refactor: Move identityMode to bridge-js.config.json following exposeToGlobal pattern

Add identityMode field to BridgeJSConfig, flow through SwiftToSkeleton and
ExportedSkeleton to BridgeJSLink. Generated JS uses config value as default
with runtime option as override via nullish coalescing.

Create dedicated BridgeJSIdentityTests target with identityMode: pointer in
its bridge-js.config.json. Remove IDENTITY_MODE env var, instantiateOptions
spread from prelude.mjs, and unittest-pointer Makefile target. Identity tests
now run as part of the normal test suite.

Author: krodak

Makefile

@@ -21,18 +21,6 @@ unittest:
 	    --disable-sandbox \
 	    js test --prelude ./Tests/prelude.mjs -Xnode --expose-gc
 
-.PHONY: unittest-pointer
-unittest-pointer:
-	@echo Running unit tests with identityMode=pointer
-	@test -n "$(SWIFT_SDK_ID)" || { \
-		echo "SWIFT_SDK_ID is not set. Run 'swift sdk list' and pass a matching SDK, e.g. 'make unittest-pointer SWIFT_SDK_ID=<id>'."; \
-		exit 2; \
-	}
-	IDENTITY_MODE=pointer swift package --swift-sdk "$(SWIFT_SDK_ID)" \
-	    $(TRACING_ARGS) \
-	    --disable-sandbox \
-	    js test --prelude ./Tests/prelude.mjs -Xnode --expose-gc
-
 .PHONY: regenerate_swiftpm_resources
 regenerate_swiftpm_resources:
 	npm run build

Package.swift

@@ -217,5 +217,17 @@ let package = Package(
             ],
             linkerSettings: testingLinkerFlags
         ),
+        .testTarget(
+            name: "BridgeJSIdentityTests",
+            dependencies: ["JavaScriptKit", "JavaScriptEventLoop"],
+            exclude: [
+                "bridge-js.config.json",
+                "Generated/JavaScript",
+            ],
+            swiftSettings: [
+                .enableExperimentalFeature("Extern")
+            ],
+            linkerSettings: testingLinkerFlags
+        ),
     ]
 )

Package@swift-6.1.swift

@@ -206,5 +206,17 @@ let package = Package(
             ],
             linkerSettings: testingLinkerFlags
         ),
+        .testTarget(
+            name: "BridgeJSIdentityTests",
+            dependencies: ["JavaScriptKit", "JavaScriptEventLoop"],
+            exclude: [
+                "bridge-js.config.json",
+                "Generated/JavaScript",
+            ],
+            swiftSettings: [
+                .enableExperimentalFeature("Extern")
+            ],
+            linkerSettings: testingLinkerFlags
+        ),
     ]
 )

Plugins/BridgeJS/Sources/BridgeJSCore/Misc.swift

@@ -342,20 +342,32 @@ public struct BridgeJSConfig: Codable {
     /// Default: `false`
     public var exposeToGlobal: Bool
 
-    public init(tools: [String: String]? = nil, exposeToGlobal: Bool = false) {
+    /// The identity mode to use for exported Swift heap objects.
+    ///
+    /// When `"pointer"`, Swift heap objects are tracked by pointer identity,
+    /// enabling identity-based caching. When `"none"` or `nil`, no identity
+    /// tracking is performed.
+    ///
+    /// Default: `nil` (treated as `"none"`)
+    public var identityMode: String?
+
+    public init(tools: [String: String]? = nil, exposeToGlobal: Bool = false, identityMode: String? = nil) {
         self.tools = tools
         self.exposeToGlobal = exposeToGlobal
+        self.identityMode = identityMode
     }
 
     enum CodingKeys: String, CodingKey {
         case tools
         case exposeToGlobal
+        case identityMode
     }
 
     public init(from decoder: Decoder) throws {
         let container = try decoder.container(keyedBy: CodingKeys.self)
         tools = try container.decodeIfPresent([String: String].self, forKey: .tools)
         exposeToGlobal = try container.decodeIfPresent(Bool.self, forKey: .exposeToGlobal) ?? false
+        identityMode = try container.decodeIfPresent(String.self, forKey: .identityMode)
     }
 
     /// Load the configuration file from the SwiftPM package target directory.
@@ -398,7 +410,8 @@ public struct BridgeJSConfig: Codable {
     func merging(overrides: BridgeJSConfig) -> BridgeJSConfig {
         return BridgeJSConfig(
             tools: (tools ?? [:]).merging(overrides.tools ?? [:], uniquingKeysWith: { $1 }),
-            exposeToGlobal: overrides.exposeToGlobal
+            exposeToGlobal: overrides.exposeToGlobal,
+            identityMode: overrides.identityMode ?? identityMode
         )
     }
 }

Plugins/BridgeJS/Sources/BridgeJSCore/SwiftToSkeleton.swift

@@ -16,14 +16,16 @@ public final class SwiftToSkeleton {
     public let progress: ProgressReporting
     public let moduleName: String
     public let exposeToGlobal: Bool
+    public let identityMode: String?
 
