[demo split #4449] 4/5 — Add debugger e2e scenarios

[allspain]

DEMO — split of #4449. This is one of 5 stacked draft PRs that breaks
#4449 — Add Live Debugger package
into reviewable increments. Original PR is untouched. This stack is for
demonstrating tooling (jj split for the surgery, gh for the stack);
all of the underlying code is Thomas Watson's work and credited via
Co-authored-by: trailers.

Stack

1. [demo split #4449] 1/5 — Foundation: expose core hooks for the live debugger package #4532 — Foundation — expose core hooks for the live debugger package (12 files / +56-10)
2. [demo split #4449] 2/5 — Add @datadog/browser-debugger package #4533 — Package — add @datadog/browser-debugger (25 files / +6433)
3. [demo split #4449] 3/5 — Extend e2e framework for the debugger package #4534 — E2E framework — extend test framework for the debugger package (12 files / +129-8)
4. [demo split #4449] 4/5 — Add debugger e2e scenarios #4535 — E2E scenarios — add debugger e2e scenarios (3 files / +318-2) ← you are here
5. [demo split #4449] 5/5 — Add instrumentation overhead benchmarks #4536 — Perf benchmarks — add instrumentation overhead benchmarks (12 files / +1222-9)

Each PR's base branch is the previous PR's head, so reviewing in order is
the intended path. Stack constructed with jj:
all 4 commits from #4449 were squashed into one change, then peeled into 5
with jj split <paths>, then pushed with jj git push.

---

What this PR contains (4/5 — E2E scenarios)

The actual debugger E2E scenarios. Builds on the framework changes from PR 3
and the package from PR 2.

Changes

• test/e2e/scenario/debugger.scenario.ts — 7 scenarios covering:
  basic snapshot sending, argument capture, return-value capture,
  exception capture on throw, template message evaluation with expression
  segments, condition evaluation (both met and not-met), and RUM correlation.
• test/apps/vanilla — adds @datadog/browser-debugger import and
  DEBUGGER_INIT support so the debugger E2E tests work in npm setup.

3 files, +318 / -2.

Tests

yarn test:e2e:init && yarn test:e2e -g "debugger".

[github-actions]

Thank you for your submission, we really appreciate it. Like many open-source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution. You can sign the CLA by just posting a Pull Request Comment same as the below format.

---

I have read the CLA Document and I hereby sign the CLA

---

Rick Klein seems not to be a GitHub user. You need a GitHub account to be able to sign the CLA. If you have already a GitHub account, please add the email address used for this commit to your account.
_{You can retrigger this bot by commenting recheck in this Pull Request. Posted by the CLA Assistant Lite bot.}

[cit-pr-commenter-54b7da]

Bundles Sizes Evolution

📦 Bundle Name	Base Size	Local Size	𝚫	𝚫%	Status
Rum	N/A	179.42 KiB	N/A	N/A	N/A
Rum Profiler	N/A	6.16 KiB	N/A	N/A	N/A
Rum Recorder	N/A	27.03 KiB	N/A	N/A	N/A
Logs	N/A	56.80 KiB	N/A	N/A	N/A
Rum Slim	N/A	135.26 KiB	N/A	N/A	N/A
Worker	N/A	23.63 KiB	N/A	N/A	N/A

🚀 CPU Performance

Pending...

🧠 Memory Performance

Pending...

🔗 RealWorld

[datadog-official]

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

🎯 Code Coverage (details)
• Patch Coverage: 100.00%
• Overall Coverage: 76.67% (+0.00%)

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: fa1a5c3 | Docs | Datadog PR Page | Give us feedback!}