diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 576b454cb..494f9e31e 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -65,6 +65,8 @@ test:js:
         - if: '$BUILD_BENCHMARK != "true"'
     timeout: 1h
     script:
+        - node packages/core/scripts/generate-sdk-version.cjs --check
+        - node --test packages/core/scripts/generate-sdk-version.test.cjs
         - yarn
         - cp jestSetup.js.override node_modules/react-native-gesture-handler/jestSetup.js
         - NODE_OPTIONS='-r dd-trace/ci/init' DD_ENV=ci DD_SERVICE=dd-sdk-reactnative yarn test
diff --git a/package.json b/package.json
index 268603687..f0578a7b9 100644
--- a/package.json
+++ b/package.json
@@ -24,9 +24,9 @@
     ]
   },
   "scripts": {
-    "prepare": "genversion --es6 --semi packages/core/src/version.ts && lerna run prepare",
-    "test": "genversion --es6 --semi packages/core/src/version.ts && jest",
-    "lint": "genversion --es6 --semi packages/core/src/version.ts && eslint .",
+    "prepare": "node packages/core/scripts/generate-sdk-version.cjs && lerna run prepare",
+    "test": "node packages/core/scripts/generate-sdk-version.cjs --check && jest",
+    "lint": "node packages/core/scripts/generate-sdk-version.cjs --check && eslint .",
     "example": "yarn --cwd example",
     "postinstall": "./packages/react-navigation/fix-react-navigation-import-in-dependencies.sh"
   },
diff --git a/packages/core/android/src/main/kotlin/com/datadog/reactnative/DdFlagsImplementation.kt b/packages/core/android/src/main/kotlin/com/datadog/reactnative/DdFlagsImplementation.kt
index 1920af4b8..e9a0f6584 100644
--- a/packages/core/android/src/main/kotlin/com/datadog/reactnative/DdFlagsImplementation.kt
+++ b/packages/core/android/src/main/kotlin/com/datadog/reactnative/DdFlagsImplementation.kt
@@ -10,7 +10,6 @@ import com.datadog.android.Datadog
 import com.datadog.android.api.InternalLogger
 import com.datadog.android.api.SdkCore
 import com.datadog.android.flags.EvaluationContextCallback
-import com.datadog.android.flags.Flags
 import com.datadog.android.flags.FlagsClient
 import com.datadog.android.flags.FlagsConfiguration
 import com.datadog.android.flags._FlagsInternalProxy
@@ -41,9 +40,16 @@ class DdFlagsImplementation(
         configuration: ReadableMap,
         promise: Promise,
     ) {
-        val flagsConfig = buildFlagsConfiguration(configuration.toMap())
+        val configMap = configuration.toMap()
+        val flagsConfig = buildFlagsConfiguration(configMap)
         if (flagsConfig != null) {
-            Flags.enable(flagsConfig, sdkCore)
+            _FlagsInternalProxy.enable(
+                flagsConfig,
+                sdkCore,
+                "dd-sdk-reactnative",
+                configMap["_ddFlagsSdkVersion"] as? String ?: "unknown",
+                SDK_VERSION,
+            )
         } else {
             InternalLogger.UNBOUND.log(
                 InternalLogger.Level.ERROR,
diff --git a/packages/core/android/src/main/kotlin/com/datadog/reactnative/SdkVersion.kt b/packages/core/android/src/main/kotlin/com/datadog/reactnative/SdkVersion.kt
index 57c91847a..b1c03c5de 100644
--- a/packages/core/android/src/main/kotlin/com/datadog/reactnative/SdkVersion.kt
+++ b/packages/core/android/src/main/kotlin/com/datadog/reactnative/SdkVersion.kt
@@ -6,5 +6,5 @@
 
 package com.datadog.reactnative
 
-// This is automatically updated by the update-version.sh script
+// Generated from packages/core/package.json. Do not edit.
 internal const val SDK_VERSION = "3.9.0"
diff --git a/packages/core/android/src/test/kotlin/com/datadog/reactnative/DdFlagsImplementationTest.kt b/packages/core/android/src/test/kotlin/com/datadog/reactnative/DdFlagsImplementationTest.kt
index fb17e03a9..7409471da 100644
--- a/packages/core/android/src/test/kotlin/com/datadog/reactnative/DdFlagsImplementationTest.kt
+++ b/packages/core/android/src/test/kotlin/com/datadog/reactnative/DdFlagsImplementationTest.kt
@@ -7,21 +7,27 @@
 package com.datadog.reactnative
 
