feat(browser): Trace continuation from server-timing headers - #18673

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Lms24 merged 3 commits into
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timfish/feat/browser-server-timing
Feb 2, 2026
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feat(browser): Trace continuation from server-timing headers#18673
Lms24 merged 3 commits into
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timfish/feat/browser-server-timing

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@timfishtimfish commented Jan 2, 2026•
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Currently the only way to propagate trace context from server to browser is via meta tags. In some cases modifying the page HTML can be difficult or have a performance impact.

This PR adds support to the browser SDK to fetch sentry-trace and baggage from the Server Timing header.

Closes#18678 (added automatically)

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size-limit report 📦

PathSize% ChangeChange
@sentry/browser25.2 kB--
@sentry/browser - with treeshaking flags23.71 kB--
@sentry/browser (incl. Tracing)42.06 kB+0.1%+38 B 🔺
@sentry/browser (incl. Tracing, Profiling)46.71 kB+0.11%+50 B 🔺
@sentry/browser (incl. Tracing, Replay)80.67 kB+0.04%+29 B 🔺
@sentry/browser (incl. Tracing, Replay) - with treeshaking flags70.34 kB+0.06%+39 B 🔺
@sentry/browser (incl. Tracing, Replay with Canvas)85.36 kB+0.03%+19 B 🔺
@sentry/browser (incl. Tracing, Replay, Feedback)97.58 kB+0.04%+34 B 🔺
@sentry/browser (incl. Feedback)41.92 kB--
@sentry/browser (incl. sendFeedback)29.89 kB--
@sentry/browser (incl. FeedbackAsync)34.89 kB--
@sentry/browser (incl. Metrics)26.31 kB--
@sentry/browser (incl. Logs)26.46 kB--
@sentry/browser (incl. Metrics & Logs)27.11 kB--
@sentry/react26.93 kB--
@sentry/react (incl. Tracing)44.3 kB+0.11%+47 B 🔺
@sentry/vue29.64 kB--
@sentry/vue (incl. Tracing)43.87 kB+0.12%+49 B 🔺
@sentry/svelte25.22 kB--
CDN Bundle27.78 kB--
CDN Bundle (incl. Tracing)42.87 kB+0.08%+34 B 🔺
CDN Bundle (incl. Tracing, Logs, Metrics)43.68 kB+0.09%+35 B 🔺
CDN Bundle (incl. Tracing, Replay)79.59 kB+0.05%+37 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback)85.04 kB+0.06%+47 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback, Logs, Metrics)85.96 kB+0.06%+50 B 🔺
CDN Bundle - uncompressed81.27 kB--
CDN Bundle (incl. Tracing) - uncompressed126.98 kB+0.14%+171 B 🔺
CDN Bundle (incl. Tracing, Logs, Metrics) - uncompressed129.82 kB+0.14%+171 B 🔺
CDN Bundle (incl. Tracing, Replay) - uncompressed243.59 kB+0.08%+171 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback) - uncompressed256.39 kB+0.07%+171 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback, Logs, Metrics) - uncompressed259.2 kB+0.07%+171 B 🔺
@sentry/nextjs (client)46.66 kB+0.1%+42 B 🔺
@sentry/sveltekit (client)42.44 kB+0.12%+48 B 🔺
@sentry/node-core51.9 kB--
@sentry/node165.45 kB--
@sentry/node - without tracing93.65 kB--
@sentry/aws-serverless109.16 kB--

View base workflow run

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timfish marked this pull request as ready for review January 2, 2026 13:47
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Comment threadpackages/browser/src/tracing/browserTracingIntegration.ts Outdated
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Thanks for adding this functionality, Tim!

If you don't mind, please also add an integration test with regular tracing. I think we have some meta-tags integration tests in our suites that we can take inspiration from.

Comment thread...ration-tests/suites/tracing/trace-lifetime/tracing-without-performance-headers/template.html Outdated
Comment threadpackages/browser/src/tracing/browserTracingIntegration.ts
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Comment threaddev-packages/browser-integration-tests/suites/tracing/trace-lifetime/pageload-headers/test.ts Outdated
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node-overhead report 🧳

Note: This is a synthetic benchmark with a minimal express app and does not necessarily reflect the real-world performance impact in an application.

ScenarioRequests/s% of BaselinePrev. Requests/sChange %
GET Baseline9,270-9,202+1%
GET With Sentry1,77419%1,734+2%
GET With Sentry (error only)6,25968%6,088+3%
POST Baseline1,213-1,185+2%
POST With Sentry60850%574+6%
POST With Sentry (error only)1,07989%1,059+2%
MYSQL Baseline3,378-3,294+3%
MYSQL With Sentry47314%448+6%
MYSQL With Sentry (error only)2,74581%2,689+2%

View base workflow run

@timfish
timfishforce-pushed the timfish/feat/browser-server-timing branch from d3377e1 to 3590824CompareJanuary 3, 2026 15:06
@timfish
timfishforce-pushed the timfish/feat/browser-server-timing branch from 3590824 to f8ce616CompareJanuary 3, 2026 15:26
@timfish
timfish requested a review from Lms24January 3, 2026 15:27
timfish
timfish commented Jan 3, 2026
View reviewed changes
Comment threaddev-packages/browser-integration-tests/suites/tracing/trace-lifetime/pageload-meta/test.ts
span_id: expect.stringMatching(/^[\da-f]{16}$/),
});
// navigation span is head of trace, so there's no parent span:
expect(navigationTraceContext?.trace_id).not.toHaveProperty('parent_span_id');

@timfishtimfishJan 3, 2026

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Cursor pointed out that the type/logic was wrong in this expection...

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Cursor Bugbot has reviewed your changes and found 1 potential issue.

Bugbot Autofix is OFF. To automatically fix reported issues with Cloud Agents, enable Autofix in the Cursor dashboard.

Comment thread...ration-tests/suites/tracing/trace-lifetime/tracing-without-performance-headers/template.html
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Thanks Tim! Let's get this in -- really nice alternative to the meta tags. I can see us migrating to this approach for frameworks where modifying the HTML isn't straight forward.

@Lms24
Lms24 merged commit 5616396 into developFeb 2, 2026
164 checks passed
@Lms24
Lms24 deleted the timfish/feat/browser-server-timing branch February 2, 2026 09:16
@Lms24Lms24 mentioned this pull request Feb 2, 2026
Merged
Lms24 added a commit that referenced this pull request Mar 18, 2026
@onurtemizkan@Lms24
feat(remix): Server Timing Headers Trace Propagation (#18653)
ae7206f
Adds automatic trace propagation from server to client via the
Server-Timing HTTP header for Remix applications. The client-side
reading of Server-Timing headers via the Performance API was added in
#18673.
Adds:
- `generateSentryServerTimingHeader(span)` public utility that generates
a Server-Timing header value containing Sentry trace context
- Automatic injection in the document request handler for normal page
responses
- Automatic injection on redirect responses from loaders and actions,
which bypass the document request handler entirely. This is an advantage
over meta tag injection, which cannot work on redirect responses since
they have no HTML body
- For Cloudflare/Hydrogen apps: call
`generateSentryServerTimingHeader()` manually and append the value to
the response's `Server-Timing` header in entry.server.tsx (see
remix-hydrogen e2e test for example)
Works on both Node.js and Cloudflare Workers environments.
Closes#18696
---------
Co-authored-by: Lukas Stracke <lukas.stracke@sentry.io>
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feat(browser): Trace continuation from server-timing headers

