fix(mlx): correct Apple Silicon GPU detection for issue #87

src/engine/mlx.rs

@@ -27,28 +27,26 @@ impl MLXEngine {
         #[cfg(target_os = "macos")]
         {
             // Check if we're on Apple Silicon (ARM64)
-            if std::env::consts::ARCH == "aarch64" {
-                // Try to detect MLX installation
-                // This is a simplified check - in a real implementation,
-                // you'd check for MLX Python packages or native libraries
-                Self::check_mlx_python_available()
-            } else {
-                false
-            }
+            std::env::consts::ARCH == "aarch64"
         }
         #[cfg(not(target_os = "macos"))]
         {
             false
         }
     }
 
+    /// Check if MLX hardware is supported (Apple Silicon + macOS)
+    pub fn is_hardware_supported() -> bool {
+        Self::check_mlx_availability()
+    }
+
     /// Public method to check if MLX is available
     pub fn is_available(&self) -> bool {
         self.mlx_available
     }
 
     /// Check if MLX Python packages are available
-    fn check_mlx_python_available() -> bool {
+    pub fn check_mlx_python_available() -> bool {
         // Try to run a simple MLX command to verify installation
         Command::new("python3")
             .args(["-c", "import mlx.core; print('MLX available')"])

src/main.rs

@@ -474,11 +474,19 @@ async fn main() -> anyhow::Result<()> {
             #[cfg(feature = "mlx")]
             {
                 use crate::engine::mlx::MLXEngine;
-                let mlx_engine = MLXEngine::new();
-                if mlx_engine.is_available() {
-                    println!("🍎 MLX Backend: Available (Apple Silicon)");
+
+                if MLXEngine::is_hardware_supported() {
+                    // Check if MLX Python packages are available
+                    let python_available = MLXEngine::check_mlx_python_available();
+                    if python_available {
+                        println!("🍎 MLX Backend: ✅ Available (Apple Silicon + MLX installed)");
+                    } else {
+                        println!("🍎 MLX Backend: ⚠️  Hardware supported (Apple Silicon detected)");
+                        println!("   📦 MLX Python packages not found");
+                        println!("   💡 Install with: pip install mlx-lm");
+                    }
                 } else {
-                    println!("🍎 MLX Backend: Not available (requires Apple Silicon)");
+                    println!("🍎 MLX Backend: ❌ Not supported (requires Apple Silicon macOS)");
                 }
             }
 
@@ -489,10 +497,26 @@ async fn main() -> anyhow::Result<()> {
 
             println!();
             println!("💡 To enable GPU acceleration:");
-            println!("   cargo install shimmy --features llama-cuda    # NVIDIA CUDA");
-            println!("   cargo install shimmy --features llama-vulkan  # Cross-platform Vulkan");
-            println!("   cargo install shimmy --features llama-opencl  # AMD/Intel OpenCL");
-            println!("   cargo install shimmy --features gpu           # All GPU backends");
+
+            #[cfg(target_os = "macos")]
+            if std::env::consts::ARCH == "aarch64" {
+                println!("   cargo install shimmy --features apple        # Apple Silicon optimized");
+                println!("   cargo install shimmy --features gpu          # All GPU backends");
+                println!("   pip install mlx-lm                           # For MLX Python support");
+            } else {
+                println!("   cargo install shimmy --features llama-cuda    # NVIDIA CUDA");
+                println!("   cargo install shimmy --features llama-vulkan  # Cross-platform Vulkan");
+                println!("   cargo install shimmy --features llama-opencl  # AMD/Intel OpenCL");
+                println!("   cargo install shimmy --features gpu           # All GPU backends");
+            }
+
+            #[cfg(not(target_os = "macos"))]
+            {
+                println!("   cargo install shimmy --features llama-cuda    # NVIDIA CUDA");
+                println!("   cargo install shimmy --features llama-vulkan  # Cross-platform Vulkan");
+                println!("   cargo install shimmy --features llama-opencl  # AMD/Intel OpenCL");
+                println!("   cargo install shimmy --features gpu           # All GPU backends");
+            }
         }
         cli::Command::Init {
             template,