 import com.datadog.android.Datadog
-import com.datadog.android.api.SdkCore
-import com.datadog.android.flags.Flags
-import com.datadog.android.flags.FlagsConfiguration
+import com.datadog.android.DatadogSite
+import com.datadog.android.api.context.DatadogContext
+import com.datadog.android.api.feature.Feature
+import com.datadog.android.api.feature.FeatureSdkCore
+import com.datadog.android.flags.model.EvaluationContext
 import com.datadog.tools.unit.toReadableMap
 import com.facebook.react.bridge.Promise
+import okhttp3.Request
+import okio.Buffer
+import org.assertj.core.api.Assertions.assertThat
+import org.json.JSONObject
 import org.junit.jupiter.api.Test
 import org.junit.jupiter.api.extension.ExtendWith
 import org.junit.jupiter.api.extension.Extensions
 import org.mockito.Mock
 import org.mockito.Mockito
 import org.mockito.junit.jupiter.MockitoExtension
-import org.mockito.kotlin.any
+import org.mockito.kotlin.argumentCaptor
 import org.mockito.kotlin.mock
-import org.mockito.kotlin.same
 import org.mockito.kotlin.verify
+import org.mockito.kotlin.whenever
 
 @Extensions(
     ExtendWith(MockitoExtension::class)
@@ -50,16 +56,18 @@ internal class DdFlagsImplementationTest {
     @Test
     fun `M resolve current SDK core W enable() called after construction`() {
         // Given
-        val staleCore = mock<SdkCore>()
-        val initializedCore = mock<SdkCore>()
+        val staleCore = mock<FeatureSdkCore>()
+        val initializedCore = mock<FeatureSdkCore>()
+        whenever(initializedCore.internalLogger).thenReturn(mock())
         var currentCore = staleCore
-        val configuration = mapOf("enabled" to true).toReadableMap()
+        val configuration = mapOf(
+            "enabled" to true,
+            "_ddFlagsSdkVersion" to "4.2.0-js.1"
+        ).toReadableMap()
         val datadogMock = Mockito.mockStatic(Datadog::class.java)
-        val flagsMock = Mockito.mockStatic(Flags::class.java)
 
         try {
-            datadogMock.`when`<SdkCore> { Datadog.getInstance() }.thenAnswer { currentCore }
-            flagsMock.`when`<Unit> { Flags.enable(any<FlagsConfiguration>(), any()) }.then { }
+            datadogMock.`when`<FeatureSdkCore> { Datadog.getInstance() }.thenAnswer { currentCore }
             val testedImplementation = DdFlagsImplementation()
             currentCore = initializedCore
 
@@ -67,11 +75,52 @@ internal class DdFlagsImplementationTest {
             testedImplementation.enable(configuration, mockPromise)
 