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, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Add copy buttons to all 
 blocks\n(function() {\n function addCopyButtons() {\n document.querySelectorAll('pre code').forEach(function(codeBlock) {\n if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;\n codeBlock.parentElement.setAttribute('data-copy-added', 'true');\n \n var btn = document.createElement('button');\n btn.textContent = 'Copy';\n btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';\n btn.onmouseover = function() { this.style.opacity = '1'; };\n btn.onmouseout = function() { this.style.opacity = '0.7'; };\n btn.onclick = function() {\n navigator.clipboard.writeText(codeBlock.textContent).then(function() {\n btn.textContent = 'Copied!';\n setTimeout(function() { btn.textContent = 'Copy'; }, 1500);\n });\n };\n codeBlock.parentElement.style.position = 'relative';\n codeBlock.parentElement.appendChild(btn);\n });\n }\n \n addCopyButtons();\n \n // Re-run on dynamic content\n var observer = new MutationObserver(addCopyButtons);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Add Copy Buttons to Code Blocks");
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '

Skip to content
feat(browser): Trace continuation from server-timing headers - #18673
Merged
Lms24 merged 3 commits into
developfrom 
timfish/feat/browser-server-timing
Feb 2, 2026
Merged
feat(browser): Trace continuation from server-timing headers#18673
Lms24 merged 3 commits into
developfrom 
timfish/feat/browser-server-timing
Conversation
@timfish
@timfishtimfish
commented
Jan 2, 2026•

edited by github-actions
Bot
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Currently the only way to propagate trace context from server to browser is via meta tags. In some cases modifying the page HTML can be difficult or have a performance impact.
This PR adds support to the browser SDK to fetch sentry-trace and baggage from the Server Timing header.
Closes#18678 (added automatically)
@github-actions
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Jan 2, 2026•

edited

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size-limit report 📦
PathSize% ChangeChange
@sentry/browser25.2 kB--
@sentry/browser - with treeshaking flags23.71 kB--
@sentry/browser (incl. Tracing)42.06 kB+0.1%+38 B 🔺
@sentry/browser (incl. Tracing, Profiling)46.71 kB+0.11%+50 B 🔺
@sentry/browser (incl. Tracing, Replay)80.67 kB+0.04%+29 B 🔺
@sentry/browser (incl. Tracing, Replay) - with treeshaking flags70.34 kB+0.06%+39 B 🔺
@sentry/browser (incl. Tracing, Replay with Canvas)85.36 kB+0.03%+19 B 🔺
@sentry/browser (incl. Tracing, Replay, Feedback)97.58 kB+0.04%+34 B 🔺
@sentry/browser (incl. Feedback)41.92 kB--
@sentry/browser (incl. sendFeedback)29.89 kB--
@sentry/browser (incl. FeedbackAsync)34.89 kB--
@sentry/browser (incl. Metrics)26.31 kB--
@sentry/browser (incl. Logs)26.46 kB--
@sentry/browser (incl. Metrics & Logs)27.11 kB--
@sentry/react26.93 kB--
@sentry/react (incl. Tracing)44.3 kB+0.11%+47 B 🔺
@sentry/vue29.64 kB--
@sentry/vue (incl. Tracing)43.87 kB+0.12%+49 B 🔺
@sentry/svelte25.22 kB--
CDN Bundle27.78 kB--
CDN Bundle (incl. Tracing)42.87 kB+0.08%+34 B 🔺
CDN Bundle (incl. Tracing, Logs, Metrics)43.68 kB+0.09%+35 B 🔺
CDN Bundle (incl. Tracing, Replay)79.59 kB+0.05%+37 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback)85.04 kB+0.06%+47 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback, Logs, Metrics)85.96 kB+0.06%+50 B 🔺
CDN Bundle - uncompressed81.27 kB--
CDN Bundle (incl. Tracing) - uncompressed126.98 kB+0.14%+171 B 🔺
CDN Bundle (incl. Tracing, Logs, Metrics) - uncompressed129.82 kB+0.14%+171 B 🔺
CDN Bundle (incl. Tracing, Replay) - uncompressed243.59 kB+0.08%+171 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback) - uncompressed256.39 kB+0.07%+171 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback, Logs, Metrics) - uncompressed259.2 kB+0.07%+171 B 🔺
@sentry/nextjs (client)46.66 kB+0.1%+42 B 🔺
@sentry/sveltekit (client)42.44 kB+0.12%+48 B 🔺
@sentry/node-core51.9 kB--
@sentry/node165.45 kB--
@sentry/node - without tracing93.65 kB--
@sentry/aws-serverless109.16 kB--
View base workflow run
@timfish
timfish
marked this pull request as ready for review
January 2, 2026 13:47
@timfish
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from Lms24January 2, 2026 13:47
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Comment threadpackages/browser/src/tracing/browserTracingIntegration.ts
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Thanks for adding this functionality, Tim!
If you don't mind, please also add an integration test with regular tracing. I think we have some meta-tags integration tests in our suites that we can take inspiration from.
Comment thread...ration-tests/suites/tracing/trace-lifetime/tracing-without-performance-headers/template.html
Outdated

Comment threadpackages/browser/src/tracing/browserTracingIntegration.ts
cursor[bot]
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reviewed
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View reviewed changes
Comment threaddev-packages/browser-integration-tests/suites/tracing/trace-lifetime/pageload-headers/test.ts
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Jan 3, 2026

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node-overhead report 🧳
Note: This is a synthetic benchmark with a minimal express app and does not necessarily reflect the real-world performance impact in an application.
ScenarioRequests/s% of BaselinePrev. Requests/sChange %
GET Baseline9,270-9,202+1%
GET With Sentry1,77419%1,734+2%
GET With Sentry (error only)6,25968%6,088+3%
POST Baseline1,213-1,185+2%
POST With Sentry60850%574+6%
POST With Sentry (error only)1,07989%1,059+2%
MYSQL Baseline3,378-3,294+3%
MYSQL With Sentry47314%448+6%
MYSQL With Sentry (error only)2,74581%2,689+2%
View base workflow run
@timfish
timfishforce-pushed
the
timfish/feat/browser-server-timing
branch
from
d3377e1 to
3590824CompareJanuary 3, 2026 15:06
@timfish
timfishforce-pushed
the
timfish/feat/browser-server-timing
branch
from
3590824 to
f8ce616CompareJanuary 3, 2026 15:26
@timfish
timfish
requested a review
from Lms24January 3, 2026 15:27
timfish
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commented
Jan 3, 2026
View reviewed changes
Comment threaddev-packages/browser-integration-tests/suites/tracing/trace-lifetime/pageload-meta/test.ts
 span_id: expect.stringMatching(/^[\da-f]{16}$/),
 });
 // navigation span is head of trace, so there's no parent span:
 expect(navigationTraceContext?.trace_id).not.toHaveProperty('parent_span_id');
@timfishtimfishJan 3, 2026

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Cursor pointed out that the type/logic was wrong in this expection...
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Cursor Bugbot has reviewed your changes and found 1 potential issue.
Bugbot Autofix is OFF. To automatically fix reported issues with Cloud Agents, enable Autofix in the Cursor dashboard.
Comment thread...ration-tests/suites/tracing/trace-lifetime/tracing-without-performance-headers/template.html
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Thanks Tim! Let's get this in -- really nice alternative to the meta tags. I can see us migrating to this approach for frameworks where modifying the HTML isn't straight forward.
@Lms24
Lms24
merged commit 5616396
into
developFeb 2, 2026

164 checks passed

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deleted the

timfish/feat/browser-server-timing

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@Lms24Lms24
mentioned this pull request
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 Merged

Lms24 added a commit
that referenced
this pull request
Mar 18, 2026
@onurtemizkan@Lms24
feat(remix): Server Timing Headers Trace Propagation (#18653)
ae7206f
Adds automatic trace propagation from server to client via the
Server-Timing HTTP header for Remix applications. The client-side
reading of Server-Timing headers via the Performance API was added in
#18673.
Adds:
- `generateSentryServerTimingHeader(span)` public utility that generates
a Server-Timing header value containing Sentry trace context
- Automatic injection in the document request handler for normal page
responses
- Automatic injection on redirect responses from loaders and actions,
which bypass the document request handler entirely. This is an advantage
over meta tag injection, which cannot work on redirect responses since
they have no HTML body
- For Cloudflare/Hydrogen apps: call
`generateSentryServerTimingHeader()` manually and append the value to
the response's `Server-Timing` header in entry.server.tsx (see
remix-hydrogen e2e test for example)
Works on both Node.js and Cloudflare Workers environments.
Closes#18696
---------
Co-authored-by: Lukas Stracke <lukas.stracke@sentry.io>
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feat(browser): Trace continuation from server-timing headers


