Switch debugger delivery to public ClientTokenAuth endpoint

[watson]

Motivation

Switch the debugger delivery API from the internal same-origin /api/ui/debugger/probe-delivery route (ValidUser session cookie auth) to the public /api/unstable/debugger/frontend/probes route (ClientTokenAuth). This is Stage 3 of the probe delivery redesign, enabling the browser SDK to fetch probes through the public Smart Edge route using the same RUM-style client token authentication model used by other Datadog frontend SDKs.

The backend route is already registered in debugger-delivery-api and allowlisted for ClientTokenAuth in Lambo.

Changes

packages/debugger/src/domain/deliveryApi.ts

• Endpoint path changed from /api/ui/debugger/probe-delivery to /api/unstable/debugger/frontend/probes
• Delivery URL is now constructed as https://api.{site}/... from the site config (defaults to datadoghq.com)
• Authentication changed from credentials: 'same-origin' (session cookies) to a dd-client-token request header
• Added proxy support: when set, the proxy origin replaces the computed API host (used by E2E tests and available for customer proxy setups)

packages/debugger/src/entries/main.ts

• Added proxy?: string to DebuggerInitConfiguration
• clientToken, site, and proxy are now forwarded to startDeliveryApiPolling

E2E test infrastructure

• Delivery mock endpoint moved from the base mock server to the intake server (since formatConfiguration already sets proxy: servers.intake.origin for all SDK configs)
• setDebuggerProbes moved from MockServerApp to IntakeServerApp
• E2E scenarios updated to call servers.intake.app.setDebuggerProbes

Test instructions

Unit tests:

yarn test:unit --spec packages/debugger/src/domain/deliveryApi.spec.ts

All debugger unit tests:

yarn test:unit --spec "packages/debugger/src/**/*.spec.ts"

To verify on staging: initialize the debugger SDK with a valid clientToken and applicationId, confirm that delivery polling requests go to https://api.datad0g.com/api/unstable/debugger/frontend/probes with a dd-client-token header (visible in the Network tab).

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

[watson]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• Switch debugger delivery to public ClientTokenAuth endpoint #4480 👈 (View in Graphite)
• Add Live Debugger package #4449 : 5 other dependent PRs (#4503 , #4508 , #4509 and 2 others)
• Fix TanStack Router lint resolution in test app #4513
• main

This stack of pull requests is managed by Graphite. Learn more about stacking.

[cit-pr-commenter-54b7da]

Bundles Sizes Evolution

📦 Bundle Name	Base Size	Local Size	𝚫	𝚫%	Status
Rum	179.42 KiB	179.42 KiB	0 B	0.00%	✅
Rum Profiler	6.16 KiB	6.16 KiB	0 B	0.00%	✅
Rum Recorder	27.03 KiB	27.03 KiB	0 B	0.00%	✅
Logs	56.80 KiB	56.80 KiB	0 B	0.00%	✅
Rum Slim	135.26 KiB	135.26 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	0.00545	0.0039	-28.44%
RUM - add action	0.0161	0.0128	-20.50%
RUM - add error	0.013999999999999999	0.012	-14.29%
RUM - add timing	0.00295	0.0033	+11.86%
RUM - start view	0.01405	0.012	-14.59%
RUM - start/stop session replay recording	0.0009	0.0008	-11.11%
Logs - log message	0.016900000000000002	0.0148	-12.43%

🧠 Memory Performance

Action Name	Base Memory Consumption	Local Memory Consumption	𝚫
RUM - add global context	31.53 KiB	31.12 KiB	-425 B
RUM - add action	101.84 KiB	113.48 KiB	+11.64 KiB
RUM - add timing	32.46 KiB	32.19 KiB	-283 B
RUM - add error	104.34 KiB	111.38 KiB	+7.04 KiB
RUM - start/stop session replay recording	32.01 KiB	31.35 KiB	-667 B
RUM - start view	489.22 KiB	495.41 KiB	+6.20 KiB
Logs - log message	99.21 KiB	92.75 KiB	-6.46 KiB

🔗 RealWorld

[datadog-prod-us1-3]

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

🎯 Code Coverage (details)
• Patch Coverage: 85.71%
• Overall Coverage: 76.67% (-0.02%)

_{This comment will be updated automatically if new data arrives.
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