             // Then
-            flagsMock.verify { Flags.enable(any<FlagsConfiguration>(), same(initializedCore)) }
+            assertSource(initializedCore, "4.2.0-js.1")
             verify(mockPromise).resolve(null)
         } finally {
-            flagsMock.close()
             datadogMock.close()
         }
     }
+
+    @Test
+    fun `M report unknown reader W enable() from older JS`() {
+        val core = mock<FeatureSdkCore>()
+        whenever(core.internalLogger).thenReturn(mock())
+        DdFlagsImplementation(core).enable(mapOf("enabled" to true).toReadableMap(), mockPromise)
+        assertSource(core, "unknown")
+    }
+
+    private fun assertSource(core: FeatureSdkCore, expectedJsVersion: String) {
+        val features = argumentCaptor<Feature>()
+        verify(core, org.mockito.kotlin.times(2)).registerFeature(features.capture())
+        val flags = features.allValues.single { it.name == "flags" }
+        // Exercise the real native serializer without exposing a test API in the SDK.
+        val getter = flags.javaClass.methods.single {
+            it.name.startsWith(
+                "getPrecomputedRequestFactory"
+            )
+        }
+        val factory = getter.invoke(flags)
+        val create = factory.javaClass.methods.single { it.name == "create" }
+        val context = mock<DatadogContext>()
+        whenever(context.site).thenReturn(DatadogSite.US1)
+        whenever(context.env).thenReturn("test")
+        whenever(context.clientToken).thenReturn("local-test-only")
+        whenever(context.featuresContext).thenReturn(emptyMap())
+        val evaluationContext = EvaluationContext("athlete", emptyMap())
+        val request = create.invoke(factory, evaluationContext, context) as Request
+        val buffer = Buffer()
+        checkNotNull(request.body).writeTo(buffer)
+        val source = JSONObject(buffer.readUtf8()).getJSONObject("data")
+            .getJSONObject("attributes").getJSONObject("source")
+        assertThat(source.getString("sdk_name")).isEqualTo("dd-sdk-reactnative")
+        assertThat(source.getString("sdk_version")).isEqualTo(expectedJsVersion)
+        assertThat(source.getString("native_bridge_version")).isEqualTo(SDK_VERSION)
+        val native = source.getJSONObject("native_sdk")
+        val buildConfig = Class.forName("com.datadog.android.flags.BuildConfig")
+        assertThat(native.getString("sdk_name")).isEqualTo("dd-sdk-android")
+        assertThat(native.getString("sdk_version")).isEqualTo(
+            buildConfig.getField("SDK_VERSION_NAME").get(null)
+        )
+    }
 }
diff --git a/packages/core/ios/Sources/DdFlagsImplementation.swift b/packages/core/ios/Sources/DdFlagsImplementation.swift
index 34020f410..f96d11c07 100644
--- a/packages/core/ios/Sources/DdFlagsImplementation.swift
+++ b/packages/core/ios/Sources/DdFlagsImplementation.swift
@@ -31,7 +31,13 @@ public class DdFlagsImplementation: NSObject {
         clientProviders.removeAll()
 
         if let config = configuration.asFlagsConfiguration() {
-            Flags.enable(with: config)
+            Flags.enable(
+                with: config,
+                in: core,
+                wrapperSDKName: "dd-sdk-reactnative",
+                wrapperSDKVersion: configuration["_ddFlagsSdkVersion"] as? String ?? "unknown",
+                nativeBridgeVersion: SdkVersion
+            )
         } else {
             consolePrint("Invalid configuration provided for Flags. Feature initialization skipped.", .error)
         }
@@ -91,6 +97,9 @@ public class DdFlagsImplementation: NSObject {
                 case .invalidResponse:
                     errorCode = "INVALID_RESPONSE"
                     errorMessage = "The flags service returned an invalid response for client '\(clientName)'."
+                case .initializationTimedOut:
+                    errorCode = "INITIALIZATION_TIMED_OUT"
+                    errorMessage = "Flag initialization timed out for client '\(clientName)'."
                 case .networkError:
                     errorCode = "NETWORK_ERROR"
                     errorMessage = "A network error occurred while fetching feature flags for client '\(clientName)'."
diff --git a/packages/core/ios/Sources/SdkVersion.swift b/packages/core/ios/Sources/SdkVersion.swift
index 9298a1fd6..e12f23daa 100644
--- a/packages/core/ios/Sources/SdkVersion.swift
+++ b/packages/core/ios/Sources/SdkVersion.swift
@@ -6,5 +6,5 @@
 
 import Foundation
 
-// This is automatically updated by the update-version.sh script
+// Generated from packages/core/package.json. Do not edit.
 let SdkVersion = "3.9.0"
diff --git a/packages/core/ios/Tests/DdFlagsTests.swift b/packages/core/ios/Tests/DdFlagsTests.swift
index 3fca72ddc..d8e9407ac 100644
--- a/packages/core/ios/Tests/DdFlagsTests.swift
+++ b/packages/core/ios/Tests/DdFlagsTests.swift
@@ -44,6 +44,22 @@ class DdFlagsTests: XCTestCase {
         waitForExpectations(timeout: 1, handler: nil)
     }
 