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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Force GitHub README to respect dark mode\n(function() {\n var style = document.createElement('style');\n style.textContent = '\n .markdown-body {\n color-scheme: dark light;\n }\n .markdown-body pre { background: #161b22 !important; }\n .markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }\n .markdown-body table th, .markdown-body table td { border-color: #30363d !important; }\n .markdown-body img { background: #0d1117; }\n .markdown-body blockquote { border-left-color: #8b949e; }\n .markdown-body hr { border-color: #30363d; }\n ';\n document.head.appendChild(style);\n})();", "GitHub Dark Mode README Fix");
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
feat(browser): Trace continuation from server-timing headers - #18673
Merged
Lms24 merged 3 commits into
developfrom 
timfish/feat/browser-server-timing
Feb 2, 2026
Merged
feat(browser): Trace continuation from server-timing headers#18673
Lms24 merged 3 commits into
developfrom 
timfish/feat/browser-server-timing
Conversation
@timfish
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commented
Jan 2, 2026•

edited by github-actions
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Currently the only way to propagate trace context from server to browser is via meta tags. In some cases modifying the page HTML can be difficult or have a performance impact.
This PR adds support to the browser SDK to fetch sentry-trace and baggage from the Server Timing header.
Closes#18678 (added automatically)
@github-actions
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commented
Jan 2, 2026•

edited

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size-limit report 📦
PathSize% ChangeChange
@sentry/browser25.2 kB--
@sentry/browser - with treeshaking flags23.71 kB--
@sentry/browser (incl. Tracing)42.06 kB+0.1%+38 B 🔺
@sentry/browser (incl. Tracing, Profiling)46.71 kB+0.11%+50 B 🔺
@sentry/browser (incl. Tracing, Replay)80.67 kB+0.04%+29 B 🔺
@sentry/browser (incl. Tracing, Replay) - with treeshaking flags70.34 kB+0.06%+39 B 🔺
@sentry/browser (incl. Tracing, Replay with Canvas)85.36 kB+0.03%+19 B 🔺
@sentry/browser (incl. Tracing, Replay, Feedback)97.58 kB+0.04%+34 B 🔺
@sentry/browser (incl. Feedback)41.92 kB--
@sentry/browser (incl. sendFeedback)29.89 kB--
@sentry/browser (incl. FeedbackAsync)34.89 kB--
@sentry/browser (incl. Metrics)26.31 kB--
@sentry/browser (incl. Logs)26.46 kB--
@sentry/browser (incl. Metrics & Logs)27.11 kB--
@sentry/react26.93 kB--
@sentry/react (incl. Tracing)44.3 kB+0.11%+47 B 🔺
@sentry/vue29.64 kB--
@sentry/vue (incl. Tracing)43.87 kB+0.12%+49 B 🔺
@sentry/svelte25.22 kB--
CDN Bundle27.78 kB--
CDN Bundle (incl. Tracing)42.87 kB+0.08%+34 B 🔺
CDN Bundle (incl. Tracing, Logs, Metrics)43.68 kB+0.09%+35 B 🔺
CDN Bundle (incl. Tracing, Replay)79.59 kB+0.05%+37 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback)85.04 kB+0.06%+47 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback, Logs, Metrics)85.96 kB+0.06%+50 B 🔺
CDN Bundle - uncompressed81.27 kB--
CDN Bundle (incl. Tracing) - uncompressed126.98 kB+0.14%+171 B 🔺
CDN Bundle (incl. Tracing, Logs, Metrics) - uncompressed129.82 kB+0.14%+171 B 🔺
CDN Bundle (incl. Tracing, Replay) - uncompressed243.59 kB+0.08%+171 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback) - uncompressed256.39 kB+0.07%+171 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback, Logs, Metrics) - uncompressed259.2 kB+0.07%+171 B 🔺
@sentry/nextjs (client)46.66 kB+0.1%+42 B 🔺
@sentry/sveltekit (client)42.44 kB+0.12%+48 B 🔺
@sentry/node-core51.9 kB--
@sentry/node165.45 kB--
@sentry/node - without tracing93.65 kB--
@sentry/aws-serverless109.16 kB--
View base workflow run
@timfish
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marked this pull request as ready for review
January 2, 2026 13:47
@timfish
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Comment threadpackages/browser/src/tracing/browserTracingIntegration.ts
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Thanks for adding this functionality, Tim!
If you don't mind, please also add an integration test with regular tracing. I think we have some meta-tags integration tests in our suites that we can take inspiration from.
Comment thread...ration-tests/suites/tracing/trace-lifetime/tracing-without-performance-headers/template.html
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Comment threaddev-packages/browser-integration-tests/suites/tracing/trace-lifetime/pageload-headers/test.ts
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node-overhead report 🧳
Note: This is a synthetic benchmark with a minimal express app and does not necessarily reflect the real-world performance impact in an application.
ScenarioRequests/s% of BaselinePrev. Requests/sChange %
GET Baseline9,270-9,202+1%
GET With Sentry1,77419%1,734+2%
GET With Sentry (error only)6,25968%6,088+3%
POST Baseline1,213-1,185+2%
POST With Sentry60850%574+6%
POST With Sentry (error only)1,07989%1,059+2%
MYSQL Baseline3,378-3,294+3%
MYSQL With Sentry47314%448+6%
MYSQL With Sentry (error only)2,74581%2,689+2%
View base workflow run
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Comment threaddev-packages/browser-integration-tests/suites/tracing/trace-lifetime/pageload-meta/test.ts
 span_id: expect.stringMatching(/^[\da-f]{16}$/),
 });
 // navigation span is head of trace, so there's no parent span:
 expect(navigationTraceContext?.trace_id).not.toHaveProperty('parent_span_id');
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Cursor pointed out that the type/logic was wrong in this expection...
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Cursor Bugbot has reviewed your changes and found 1 potential issue.
Bugbot Autofix is OFF. To automatically fix reported issues with Cloud Agents, enable Autofix in the Cursor dashboard.
Comment thread...ration-tests/suites/tracing/trace-lifetime/tracing-without-performance-headers/template.html
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Thanks Tim! Let's get this in -- really nice alternative to the meta tags. I can see us migrating to this approach for frameworks where modifying the HTML isn't straight forward.
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@onurtemizkan@Lms24
feat(remix): Server Timing Headers Trace Propagation (#18653)
ae7206f
Adds automatic trace propagation from server to client via the
Server-Timing HTTP header for Remix applications. The client-side
reading of Server-Timing headers via the Performance API was added in
#18673.
Adds:
- `generateSentryServerTimingHeader(span)` public utility that generates
a Server-Timing header value containing Sentry trace context
- Automatic injection in the document request handler for normal page
responses
- Automatic injection on redirect responses from loaders and actions,
which bypass the document request handler entirely. This is an advantage
over meta tag injection, which cannot work on redirect responses since
they have no HTML body
- For Cloudflare/Hydrogen apps: call
`generateSentryServerTimingHeader()` manually and append the value to
the response's `Server-Timing` header in entry.server.tsx (see
remix-hydrogen e2e test for example)
Works on both Node.js and Cloudflare Workers environments.
Closes#18696
---------
Co-authored-by: Lukas Stracke <lukas.stracke@sentry.io>
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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Highlight search terms from Google/DuckDuckGo/Bing referrer\n(function() {\n var ref = document.referrer;\n var terms = [];\n \n if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {\n var url = new URL(ref);\n var q = url.searchParams.get('q') || url.searchParams.get('p');\n if (q) {\n terms = q.split(/\\s+/).filter(function(t) { return t.length > 2; });\n }\n }\n \n if (terms.length === 0) return;\n \n var style = document.createElement('style');\n style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';\n document.head.appendChild(style);\n \n function highlight(node) {\n if (node.nodeType === 3) { // text node\n var text = node.textContent;\n var found = false;\n terms.forEach(function(term) {\n var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\\]\\\\]/g, '\\\\') + ')', 'gi');\n if (regex.test(text)) {\n found = true;\n var frag = document.createDocumentFragment();\n var parts = text.split(regex);\n parts.forEach(function(part, i) {\n if (i % 2 === 0) {\n frag.appendChild(document.createTextNode(part));\n } else {\n var span = document.createElement('span');\n span.className = 'userscript-highlight';\n span.textContent = part;\n frag.appendChild(span);\n }\n });\n node.parentNode.replaceChild(frag, node);\n }\n });\n } else if (node.nodeType === 1 && node.childNodes) { // element\n var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];\n if (!skipTags.includes(node.tagName)) {\n Array.from(node.childNodes).forEach(highlight);\n }\n }\n }\n \n highlight(document.body);\n \n // Re-highlight on dynamic content\n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1 || node.nodeType === 3) highlight(node);\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Highlight Search Terms");
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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feat(browser): Trace continuation from server-timing headers - #18673
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timfish/feat/browser-server-timing
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feat(browser): Trace continuation from server-timing headers#18673
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Currently the only way to propagate trace context from server to browser is via meta tags. In some cases modifying the page HTML can be difficult or have a performance impact.
This PR adds support to the browser SDK to fetch sentry-trace and baggage from the Server Timing header.
Closes#18678 (added automatically)
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size-limit report 📦
PathSize% ChangeChange
@sentry/browser25.2 kB--
@sentry/browser - with treeshaking flags23.71 kB--
@sentry/browser (incl. Tracing)42.06 kB+0.1%+38 B 🔺
@sentry/browser (incl. Tracing, Profiling)46.71 kB+0.11%+50 B 🔺
@sentry/browser (incl. Tracing, Replay)80.67 kB+0.04%+29 B 🔺
@sentry/browser (incl. Tracing, Replay) - with treeshaking flags70.34 kB+0.06%+39 B 🔺
@sentry/browser (incl. Tracing, Replay with Canvas)85.36 kB+0.03%+19 B 🔺
@sentry/browser (incl. Tracing, Replay, Feedback)97.58 kB+0.04%+34 B 🔺
@sentry/browser (incl. Feedback)41.92 kB--
@sentry/browser (incl. sendFeedback)29.89 kB--
@sentry/browser (incl. FeedbackAsync)34.89 kB--
@sentry/browser (incl. Metrics)26.31 kB--
@sentry/browser (incl. Logs)26.46 kB--
@sentry/browser (incl. Metrics & Logs)27.11 kB--
@sentry/react26.93 kB--
@sentry/react (incl. Tracing)44.3 kB+0.11%+47 B 🔺
@sentry/vue29.64 kB--
@sentry/vue (incl. Tracing)43.87 kB+0.12%+49 B 🔺
@sentry/svelte25.22 kB--
CDN Bundle27.78 kB--
CDN Bundle (incl. Tracing)42.87 kB+0.08%+34 B 🔺
CDN Bundle (incl. Tracing, Logs, Metrics)43.68 kB+0.09%+35 B 🔺
CDN Bundle (incl. Tracing, Replay)79.59 kB+0.05%+37 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback)85.04 kB+0.06%+47 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback, Logs, Metrics)85.96 kB+0.06%+50 B 🔺
CDN Bundle - uncompressed81.27 kB--
CDN Bundle (incl. Tracing) - uncompressed126.98 kB+0.14%+171 B 🔺
CDN Bundle (incl. Tracing, Logs, Metrics) - uncompressed129.82 kB+0.14%+171 B 🔺
CDN Bundle (incl. Tracing, Replay) - uncompressed243.59 kB+0.08%+171 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback) - uncompressed256.39 kB+0.07%+171 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback, Logs, Metrics) - uncompressed259.2 kB+0.07%+171 B 🔺
@sentry/nextjs (client)46.66 kB+0.1%+42 B 🔺
@sentry/sveltekit (client)42.44 kB+0.12%+48 B 🔺
@sentry/node-core51.9 kB--
@sentry/node165.45 kB--
@sentry/node - without tracing93.65 kB--
@sentry/aws-serverless109.16 kB--
View base workflow run
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Comment threadpackages/browser/src/tracing/browserTracingIntegration.ts
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Thanks for adding this functionality, Tim!
If you don't mind, please also add an integration test with regular tracing. I think we have some meta-tags integration tests in our suites that we can take inspiration from.
Comment thread...ration-tests/suites/tracing/trace-lifetime/tracing-without-performance-headers/template.html
Outdated

