test(harness): stabilize runtime cold-start test

[pauldambra]

Problem

The harness runtime integration test performs a cold import and full native Pi runtime initialization. Under concurrent CI load, that valid setup can exceed Vitest's default five-second timeout and fail unrelated pull requests.

Why: The test needs enough time to exercise the real runtime consistently in CI without weakening timeout coverage across the rest of the harness suite.

Changes

Give only the cold-start runtime test a 15-second timeout. All other harness tests retain Vitest's default timeout.

How did you test this?

• pnpm exec biome check --write packages/harness/src/runtime.test.ts
• pnpm --filter @posthog/shared build
• pnpm --filter @posthog/harness test (661 tests passed)
• pnpm --filter @posthog/harness typecheck
• git diff --check

Automatic notifications

• Publish to changelog?
• Alert Sales and Marketing teams?

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Created with PostHog Code

[trunk-io]

😎 Merged directly without going through the merge queue, as the queue was empty and the PR was up to date with the target branch - details.

[github-actions]

React Doctor found no issues in the changed files. 🎉

_{Reviewed by React Doctor for commit 77b8a47.}

[github-actions]

Diff matches description exactly — only adds a 15s timeout option to one existing test, no logic changes, purely test-file scope.

• 👍 on the PR from chatgpt-codex-connector[bot].

Gate mechanics and policy version

Gate		Result
prerequisites	✓	all clear
deny-list	✓	no deny categories matched
size	✓	0L, 0F substantive, 72L/1F incl. docs/generated/snapshots — within ceiling
tier	✓	T0 auto-approve: T0-deterministic (72L, 1F, single-area, test)
stamphog 2.0.0b3		.stamphog/policy.yml @ aebec27 · reviewed head 77b8a47