✨ Add @datadog/browser-remote-config standalone package and @datadog/browser-sdk-endpoint bundle generator

[mormubis]

Motivation

Right now the only way to use remote configuration with the RUM SDK is to pass `remoteConfigurationId` to `DD_RUM.init()`, which triggers a fetch to the RC endpoint at page load. This PR is the foundation for SSI (Server-Side Injection): pre-fetch the RC on the server, generate a self-contained bundle with the SDK and config embedded, serve it as a single `<script>` tag. No RC fetch at page load, no `init()` call needed in app code.

Changes

Two packages:

`@datadog/browser-remote-config` extracts the RC logic into a standalone package. The main addition is a `contextItemHandler` strategy on `resolveDynamicValues` that controls how `ContextItem[]` arrays (the `user` and `context` fields in the RC schema) get resolved. The browser entry point uses getter properties that evaluate against live browser APIs at read time. The Node entry point serializes them as inline JS expressions instead (`__dd_getJs('window.user')`) for embedding in generated bundles.

`@datadog/browser-sdk-endpoint` is a Node.js package that fetches the RC config, runs the code-gen path to turn `DynamicOption` descriptors into inline expressions, downloads the SDK from CDN, and assembles a self-contained IIFE. The `generateBundle` API is designed to sit behind an Express endpoint with per-config caching.

The `contextItemHandler` strategy is the architectural backbone. The browser handler returns a plain object via getters. The Node handler returns a `CodeExpression` (a branded marker type) that tells `serializeConfigToJs` to inline the string as raw JS rather than JSON-encode it. That distinction is what lets the same config tree produce either a live-resolved object in the browser or a JS object literal with embedded expressions in a bundle.

One non-obvious thing worth calling out: `nodeContextItemHandler` receives a `resolve` callback from `resolveDynamicValues`, but calling `resolve(dynamicOption)` in Node context would try to run the live browser resolvers (`window.*`, `getCookie`) and crash. The handler ignores `_resolve` entirely and calls `serializeDynamicValueToJs` directly. Safe because `ContextItem.value` is always a `DynamicOption`.

Test instructions

1. `yarn test:unit --spec packages/remote-config/src/remoteConfiguration.spec.ts` (46 tests)
2. `yarn test:unit --spec packages/remote-config/src/nodeResolution.spec.ts` (18 tests)
3. `node --test packages/endpoint/src/bundleGenerator.spec.ts` (10 tests)

Checklist

• Tested locally
• Tested on staging
• Added unit tests for this change.
• Added e2e/integration tests for this change. (endpoint package needs a more involved test setup, leaving for follow-up)
• 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	N/A	175.10 KiB	N/A	N/A	N/A
Rum Profiler	N/A	6.16 KiB	N/A	N/A	N/A
Rum Recorder	N/A	27.46 KiB	N/A	N/A	N/A
Logs	N/A	56.80 KiB	N/A	N/A	N/A
Rum Slim	N/A	130.74 KiB	N/A	N/A	N/A
Worker	N/A	23.63 KiB	N/A	N/A	N/A

🚀 CPU Performance

Action Name	Base CPU Time (ms)	Local CPU Time (ms)	𝚫%
RUM - add global context	0.005	0.0053	+6.00%
RUM - add action	0.014	0.0181	+29.29%
RUM - add error	0.0134	0.0233	+73.88%
RUM - add timing	0.0035	0.0047	+34.29%
RUM - start view	0.0164	0.0222	+35.37%
RUM - start/stop session replay recording	0.001	0.0014	+40.00%
Logs - log message	0.0165	0.0329	+99.39%

🧠 Memory Performance

Action Name	Base Memory Consumption	Local Memory Consumption	𝚫
addglobalcontext	N/A	26.15 KiB	N/A
addaction	N/A	52.46 KiB	N/A
addtiming	N/A	26.52 KiB	N/A
adderror	N/A	56.78 KiB	N/A
startstopsessionreplayrecording	N/A	25.48 KiB	N/A
startview	N/A	466.47 KiB	N/A
logmessage	N/A	44.43 KiB	N/A

🔗 RealWorld

[datadog-datadog-prod-us1-2]

✅ Tests

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

🎯 Code Coverage (details)
• Patch Coverage: 74.19%
• Overall Coverage: 77.20% (-0.01%)

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: ecaf9de | Docs | Datadog PR Page | Was this helpful? React with 👍/👎 or give us feedback!}