Comment threadpackages/browser/src/tracing/browserTracingIntegration.ts
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Comment threaddev-packages/browser-integration-tests/suites/tracing/trace-lifetime/pageload-headers/test.ts
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node-overhead report 🧳
Note: This is a synthetic benchmark with a minimal express app and does not necessarily reflect the real-world performance impact in an application.
ScenarioRequests/s% of BaselinePrev. Requests/sChange %
GET Baseline9,270-9,202+1%
GET With Sentry1,77419%1,734+2%
GET With Sentry (error only)6,25968%6,088+3%
POST Baseline1,213-1,185+2%
POST With Sentry60850%574+6%
POST With Sentry (error only)1,07989%1,059+2%
MYSQL Baseline3,378-3,294+3%
MYSQL With Sentry47314%448+6%
MYSQL With Sentry (error only)2,74581%2,689+2%
View base workflow run
@timfish
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3590824 to
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View reviewed changes
Comment threaddev-packages/browser-integration-tests/suites/tracing/trace-lifetime/pageload-meta/test.ts
 span_id: expect.stringMatching(/^[\da-f]{16}$/),
 });
 // navigation span is head of trace, so there's no parent span:
 expect(navigationTraceContext?.trace_id).not.toHaveProperty('parent_span_id');
@timfishtimfishJan 3, 2026

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Cursor pointed out that the type/logic was wrong in this expection...
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Cursor Bugbot has reviewed your changes and found 1 potential issue.
Bugbot Autofix is OFF. To automatically fix reported issues with Cloud Agents, enable Autofix in the Cursor dashboard.
Comment thread...ration-tests/suites/tracing/trace-lifetime/tracing-without-performance-headers/template.html
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Thanks Tim! Let's get this in -- really nice alternative to the meta tags. I can see us migrating to this approach for frameworks where modifying the HTML isn't straight forward.
@Lms24
Lms24
merged commit 5616396
into
developFeb 2, 2026

164 checks passed

@Lms24
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deleted the

timfish/feat/browser-server-timing

branch
February 2, 2026 09:16
@Lms24Lms24
mentioned this pull request
Feb 2, 2026
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Lms24 added a commit
that referenced
this pull request
Mar 18, 2026
@onurtemizkan@Lms24
feat(remix): Server Timing Headers Trace Propagation (#18653)
ae7206f
Adds automatic trace propagation from server to client via the
Server-Timing HTTP header for Remix applications. The client-side
reading of Server-Timing headers via the Performance API was added in
#18673.
Adds:
- `generateSentryServerTimingHeader(span)` public utility that generates
a Server-Timing header value containing Sentry trace context
- Automatic injection in the document request handler for normal page
responses
- Automatic injection on redirect responses from loaders and actions,
which bypass the document request handler entirely. This is an advantage
over meta tag injection, which cannot work on redirect responses since
they have no HTML body
- For Cloudflare/Hydrogen apps: call
`generateSentryServerTimingHeader()` manually and append the value to
the response's `Server-Timing` header in entry.server.tsx (see
remix-hydrogen e2e test for example)
Works on both Node.js and Cloudflare Workers environments.
Closes#18696
---------
Co-authored-by: Lukas Stracke <lukas.stracke@sentry.io>
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feat(browser): Trace continuation from server-timing headers


