🔬 gate session renewal debug context behind a feature flag

[BenoitZugmeyer]

Motivation

The session renewal debug context (SessionRenewalEvent payload — cookie reads, session state
snapshots, and the is_session_renewal/renew_event fields attached to view contexts) was
unconditionally collected on every session renewal. This adds unnecessary overhead and pollutes
view context for all users. Gating it behind a flag allows enabling it only when actively
investigating session lifecycle issues.

Changes

• Add session_renewal_debug_context experimental feature flag
• Gate collection of SessionDebugContext (cookie reads, state snapshots) behind the flag; renewObservable notifies with undefined when the flag is off
• Gate attaching is_session_renewal / renew_event to the renewed view context behind the flag

Test instructions

1. Run yarn dev and open the sandbox at http://localhost:8080
2. Without the flag: trigger a session renewal (e.g. expire the session cookie and interact with the page). Confirm no renew_event or is_session_renewal fields appear on the resulting view event.
3. With the flag enabled (add session_renewal_debug_context to enableExperimentalFeatures in sandbox/index.html): repeat and confirm renew_event with full debug context appears on the view.

Checklist

• Tested locally
• Tested on staging
• Added unit tests for this change.
• Added e2e/integration tests for this change.
• Updated documentation and/or relevant AGENTS.md file

[cit-pr-commenter-54b7da]

Bundles Sizes Evolution

📦 Bundle Name	Base Size	Local Size	𝚫	𝚫%	Status
Rum	168.82 KiB	168.99 KiB	+169 B	+0.10%	✅
Rum Profiler	6.09 KiB	6.09 KiB	0 B	0.00%	✅
Rum Recorder	21.25 KiB	21.25 KiB	0 B	0.00%	✅
Logs	54.37 KiB	54.55 KiB	+180 B	+0.32%	✅
Rum Slim	127.19 KiB	127.34 KiB	+153 B	+0.12%	✅
Worker	22.99 KiB	22.99 KiB	0 B	0.00%	✅

🚀 CPU Performance

Action Name	Base CPU Time (ms)	Local CPU Time (ms)	𝚫%
addglobalcontext	N/A	0.0028	N/A
addaction	N/A	0.0178	N/A
adderror	N/A	0.0134	N/A
addtiming	N/A	0.0008	N/A
startview	N/A	0.0148	N/A
startstopsessionreplayrecording	N/A	0.001	N/A
logmessage	N/A	0.0208	N/A

🧠 Memory Performance

Action Name	Base Memory Consumption	Local Memory Consumption	𝚫
addglobalcontext	N/A	36.61 KiB	N/A
addaction	N/A	81.08 KiB	N/A
addtiming	N/A	37.26 KiB	N/A
adderror	N/A	68.58 KiB	N/A
startstopsessionreplayrecording	N/A	41.12 KiB	N/A
startview	N/A	476.41 KiB	N/A
logmessage	N/A	52.52 KiB	N/A

🔗 RealWorld

[datadog-prod-us1-4]

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

🎯 Code Coverage (details)
• Patch Coverage: 87.50%
• Overall Coverage: 77.57% (-0.01%)

_{This comment will be updated automatically if new data arrives.
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