✨ support asynchronous beforeSend callbacks

[BenoitZugmeyer]

Motivation

Allow RUM and Logs beforeSend callbacks to perform asynchronous enrichment or filtering before an event is sent—for example, reading a fetch response from the resource event domain context.

Changes

• Support Promise<boolean> results from RUM and Logs beforeSend callbacks while preserving synchronous callback behavior.
• Centralize callback execution, error handling, and RUM field-modification enforcement in Browser Core.
• Add unit coverage and an E2E scenario that enriches a RUM resource event from its fetch response.

Test instructions

1. In the sandbox, initialize RUM with an async beforeSend callback.
2. For fetch resource events, read context.response.text() and add the result to the event context.
3. Make a fetch request and verify that the resulting RUM resource event contains the added context value.

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

[datadog-datadog-prod-us1]

🎉 All green!

🧪 All tests passed
❄️ No new flaky tests detected

🎯 Code Coverage (details)
• Patch Coverage: 74.36%
• Overall Coverage: 77.24% (+0.04%)

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: 24b825a | Docs | View more details | Give us feedback!}

[cit-pr-commenter-54b7da]

Bundles Sizes Evolution

📦 Bundle Name	Base Size	Local Size	𝚫	𝚫%	Status
Rum	180.54 KiB	180.81 KiB	+274 B	+0.15%	✅
Rum Profiler	8.43 KiB	8.43 KiB	0 B	0.00%	✅
Rum Recorder	21.12 KiB	21.12 KiB	0 B	0.00%	✅
Logs	57.04 KiB	57.17 KiB	+141 B	+0.24%	✅
Rum Salesforce	N/A	138.75 KiB	N/A	N/A	N/A
Rum Slim	138.49 KiB	138.75 KiB	+267 B	+0.19%	✅
Worker	22.96 KiB	22.96 KiB	0 B	0.00%	✅
Rum Shopify	N/A	200.38 KiB	N/A	N/A	N/A
Rum-shopify Profiler	N/A	8.43 KiB	N/A	N/A	N/A
Rum-shopify Recorder	N/A	3.72 KiB	N/A	N/A	N/A

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 650935c9a5

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 7243a4b61a

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: eb3d440f0b

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 24b825af7c

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".