fix(core): Emit processed metric (#18222)

We were emitting the non-processed metric in the hook before – I changed
this behaviour + added a test to verify.

Author: chargome

dev-packages/browser-integration-tests/suites/public-api/metrics/afterCaptureMetric/init.js

@@ -0,0 +1,25 @@
+import * as Sentry from '@sentry/browser';
+
+window.Sentry = Sentry;
+
+Sentry.init({
+  dsn: 'https://public@dsn.ingest.sentry.io/1337',
+  release: '1.0.0',
+  environment: 'test',
+  integrations: integrations => {
+    return integrations.filter(integration => integration.name !== 'BrowserSession');
+  },
+  beforeSendMetric: metric => {
+    if (metric.name === 'test.counter') {
+      return {
+        ...metric,
+        attributes: {
+          ...metric.attributes,
+          modified: 'by-beforeSendMetric',
+          original: undefined,
+        },
+      };
+    }
+    return metric;
+  },
+});

dev-packages/browser-integration-tests/suites/public-api/metrics/afterCaptureMetric/subject.js

@@ -0,0 +1,14 @@
+// Store captured metrics from the afterCaptureMetric event
+window.capturedMetrics = [];
+
+const client = Sentry.getClient();
+
+client.on('afterCaptureMetric', metric => {
+  window.capturedMetrics.push(metric);
+});
+
+// Capture metrics - these should be processed by beforeSendMetric
+Sentry.metrics.count('test.counter', 1, { attributes: { endpoint: '/api/test', original: 'value' } });
+Sentry.metrics.gauge('test.gauge', 42, { unit: 'millisecond', attributes: { server: 'test-1' } });
+
+Sentry.flush();

dev-packages/browser-integration-tests/suites/public-api/metrics/afterCaptureMetric/test.ts

@@ -0,0 +1,59 @@
+import { expect } from '@playwright/test';
+import { sentryTest } from '../../../../utils/fixtures';
+
+sentryTest(
+  'should emit afterCaptureMetric event with processed metric from beforeSendMetric',
+  async ({ getLocalTestUrl, page }) => {
+    const bundle = process.env.PW_BUNDLE || '';
+    if (bundle.startsWith('bundle') || bundle.startsWith('loader')) {
+      sentryTest.skip();
+    }
+
+    const url = await getLocalTestUrl({ testDir: __dirname });
+    await page.goto(url);
+
+    await page.waitForFunction(() => {
+      return (window as any).capturedMetrics.length >= 2;
+    });
+
+    const capturedMetrics = await page.evaluate(() => {
+      return (window as any).capturedMetrics;
+    });
+
+    expect(capturedMetrics).toHaveLength(2);
+
+    // Verify the counter metric was modified by beforeSendMetric
+    expect(capturedMetrics[0]).toMatchObject({
+      name: 'test.counter',
+      type: 'counter',
+      value: 1,
+      attributes: {
+        endpoint: '/api/test',
+        modified: 'by-beforeSendMetric',
+        'sentry.release': '1.0.0',
+        'sentry.environment': 'test',
+        'sentry.sdk.name': 'sentry.javascript.browser',
+      },
+    });
+
+    // Verify the 'original' attribute was removed by beforeSendMetric
+    expect(capturedMetrics[0].attributes.original).toBeUndefined();
+
+    // Verify the gauge metric was not modified (no beforeSendMetric processing)
+    expect(capturedMetrics[1]).toMatchObject({
+      name: 'test.gauge',
+      type: 'gauge',
+      unit: 'millisecond',
+      value: 42,
+      attributes: {
+        server: 'test-1',
+        'sentry.release': '1.0.0',
+        'sentry.environment': 'test',
+        'sentry.sdk.name': 'sentry.javascript.browser',
+      },
+    });
+
+    expect(capturedMetrics[0].attributes['sentry.sdk.version']).toBeDefined();
+    expect(capturedMetrics[1].attributes['sentry.sdk.version']).toBeDefined();
+  },
+);

packages/core/src/metrics/internal.ts

@@ -243,7 +243,7 @@ export function _INTERNAL_captureMetric(beforeMetric: Metric, options?: Internal
 
   captureSerializedMetric(client, serializedMetric);
 
-  client.emit('afterCaptureMetric', enrichedMetric);
+  client.emit('afterCaptureMetric', processedMetric);
 }
 
 /**