From df8b74f854057356241cb629b418152633b1d90a Mon Sep 17 00:00:00 2001
From: Ben Williams <git@biwills.com>
Date: Mon, 17 Aug 2026 19:20:14 -0700
Subject: [PATCH 1/3] Fix macOS Swift SDK selection

---
 .github/workflows/ci.yml                  |  7 +++++++
 packages/swift-node/src/compiler.ts       | 18 +++++++++++++++++-
 packages/swift-node/test/compiler.test.ts | 12 ++++++++++++
 3 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 1dbd425..40b657d 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -159,6 +159,13 @@ jobs:
           node-version: '24'
           cache: true
 
+      # This example imports Foundation and Security. Run it with the same
+      # externally selected toolchain pattern supported by swift-node.
+      - name: Install selected macOS Swift toolchain
+        uses: SwiftyLab/setup-swift@38f54a76b70d989321de9dc7c840618c08cf56e9 # v1.14.0
+        with:
+          swift-version: 6.3.3
+
       - name: Verify toolchain
         run: |
           swiftc --version
diff --git a/packages/swift-node/src/compiler.ts b/packages/swift-node/src/compiler.ts
index f4eb5f3..c34fd22 100644
--- a/packages/swift-node/src/compiler.ts
+++ b/packages/swift-node/src/compiler.ts
@@ -275,9 +275,25 @@ export function swiftCompileArgs(
   return args
 }
 
+/**
+ * Invoke the macOS compiler through xcrun so it receives the selected Xcode
+ * SDK. xcrun also honors TOOLCHAINS, which lets callers use a Swift toolchain
+ * installed alongside Xcode without losing access to Apple frameworks.
+ */
+export function swiftcInvocation(
+  args: string[],
+  platform = process.platform,
+): { command: string; args: string[] } {
+  if (platform === 'darwin') {
+    return { command: 'xcrun', args: ['--sdk', 'macosx', 'swiftc', ...args] }
+  }
+  return { command: 'swiftc', args }
+}
+
 export function compileSwift(config: CompilerConfig): string {
   const outputFile = path.join(config.objDir, 'swift.o')
-  run('swiftc', swiftCompileArgs(config), config.projectDir)
+  const { command, args } = swiftcInvocation(swiftCompileArgs(config))
+  run(command, args, config.projectDir)
   return outputFile
 }
 
diff --git a/packages/swift-node/test/compiler.test.ts b/packages/swift-node/test/compiler.test.ts
index 271712a..97a30b2 100644
--- a/packages/swift-node/test/compiler.test.ts
+++ b/packages/swift-node/test/compiler.test.ts
@@ -10,6 +10,7 @@ import {
   needsNodeGypInstall,
   nodeGypDevDir,
   swiftCompileArgs,
+  swiftcInvocation,
 } from '../src/compiler'
 
 const config = {
@@ -44,6 +45,17 @@ describe('cross-platform compiler commands', () => {
     )
   })
 
+  it('invokes the macOS Swift compiler through xcrun with the macOS SDK', () => {
+    const swiftArgs = swiftCompileArgs(config, 'darwin', 'arm64')
+
+    expect(swiftcInvocation(swiftArgs, 'darwin')).toEqual({
+      command: 'xcrun',
+      args: ['--sdk', 'macosx', 'swiftc', ...swiftArgs],
+    })
+    expect(swiftcInvocation(swiftArgs, 'linux')).toEqual({ command: 'swiftc', args: swiftArgs })
+    expect(swiftcInvocation(swiftArgs, 'win32')).toEqual({ command: 'swiftc', args: swiftArgs })
+  })
+
   it('uses the configured deployment target consistently on Apple Silicon', () => {
     expect(macosDeploymentTarget('10.15', 'arm64')).toBe('10.15')
     expect(macosDeploymentTarget('10.15', 'x64')).toBe('10.15')

From 85499f7f026c864f2506f49af5f6b32298400f8e Mon Sep 17 00:00:00 2001
From: Ben Williams <git@biwills.com>
Date: Mon, 17 Aug 2026 19:35:49 -0700
Subject: [PATCH 2/3] fix: preserve explicit macOS SDK selection

