Add Live Debugger package

Introduce the browser debugger SDK and probe execution pipeline so
browser code can evaluate conditions, capture snapshots, and render
probe messages at runtime. Add Delivery API polling plus sandbox and
performance tooling to support probe delivery and testing.

Author: watson

eslint-local-rules/disallowSideEffects.js

@@ -29,6 +29,7 @@ const pathsWithSideEffect = new Set([
   `${packagesRoot}/logs/src/entries/main.ts`,
   `${packagesRoot}/rum/src/entries/main.ts`,
   `${packagesRoot}/rum-slim/src/entries/main.ts`,
+  `${packagesRoot}/debugger/src/entries/main.ts`,
 ])
 
 // Those packages are known to have no side effects when evaluated

packages/core/src/domain/configuration/configuration.ts

@@ -276,7 +276,7 @@ export interface InitConfiguration {
    *
    * @internal
    */
-  source?: 'browser' | 'flutter' | 'unity' | undefined
+  source?: 'browser' | 'flutter' | 'unity' | 'dd_debugger' | undefined
 
   /**
    * [Internal option] Additional configuration for the SDK.
@@ -331,7 +331,7 @@ export interface Configuration extends TransportConfiguration {
 
   // internal
   sdkVersion: string | undefined
-  source: 'browser' | 'flutter' | 'unity'
+  source: 'browser' | 'flutter' | 'unity' | 'dd_debugger'
   variant: string | undefined
 }
 

packages/core/src/domain/configuration/transportConfiguration.ts

@@ -14,7 +14,7 @@ export interface TransportConfiguration {
   datacenter?: string | undefined
   replica?: ReplicaConfiguration
   site: Site
-  source: 'browser' | 'flutter' | 'unity'
+  source: 'browser' | 'flutter' | 'unity' | 'dd_debugger'
 }
 
 export interface ReplicaConfiguration {
@@ -38,7 +38,7 @@ export function computeTransportConfiguration(initConfiguration: InitConfigurati
 }
 
 function validateSource(source: string | undefined) {
-  if (source === 'flutter' || source === 'unity') {
+  if (source === 'flutter' || source === 'unity' || source === 'dd_debugger') {
     return source
   }
   return 'browser'

packages/core/src/domain/telemetry/telemetryEvent.types.ts

@@ -585,6 +585,7 @@ export interface CommonTelemetryProperties {
     | 'kotlin-multiplatform'
     | 'electron'
     | 'rum-cpp'
+    | 'dd_debugger'
   /**
    * The version of the SDK generating the telemetry event
    */

packages/core/src/index.ts

@@ -7,6 +7,7 @@ export {
   isSampleRate,
   buildEndpointHost,
   isIntakeUrl,
+  computeTransportConfiguration,
 } from './domain/configuration'
 export * from './domain/intakeSites'
 export type { TrackingConsentState } from './domain/trackingConsent'
@@ -57,7 +58,7 @@ export {
   SESSION_NOT_TRACKED,
   SessionPersistence,
 } from './domain/session/sessionConstants'
-export type { BandwidthStats, HttpRequest, HttpRequestEvent, Payload, FlushEvent, FlushReason } from './transport'
+export type { Batch, BandwidthStats, HttpRequest, HttpRequestEvent, Payload, FlushEvent, FlushReason } from './transport'
 export {
   createHttpRequest,
   canUseEventBridge,

packages/core/src/transport/index.ts

@@ -2,6 +2,7 @@ export type { BandwidthStats, HttpRequest, HttpRequestEvent, Payload, RetryInfo
 export { createHttpRequest } from './httpRequest'
 export type { BrowserWindowWithEventBridge, DatadogEventBridge } from './eventBridge'
 export { canUseEventBridge, bridgeSupports, getEventBridge, BridgeCapability } from './eventBridge'
+export type { Batch } from './batch'
 export { createBatch } from './batch'
 export type { FlushController, FlushEvent, FlushReason } from './flushController'
 export { createFlushController, FLUSH_DURATION_LIMIT } from './flushController'