     private var sourceFiles: [(sourceFile: SourceFileSyntax, inputFilePath: String)] = []
     let typeDeclResolver: TypeDeclResolver
 
-    public init(progress: ProgressReporting, moduleName: String, exposeToGlobal: Bool) {
+    public init(progress: ProgressReporting, moduleName: String, exposeToGlobal: Bool, identityMode: String? = nil) {
         self.progress = progress
         self.moduleName = moduleName
         self.exposeToGlobal = exposeToGlobal
+        self.identityMode = identityMode
         self.typeDeclResolver = TypeDeclResolver()
 
         // Index known types provided by JavaScriptKit
@@ -42,7 +44,7 @@ public final class SwiftToSkeleton {
     public func finalize() throws -> BridgeJSSkeleton {
         var perSourceErrors: [(inputFilePath: String, errors: [DiagnosticError])] = []
         var importedFiles: [ImportedFileSkeleton] = []
-        var exported = ExportedSkeleton(functions: [], classes: [], enums: [], exposeToGlobal: exposeToGlobal)
+        var exported = ExportedSkeleton(functions: [], classes: [], enums: [], exposeToGlobal: exposeToGlobal, identityMode: identityMode)
         var exportCollectors: [ExportSwiftAPICollector] = []
 
         for (sourceFile, inputFilePath) in sourceFiles {

Plugins/BridgeJS/Sources/BridgeJSLink/BridgeJSLink.swift

@@ -983,7 +983,8 @@ public struct BridgeJSLink {
 
         try printer.indent {
             printer.write(lines: generateVariableDeclarations())
-            printer.write("const identityMode = options.identityMode === \"pointer\" ? \"pointer\" : \"none\";")
+            let configIdentityMode = skeletons.compactMap(\.exported).first?.identityMode ?? "none"
+            printer.write("const identityMode = options.identityMode ?? \"\(configIdentityMode)\";")
             printer.write(
                 "const shouldUseIdentityMap = identityMode === \"pointer\" && typeof WeakRef !== \"undefined\" && typeof FinalizationRegistry !== \"undefined\";"
             )

Plugins/BridgeJS/Sources/BridgeJSSkeleton/BridgeJSSkeleton.swift

@@ -890,20 +890,28 @@ public struct ExportedSkeleton: Codable {
     /// through the exports object.
     public var exposeToGlobal: Bool
 
+    /// The identity mode for exported Swift heap objects.
+    ///
+    /// When `"pointer"`, Swift heap objects are tracked by pointer identity.
+    /// When `"none"` or `nil`, no identity tracking is performed.
+    public var identityMode: String?
+
     public init(
         functions: [ExportedFunction],
         classes: [ExportedClass],
         enums: [ExportedEnum],
         structs: [ExportedStruct] = [],
         protocols: [ExportedProtocol] = [],
-        exposeToGlobal: Bool
+        exposeToGlobal: Bool,
+        identityMode: String? = nil
     ) {
         self.functions = functions
         self.classes = classes
         self.enums = enums
         self.structs = structs
         self.protocols = protocols
         self.exposeToGlobal = exposeToGlobal
+        self.identityMode = identityMode
     }
 
     public mutating func append(_ other: ExportedSkeleton) {
@@ -913,6 +921,7 @@ public struct ExportedSkeleton: Codable {
         self.structs.append(contentsOf: other.structs)
         self.protocols.append(contentsOf: other.protocols)
         assert(self.exposeToGlobal == other.exposeToGlobal)
+        assert(self.identityMode == other.identityMode)
     }
 
     public var isEmpty: Bool {

Plugins/BridgeJS/Sources/BridgeJSTool/BridgeJSTool.swift

@@ -165,7 +165,8 @@ import BridgeJSUtilities
             let swiftToSkeleton = SwiftToSkeleton(
                 progress: progress,
                 moduleName: moduleName,
-                exposeToGlobal: config.exposeToGlobal
+                exposeToGlobal: config.exposeToGlobal,
+                identityMode: config.identityMode
             )
             for inputFile in inputFiles.sorted() {
                 try withSpan("Parsing \(inputFile)") {

Plugins/BridgeJS/Tests/BridgeJSToolTests/BridgeJSLinkTests.swift

@@ -124,7 +124,7 @@ import Testing
 
         #expect(outputDts.contains("identityMode?: \"none\" | \"pointer\";"))
         #expect(
-            outputJs.contains("const identityMode = options.identityMode === \"pointer\" ? \"pointer\" : \"none\";")
+            outputJs.contains("const identityMode = options.identityMode ?? \"none\";")
         )
         #expect(
             outputJs.contains(

Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/ArrayTypes.js

@@ -43,7 +43,7 @@ export async function createInstantiator(options, swift) {
 
     let _exports = null;
     let bjs = null;
-    const identityMode = options.identityMode === "pointer" ? "pointer" : "none";
+    const identityMode = options.identityMode ?? "none";
     const shouldUseIdentityMap = identityMode === "pointer" && typeof WeakRef !== "undefined" && typeof FinalizationRegistry !== "undefined";
     const __bjs_createPointHelpers = () => ({
         lower: (value) => {