Include applicationId in snapshot payload and tags

Browser snapshots need to carry the RUM application identity so the
web UI can resolve source metadata via the browser-build lookup when
git tags are absent.

Author: watson

packages/debugger/src/domain/api.spec.ts

@@ -321,6 +321,34 @@ describe('api', () => {
       expect(snapshot.duration).toBeGreaterThanOrEqual(10000000) // Should be in nanoseconds (>= 10ms)
     })
 
+    it('should include applicationId in snapshot payload and tags', () => {
+      initDebuggerTransport(
+        { service: 'test-service', env: 'test-env', applicationId: 'app-123' } as any,
+        { add: mockBatchAdd } as any
+      )
+
+      const probe: Probe = {
+        id: 'test-probe',
+        version: 0,
+        type: 'LOG_PROBE',
+        where: { typeName: 'TestClass', methodName: 'appIdTest' },
+        template: 'Test',
+        captureSnapshot: false,
+        capture: {},
+        sampling: { snapshotsPerSecond: 5000 },
+        evaluateAt: 'ENTRY',
+      }
+      addProbe(probe)
+
+      const probes = getProbes('TestClass;appIdTest')!
+      onEntry(probes, {}, {})
+      onReturn(probes, null, {}, {}, {})
+
+      const payload = mockBatchAdd.calls.mostRecent().args[0]
+      expect(payload.application_id).toBe('app-123')
+      expect(payload.ddtags).toContain('application_id:app-123')
+    })
+
     it('should omit trace correlation when no active span context is available', () => {
       const probe: Probe = {
         id: 'test-probe',

packages/debugger/src/domain/api.ts

@@ -299,12 +299,14 @@ function sendDebuggerSnapshot(probe: InitializedProbe, result: ActiveEntry): voi
     buildTag('version', debuggerConfig.version),
     buildTag('debugger_version', debuggerApi.version),
     buildTag('host_name', hostname),
+    buildTag('application_id', debuggerConfig.applicationId),
   ]
 
   const payload: Context = {
     message: result.message || '',
     hostname,
     service: debuggerConfig.service,
+    application_id: debuggerConfig.applicationId,
     ddtags: ddtags.join(','),
     logger,
     ...(dd ? { dd } : {}),