packages/debugger/README.md

@@ -0,0 +1,88 @@
+# Live Debugger Browser Monitoring
+
+Datadog Live Debugger enables you to capture function execution snapshots, evaluate conditions, and collect runtime data from your application without modifying source code.
+
+## Usage
+
+To start using the live debugger, add [`@datadog/browser-debugger`](https://www.npmjs.com/package/@datadog/browser-debugger) to your `package.json` file, then initialize it with:
+
+```javascript
+import { datadogLiveDebugger } from '@datadog/browser-debugger'
+
+datadogLiveDebugger.init({
+  clientToken: '<DATADOG_CLIENT_TOKEN>',
+  applicationId: '<DATADOG_APPLICATION_ID>',
+  service: 'my-web-application',
+  site: '<DATADOG_SITE>',
+  env: 'production',
+  version: '1.0.0',
+})
+```
+
+The debugger automatically polls for probe updates from the Delivery API.
+
+You can also add probes programmatically:
+
+```javascript
+datadogLiveDebugger.addProbe({
+  id: 'probe-1',
+  version: 0,
+  type: 'LOG_PROBE',
+  where: { typeName: 'MyClass', methodName: 'myMethod' },
+  template: 'Method executed with duration: {@duration}ms',
+  segments: [
+    { str: 'Method executed with duration: ' },
+    { dsl: '@duration', json: { ref: '@duration' } },
+    { str: 'ms' },
+  ],
+  captureSnapshot: true,
+  capture: { maxReferenceDepth: 3 },
+  sampling: { snapshotsPerSecond: 5000 },
+  evaluateAt: 'EXIT',
+})
+```
+
+## Integration with RUM
+
+The Live Debugger integrates seamlessly with Datadog RUM to provide enhanced context and correlation:
+
+```javascript
+import { datadogRum } from '@datadog/browser-rum'
+import { datadogLiveDebugger } from '@datadog/browser-debugger'
+
+// Initialize RUM first
+datadogRum.init({
+  applicationId: '<DATADOG_APPLICATION_ID>',
+  clientToken: '<DATADOG_CLIENT_TOKEN>',
+  site: '<DATADOG_SITE>',
+  service: 'my-web-application',
+  env: 'production',
+})
+
+// Then initialize Live Debugger
+datadogLiveDebugger.init({
+  clientToken: '<DATADOG_CLIENT_TOKEN>',
+  applicationId: '<DATADOG_APPLICATION_ID>',
+  service: 'my-web-application',
+  site: '<DATADOG_SITE>',
+  env: 'production',
+})
+
+// Add your probe configurations
+// datadogLiveDebugger.addProbe({ ... })
+```
+
+When both are initialized, debugger snapshots will automatically include RUM context (session, view, user action).
+
+## Features
+
+- **Dynamic Instrumentation**: Capture function entry/exit without code changes
+- **Conditional Breakpoints**: Evaluate conditions before capturing snapshots
+- **Template Expressions**: Evaluate custom messages with runtime context
+- **Rate Limiting**: Built-in sampling to prevent performance impact
+- **Stack Traces**: Automatic stack trace capture for debugging
+- **Variable Capture**: Deep capture of arguments, locals, and return values
+
+<!-- Note: all URLs should be absolute -->
+
+[1]: https://docs.datadoghq.com/dynamic_instrumentation/

packages/debugger/package.json

@@ -0,0 +1,26 @@
+{
+  "name": "@datadog/browser-debugger",
+  "version": "6.30.1",
+  "license": "Apache-2.0",
+  "main": "cjs/entries/main.js",
+  "module": "esm/entries/main.js",
+  "types": "cjs/entries/main.d.ts",
+  "scripts": {
+    "build": "node ../../scripts/build/build-package.ts --modules --bundle datadog-debugger.js",
+    "build:bundle": "node ../../scripts/build/build-package.ts --bundle datadog-debugger.js"
+  },
+  "dependencies": {
+    "@datadog/browser-core": "6.30.1"
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/DataDog/browser-sdk.git",
+    "directory": "packages/debugger"
+  },
+  "volta": {
+    "extends": "../../package.json"
+  },
+  "publishConfig": {
+    "access": "public"
+  }
+}