add prometheus exporter + test suite

- prometheus-exporter.py: stdlib-only HTTP metrics on :9090/metrics
- Exposes: ALSA status, hw_ptr rate, service health, mixer controls
- MIDI counters: notes_on, notes_off, errors
- test-unit.py: 10-test suite covering full MIDI→Pd→Audio pipeline
- test-tone.pd, test-midi-log.pd: minimal debug patches
- systemd service for exporter
- install.sh/deploy updated to include exporter

scripts/test-e2e.sh

@@ -0,0 +1,61 @@
+#!/usr/bin/env bash
+# test-e2e.sh — End-to-end: send MIDI note → Pd → audio output
+# Usage: ./scripts/test-e2e.sh [board_ip] [note] [duration]
+set -euo pipefail
+
+BOARD="${1:-192.168.9.167}"
+NOTE="${2:-60}"
+DURATION="${3:-3}"
+SSH_KEY="/home/david/.ssh/unoq_deploy_key"
+SSH_OPTS="-o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null -i $SSH_KEY"
+
+echo "=== End-to-End Test: MIDI → Pd → Audio ==="
+echo "Board: $BOARD"
+echo "Note: $NOTE, Duration: ${DURATION}s"
+
+# 1. Check Pd is running
+echo ""
+echo "--- Step 1: Verify Pd is running ---"
+PID=$(ssh $SSH_OPTS "arduino@$BOARD" "pgrep -f 'pd.*synth.pd' | head -1 || true")
+if [ -z "$PID" ]; then
+    echo "[FAIL] Pd is not running!"
+    exit 1
+fi
+echo "[OK] Pd running (PID: $PID)"
+
+# 2. Check audio device status before
+echo ""
+echo "--- Step 2: ALSA status before MIDI ---"
+ssh $SSH_OPTS "arduino@$BOARD" "cat /proc/asound/card0/pcm0p/sub0/status 2>/dev/null || echo 'No status'"
+
+# 3. Send MIDI note-on
+echo ""
+echo "--- Step 3: Send MIDI note-on ---"
+python3 -c "import socket; s=socket.socket(socket.AF_INET,socket.SOCK_DGRAM); s.sendto(b'midi 144 $NOTE 100;', ('$BOARD', 8081)); s.close()"
+echo "[OK] Note-on sent"
+
+# 4. Monitor audio device during note
+echo ""
+echo "--- Step 4: Monitor ALSA during note (${DURATION}s) ---"
+for i in $(seq 1 "$DURATION"); do
+    STATUS=$(ssh $SSH_OPTS "arduino@$BOARD" "cat /proc/asound/card0/pcm0p/sub0/status 2>/dev/null | head -1 || echo 'unknown'")
+    echo "  [${i}/${DURATION}s] $STATUS"
+    sleep 1
+done
+
+# 5. Send note-off
+echo ""
+echo "--- Step 5: Send MIDI note-off ---"
+python3 -c "import socket; s=socket.socket(socket.AF_INET,socket.SOCK_DGRAM); s.sendto(b'midi 128 $NOTE 0;', ('$BOARD', 8081)); s.close()"
+echo "[OK] Note-off sent"
+
+# 6. Check ALSA after
+sleep 0.5
+echo ""
+echo "--- Step 6: ALSA status after note-off ---"
+ssh $SSH_OPTS "arduino@$BOARD" "cat /proc/asound/card0/pcm0p/sub0/status 2>/dev/null || echo 'No status'"
+
+echo ""
+echo "=== E2E Test Complete ==="
+echo "If ALSA showed 'RUNNING' during step 4, the MIDI→Pd→Audio pipeline works."
+echo "Connect headphones to JMISC: GND=35, HPH_L=36, HPH_R=38"