Add diagnostics for macOS MLX CLI crash (exit 255)

Capture stdout/stderr separately, add verbose logging (-vv), check
crash reports, and print system info to debug the silent crash.

Signed-off-by: Michael Yuan <michael@secondstate.io>
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: juntao

.github/workflows/integration-test.yml

@@ -392,12 +392,55 @@ jobs:
           find target/release/build -name "mlx.metallib" -exec cp {} target/release/ \;
           ls -lh target/release/mlx.metallib
 
+      - name: Diagnostic — check binary and environment
+        run: |
+          echo "=== Binary info ==="
+          file target/release/transcribe
+          otool -L target/release/transcribe | head -20
+          echo ""
+          echo "=== Metallib ==="
+          ls -lh target/release/mlx.metallib || echo "NO METALLIB FOUND"
+          echo ""
+          echo "=== Model files ==="
+          ls -lh "$MODEL_DIR/"
+          echo ""
+          echo "=== System memory ==="
+          sysctl hw.memsize
+          vm_stat | head -10
+          echo ""
+          echo "=== Metal GPU ==="
+          system_profiler SPDisplaysDataType 2>/dev/null | head -20 || true
+
       - name: CLI — transcribe sample2.wav
         run: |
-          result=$(./target/release/transcribe \
+          set +e
+          echo "Starting transcription..."
+          ./target/release/transcribe \
+            -vv \
             --model-dir "$MODEL_DIR" \
             --language en \
-            tests/fixtures/sample2.wav)
+            tests/fixtures/sample2.wav \
+            > /tmp/transcribe_stdout.txt 2> /tmp/transcribe_stderr.txt
+          EXIT_CODE=$?
+          echo "Exit code: $EXIT_CODE"
+          echo ""
+          echo "=== STDOUT ==="
+          cat /tmp/transcribe_stdout.txt
+          echo ""
+          echo "=== STDERR ==="
+          cat /tmp/transcribe_stderr.txt
+          echo ""
+          if [ $EXIT_CODE -ne 0 ]; then
+            echo "Process crashed with exit code $EXIT_CODE"
+            # Check for crash logs
+            ls -lt ~/Library/Logs/DiagnosticReports/ 2>/dev/null | head -5
+            for f in $(ls -t ~/Library/Logs/DiagnosticReports/transcribe* 2>/dev/null | head -1); do
+              echo "=== Crash report ==="
+              head -100 "$f"
+            done
+            exit $EXIT_CODE
+          fi
+          result=$(cat /tmp/transcribe_stdout.txt)
           echo "Transcript: $result"
           echo "$result" | grep -qi "fox\|lazy\|dog"