+    func testInitializationTimeoutIsReturnedToJavaScript() {
+        let completion = expectation(description: "Timeout rejects")
+        let client = MockFlagsClient()
+        client.errorToReturn = .initializationTimedOut
+        implementation.clientProviders["test_client"] = { client }
+        implementation.setEvaluationContext(
+            "test_client", targetingKey: "athlete", attributes: [:],
+            resolve: { _ in XCTFail("Expected rejection") },
+            reject: { code, _, _ in
+                XCTAssertEqual(code, "INITIALIZATION_TIMED_OUT")
+                completion.fulfill()
+            }
+        )
+        waitForExpectations(timeout: 1)
+    }
+
     func testSetEvaluationContextSuccess() {
         let expectation = self.expectation(description: "SetEvaluationContext resolves with flags")
 
diff --git a/packages/core/package.json b/packages/core/package.json
index 74c6cabc3..75e2f63b9 100644
--- a/packages/core/package.json
+++ b/packages/core/package.json
@@ -61,7 +61,8 @@
     "scripts": {
         "test": "jest",
         "lint": "eslint .",
-        "prepare": "rm -rf lib && yarn bob build",
+        "prepare": "node scripts/generate-sdk-version.cjs && rm -rf lib && yarn bob build",
+        "prepack": "node scripts/generate-sdk-version.cjs --check && yarn bob build",
         "postinstall": "node scripts/replace-react-require.js # Use node to execute the script for Windows, see https://github.com/DataDog/dd-sdk-reactnative/issues/358"
     },
     "peerDependencies": {
diff --git a/packages/core/scripts/SDK-IDENTITY.md b/packages/core/scripts/SDK-IDENTITY.md
new file mode 100644
index 000000000..e593aabd2
--- /dev/null
+++ b/packages/core/scripts/SDK-IDENTITY.md
@@ -0,0 +1,32 @@
+# Flags request identity
+
+`packages/core/package.json` is the version source. Normal `yarn prepare` generates the JavaScript, Swift, and Kotlin constants.
+The release script calls this workflow after Lerna changes the package version. No customer step is required.
+CI checks generated files before building. Packing checks the generated files and rebuilds JavaScript before creating the archive.
+
+Run the generator checks with:
+
+```sh
+node packages/core/scripts/generate-sdk-version.cjs --check
+node --test packages/core/scripts/generate-sdk-version.test.cjs
+```
+
+The JavaScript Flags reader sends its generated version to the native bridge automatically.
+The bridge adds its compiled package version. The native SDK supplies its own Flags artifact version.
+For example, an over-the-air JavaScript update can produce:
+
+```json
+{
+  "sdk_name": "dd-sdk-reactnative",
+  "sdk_version": "4.2.0",
+  "native_bridge_version": "4.1.0",
+  "native_sdk": {"sdk_name": "dd-sdk-ios", "sdk_version": "3.18.0"}
+}
+```
+
+These values are compatibility information, not authentication. The backend must check every reader that can affect an encoding.
+An older JavaScript bundle reports an unknown reader version. The bridge must not substitute its own version for that reader.
+
+The internal native enable interfaces require the companion iOS and Android changes before this PR can merge.
+Update the native dependency pins after those interfaces are released. Do not substitute a declared dependency version for the actual native artifact version.
+Local validation can use the companion native builds. No native version is duplicated in this repository.
diff --git a/packages/core/scripts/generate-sdk-version.cjs b/packages/core/scripts/generate-sdk-version.cjs
new file mode 100644
index 000000000..6013501ea
--- /dev/null
+++ b/packages/core/scripts/generate-sdk-version.cjs
@@ -0,0 +1,47 @@
+/*
+ * Unless explicitly stated otherwise all files in this repository are licensed under the Apache License Version 2.0.
+ * This product includes software developed at Datadog (https://www.datadoghq.com/).
+ * Copyright 2016-Present Datadog, Inc.
+ */
+
+const fs = require('node:fs');
+const path = require('node:path');
+
+const license = `/*
+ * Unless explicitly stated otherwise all files in this repository are licensed under the Apache License Version 2.0.
+ * This product includes software developed at Datadog (https://www.datadoghq.com/).
