Merge PR #476: MetalRT backend + iOS demo polish (rebased on main)

Introduces a new MetalRT GPU-accelerated inference backend (LLM/STT/TTS/VLM)
for Apple Silicon on iOS + substantial iOS example-app polish (thinking
mode, benchmark metrics, tool-calling fixes, voice-session error gating).

Note: RAC_FRAMEWORK_METALRT = 10. Genie (which claimed slot 10 on the
reverted smonga/genie_support merge) is not currently on main. If #462
re-adds Genie, we will renumber Genie to slot 11 in that merge.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: sanchitmonga22

Package.swift

@@ -43,6 +43,15 @@ let useLocalBinaries = false //  Toggle: true for local dev, false for release
 // Updated automatically by CI/CD during releases
 let sdkVersion = "0.19.7"
 
+// MetalRT remote binary availability flag.
+// Set to `false` until a real checksum for RABackendMetalRT-v<sdkVersion>.zip
+// has been published. When `false`, the MetalRT product/targets are only
+// exposed under `useLocalBinaries = true`, so SPM resolution will not fail
+// for external consumers due to a placeholder checksum.
+let metalrtRemoteBinaryAvailable = false
+
+let includeMetalRT = useLocalBinaries || metalrtRemoteBinaryAvailable
+
 let package = Package(
     name: "runanywhere-sdks",
     platforms: [
@@ -81,7 +90,8 @@ let package = Package(
             name: "RunAnywhereWhisperKit",
             targets: ["WhisperKitRuntime"]
         ),
-    ],
+
+    ] + metalRTProducts(),
     dependencies: [
         .package(url: "https://github.com/apple/swift-crypto.git", from: "3.0.0"),
         .package(url: "https://github.com/Alamofire/Alamofire.git", from: "5.9.0"),
@@ -221,9 +231,62 @@ let package = Package(
             path: "sdk/runanywhere-swift/Tests/RunAnywhereTests"
         ),
 
-    ] + binaryTargets()
+    ] + metalRTTargets() + binaryTargets()
 )
 
+// =============================================================================
+// METALRT PRODUCT / TARGET GATING
+// =============================================================================
+// The RABackendMetalRT.xcframework is not yet published to GitHub releases
+// with a real checksum. To avoid SPM resolution failures for external
+// consumers due to a placeholder zero-checksum binary target, the MetalRT
+// product and its dependent targets are only included when:
+//   - `useLocalBinaries == true` (local dev with a checked-out xcframework), or
+//   - `metalrtRemoteBinaryAvailable == true` (once a real checksum is wired in).
+func metalRTProducts() -> [Product] {
+    guard includeMetalRT else { return [] }
+    return [
+        .library(
+            name: "RunAnywhereMetalRT",
+            targets: ["MetalRTRuntime"]
+        ),
+    ]
+}
+
+func metalRTTargets() -> [Target] {
+    guard includeMetalRT else { return [] }
+    return [
+        // MetalRT C Bridge Module - exposes rac_backend_metalrt_register()
+        .target(
+            name: "MetalRTBackend",
+            dependencies: ["RABackendMetalRTBinary"],
+            path: "sdk/runanywhere-swift/Sources/MetalRTRuntime/include",
+            publicHeadersPath: "."
+        ),
+        // MetalRT Runtime Backend (custom Metal GPU kernels)
+        .target(
+            name: "MetalRTRuntime",
+            dependencies: [
+                "RunAnywhere",
+                "MetalRTBackend",
+                "RABackendMetalRTBinary",
+            ],
+            path: "sdk/runanywhere-swift/Sources/MetalRTRuntime",
+            exclude: ["include"],
+            resources: [
+                .copy("Resources/default.metallib"),
+            ],
+            linkerSettings: [
+                .linkedLibrary("c++"),
+                .linkedFramework("Accelerate"),
+                .linkedFramework("Metal"),
+                .linkedFramework("CoreGraphics"),
+                .linkedFramework("ImageIO"),
+            ]
+        ),
+    ]
+}
+
 // =============================================================================
 // BINARY TARGET SELECTION
 // =============================================================================
@@ -251,6 +314,10 @@ func binaryTargets() -> [Target] {
                 name: "RABackendONNXBinary",
                 path: "sdk/runanywhere-swift/Binaries/RABackendONNX.xcframework"
             ),
+            .binaryTarget(
+                name: "RABackendMetalRTBinary",
+                path: "sdk/runanywhere-swift/Binaries/RABackendMetalRT.xcframework"
+            ),
         ]
 
