feat(attributes): Add LCP and CLS web vital report event attribute#319
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feat(attributes): Add LCP and CLS web vital report event attribute#319
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Lms24
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cleptric,
lcian,
mjq and
nsdeschenes
as code owners
Semver Impact of This PR🟡 Minor (new features) 📋 Changelog PreviewThis is how your changes will appear in the changelog. New Features ✨Attributes
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Cursor Bugbot has reviewed your changes and found 1 potential issue.
Bugbot Autofix prepared a fix for the issue found in the latest run.
- ✅ Fixed: Generated files edited without source model JSON files
- Created the missing source JSON files browser__web_vital__cls__report_event.json and browser__web_vital__lcp__report_event.json in model/attributes/browser/ with proper metadata and PR reference 319.
Or push these changes by commenting:
@cursor push c0d4f4cf46
Preview (c0d4f4cf46)
diff --git a/model/attributes/browser/browser__web_vital__cls__report_event.json b/model/attributes/browser/browser__web_vital__cls__report_event.json
new file mode 100644
--- /dev/null
+++ b/model/attributes/browser/browser__web_vital__cls__report_event.json
@@ -1,0 +1,18 @@
+{
+ "key": "browser.web_vital.cls.report_event",
+ "brief": "The event that caused the SDK to report CLS (pagehide or navigation)",
+ "type": "string",
+ "pii": {
+ "key": "maybe"
+ },
+ "is_in_otel": false,
+ "example": "navigation",
+ "sdks": ["javascript-browser"],
+ "changelog": [
+ {
+ "version": "next",
+ "prs": [319],
+ "description": "Added browser.web_vital.cls.report_event attribute"
+ }
+ ]
+}
diff --git a/model/attributes/browser/browser__web_vital__lcp__report_event.json b/model/attributes/browser/browser__web_vital__lcp__report_event.json
new file mode 100644
--- /dev/null
+++ b/model/attributes/browser/browser__web_vital__lcp__report_event.json
@@ -1,0 +1,18 @@
+{
+ "key": "browser.web_vital.lcp.report_event",
+ "brief": "The event that caused the SDK to report LCP (pagehide or navigation)",
+ "type": "string",
+ "pii": {
+ "key": "maybe"
+ },
+ "is_in_otel": false,
+ "example": "pagehide",
+ "sdks": ["javascript-browser"],
+ "changelog": [
+ {
+ "version": "next",
+ "prs": [319],
+ "description": "Added browser.web_vital.lcp.report_event attribute"
+ }
+ ]
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Lms24
commented
Apr 14, 2026
Comment on lines
+12
to
+16
| "deprecation": { | ||
| "replacement": null, | ||
| "reason": "The report event is now recorded as a browser.web_vital.lcp.report_event or browser.web_vital.cls.report_event attribute. No backfill required.", | ||
| "_status": null | ||
| }, |
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I documented the old attribute (currently still sent with v1 standalone web vital spans) and marked it as deprecated. Since there's no 1:1 replacement but SDKs send one of two different attributes depending on the span, I left repalcement and _status intentionally on null since I don't think we can backfill this at all. Given there's no product logic around these attributes I think that's fine but happy to do something else if reviewers have concerns.
cleptric
approved these changes
Apr 14, 2026
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Two web vital attributes were missing which we should still include for web vital meta information:
browser.web_vital.lcp.report_eventbrowser.web_vital.cls.report_eventThese attributes carry information on what event caused the SDK to report a web vital span for CLS and LCP: Either a
pagehideornavigationevent. More events could follow in the future.For both of these web vitals, we previously sent
sentry.report_eventbut in retrospect I believe this was a bad naming choice (my fault lol). Given we have a common pattern now for web vitals, let's align these. No product logic depends on these attributes. They're merely meta information.ref: