay_param_key = "delay.feedback"
+        preset = Preset(
+            name="Delay Test",
+            bank=0,
+            program=0,
+            chain=[
+                FXBlock(fx_type=FXType.DELAY, params={"feedback": 0.5, "mix": 0.3}),
+            ],
+            midi_mappings={
+                delay_param_key: MIDIMapping(
+                    cc_number=14, channel=0, min_val=0.0, max_val=1.0
+                ),
+            },
+        )
+        preset_manager.save(preset)
+        preset_manager.midi_pc(channel=0, program=0)  # Select it
+
+        # Set up PedalApp-like context
+        app = PedalApp.__new__(PedalApp)
+        app.pipeline = mock_pipeline
+        app.presets = preset_manager
+
+        # We need to track if the preset's param was updated.
+        # _on_midi_cc logs the mapping but doesn't apply changes to the
+        # pipeline yet — that's a future enhancement. For now, verify
+        # the callback completes without error and the mapping is found.
+
+        # CC#14 = delay.feedback = 100/127
+        app._on_midi_cc(value=100, cc_number=14, channel=0)
+
+        # At minimum, it shouldn't crash. The pipeline's master_volume
+        # should remain unchanged (CC#14 is not expression pedal).
+        assert mock_pipeline._master_volume == 0.8
+
+    def test_cc_mapping_only_matches_correct_cc(
+        self, preset_manager: PresetManager, mock_pipeline: MockPipeline
+    ) -> None:
+        """CC that doesn't match any mapping should not affect anything."""
+        from main import PedalApp
+
+        preset = Preset(
+            name="Test",
+            bank=0,
+            program=0,
+            midi_mappings={"reverb.mix": MIDIMapping(cc_number=14)},
+        )
+        preset_manager.save(preset)
+        preset_manager.midi_pc(channel=0, program=0)
+
+        app = PedalApp.__new__(PedalApp)
+        app.pipeline = mock_pipeline
+        app.presets = preset_manager
+
+        # CC#99 has no mapping — should be no-op
+        app._on_midi_cc(value=64, cc_number=99, channel=0)
+        # CC#14 has a mapping — should be found
+        app._on_midi_cc(value=64, cc_number=14, channel=0)
+
+        # Both should complete without error
+        assert mock_pipeline._master_volume == 0.8
+
+    def test_no_pipeline_no_crash(self) -> None:
+        """CC handler should not crash if pipeline or presets are missing."""
+        from main import PedalApp
+
+        app = PedalApp.__new__(PedalApp)
+        app.pipeline = None
+        app.presets = None
+
+        # These should be no-ops
+        app._on_midi_cc(value=64, cc_number=11, channel=0)
+        app._on_midi_pc(channel=0, program=0)
+
+
+# ═══════════════════════════════════════════════════════════════════
+# Full parse → dispatch → callback chain tests
+# ═══════════════════════════════════════════════════════════════════
+
+
+class TestFullMIDIChain:
+    """End-to-end: raw MIDI bytes → handler → callback → application logic."""
+
+    def test_pc_full_chain(self, preset_manager: PresetManager) -> None:
+        """PC message bytes → handler → preset change."""
+        handler = MIDIHandler()
+        handler.set_pc_callback(lambda ch, pg: preset_manager.midi_pc(ch, pg))
+
+        # Save a preset at bank 3, program 1
+        preset_manager.save(Preset(name="PC Test", bank=3, program=1))
+
+        # Send MIDI Program Change: channel=3, program=1
+        ev = handler.parse(bytes([PROGRAM_CHANGE | 3, 1]))
+        assert ev is not None
+        handler.dispatch(ev)
+
+        assert preset_manager.current_bank == 3
+        assert preset_manager.current_program == 1
+
+        loaded = preset_manager.load(3, 1)
+        assert loaded.name == "PC Test"
+
+    def test_expression_full_chain(self, mock_pipeline: MockPipeline) -> None:
+        """CC#11 bytes → handler → expression pedal → master volume."""
+        handler = MIDIHandler()
+        results: list[tuple[int, int, int]] = []
+
+        # Register like PedalApp does — lambda captures CC#11
+        for cc in range(128):
+            handler.register_cc(
+                cc, lambda val, ch, cc_num=cc: results.append((val, cc_num, ch))
+            )
+
+        # Send CC#11 = expression pedal, value 96
+        ev = handler.parse(bytes([CONTROL_CHANGE | 0, CC_EXPRESSION, 96]))
+        assert ev is not None
+        assert ev.type == "cc"
+        assert ev.cc_number == CC_EXPRESSION
+        assert ev.cc_value == 96
+        handler.dispatch(ev)
+
+        # Verify the lambda was called with correct CC number
+        assert len(results) == 1
+        val, cc_num, ch = results[0]
+        assert cc_num == 11  # CC#11, not MIDI channel
+        assert val == 96
+
+    def test_midi_channel_preserved_through_chain(self) -> None:
+        """MIDI channel should survive parse → dispatch."""
+        handler = MIDIHandler()
+        results: list[tuple[int, int, int]] = []
+
+        for cc in range(128):
+            handler.register_cc(
+                cc, lambda val, ch, cc_num=cc: results.append((val, cc_num, ch))
+            )
+
+        # CC#7 on MIDI channel 15
+        ev = handler.parse(bytes([CONTROL_CHANGE | 15, 7, 100]))
+        assert ev is not None
+        handler.dispatch(ev)
+
+        assert len(results) == 1
+        val, cc_num, ch = results[0]
+        assert val == 100
+        assert cc_num == 7
+        assert ch == 15  # MIDI channel preserved
+
+    def test_pc_different_banks(self, preset_manager: PresetManager) -> None:
+        """PC messages targeting different banks should switch correctly."""