+ * Copyright 2016-Present Datadog, Inc.
+ */
+`;
+
+function generate(packageRoot, check = false) {
+    const { version } = JSON.parse(fs.readFileSync(path.join(packageRoot, 'package.json'), 'utf8'));
+    const numeric = '(0|[1-9][0-9]*)';
+    const prerelease = '(0|[1-9][0-9]*|[0-9]*[A-Za-z-][0-9A-Za-z-]*)';
+    const semver = new RegExp(`^${numeric}\\.${numeric}\\.${numeric}(?:-${prerelease}(?:\\.${prerelease})*)?(?:\\+[0-9A-Za-z-]+(?:\\.[0-9A-Za-z-]+)*)?$`);
+    if (typeof version !== 'string' || !semver.test(version)) {
+        throw new Error('The core package must have a valid SemVer version.');
+    }
+    const generated = '// Generated from packages/core/package.json. Do not edit.\n';
+    const outputs = {
+        'src/version.ts': `${generated}export const version = '${version}';\n`,
+        'ios/Sources/SdkVersion.swift': `${license}\nimport Foundation\n\n${generated}let SdkVersion = "${version}"\n`,
+        'android/src/main/kotlin/com/datadog/reactnative/SdkVersion.kt': `${license}\npackage com.datadog.reactnative\n\n${generated}internal const val SDK_VERSION = "${version}"\n`
+    };
+    for (const [relative, expected] of Object.entries(outputs)) {
+        const file = path.join(packageRoot, relative);
+        if (check) {
+            if (!fs.existsSync(file) || fs.readFileSync(file, 'utf8') !== expected) {
+                throw new Error(`Missing or stale SDK version: ${relative}. Run yarn prepare.`);
+            }
+        } else {
+            fs.mkdirSync(path.dirname(file), { recursive: true });
+            fs.writeFileSync(file, expected);
+        }
+    }
+}
+
+if (require.main === module) {
+    generate(path.resolve(__dirname, '..'), process.argv.includes('--check'));
+}
+module.exports = { generate };
diff --git a/packages/core/scripts/generate-sdk-version.test.cjs b/packages/core/scripts/generate-sdk-version.test.cjs
new file mode 100644
index 000000000..52253bd91
--- /dev/null
+++ b/packages/core/scripts/generate-sdk-version.test.cjs
@@ -0,0 +1,35 @@
+const { test } = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const os = require('node:os');
+const path = require('node:path');
+const { generate } = require('./generate-sdk-version.cjs');
+
+for (const version of ['3.9.0', '4.0.0', '4.1.0-rc.2+build.42']) {
+    test(`generates all three shipped identities from ${version}`, t => {
+        const root = fs.mkdtempSync(path.join(os.tmpdir(), 'rn-sdk-version-'));
+        t.after(() => fs.rmSync(root, { recursive: true, force: true }));
+        fs.writeFileSync(path.join(root, 'package.json'), JSON.stringify({ version }));
+        generate(root);
+        generate(root, true);
+        for (const relative of ['src/version.ts', 'ios/Sources/SdkVersion.swift', 'android/src/main/kotlin/com/datadog/reactnative/SdkVersion.kt']) {
+            assert.ok(fs.readFileSync(path.join(root, relative), 'utf8').includes(version));
+        }
+        fs.writeFileSync(path.join(root, 'src/version.ts'), 'stale');
+        assert.throws(() => generate(root, true), /stale/);
+        generate(root);
+        fs.unlinkSync(path.join(root, 'ios/Sources/SdkVersion.swift'));
+        assert.throws(() => generate(root, true), /Missing/);
+        generate(root);
+        generate(root, true);
+    });
+}
+
+test('rejects absent and invalid package versions', t => {
+    const root = fs.mkdtempSync(path.join(os.tmpdir(), 'rn-sdk-version-'));
+    t.after(() => fs.rmSync(root, { recursive: true, force: true }));
+    for (const version of [undefined, '', '1.2', '01.2.3', '1.2.3-01']) {
+        fs.writeFileSync(path.join(root, 'package.json'), JSON.stringify({ version }));
+        assert.throws(() => generate(root), /SemVer/);
+    }
+});
diff --git a/packages/core/src/flags/DdFlags.ts b/packages/core/src/flags/DdFlags.ts
index 43714d598..9114a6667 100644
--- a/packages/core/src/flags/DdFlags.ts
+++ b/packages/core/src/flags/DdFlags.ts
@@ -8,6 +8,7 @@ import { InternalLog } from '../InternalLog';
 import { SdkVerbosity } from '../config/types/SdkVerbosity';
 import type { DdNativeFlagsType } from '../nativeModulesTypes';
 import { getGlobalInstance } from '../utils/singletonUtils';
+import { version } from '../version';
 