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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Strip utm_, fbclid, gclid, etc. from all links on page\n(function() {\n var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',\n 'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',\n 'ref', 'ref_src', 'source', 'medium', 'campaign'];\n \n function cleanUrl(url) {\n try {\n var u = new URL(url, window.location.origin);\n var changed = false;\n trackingParams.forEach(function(p) {\n if (u.searchParams.has(p)) {\n u.searchParams.delete(p);\n changed = true;\n }\n });\n return changed ? u.toString() : url;\n } catch (e) {\n return url;\n }\n }\n \n function cleanLinks() {\n document.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n \n cleanLinks();\n \n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1) {\n if (node.tagName === 'A') cleanLinks();\n node.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Remove Tracking Parameters from Links");
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '

Skip to content
feat(browser): Trace continuation from server-timing headers - #18673
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Lms24 merged 3 commits into
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timfish/feat/browser-server-timing
Feb 2, 2026
Merged
feat(browser): Trace continuation from server-timing headers#18673
Lms24 merged 3 commits into
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@timfish
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Jan 2, 2026•

edited by github-actions
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Currently the only way to propagate trace context from server to browser is via meta tags. In some cases modifying the page HTML can be difficult or have a performance impact.
This PR adds support to the browser SDK to fetch sentry-trace and baggage from the Server Timing header.
Closes#18678 (added automatically)
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size-limit report 📦
PathSize% ChangeChange
@sentry/browser25.2 kB--
@sentry/browser - with treeshaking flags23.71 kB--
@sentry/browser (incl. Tracing)42.06 kB+0.1%+38 B 🔺
@sentry/browser (incl. Tracing, Profiling)46.71 kB+0.11%+50 B 🔺
@sentry/browser (incl. Tracing, Replay)80.67 kB+0.04%+29 B 🔺
@sentry/browser (incl. Tracing, Replay) - with treeshaking flags70.34 kB+0.06%+39 B 🔺
@sentry/browser (incl. Tracing, Replay with Canvas)85.36 kB+0.03%+19 B 🔺
@sentry/browser (incl. Tracing, Replay, Feedback)97.58 kB+0.04%+34 B 🔺
@sentry/browser (incl. Feedback)41.92 kB--
@sentry/browser (incl. sendFeedback)29.89 kB--
@sentry/browser (incl. FeedbackAsync)34.89 kB--
@sentry/browser (incl. Metrics)26.31 kB--
@sentry/browser (incl. Logs)26.46 kB--
@sentry/browser (incl. Metrics & Logs)27.11 kB--
@sentry/react26.93 kB--
@sentry/react (incl. Tracing)44.3 kB+0.11%+47 B 🔺
@sentry/vue29.64 kB--
@sentry/vue (incl. Tracing)43.87 kB+0.12%+49 B 🔺
@sentry/svelte25.22 kB--
CDN Bundle27.78 kB--
CDN Bundle (incl. Tracing)42.87 kB+0.08%+34 B 🔺
CDN Bundle (incl. Tracing, Logs, Metrics)43.68 kB+0.09%+35 B 🔺
CDN Bundle (incl. Tracing, Replay)79.59 kB+0.05%+37 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback)85.04 kB+0.06%+47 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback, Logs, Metrics)85.96 kB+0.06%+50 B 🔺
CDN Bundle - uncompressed81.27 kB--
CDN Bundle (incl. Tracing) - uncompressed126.98 kB+0.14%+171 B 🔺
CDN Bundle (incl. Tracing, Logs, Metrics) - uncompressed129.82 kB+0.14%+171 B 🔺
CDN Bundle (incl. Tracing, Replay) - uncompressed243.59 kB+0.08%+171 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback) - uncompressed256.39 kB+0.07%+171 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback, Logs, Metrics) - uncompressed259.2 kB+0.07%+171 B 🔺
@sentry/nextjs (client)46.66 kB+0.1%+42 B 🔺
@sentry/sveltekit (client)42.44 kB+0.12%+48 B 🔺
@sentry/node-core51.9 kB--
@sentry/node165.45 kB--
@sentry/node - without tracing93.65 kB--
@sentry/aws-serverless109.16 kB--
View base workflow run
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marked this pull request as ready for review
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Comment threadpackages/browser/src/tracing/browserTracingIntegration.ts
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Thanks for adding this functionality, Tim!
If you don't mind, please also add an integration test with regular tracing. I think we have some meta-tags integration tests in our suites that we can take inspiration from.
Comment thread...ration-tests/suites/tracing/trace-lifetime/tracing-without-performance-headers/template.html
Outdated

Comment threadpackages/browser/src/tracing/browserTracingIntegration.ts
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Comment threaddev-packages/browser-integration-tests/suites/tracing/trace-lifetime/pageload-headers/test.ts
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node-overhead report 🧳
Note: This is a synthetic benchmark with a minimal express app and does not necessarily reflect the real-world performance impact in an application.
ScenarioRequests/s% of BaselinePrev. Requests/sChange %
GET Baseline9,270-9,202+1%
GET With Sentry1,77419%1,734+2%
GET With Sentry (error only)6,25968%6,088+3%
POST Baseline1,213-1,185+2%
POST With Sentry60850%574+6%
POST With Sentry (error only)1,07989%1,059+2%
MYSQL Baseline3,378-3,294+3%
MYSQL With Sentry47314%448+6%
MYSQL With Sentry (error only)2,74581%2,689+2%
View base workflow run
@timfish
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3590824CompareJanuary 3, 2026 15:06
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Comment threaddev-packages/browser-integration-tests/suites/tracing/trace-lifetime/pageload-meta/test.ts
 span_id: expect.stringMatching(/^[\da-f]{16}$/),
 });
 // navigation span is head of trace, so there's no parent span:
 expect(navigationTraceContext?.trace_id).not.toHaveProperty('parent_span_id');
@timfishtimfishJan 3, 2026

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Cursor pointed out that the type/logic was wrong in this expection...
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Cursor Bugbot has reviewed your changes and found 1 potential issue.
Bugbot Autofix is OFF. To automatically fix reported issues with Cloud Agents, enable Autofix in the Cursor dashboard.
Comment thread...ration-tests/suites/tracing/trace-lifetime/tracing-without-performance-headers/template.html
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Thanks Tim! Let's get this in -- really nice alternative to the meta tags. I can see us migrating to this approach for frameworks where modifying the HTML isn't straight forward.
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@onurtemizkan@Lms24
feat(remix): Server Timing Headers Trace Propagation (#18653)
ae7206f
Adds automatic trace propagation from server to client via the
Server-Timing HTTP header for Remix applications. The client-side
reading of Server-Timing headers via the Performance API was added in
#18673.
Adds:
- `generateSentryServerTimingHeader(span)` public utility that generates
a Server-Timing header value containing Sentry trace context
- Automatic injection in the document request handler for normal page
responses
- Automatic injection on redirect responses from loaders and actions,
which bypass the document request handler entirely. This is an advantage
over meta tag injection, which cannot work on redirect responses since
they have no HTML body
- For Cloudflare/Hydrogen apps: call
`generateSentryServerTimingHeader()` manually and append the value to
the response's `Server-Timing` header in entry.server.tsx (see
remix-hydrogen e2e test for example)
Works on both Node.js and Cloudflare Workers environments.
Closes#18696
---------
Co-authored-by: Lukas Stracke <lukas.stracke@sentry.io>
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feat(browser): Trace continuation from server-timing headers


