⚗️ [RUM-13259] Add shadow DOM support for action selectors

[rgaignault]

Motivation

Second part of shadow DOM support for actions. This PR adds selector generation for elements inside shadow DOM, using a /shadow/ marker to indicate shadow boundaries.
Follows up on the first PR that added action name support.

Changes

• Generate selectors that cross shadow DOM boundaries with /shadow/ marker
• Added unit tests for shadow DOM selectors
• Added e2e tests for selector generation

These two pictures are coming from the same click with and without the parameter enabled. The selector is correct and more precise that's why the width and height are smaller.

Before

After

Selector query

Test instructions

Checklist

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

[chatgpt-codex-connector]

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[cit-pr-commenter]

Bundles Sizes Evolution

📦 Bundle Name	Base Size	Local Size	𝚫	𝚫%	Status
Rum	171.96 KiB	172.21 KiB	+261 B	+0.15%	✅
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	127.99 KiB	+261 B	+0.20%	✅
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	0.0086	0.005	-41.86%
RUM - add action	0.0267	0.0192	-28.09%
RUM - add error	0.0205	0.0164	-20.00%
RUM - add timing	0.0047	0.0033	-29.79%
RUM - start view	0.0159	0.0188	+18.24%
RUM - start/stop session replay recording	0.001	0.0009	-10.00%
Logs - log message	0.0215	0.0214	-0.47%

🧠 Memory Performance

Action Name	Base Memory Consumption	Local Memory Consumption	𝚫
RUM - add global context	25.94 KiB	27.19 KiB	+1.25 KiB
RUM - add action	112.96 KiB	114.69 KiB	+1.73 KiB
RUM - add timing	27.34 KiB	26.70 KiB	-652 B
RUM - add error	115.92 KiB	116.44 KiB	+528 B
RUM - start/stop session replay recording	25.90 KiB	25.37 KiB	-548 B
RUM - start view	506.44 KiB	504.18 KiB	-2.26 KiB
Logs - log message	46.62 KiB	45.31 KiB	-1.31 KiB

🔗 RealWorld

[datadog-datadog-prod-us1]

✅ Tests

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

🎯 Code Coverage (details)
• Patch Coverage: 83.87%
• Overall Coverage: 77.18% (+0.02%)

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: a0385e1 | Docs | Datadog PR Page | Was this helpful? Give us feedback!}

[BeltranBulbarellaDD]

Nice! Works perfectly with the html test
Looks good in the explorer UI too

[sethfowler-datadog]

LGTM!

[rgaignault]

/to-staging

[gh-worker-devflow-routing-ef8351]

View all feedbacks in Devflow UI.

2026-01-26 12:39:42 UTC ℹ️ Start processing command /to-staging

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2026-01-26 12:39:50 UTC ℹ️ Branch Integration: starting soon, merge expected in approximately 0s (p90)

Commit 72be44cef8 will soon be integrated into staging-05.

---

2026-01-26 12:59:44 UTC ℹ️ Branch Integration: this commit was successfully integrated

Commit 72be44cef8 has been merged into staging-05 in merge commit 0debb8f7a3.

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-05