♻️ encode cookie options in cookie value

[thomas-lebeau]

Motivation

Some initialization options (usePartitionedCrossSiteSessionCookie and trackSessionAccrossSubdomain) affects the scope of the cookie, If theses options are not in sync between each instance of the SDK (i.e. LOGS and RUM), then multiple cookies with the same name can be created can can crash one of the SDKs.

Changes

• Encode and include the relevant init configuration option in the cookie value
• If multiple cookies with the same name are found, find the one matching the current init config
• In this encoded config, include a cookie version to ease future migration if necessary

Note

To reduce the risk as much as possible, I did the change only for the session cookie and kept the cookie utils used by other cookies untouched.

Test instructions

Checklist

• Tested locally
• Tested on staging
• Added unit tests for this change.
• Added e2e/integration tests for this change.

[cit-pr-commenter]

Bundles Sizes Evolution

📦 Bundle Name	Base Size	Local Size	𝚫	𝚫%	Status
Rum	162.08 KiB	162.82 KiB	+754 B	+0.45%	✅
Rum Recorder	19.78 KiB	19.78 KiB	0 B	0.00%	✅
Rum Profiler	4.89 KiB	4.89 KiB	0 B	0.00%	✅
Logs	55.77 KiB	56.50 KiB	+747 B	+1.31%	✅
Flagging	944 B	944 B	0 B	0.00%	✅
Rum Slim	119.06 KiB	119.78 KiB	+735 B	+0.60%	✅
Worker	23.60 KiB	23.60 KiB	0 B	0.00%	✅

🚀 CPU Performance

Action Name	Base CPU Time (ms)	Local CPU Time (ms)	𝚫%
RUM - add global context	0.0045	0.004	-11.11%
RUM - add action	0.014	0.0122	-12.86%
RUM - add error	0.0122	0.012	-1.64%
RUM - add timing	0.003	0.003	0.00%
RUM - start view	0.0037	0.0033	-10.81%
RUM - start/stop session replay recording	0.001	0.0007	-30.00%
Logs - log message	0.0176	0.0126	-28.41%

🧠 Memory Performance

Action Name	Base Memory Consumption	Local Memory Consumption	𝚫
RUM - add global context	25.46 KiB	25.83 KiB	+383 B
RUM - add action	45.97 KiB	46.51 KiB	+556 B
RUM - add timing	24.34 KiB	24.58 KiB	+245 B
RUM - add error	51.44 KiB	49.60 KiB	-1.84 KiB
RUM - start/stop session replay recording	24.89 KiB	24.14 KiB	-772 B
RUM - start view	422.83 KiB	429.79 KiB	+6.96 KiB
Logs - log message	43.14 KiB	44.32 KiB	+1.18 KiB

🔗 RealWorld

[datadog-official]

✅ Tests

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

🎯 Code Coverage
• Patch Coverage: 82.61%
• Total Coverage: 92.63% (-0.04%)

View detailed report

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

Nit:

Suggested change

	byte |= configuration.usePartitionedCrossSiteSessionCookie ? 1 : 0 << 1 // Store useCrossSiteScripting in next bit
	byte |= configuration.usePartitionedCrossSiteSessionCookie ? 1 : 0 // Store useCrossSiteScripting in next bit

Suggestion: FMU we are using 7 bits on the 8 available bits. We might want to give the version one more bit, so we can have up to 7 versions?

[BenoitZugmeyer]

Nit: to simplify a bit, always return an array (similar to cookieStore.getAll())

Suggested change

	export function getCookies(name: string): string[] | undefined {
	return findAllCommaSeparatedValues(document.cookie).get(name)
	}
	export function getCookies(name: string): string[] {
	return findAllCommaSeparatedValues(document.cookie).get(name) || []
	}

[BenoitZugmeyer]

Suggestion: factorize a bit

let rawSession
let cookieContext
if (sessionStoreStrategyType.type === SessionPersistence.COOKIE) {
  rawSession = retrieveSessionCookie(configuration, sessionStoreStrategyType.cookieOptions)
  cookieContext = {
    cookie: await getSessionCookies(),
    currentDomain: `${window.location.protocol}//${window.location.hostname}`,
  }
} else {
  rawSession = retrieveSessionFromLocalStorage()
}


  // monitor-until: forever, could be handy to troubleshoot issues until session manager rework
  addTelemetryDebug('Unexpected session state', {
    sessionStoreStrategyType: sessionStoreStrategyType.type,
    session: rawSession,
    isSyntheticsTest: isSyntheticsTest(),
    createdTimestamp: rawSession?.created,
    expireTimestamp: rawSession?.expire,
    ...cookieContext
  })

[BenoitZugmeyer]

Thought: after we remove the feature flag, it could be nice to remove the waitForTimeout and use something like expect.poll

[thomas-lebeau]

/to-staging

[dd-devflow-routing-codex]

View all feedbacks in Devflow UI.

2025-10-13 12:33:03 UTC ℹ️ Start processing command /to-staging

---

2025-10-13 12:33:10 UTC ℹ️ Branch Integration: starting soon, merge expected in approximately 11m (p90)

Commit 232186dbf0 will soon be integrated into staging-42.

---

2025-10-13 12:44:01 UTC ℹ️ Branch Integration: this commit was successfully integrated

Commit 232186dbf0 has been merged into staging-42 in merge commit a873893577.

Check out the triggered pipeline on Gitlab 🦊

If you need to revert this integration, you can use the following command: /code revert-integration -b staging-42

[BenoitZugmeyer]

💬 suggestion: use cookieOption.partitioned or crossSite instead of exposing this property to the config‏