---
 packages/swift-node/src/compiler.ts       | 11 ++++++++---
 packages/swift-node/test/compiler.test.ts |  8 ++++++--
 2 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/packages/swift-node/src/compiler.ts b/packages/swift-node/src/compiler.ts
index c34fd22..de7835f 100644
--- a/packages/swift-node/src/compiler.ts
+++ b/packages/swift-node/src/compiler.ts
@@ -276,16 +276,21 @@ export function swiftCompileArgs(
 }
 
 /**
- * Invoke the macOS compiler through xcrun so it receives the selected Xcode
- * SDK. xcrun also honors TOOLCHAINS, which lets callers use a Swift toolchain
+ * Invoke the macOS compiler through xcrun so it receives an Xcode SDK.
+ * Preserve an explicit SDKROOT; otherwise select the default macOS SDK.
+ * xcrun also honors TOOLCHAINS, which lets callers use a Swift toolchain
  * installed alongside Xcode without losing access to Apple frameworks.
  */
 export function swiftcInvocation(
   args: string[],
   platform = process.platform,
+  sdkRoot = process.env.SDKROOT,
 ): { command: string; args: string[] } {
   if (platform === 'darwin') {
-    return { command: 'xcrun', args: ['--sdk', 'macosx', 'swiftc', ...args] }
+    return {
+      command: 'xcrun',
+      args: [...(sdkRoot ? [] : ['--sdk', 'macosx']), 'swiftc', ...args],
+    }
   }
   return { command: 'swiftc', args }
 }
diff --git a/packages/swift-node/test/compiler.test.ts b/packages/swift-node/test/compiler.test.ts
index 97a30b2..3544f61 100644
--- a/packages/swift-node/test/compiler.test.ts
+++ b/packages/swift-node/test/compiler.test.ts
@@ -45,13 +45,17 @@ describe('cross-platform compiler commands', () => {
     )
   })
 
-  it('invokes the macOS Swift compiler through xcrun with the macOS SDK', () => {
+  it('uses xcrun for macOS Swift while preserving an explicit SDK selection', () => {
     const swiftArgs = swiftCompileArgs(config, 'darwin', 'arm64')
 
-    expect(swiftcInvocation(swiftArgs, 'darwin')).toEqual({
+    expect(swiftcInvocation(swiftArgs, 'darwin', '')).toEqual({
       command: 'xcrun',
       args: ['--sdk', 'macosx', 'swiftc', ...swiftArgs],
     })
+    expect(swiftcInvocation(swiftArgs, 'darwin', '/custom/MacOSX.sdk')).toEqual({
+      command: 'xcrun',
+      args: ['swiftc', ...swiftArgs],
+    })
     expect(swiftcInvocation(swiftArgs, 'linux')).toEqual({ command: 'swiftc', args: swiftArgs })
     expect(swiftcInvocation(swiftArgs, 'win32')).toEqual({ command: 'swiftc', args: swiftArgs })
   })

From 5a51e87b454c63fa6edc07fe3c8a7385a9b144fc Mon Sep 17 00:00:00 2001
From: Ben Williams <git@biwills.com>
Date: Mon, 17 Aug 2026 19:41:32 -0700
Subject: [PATCH 3/3] release: bump packages to 0.3.0

---
 packages/swift-node-unplugin/package.json | 4 ++--
 packages/swift-node/package.json          | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/packages/swift-node-unplugin/package.json b/packages/swift-node-unplugin/package.json
index d1f3ee3..c3a01c8 100644
--- a/packages/swift-node-unplugin/package.json
+++ b/packages/swift-node-unplugin/package.json
@@ -1,6 +1,6 @@
 {
   "name": "swift-node-unplugin",
-  "version": "0.2.0",
+  "version": "0.3.0",
   "description": "Unplugin adapters that build and bundle Swift Node native assets.",
   "type": "module",
   "types": "./dist/index.d.ts",
@@ -102,7 +102,7 @@
     "test": "vp test run"
   },
   "peerDependencies": {
-    "swift-node": "^0.2.0"
+    "swift-node": "^0.3.0"
   },
   "dependencies": {
     "unplugin": "3.3.0"
diff --git a/packages/swift-node/package.json b/packages/swift-node/package.json
index db56b8d..4c7666e 100644
--- a/packages/swift-node/package.json
+++ b/packages/swift-node/package.json
@@ -1,6 +1,6 @@
 {
   "name": "swift-node",
-  "version": "0.2.0",
+  "version": "0.3.0",
   "type": "module",
   "description": "Node-API bridge for Swift. Write Node native addons in Swift without C++ glue.",
   "bin": {