[APPS-2792] Add: local-execution resilience tests

[tyffical]

Motivation

• Local-execution resilience testing milestone from the Local Node Execution Kickoff doc.
  • Renamed/descoped from "Chaos-engineering resilience testing" since domains/chaos-engineering targets Datadog-owned Kubernetes clusters — a mismatch for this in-process, customer-dev-server model.
• Two targeted checks, not fixes:
  • Empirically confirm the RFC's "no process isolation" decision has the failure modes it assumes, rather than leave them unverified.

Architecture

• The process.exit() test can't call runScriptLocally directly in the main Jest process — exiting would kill the whole test run.
• It spawns the fixture as a child process instead, and asserts on the child's exit behavior:

Jest test process
  └─ spawns ──▶ local-execution.process-exit.fixture.ts (child process)
                  runScriptLocally() → customer fn calls process.exit()
                  → child terminates immediately
  └─ asserts on the child's exit code

Changes

2 changes across 2 files

What changed	File
New test confirming a synchronous CPU-bound loop starves the event loop, so the current Promise.race timeout never fires — it can only settle once the loop finishes on its own.	local-execution.resilience.test.ts
New test confirming process.exit() inside the customer function terminates the whole process immediately, bypassing runScriptLocally's try/finally cleanup — spawns a dedicated fixture as its own Jest process (since process.exit() can't safely run inside this Jest process) so the observed behavior is the real executeScriptLocally/runScriptLocally code path, not a hand-rolled emulation of it.	local-execution.resilience.test.ts, local-execution.process-exit.fixture.ts

• The third checklist item ("the queue survives a rejected execution and keeps running") is already covered by an existing test in local-execution.test.ts.

QA Instructions

• Test-only change with no HTTP surface — verified via the unit test commands below, not a live endpoint.

yarn workspace @dd/tests test:unit packages/plugins/apps/src/vite/local-execution.resilience.test.ts
# Expected: 2 passed ✅ VERIFIED

yarn build:all && yarn test:unit
# Full, unscoped suite — a scoped run can't catch a process-wide guard leaking into
# an unrelated package's tests via a shared Jest worker (see the Confluence QA guide).
# Expected: Test Suites: 93 passed / Tests: 2261 passed, 1 skipped ✅ VERIFIED

yarn workspace @dd/apps-plugin run typecheck
# Expected: clean exit ✅ VERIFIED

Blast Radius

• Test-only change; no production code touched.
• Risk: low.

Out of Scope / Follow-ups

1 item deferred

Item	Status	Next step
Whether to pursue real process/thread isolation (e.g. pooled worker_threads) to close the confirmed sync-hang and process.exit() gaps	deferred	These tests exist to inform that decision with real data — a follow-up design discussion, not blocking this PR.

Documentation

• RFC: Local Node execution for High Code Apps backend functions — "Run in-process instead of forking an isolated child process" trade-off this milestone verifies.
• QA guide: Confluence page 7100498075 — exact local/staging QA commands for this repo.

[datadog-prod-us1-6]

✅ All CI checks and tests passed.

🎉 All green!

🧪 All tests passed
❄️ No new flaky tests detected

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: 603a8f1 | Docs | View more details | Give us feedback!}

[tyffical]

@codex review

[chatgpt-codex-connector]

Codex Review Summary

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-01T18:10:57.263400Z	8c7928f	Manual request

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[Copilot]

Pull request overview

Friend, this PR adds resilience tests documenting known limitations of in-process backend execution.

Changes:

• Tests synchronous CPU-bound timeout starvation.
• Tests process.exit() cleanup behavior in a subprocess.

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Reviewed commit: 8c7928f483

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[tyffical]

Superseded by #496 — this PR could not be reopened because its base branch (tiffany.trinh/apps-2792-secret-store-parity) was deleted, and GitHub blocks both reopening and re-basing a closed, stack-tracked PR once its base ref is gone. Same content, now rebased directly onto #490 (tiffany.trinh/apps-2792-dev-verify-cli).