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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Auto-enable theater mode on YouTube\n(function() {\n function tryTheater() {\n var btn = document.querySelector('button[aria-label=\"Theater mode\"], ytd-player #player button[title=\"Theater mode\"]');\n if (btn && !btn.classList.contains('activated')) {\n btn.click();\n }\n }\n \n // Try immediately\n tryTheater();\n \n // Try after navigation (SPA)\n var lastUrl = location.href;\n setInterval(function() {\n if (location.href !== lastUrl) {\n lastUrl = location.href;\n setTimeout(tryTheater, 500);\n }\n }, 1000);\n \n // Also try on player load\n var observer = new MutationObserver(tryTheater);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "YouTube Theater Mode Default");
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
feat(browser): Trace continuation from server-timing headers - #18673
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feat(browser): Trace continuation from server-timing headers#18673
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Jan 2, 2026•

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Currently the only way to propagate trace context from server to browser is via meta tags. In some cases modifying the page HTML can be difficult or have a performance impact.
This PR adds support to the browser SDK to fetch sentry-trace and baggage from the Server Timing header.
Closes#18678 (added automatically)
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size-limit report 📦
PathSize% ChangeChange
@sentry/browser25.2 kB--
@sentry/browser - with treeshaking flags23.71 kB--
@sentry/browser (incl. Tracing)42.06 kB+0.1%+38 B 🔺
@sentry/browser (incl. Tracing, Profiling)46.71 kB+0.11%+50 B 🔺
@sentry/browser (incl. Tracing, Replay)80.67 kB+0.04%+29 B 🔺
@sentry/browser (incl. Tracing, Replay) - with treeshaking flags70.34 kB+0.06%+39 B 🔺
@sentry/browser (incl. Tracing, Replay with Canvas)85.36 kB+0.03%+19 B 🔺
@sentry/browser (incl. Tracing, Replay, Feedback)97.58 kB+0.04%+34 B 🔺
@sentry/browser (incl. Feedback)41.92 kB--
@sentry/browser (incl. sendFeedback)29.89 kB--
@sentry/browser (incl. FeedbackAsync)34.89 kB--
@sentry/browser (incl. Metrics)26.31 kB--
@sentry/browser (incl. Logs)26.46 kB--
@sentry/browser (incl. Metrics & Logs)27.11 kB--
@sentry/react26.93 kB--
@sentry/react (incl. Tracing)44.3 kB+0.11%+47 B 🔺
@sentry/vue29.64 kB--
@sentry/vue (incl. Tracing)43.87 kB+0.12%+49 B 🔺
@sentry/svelte25.22 kB--
CDN Bundle27.78 kB--
CDN Bundle (incl. Tracing)42.87 kB+0.08%+34 B 🔺
CDN Bundle (incl. Tracing, Logs, Metrics)43.68 kB+0.09%+35 B 🔺
CDN Bundle (incl. Tracing, Replay)79.59 kB+0.05%+37 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback)85.04 kB+0.06%+47 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback, Logs, Metrics)85.96 kB+0.06%+50 B 🔺
CDN Bundle - uncompressed81.27 kB--
CDN Bundle (incl. Tracing) - uncompressed126.98 kB+0.14%+171 B 🔺
CDN Bundle (incl. Tracing, Logs, Metrics) - uncompressed129.82 kB+0.14%+171 B 🔺
CDN Bundle (incl. Tracing, Replay) - uncompressed243.59 kB+0.08%+171 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback) - uncompressed256.39 kB+0.07%+171 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback, Logs, Metrics) - uncompressed259.2 kB+0.07%+171 B 🔺
@sentry/nextjs (client)46.66 kB+0.1%+42 B 🔺
@sentry/sveltekit (client)42.44 kB+0.12%+48 B 🔺
@sentry/node-core51.9 kB--
@sentry/node165.45 kB--
@sentry/node - without tracing93.65 kB--
@sentry/aws-serverless109.16 kB--
View base workflow run
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Comment threadpackages/browser/src/tracing/browserTracingIntegration.ts
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Thanks for adding this functionality, Tim!
If you don't mind, please also add an integration test with regular tracing. I think we have some meta-tags integration tests in our suites that we can take inspiration from.
Comment thread...ration-tests/suites/tracing/trace-lifetime/tracing-without-performance-headers/template.html
Outdated

Comment threadpackages/browser/src/tracing/browserTracingIntegration.ts
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Comment threaddev-packages/browser-integration-tests/suites/tracing/trace-lifetime/pageload-headers/test.ts
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node-overhead report 🧳
Note: This is a synthetic benchmark with a minimal express app and does not necessarily reflect the real-world performance impact in an application.
ScenarioRequests/s% of BaselinePrev. Requests/sChange %
GET Baseline9,270-9,202+1%
GET With Sentry1,77419%1,734+2%
GET With Sentry (error only)6,25968%6,088+3%
POST Baseline1,213-1,185+2%
POST With Sentry60850%574+6%
POST With Sentry (error only)1,07989%1,059+2%
MYSQL Baseline3,378-3,294+3%
MYSQL With Sentry47314%448+6%
MYSQL With Sentry (error only)2,74581%2,689+2%
View base workflow run
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3590824 to
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View reviewed changes
Comment threaddev-packages/browser-integration-tests/suites/tracing/trace-lifetime/pageload-meta/test.ts
 span_id: expect.stringMatching(/^[\da-f]{16}$/),
 });
 // navigation span is head of trace, so there's no parent span:
 expect(navigationTraceContext?.trace_id).not.toHaveProperty('parent_span_id');
@timfishtimfishJan 3, 2026

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Cursor pointed out that the type/logic was wrong in this expection...
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Cursor Bugbot has reviewed your changes and found 1 potential issue.
Bugbot Autofix is OFF. To automatically fix reported issues with Cloud Agents, enable Autofix in the Cursor dashboard.
Comment thread...ration-tests/suites/tracing/trace-lifetime/tracing-without-performance-headers/template.html
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Thanks Tim! Let's get this in -- really nice alternative to the meta tags. I can see us migrating to this approach for frameworks where modifying the HTML isn't straight forward.
@Lms24
Lms24
merged commit 5616396
into
developFeb 2, 2026

164 checks passed

@Lms24
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deleted the

timfish/feat/browser-server-timing

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mentioned this pull request
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Mar 18, 2026
@onurtemizkan@Lms24
feat(remix): Server Timing Headers Trace Propagation (#18653)
ae7206f
Adds automatic trace propagation from server to client via the
Server-Timing HTTP header for Remix applications. The client-side
reading of Server-Timing headers via the Performance API was added in
#18673.
Adds:
- `generateSentryServerTimingHeader(span)` public utility that generates
a Server-Timing header value containing Sentry trace context
- Automatic injection in the document request handler for normal page
responses
- Automatic injection on redirect responses from loaders and actions,
which bypass the document request handler entirely. This is an advantage
over meta tag injection, which cannot work on redirect responses since
they have no HTML body
- For Cloudflare/Hydrogen apps: call
`generateSentryServerTimingHeader()` manually and append the value to
the response's `Server-Timing` header in entry.server.tsx (see
remix-hydrogen e2e test for example)
Works on both Node.js and Cloudflare Workers environments.
Closes#18696
---------
Co-authored-by: Lukas Stracke <lukas.stracke@sentry.io>
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feat(browser): Trace continuation from server-timing headers


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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Remove or un-stick sticky/fixed headers that block content\n(function() {\n function unstick() {\n document.querySelectorAll('header, nav, [role=\"banner\"], .header, .navbar, .sticky, .fixed-top, [style*=\"position: fixed\"], [style*=\"position:sticky\"]').forEach(function(el) {\n if (el.style.position === 'fixed' || el.style.position === 'sticky' || \n getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {\n el.style.position = 'static';\n el.style.top = 'auto';\n el.style.zIndex = 'auto';\n }\n });\n }\n \n unstick();\n \n var observer = new MutationObserver(unstick);\n observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });\n})();", "Kill Sticky Headers");
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
feat(browser): Trace continuation from server-timing headers - #18673
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Feb 2, 2026
Merged
feat(browser): Trace continuation from server-timing headers#18673
Lms24 merged 3 commits into
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Jan 2, 2026•

