fix: add portaudio to LD_LIBRARY_PATH and add flake lockfile

Move LD_LIBRARY_PATH out of env block and include portaudio so
audio devices are discoverable at runtime. Add flake.lock and
a quick microphone test script.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

flake.lock

@@ -0,0 +1,27 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1779786838,
+        "narHash": "sha256-0geHoGiR5f8qiXg+gO4rSF6Up6Var+kKqiOv9AO/uUc=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "f44f7788c891fbe5542177df78374f8cdab10e8f",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -21,11 +21,10 @@
           cudaPackages.cudatoolkit
         ];
 
-        env = {
-          LD_LIBRARY_PATH = pkgs.lib.makeLibraryPath [
-            pkgs.cudaPackages.cudatoolkit
-          ];
-        };
+        LD_LIBRARY_PATH = pkgs.lib.makeLibraryPath [
+          pkgs.portaudio
+          pkgs.cudaPackages.cudatoolkit
+        ];
       };
     };
 }

test_mic.py

@@ -0,0 +1,88 @@
+"""Quick microphone tests. Run: uv run python test_mic.py"""
+
+import numpy as np
+import sounddevice as sd
+import sys
+import time
+
+SAMPLE_RATE = 16000
+
+
+def test_device_info():
+    """Show which device will be used for recording."""
+    default_input = sd.default.device[0]
+    info = sd.query_devices(default_input)
+    print(f"Default input device [{default_input}]: {info['name']}")
+    print(f"  Max input channels: {info['max_input_channels']}")
+    print(f"  Default sample rate: {info['default_samplerate']}")
+    assert info["max_input_channels"] > 0, "Default device has no input channels!"
+    print("  PASS\n")
+
+
+def test_record_1s():
+    """Record 1 second and check we got non-silent audio."""
+    print("Recording 1 second... (speak or make noise!)")
+    audio = sd.rec(SAMPLE_RATE, samplerate=SAMPLE_RATE, channels=1, dtype="float32")
+    sd.wait()
+    audio = audio.flatten()
+
+    peak = np.max(np.abs(audio))
+    rms = np.sqrt(np.mean(audio ** 2))
+    print(f"  Samples: {len(audio)}")
+    print(f"  Peak amplitude: {peak:.4f}")
+    print(f"  RMS: {rms:.6f}")
+
+    assert len(audio) == SAMPLE_RATE, f"Expected {SAMPLE_RATE} samples, got {len(audio)}"
+    assert peak > 0, "All zeros — mic not capturing anything"
+    if peak < 0.001:
+        print("  WARNING: Very low signal — mic might be muted or too far away")
+    else:
+        print("  Signal level looks good")
+    print("  PASS\n")
+
+
+def test_record_levels():
+    """Record 3 seconds in 1-second chunks, show live levels."""
+    print("Recording 3 seconds — speak during seconds 2-3 for comparison...")
+    for i in range(3):
+        audio = sd.rec(SAMPLE_RATE, samplerate=SAMPLE_RATE, channels=1, dtype="float32")
+        sd.wait()
+        audio = audio.flatten()
+        rms = np.sqrt(np.mean(audio ** 2))
+        peak = np.max(np.abs(audio))
+        bar = "#" * int(min(peak * 200, 50))
+        print(f"  Second {i+1}: peak={peak:.4f} rms={rms:.6f} |{bar}")
+    print("  PASS\n")
+
+
+def test_stream_callback():
+    """Test that InputStream callback fires correctly."""
+    frames_received = []
+
+    def callback(indata, frames, time_info, status):
+        if status:
+            print(f"  Status: {status}")
+        frames_received.append(len(indata))
+
+    print("Testing InputStream callback for 1 second...")
+    with sd.InputStream(samplerate=SAMPLE_RATE, channels=1, dtype="float32",
+                        callback=callback, blocksize=800):
+        time.sleep(1)
+
+    total_frames = sum(frames_received)
+    expected = SAMPLE_RATE
+    print(f"  Callbacks fired: {len(frames_received)}")
+    print(f"  Total frames: {total_frames} (expected ~{expected})")
+    print(f"  Blocksize per callback: {frames_received[0] if frames_received else 'N/A'}")
+    assert len(frames_received) > 0, "No callbacks received!"
+    assert abs(total_frames - expected) < expected * 0.2, f"Frame count off by >20%"
+    print("  PASS\n")
+
+
+if __name__ == "__main__":
+    print("=== Microphone Tests ===\n")
+    test_device_info()
+    test_record_1s()
+    test_record_levels()
+    test_stream_callback()
+    print("All tests passed!")