✨ Compute session tracking type in developer extension for SDK v7 support

[thomas-lebeau]

Motivation

SDK v7 will no longer store the session tracking type (logs/rum) in the session cookie. The developer extension currently reads these values directly from the cookie to display session tracking status in the Infos tab.

This change computes the tracking type locally in the extension using the same isSampled function from @datadog/browser-rum-core, so the Infos tab continues to work correctly with SDK v7.

Changes

• Add sampler.ts with computeRumTrackingType and computeLogsTrackingType functions that reuse isSampled from @datadog/browser-rum-core
• Update infosTab.tsx to compute the tracking type from the session ID and SDK config when the cookie does not contain it (SDK v7), falling back to the cookie value when available (SDK v6)
• Add @defaultValue JSDoc annotations for traceSampleRate and sessionReplaySampleRate in RumInitConfiguration

Test instructions

1. Open a page instrumented with the Browser SDK
2. Open the Datadog Developer Extension and go to the Infos tab
3. Verify that the Logs and RUM session tracking types are displayed correctly

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	171.96 KiB	171.96 KiB	0 B	0.00%	✅
Rum Profiler	4.67 KiB	4.67 KiB	0 B	0.00%	✅
Rum Recorder	24.88 KiB	24.88 KiB	0 B	0.00%	✅
Logs	56.29 KiB	56.29 KiB	0 B	0.00%	✅
Flagging	944 B	944 B	0 B	0.00%	✅
Rum Slim	127.73 KiB	127.73 KiB	0 B	0.00%	✅
Worker	23.63 KiB	23.63 KiB	0 B	0.00%	✅

🚀 CPU Performance

Action Name	Base CPU Time (ms)	Local CPU Time (ms)	𝚫%
RUM - add global context	0.0039	0.0048	+23.08%
RUM - add action	0.0125	0.0136	+8.80%
RUM - add error	0.0124	0.014	+12.90%
RUM - add timing	0.0025	0.0025	0.00%
RUM - start view	0.0119	0.0123	+3.36%

🧠 Memory Performance

Action Name	Base Memory Consumption	Local Memory Consumption	𝚫
RUM - add global context	27.19 KiB	26.71 KiB	-493 B
RUM - add action	110.94 KiB	111.79 KiB	+865 B
RUM - add timing	26.53 KiB	26.47 KiB	-58 B
RUM - add error	120.44 KiB	115.31 KiB	-5.13 KiB
RUM - start/stop session replay recording	25.73 KiB	26.01 KiB	+286 B
RUM - start view	500.61 KiB	501.10 KiB	+506 B
Logs - log message	45.04 KiB	45.80 KiB	+782 B

🔗 RealWorld

[datadog-datadog-prod-us1]

✅ Tests

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

🎯 Code Coverage (details)
• Patch Coverage: 100.00%
• Overall Coverage: 77.16% (+0.00%)

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: a46373f | Docs | Datadog PR Page | Was this helpful? Give us feedback!}

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Show "Not tracked" when v7 session has no id

The new fallback only computes logsTrackingType/rumTrackingType when sessionId is present. For sampled-out sessions, the SDK does not persist a session id (the session store only assigns id for tracked sessions), so in v7 environments where cookie logs/rum fields are removed this leaves both values undefined and the Infos tab displays empty values instead of Not tracked. This will affect any deployment using sessionSampleRate < 100.

Useful? React with 👍 / 👎.

[thomas-lebeau]

Not an issue — SDK v7 still writes the session ID to the cookie for all sessions (tracked and untracked). When a session is sampled out, the ID is present in the cookie but the logs/rum fields are absent. In that case, sessionId will be defined, computeLogsTrackingType/computeRumTrackingType will run, and they will correctly return '0' (not tracked).

[chatgpt-codex-connector]

Use effective RUM sampling rates for fallback computation

This recomputation relies on infos.rum.config, which is read from DD_RUM.getInitConfiguration(); that API returns the original init config and does not include remote-configuration overrides applied at startup. If remote config changes sessionSampleRate or sessionReplaySampleRate, the extension will compute a deterministic tracking type that can differ from the active SDK decision, so the displayed RUM tracking status becomes incorrect in remote-config-enabled setups.

Useful? React with 👍 / 👎.

[thomas-lebeau]

Not an issue — getInitConfiguration() already includes remote config overrides. When remote config is applied, the SDK merges the overrides into a copy of the init configuration and stores that as cachedInitConfiguration, which is what getInitConfiguration() returns. So infos.rum.config reflects the effective sample rates.

[mormubis]

Nice! I completely forgot that the devtool would fail without this. 👏