+        handler = MIDIHandler()
+        handler.set_pc_callback(lambda ch, pg: preset_manager.midi_pc(ch, pg))
+
+        # Save presets in different banks
+        preset_manager.save(Preset(name="Bank 0", bank=0, program=0))
+        preset_manager.save(Preset(name="Bank 3", bank=3, program=2))
+        preset_manager.save(Preset(name="Bank 7", bank=7, program=1))
+
+        # Switch to bank 3, program 2
+        ev = handler.parse(bytes([PROGRAM_CHANGE | 3, 2]))
+        assert ev is not None
+        handler.dispatch(ev)
+        assert preset_manager.current_bank == 3
+        assert preset_manager.current_program == 2
+        assert preset_manager.load(3, 2).name == "Bank 3"
+
+        # Switch to bank 0, program 0
+        ev = handler.parse(bytes([PROGRAM_CHANGE | 0, 0]))
+        assert ev is not None
+        handler.dispatch(ev)
+        assert preset_manager.current_bank == 0
+        assert preset_manager.current_program == 0
+        assert preset_manager.load(0, 0).name == "Bank 0"
+
+
+# ═══════════════════════════════════════════════════════════════════
+# Expression pedal edge cases
+# ═══════════════════════════════════════════════════════════════════
+
+
+class TestExpressionPedalEdgeCases:
+    """Expression pedal boundary conditions."""
+
+    def test_expression_min_value(self, mock_pipeline: MockPipeline) -> None:
+        """CC#11 value 0 should set master volume to 0."""
+        from main import PedalApp
+
+        app = PedalApp.__new__(PedalApp)
+        app.pipeline = mock_pipeline
+        app.presets = None
+
+        app._on_midi_cc(value=0, cc_number=11, channel=0)
+        assert mock_pipeline._master_volume == 0.0
+
+    def test_expression_max_value(self, mock_pipeline: MockPipeline) -> None:
+        """CC#11 value 127 should set master volume to 1.0."""
+        from main import PedalApp
+
+        app = PedalApp.__new__(PedalApp)
+        app.pipeline = mock_pipeline
+        app.presets = None
+
+        app._on_midi_cc(value=127, cc_number=11, channel=0)
+        assert mock_pipeline._master_volume == 1.0
+
+    def test_expression_above_127_clipped_by_handler(self) -> None:
+        """CC value >127 should be clipped at parse time."""
+        handler = MIDIHandler()
+
+        # MIDI protocol constrains to 7-bit, but verify parse handles it
+        ev = handler.parse(bytes([CONTROL_CHANGE | 0, 11, 127]))
+        assert ev is not None
+        assert ev.cc_value <= 127
+
+    def test_expression_on_wrong_channel_still_works(
+        self, mock_pipeline: MockPipeline
+    ) -> None:
+        """Expression pedal (CC#11) should work on any MIDI channel."""
+        from main import PedalApp
+
+        app = PedalApp.__new__(PedalApp)
+        app.pipeline = mock_pipeline
+        app.presets = None
+
+        # Expression on MIDI channel 7
+        app._on_midi_cc(value=100, cc_number=11, channel=7)
+        assert mock_pipeline._master_volume == pytest.approx(100.0 / 127.0)
+
+
+# ═══════════════════════════════════════════════════════════════════
+# Program Change edge cases
+# ═══════════════════════════════════════════════════════════════════
+
+
+class TestProgramChangeEdgeCases:
+    """Program Change boundary conditions."""
+
+    def test_pc_program_127_valid(self, preset_manager: PresetManager) -> None:
+        """Program 127 (max for MIDI) gets clamped to PRESETS_PER_BANK-1."""
+        preset_manager.save(Preset(name="Max PG", bank=0, program=127))
+        result = preset_manager.midi_pc(channel=0, program=127)
+        # program is clamped to PRESETS_PER_BANK - 1 = 3
+        assert result.program == 3
+
+    def test_pc_program_clamped(self, preset_manager: PresetManager) -> None:
+        """Program > 127 should be clamped to 3 (PRESETS_PER_BANK-1)."""
+        # midi_pc calls _select_and_activate which clamps program
+        # to [0, PRESETS_PER_BANK-1] = [0, 3]
+        # So program=127 becomes 3
+        result = preset_manager.midi_pc(channel=0, program=127)
+        assert result.program == 3  # Clamped to max index
+
+    def test_pc_rapid_switching(self, preset_manager: PresetManager) -> None:
+        """Rapid PC messages should switch presets without error."""
+        handler = MIDIHandler()
+        handler.set_pc_callback(lambda ch, pg: preset_manager.midi_pc(ch, pg))
+
+        for bank in range(4):
+            for prog in range(4):
+                preset_manager.save(
+                    Preset(name=f"Rapid B{bank}P{prog}", bank=bank, program=prog)
+                )
+
+        # Rapid-fire PC messages
+        import time
+
+        for bank in range(4):
+            for prog in range(4):
+                ev = handler.parse(bytes([PROGRAM_CHANGE | bank, prog]))
+                assert ev is not None
+                handler.dispatch(ev)
+                time.sleep(0.001)  # Small yield between dispatches
+
+        # Should end on the last one
+        assert preset_manager.current_bank == 3
+        assert preset_manager.current_program == 3