Use swift-embedded-foundation instead of Foundation shims

.github/workflows/swift-wasm.yml

@@ -55,6 +55,7 @@ jobs:
     - name: Build
       run: >-
         SWIFTPM_ENABLE_MACROS=0
+        SWIFT_EMBEDDED=1
         swift build
         -c ${{ matrix.config }}
         --swift-sdk swift-6.3.2-RELEASE_wasm-embedded

Package.swift

@@ -81,6 +81,23 @@ package.targets[package.targets.count - 1] = .testTarget(
     ]
 )
 
+// Embedded Swift support (Foundation-free builds)
+let enableEmbedded = environment["SWIFT_EMBEDDED"] == "1"
+if enableEmbedded {
+    package.dependencies += [
+        .package(
+            url: "https://github.com/PureSwift/swift-embedded-foundation.git",
+            from: "0.1.0"
+        )
+    ]
+    package.targets[0].dependencies += [
+        .product(
+            name: "FoundationEmbedded",
+            package: "swift-embedded-foundation"
+        )
+    ]
+}
+
 // Skip (skip.dev) Fuse (native) transpilation support
 let enableSkipFuse = environment["SKIP_FUSE"] == "1"
 if enableSkipFuse {

Sources/CoreModel/FoundationShims.swift

@@ -0,0 +1,19 @@
+//
+//  FoundationShims.swift
+//  CoreModel
+//
+//  Re-exports Foundation value types from `FoundationEmbedded`
+//  (https://github.com/PureSwift/swift-embedded-foundation) for platforms
+//  without Foundation (e.g. Embedded Swift).
+//
+
+#if !canImport(FoundationEssentials) && !canImport(Foundation)
+import FoundationEmbedded
+
+public typealias Data = FoundationEmbedded.Data
+public typealias UUID = FoundationEmbedded.UUID
+public typealias Date = FoundationEmbedded.Date
+public typealias TimeInterval = FoundationEmbedded.TimeInterval
+public typealias Decimal = FoundationEmbedded.Decimal
+public typealias URL = FoundationEmbedded.URL
+#endif