RUM and Session Replay: SDK init, sample rates, CSP, clean-profile test
# RUM plus Session Replay wiring
## Setup
1. In the Datadog app: Digital Experience, add application, JavaScript type. Copy the `clientToken` and `applicationId`.
2. Install the browser SDK (npm into your frontend bundle is the recommended path).
3. Init early in the page lifecycle:
- `applicationId` and `clientToken` from step 1.
- `site` matching your org region (same trap as everything else).
- `service` and `env` matching your backend unified tagging so frontend and backend sessions join.
- `sessionSampleRate`: 100 while validating, then lower for production volume.
- Session Replay: enable it and set its sample rate separately; replay is the expensive one, sample it harder than sessions.
- Privacy: default text masking is on for a reason. Decide what unmasking you actually need before turning it off.
## Pre-flight (do these before calling it done)
- **CSP**: add the SDK script and intake domains to your Content Security Policy, or the SDK silently never loads.
- **Ad blockers**: test in a clean browser profile. Blockers nuke the SDK and your testing will false-negative.
- **Consent gates**: if the SDK loads after consent, undocumented users produce no sessions. That is a product decision, make it deliberately.
## Verify
Devtools Network shows intake requests on load and interactions. Sessions appear in the explorer within a minute. Click a session, play the replay, and confirm backend traces link from the frontend spans. If the link is missing, the service/env tags disagree between frontend and backend.Find related guidance
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