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Currently the only way to propagate trace context from server to browser is via meta tags. In some cases modifying the page HTML can be difficult or have a performance impact.
This PR adds support to the browser SDK to fetch sentry-trace and baggage from the Server Timing header.
Closes#18678 (added automatically)
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size-limit report 📦
PathSize% ChangeChange
@sentry/browser25.2 kB--
@sentry/browser - with treeshaking flags23.71 kB--
@sentry/browser (incl. Tracing)42.06 kB+0.1%+38 B 🔺
@sentry/browser (incl. Tracing, Profiling)46.71 kB+0.11%+50 B 🔺
@sentry/browser (incl. Tracing, Replay)80.67 kB+0.04%+29 B 🔺
@sentry/browser (incl. Tracing, Replay) - with treeshaking flags70.34 kB+0.06%+39 B 🔺
@sentry/browser (incl. Tracing, Replay with Canvas)85.36 kB+0.03%+19 B 🔺
@sentry/browser (incl. Tracing, Replay, Feedback)97.58 kB+0.04%+34 B 🔺
@sentry/browser (incl. Feedback)41.92 kB--
@sentry/browser (incl. sendFeedback)29.89 kB--
@sentry/browser (incl. FeedbackAsync)34.89 kB--
@sentry/browser (incl. Metrics)26.31 kB--
@sentry/browser (incl. Logs)26.46 kB--
@sentry/browser (incl. Metrics & Logs)27.11 kB--
@sentry/react26.93 kB--
@sentry/react (incl. Tracing)44.3 kB+0.11%+47 B 🔺
@sentry/vue29.64 kB--
@sentry/vue (incl. Tracing)43.87 kB+0.12%+49 B 🔺
@sentry/svelte25.22 kB--
CDN Bundle27.78 kB--
CDN Bundle (incl. Tracing)42.87 kB+0.08%+34 B 🔺
CDN Bundle (incl. Tracing, Logs, Metrics)43.68 kB+0.09%+35 B 🔺
CDN Bundle (incl. Tracing, Replay)79.59 kB+0.05%+37 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback)85.04 kB+0.06%+47 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback, Logs, Metrics)85.96 kB+0.06%+50 B 🔺
CDN Bundle - uncompressed81.27 kB--
CDN Bundle (incl. Tracing) - uncompressed126.98 kB+0.14%+171 B 🔺
CDN Bundle (incl. Tracing, Logs, Metrics) - uncompressed129.82 kB+0.14%+171 B 🔺
CDN Bundle (incl. Tracing, Replay) - uncompressed243.59 kB+0.08%+171 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback) - uncompressed256.39 kB+0.07%+171 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback, Logs, Metrics) - uncompressed259.2 kB+0.07%+171 B 🔺
@sentry/nextjs (client)46.66 kB+0.1%+42 B 🔺
@sentry/sveltekit (client)42.44 kB+0.12%+48 B 🔺
@sentry/node-core51.9 kB--
@sentry/node165.45 kB--
@sentry/node - without tracing93.65 kB--
@sentry/aws-serverless109.16 kB--
View base workflow run
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Comment threadpackages/browser/src/tracing/browserTracingIntegration.ts
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Thanks for adding this functionality, Tim!
If you don't mind, please also add an integration test with regular tracing. I think we have some meta-tags integration tests in our suites that we can take inspiration from.
Comment thread...ration-tests/suites/tracing/trace-lifetime/tracing-without-performance-headers/template.html
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Comment threadpackages/browser/src/tracing/browserTracingIntegration.ts
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Comment threaddev-packages/browser-integration-tests/suites/tracing/trace-lifetime/pageload-headers/test.ts
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node-overhead report 🧳
Note: This is a synthetic benchmark with a minimal express app and does not necessarily reflect the real-world performance impact in an application.
ScenarioRequests/s% of BaselinePrev. Requests/sChange %
GET Baseline9,270-9,202+1%
GET With Sentry1,77419%1,734+2%
GET With Sentry (error only)6,25968%6,088+3%
POST Baseline1,213-1,185+2%
POST With Sentry60850%574+6%
POST With Sentry (error only)1,07989%1,059+2%
MYSQL Baseline3,378-3,294+3%
MYSQL With Sentry47314%448+6%
MYSQL With Sentry (error only)2,74581%2,689+2%
View base workflow run
@timfish
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3590824CompareJanuary 3, 2026 15:06
@timfish
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3590824 to
f8ce616CompareJanuary 3, 2026 15:26
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timfish
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View reviewed changes
Comment threaddev-packages/browser-integration-tests/suites/tracing/trace-lifetime/pageload-meta/test.ts
 span_id: expect.stringMatching(/^[\da-f]{16}$/),
 });
 // navigation span is head of trace, so there's no parent span:
 expect(navigationTraceContext?.trace_id).not.toHaveProperty('parent_span_id');
@timfishtimfishJan 3, 2026

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Cursor pointed out that the type/logic was wrong in this expection...
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Cursor Bugbot has reviewed your changes and found 1 potential issue.
Bugbot Autofix is OFF. To automatically fix reported issues with Cloud Agents, enable Autofix in the Cursor dashboard.
Comment thread...ration-tests/suites/tracing/trace-lifetime/tracing-without-performance-headers/template.html
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Thanks Tim! Let's get this in -- really nice alternative to the meta tags. I can see us migrating to this approach for frameworks where modifying the HTML isn't straight forward.
@Lms24
Lms24
merged commit 5616396
into
developFeb 2, 2026

164 checks passed

@Lms24
Lms24
deleted the

timfish/feat/browser-server-timing

branch
February 2, 2026 09:16
@Lms24Lms24
mentioned this pull request
Feb 2, 2026
 Merged

Lms24 added a commit
that referenced
this pull request
Mar 18, 2026
@onurtemizkan@Lms24
feat(remix): Server Timing Headers Trace Propagation (#18653)
ae7206f
Adds automatic trace propagation from server to client via the
Server-Timing HTTP header for Remix applications. The client-side
reading of Server-Timing headers via the Performance API was added in
#18673.
Adds:
- `generateSentryServerTimingHeader(span)` public utility that generates
a Server-Timing header value containing Sentry trace context
- Automatic injection in the document request handler for normal page
responses
- Automatic injection on redirect responses from loaders and actions,
which bypass the document request handler entirely. This is an advantage
over meta tag injection, which cannot work on redirect responses since
they have no HTML body
- For Cloudflare/Hydrogen apps: call
`generateSentryServerTimingHeader()` manually and append the value to
the response's `Server-Timing` header in entry.server.tsx (see
remix-hydrogen e2e test for example)
Works on both Node.js and Cloudflare Workers environments.
Closes#18696
---------
Co-authored-by: Lukas Stracke <lukas.stracke@sentry.io>
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feat(browser): Trace continuation from server-timing headers


