Disable Jetpack Stats for local sites

[shaunandrews]

Related issues

• Related to https://linear.app/a8c/issue/STU-1945/investigate-localhost-traffic-inflating-wordpresscomjetpack-stats

How AI was used in this PR

Codex investigated the localhost Stats repro, confirmed that local Studio-rendered pages can emit Jetpack Stats pixels with live blog IDs, and prepared this scoped fix. I reviewed the generated change and kept the PR limited to the Studio MU plugin behavior plus a regression test.

Proposed Changes

• Prevent Studio-served local sites from reporting page views to the remote WordPress.com/Jetpack Stats site when an imported or synced local database still contains a live Jetpack connection.
• Preserve the existing local-development behavior that disables Jetpack Protect for auto-login, while also disabling Jetpack Stats through the same module filter path.
• Keep the fix server-side in the local WordPress runtime so it applies to Studio previews, thumbnail captures, and local sites opened in an external browser.

Testing Instructions

• npx eslint --fix tools/common/lib/mu-plugins.ts tools/common/lib/tests/mu-plugins.test.ts
• npm test -- tools/common/lib/tests/mu-plugins.test.ts
• npm run typecheck

Pre-merge Checklist

• Have you checked for TypeScript, React or other console errors?

[wpmobilebot]

📊 Performance Test Results

Comparing 763cd63 vs trunk

app-size

Metric	trunk	763cd63	Diff	Change
App Size (Mac)	1419.35 MB	1419.36 MB	+0.00 MB	⚪ 0.0%

site-editor

Metric	trunk	763cd63	Diff	Change
load	1080 ms	1121 ms	+41 ms	⚪ 0.0%

site-startup

Metric	trunk	763cd63	Diff	Change
siteCreation	6492 ms	6524 ms	+32 ms	⚪ 0.0%
siteStartup	2392 ms	2397 ms	+5 ms	⚪ 0.0%

---

Results are median values from multiple test runs.

Legend: 🟢 Improvement (faster) | 🔴 Regression (slower) | ⚪ No change (<50ms diff)

[sejas]

@shaunandrews I thought about implementing this same solution when I found you (and your agents) already created the PR. 💫

[sejas]

The code looks good to me, but I'm still seeing the pixel and the stats module active. I'll investigate more next week. Happy to take over this PR.

[shaunandrews]

Please do!

[sejas]

I confirmed this is the right fix and works for new sites. It doesn't work for old sites because there is a bug where the mu-plugins don't get new changes. I'll create a separate PR to fix that.

Thanks Shaun!

[sejas]