tests/apple_silicon_detection_test.rs

@@ -0,0 +1,105 @@
+/// Apple Silicon GPU Detection Regression Test
+/// 
+/// Tests for issue #87: "Cannot get apple gpu info"
+/// Ensures Apple Silicon hardware detection works properly regardless of MLX Python package installation
+/// 
+/// Issue: User with Apple M3 Pro received "MLX Backend: Not available (requires Apple Silicon)"
+/// Root cause: check_mlx_availability() was checking for MLX Python packages instead of just hardware
+/// Solution: Separate hardware detection from software installation checks
+
+#[cfg(test)]
+mod apple_silicon_tests {
+    use shimmy::engine::mlx::MLXEngine;
+
+    #[test]
+    fn test_hardware_detection_independent_of_python_packages() {
+        // This test ensures that Apple Silicon hardware detection
+        // works regardless of whether MLX Python packages are installed
+
+        let hardware_supported = MLXEngine::is_hardware_supported();
+        let python_available = MLXEngine::check_mlx_python_available();
+
+        // On Apple Silicon macOS, hardware should be detected even if Python packages aren't installed
+        #[cfg(all(target_os = "macos", target_arch = "aarch64"))]
+        {
+            // Hardware should always be detected on Apple Silicon macOS
+            assert!(hardware_supported, 
+                "Apple Silicon hardware should be detected on aarch64 macOS");
+
+            // Python packages may or may not be installed, that's separate
+            // We don't assert anything about python_available since it depends on user setup
+            println!("Apple Silicon detected: {}", hardware_supported);
+            println!("MLX Python packages available: {}", python_available);
+        }
+
+        // On non-Apple Silicon systems, hardware should not be detected
+        #[cfg(not(all(target_os = "macos", target_arch = "aarch64")))]
+        {
+            assert!(!hardware_supported, 
+                "Apple Silicon hardware should not be detected on non-Apple Silicon systems");
+
+            // Python packages might still be installed on non-Apple Silicon (e.g., for development)
+            // but that's not what we're testing here
+            println!("Apple Silicon detected: {}", hardware_supported);
+            println!("MLX Python packages available: {}", python_available);
+        }
+    }
+
+    #[test]
+    fn test_mlx_engine_creation() {
+        // Test that MLXEngine can be created without panicking
+        let engine = MLXEngine::new();
+
+        // The engine should reflect hardware capabilities
+        let is_available = engine.is_available();
+        let hardware_supported = MLXEngine::is_hardware_supported();
+
+        // These should be consistent
+        assert_eq!(is_available, hardware_supported,
+            "Engine availability should match hardware support");
+    }
+
+    #[test] 
+    fn test_gpu_info_output_regression() {
+        // This test ensures that gpu-info command would provide helpful output
+        // for Apple Silicon users, even without MLX Python packages
+
+        #[cfg(all(target_os = "macos", target_arch = "aarch64"))]
+        {
+            let hardware_supported = MLXEngine::is_hardware_supported();
+            let python_available = MLXEngine::check_mlx_python_available();
+
+            // Simulate the output logic from main.rs
+            if hardware_supported {
+                if python_available {
+                    println!("🍎 MLX Backend: ✅ Available (Apple Silicon + MLX installed)");
+                } else {
+                    println!("🍎 MLX Backend: ⚠️  Hardware supported (Apple Silicon detected)");
+                    println!("   📦 MLX Python packages not found");
+                    println!("   💡 Install with: pip install mlx-lm");
+                }
+            } else {
+                println!("🍎 MLX Backend: ❌ Not supported (requires Apple Silicon macOS)");
+            }
+
+            // The key fix: we should never see "Not supported" on Apple Silicon
+            assert!(hardware_supported, 
+                "Apple Silicon users should see 'Hardware supported' not 'Not supported'");
+        }
+    }
+
+    #[test]
+    fn test_python_detection_graceful_failure() {
+        // Ensure MLX Python detection fails gracefully when python3 is not available
+        // or when MLX packages are not installed
+
+        let python_available = MLXEngine::check_mlx_python_available();
+
+        // This should not panic regardless of system state
+        // Result can be true or false depending on whether MLX is installed
+        println!("MLX Python packages detected: {}", python_available);
+
+        // Test should pass whether MLX is installed or not
+        assert!(true, "Python detection should complete without panic");
+    }
+}