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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Universal Dark Mode - works on any site\n(function() {\n var enabled = true;\n \n function applyDarkMode() {\n if (!enabled) return;\n \n // Create style element if it doesn't exist\n var style = document.getElementById('universal-dark-mode-style');\n if (!style) {\n style = document.createElement('style');\n style.id = 'universal-dark-mode-style';\n document.head.appendChild(style);\n }\n \n // Dark mode CSS - inverts colors but preserves images/video\n style.textContent = '\n /* Invert everything except media */\n html {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #1a1a2e !important;\n }\n \n /* Restore images, videos, iframes, canvas */\n img, video, iframe, canvas, svg, picture, [style*=\"background-image\"] {\n filter: invert(1) hue-rotate(180deg) !important;\n }\n \n /* Preserve specific elements that should not be inverted */\n .no-dark-mode, .no-dark-mode *,\n [data-theme=\"light\"], [data-theme=\"light\"],\n .ace_editor, .ace_editor *,\n .CodeMirror, .CodeMirror *,\n .monaco-editor, .monaco-editor *,\n .markdown-body pre, .markdown-body pre *,\n .highlight, .highlight *,\n pre code, pre code * {\n filter: none !important;\n }\n \n /* Fix common UI elements */\n .modal, .popup, .dropdown-menu, .tooltip, .popover {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #2d2d44 !important;\n border-color: #444 !important;\n }\n \n /* Scrollbars */\n ::-webkit-scrollbar { background: #1a1a2e !important; }\n ::-webkit-scrollbar-thumb { background: #444 !important; }\n ::-webkit-scrollbar-thumb:hover { background: #555 !important; }\n \n /* Selection */\n ::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ';\n }\n \n function removeDarkMode() {\n var style = document.getElementById('universal-dark-mode-style');\n if (style) style.remove();\n }\n \n // Toggle with Alt+Shift+D\n document.addEventListener('keydown', function(e) {\n if (e.altKey && e.shiftKey && e.key === 'D') {\n e.preventDefault();\n enabled = !enabled;\n if (enabled) {\n applyDarkMode();\n console.log('[Universal Dark Mode] Enabled');\n } else {\n removeDarkMode();\n console.log('[Universal Dark Mode] Disabled');\n }\n }\n });\n \n // Apply on load\n applyDarkMode();\n \n // Re-apply on dynamic content\n var observer = new MutationObserver(function(mutations) {\n if (enabled && !document.getElementById('universal-dark-mode-style')) {\n applyDarkMode();\n }\n });\n observer.observe(document.head, { childList: true });\n \n console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');\n})();", "Universal Dark Mode");
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();

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feat(browser): Trace continuation from server-timing headers - #18673
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feat(browser): Trace continuation from server-timing headers#18673
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Currently the only way to propagate trace context from server to browser is via meta tags. In some cases modifying the page HTML can be difficult or have a performance impact.
This PR adds support to the browser SDK to fetch sentry-trace and baggage from the Server Timing header.
Closes#18678 (added automatically)
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size-limit report 📦
PathSize% ChangeChange
@sentry/browser25.2 kB--
@sentry/browser - with treeshaking flags23.71 kB--
@sentry/browser (incl. Tracing)42.06 kB+0.1%+38 B 🔺
@sentry/browser (incl. Tracing, Profiling)46.71 kB+0.11%+50 B 🔺
@sentry/browser (incl. Tracing, Replay)80.67 kB+0.04%+29 B 🔺
@sentry/browser (incl. Tracing, Replay) - with treeshaking flags70.34 kB+0.06%+39 B 🔺
@sentry/browser (incl. Tracing, Replay with Canvas)85.36 kB+0.03%+19 B 🔺
@sentry/browser (incl. Tracing, Replay, Feedback)97.58 kB+0.04%+34 B 🔺
@sentry/browser (incl. Feedback)41.92 kB--
@sentry/browser (incl. sendFeedback)29.89 kB--
@sentry/browser (incl. FeedbackAsync)34.89 kB--
@sentry/browser (incl. Metrics)26.31 kB--
@sentry/browser (incl. Logs)26.46 kB--
@sentry/browser (incl. Metrics & Logs)27.11 kB--
@sentry/react26.93 kB--
@sentry/react (incl. Tracing)44.3 kB+0.11%+47 B 🔺
@sentry/vue29.64 kB--
@sentry/vue (incl. Tracing)43.87 kB+0.12%+49 B 🔺
@sentry/svelte25.22 kB--
CDN Bundle27.78 kB--
CDN Bundle (incl. Tracing)42.87 kB+0.08%+34 B 🔺
CDN Bundle (incl. Tracing, Logs, Metrics)43.68 kB+0.09%+35 B 🔺
CDN Bundle (incl. Tracing, Replay)79.59 kB+0.05%+37 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback)85.04 kB+0.06%+47 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback, Logs, Metrics)85.96 kB+0.06%+50 B 🔺
CDN Bundle - uncompressed81.27 kB--
CDN Bundle (incl. Tracing) - uncompressed126.98 kB+0.14%+171 B 🔺
CDN Bundle (incl. Tracing, Logs, Metrics) - uncompressed129.82 kB+0.14%+171 B 🔺
CDN Bundle (incl. Tracing, Replay) - uncompressed243.59 kB+0.08%+171 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback) - uncompressed256.39 kB+0.07%+171 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback, Logs, Metrics) - uncompressed259.2 kB+0.07%+171 B 🔺
@sentry/nextjs (client)46.66 kB+0.1%+42 B 🔺
@sentry/sveltekit (client)42.44 kB+0.12%+48 B 🔺
@sentry/node-core51.9 kB--
@sentry/node165.45 kB--
@sentry/node - without tracing93.65 kB--
@sentry/aws-serverless109.16 kB--
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Comment threadpackages/browser/src/tracing/browserTracingIntegration.ts
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Thanks for adding this functionality, Tim!
If you don't mind, please also add an integration test with regular tracing. I think we have some meta-tags integration tests in our suites that we can take inspiration from.
Comment thread...ration-tests/suites/tracing/trace-lifetime/tracing-without-performance-headers/template.html
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Comment threadpackages/browser/src/tracing/browserTracingIntegration.ts
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Comment threaddev-packages/browser-integration-tests/suites/tracing/trace-lifetime/pageload-headers/test.ts
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node-overhead report 🧳
Note: This is a synthetic benchmark with a minimal express app and does not necessarily reflect the real-world performance impact in an application.
ScenarioRequests/s% of BaselinePrev. Requests/sChange %
GET Baseline9,270-9,202+1%
GET With Sentry1,77419%1,734+2%
GET With Sentry (error only)6,25968%6,088+3%
POST Baseline1,213-1,185+2%
POST With Sentry60850%574+6%
POST With Sentry (error only)1,07989%1,059+2%
MYSQL Baseline3,378-3,294+3%
MYSQL With Sentry47314%448+6%
MYSQL With Sentry (error only)2,74581%2,689+2%
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Comment threaddev-packages/browser-integration-tests/suites/tracing/trace-lifetime/pageload-meta/test.ts
 span_id: expect.stringMatching(/^[\da-f]{16}$/),
 });
 // navigation span is head of trace, so there's no parent span:
 expect(navigationTraceContext?.trace_id).not.toHaveProperty('parent_span_id');
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Cursor pointed out that the type/logic was wrong in this expection...
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Cursor Bugbot has reviewed your changes and found 1 potential issue.
Bugbot Autofix is OFF. To automatically fix reported issues with Cloud Agents, enable Autofix in the Cursor dashboard.
Comment thread...ration-tests/suites/tracing/trace-lifetime/tracing-without-performance-headers/template.html
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Thanks Tim! Let's get this in -- really nice alternative to the meta tags. I can see us migrating to this approach for frameworks where modifying the HTML isn't straight forward.
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feat(remix): Server Timing Headers Trace Propagation (#18653)
ae7206f
Adds automatic trace propagation from server to client via the
Server-Timing HTTP header for Remix applications. The client-side
reading of Server-Timing headers via the Performance API was added in
#18673.
Adds:
- `generateSentryServerTimingHeader(span)` public utility that generates
a Server-Timing header value containing Sentry trace context
- Automatic injection in the document request handler for normal page
responses
- Automatic injection on redirect responses from loaders and actions,
which bypass the document request handler entirely. This is an advantage
over meta tag injection, which cannot work on redirect responses since
they have no HTML body
- For Cloudflare/Hydrogen apps: call
`generateSentryServerTimingHeader()` manually and append the value to
the response's `Server-Timing` header in entry.server.tsx (see
remix-hydrogen e2e test for example)
Works on both Node.js and Cloudflare Workers environments.
Closes#18696
---------
Co-authored-by: Lukas Stracke <lukas.stracke@sentry.io>
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feat(browser): Trace continuation from server-timing headers


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