         // ONNX Runtime xcframeworks - split by platform
@@ -302,6 +369,19 @@ func binaryTargets() -> [Target] {
             ),
         ]
 
+        // MetalRT remote binary is only appended once a real checksum has been
+        // published. Until then the MetalRT product/targets are omitted from
+        // the package graph entirely (see metalRTProducts/metalRTTargets).
+        if metalrtRemoteBinaryAvailable {
+            targets.append(
+                .binaryTarget(
+                    name: "RABackendMetalRTBinary",
+                    url: "https://github.com/RunanywhereAI/runanywhere-sdks/releases/download/v\(sdkVersion)/RABackendMetalRT-v\(sdkVersion).zip",
+                    checksum: "0000000000000000000000000000000000000000000000000000000000000000" // TODO: replace with real checksum
+                )
+            )
+        }
+
         return targets
     }
 }

examples/ios/RunAnywhereAI/RunAnywhereAI.xcodeproj/project.pbxproj

@@ -15,6 +15,7 @@
 		58ABEDD22ED16DA40058D033 /* RunAnywhereONNX in Frameworks */ = {isa = PBXBuildFile; productRef = 58ABEDD12ED16DA40058D033 /* RunAnywhereONNX */; };
 		58LLAMACPP12ED16DA40058D0 /* RunAnywhereLlamaCPP in Frameworks */ = {isa = PBXBuildFile; productRef = 58LLAMACPP02ED16DA40058D0 /* RunAnywhereLlamaCPP */; };
 		58WHISPERKIT1ED16DA40058D0 /* RunAnywhereWhisperKit in Frameworks */ = {isa = PBXBuildFile; productRef = 58WHISPERKIT0ED16DA40058D0 /* RunAnywhereWhisperKit */; };
+		58METALRT12ED16DA40058D0 /* RunAnywhereMetalRT in Frameworks */ = {isa = PBXBuildFile; productRef = 58METALRT02ED16DA40058D0 /* RunAnywhereMetalRT */; };
 		RACACTIVITY01ACTIVITY01RAC /* DictationActivityAttributes.swift in Sources */ = {isa = PBXBuildFile; fileRef = RACACTIVITY02ACTIVITY02RAC /* DictationActivityAttributes.swift */; };
 		RACSHARED01RACSHARED01RACS /* SharedConstants.swift in Sources */ = {isa = PBXBuildFile; fileRef = RACSHARED02RACSHARED02RACS /* SharedConstants.swift */; };
 		RACSHARED03RACSHARED03RACS /* SharedDataBridge.swift in Sources */ = {isa = PBXBuildFile; fileRef = RACSHARED04RACSHARED04RACS /* SharedDataBridge.swift */; };
@@ -169,6 +170,7 @@
 				541C59DA2E63772A00DD7839 /* RunAnywhere in Frameworks */,
 				58LLAMACPP12ED16DA40058D0 /* RunAnywhereLlamaCPP in Frameworks */,
 				58WHISPERKIT1ED16DA40058D0 /* RunAnywhereWhisperKit in Frameworks */,
+				58METALRT12ED16DA40058D0 /* RunAnywhereMetalRT in Frameworks */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -309,6 +311,7 @@
 				58ABEDD12ED16DA40058D033 /* RunAnywhereONNX */,
 				58LLAMACPP02ED16DA40058D0 /* RunAnywhereLlamaCPP */,
 				58WHISPERKIT0ED16DA40058D0 /* RunAnywhereWhisperKit */,
+				58METALRT02ED16DA40058D0 /* RunAnywhereMetalRT */,
 			);
 			productName = RunAnywhereAI;
 			productReference = 5480A1F02E2F250200337F2F /* RunAnywhereAI.app */;
@@ -1080,6 +1083,11 @@
 			package = 58E021172E52A86000B722EF /* XCLocalSwiftPackageReference "../../.." */;
 			productName = RunAnywhereWhisperKit;
 		};
+		58METALRT02ED16DA40058D0 /* RunAnywhereMetalRT */ = {
+			isa = XCSwiftPackageProductDependency;
+			package = 58E021172E52A86000B722EF /* XCLocalSwiftPackageReference "../../.." */;
+			productName = RunAnywhereMetalRT;
+		};
 /* End XCSwiftPackageProductDependency section */
 	};
 	rootObject = 5480A1E82E2F250200337F2F /* Project object */;