 import { FlagsClient } from './FlagsClient';
 import type { DdFlagsType, FlagsConfiguration } from './types';
@@ -32,7 +33,12 @@ class DdFlagsWrapper implements DdFlagsType {
     private clients: Record<string, FlagsClient> = {};
 
     enable = async (configuration: FlagsConfiguration = {}): Promise<void> => {
-        await this.nativeFlags.enable({ enabled: true, ...configuration });
+        await this.nativeFlags.enable({
+            enabled: true,
+            ...configuration,
+            // The loaded bundle can differ from the compiled native bridge.
+            _ddFlagsSdkVersion: version
+        });
 
         this.isFeatureEnabled = true;
     };
diff --git a/packages/core/src/flags/__tests__/DdFlags.test.ts b/packages/core/src/flags/__tests__/DdFlags.test.ts
index 01e65d431..8a574e3c2 100644
--- a/packages/core/src/flags/__tests__/DdFlags.test.ts
+++ b/packages/core/src/flags/__tests__/DdFlags.test.ts
@@ -8,6 +8,7 @@ import { NativeModules } from 'react-native';
 
 import { InternalLog } from '../../InternalLog';
 import { SdkVerbosity } from '../../config/types/SdkVerbosity';
+import { version } from '../../version';
 import { DdFlags } from '../DdFlags';
 
 jest.mock('../../InternalLog', () => {
@@ -33,7 +34,8 @@ describe('DdFlags', () => {
         await DdFlags.enable();
 
         expect(NativeModules.DdFlags.enable).toHaveBeenCalledWith({
-            enabled: true
+            enabled: true,
+            _ddFlagsSdkVersion: version
         });
     });
 
@@ -42,7 +44,9 @@ describe('DdFlags', () => {
             customExposureEndpoint: 'https://example.com',
             customFlagsEndpoint: 'https://example.com',
             trackExposures: false,
-            rumIntegrationEnabled: false
+            rumIntegrationEnabled: false,
+            // An application value must not replace package identity.
+            ...{ _ddFlagsSdkVersion: '99.99.99-application' }
         });
 
         expect(NativeModules.DdFlags.enable).toHaveBeenCalledWith({
@@ -50,7 +54,8 @@ describe('DdFlags', () => {
             customExposureEndpoint: 'https://example.com',
             customFlagsEndpoint: 'https://example.com',
             trackExposures: false,
-            rumIntegrationEnabled: false
+            rumIntegrationEnabled: false,
+            _ddFlagsSdkVersion: version
         });
     });
 
diff --git a/packages/core/src/version.ts b/packages/core/src/version.ts
index 3ce867548..c6b20661d 100644
--- a/packages/core/src/version.ts
+++ b/packages/core/src/version.ts
@@ -1,2 +1,2 @@
-// generated by genversion
+// Generated from packages/core/package.json. Do not edit.
 export const version = '3.9.0';
diff --git a/update-version.sh b/update-version.sh
index 097fba0ee..5263c2f95 100755
--- a/update-version.sh
+++ b/update-version.sh
@@ -2,10 +2,6 @@
 
 set -e
 
-# Change version in native files
-sed -i '' -e "s/\".*\"/\"$1\"/g" packages/core/ios/Sources/SdkVersion.swift
-sed -i '' -e "s/\".*\"/\"$1\"/g" packages/core/android/src/main/kotlin/com/datadog/reactnative/SdkVersion.kt
-
 # Change version
 yarn run lerna version $1 --ignore-changes --no-git-tag-version --no-push
 yarn prepare