Tracks: preview site events (STU-2119)

[wojtekn]

Related issues

• Fixes STU-2119

How AI was used in this PR

Claude Code explored the existing Tracks patterns (the sibling STU-2115/STU-2116 work), drafted and verified the plan, and implemented the events, tests, and docs. I reviewed the emitter loci, the CLI-vs-renderer split, and the delete-all decision, and verified the emit paths myself (unit tests + a CLI smoke test confirming channel attribution).

Proposed Changes

Preview-site sharing (WordPress.com hosted previews) had no analytics, so we couldn't tell how many users share their work via preview links, or how reliable create/update is in the field. This adds Tracks events across the preview-site lifecycle:

• studio_preview_site_create / studio_preview_site_update — with success, failure_reason, and time_ms, so we get both adoption and a success/latency funnel.
• studio_preview_site_delete — a single preview deleted.
• studio_preview_site_delete_all — the "delete all" action, carrying a count of previews removed.
• studio_preview_site_open — a user opening a preview URL to visit it.

Create/update/delete/delete-all all fire from the CLI, which is the sole funnel: the desktop Previews tab delegates every one of these actions to the app-spawned CLI, so each action is counted exactly once whether it originated in the UI or standalone, and is attributed to the right surface via channel/ui_version. open has no CLI equivalent and fires from the renderer. No PII is ever sent — no site names, paths, or URLs; failure_reason is a coarse, low-cardinality bucket and the raw error is never included.

Testing Instructions

1. Start Studio npm start
2. Open a site's Previews tab.
3. Create, Update, Delete, and Delete-all a preview site; confirm the console logs Would have recorded Tracks event: studio_preview_site_* with channel: studio-ui and the correct ui_version, and that each action logs exactly once.
4. Click a preview's URL and confirm studio_preview_site_open logs.
5. Confirm CLI paths: studio preview create/update/delete [--all] log the same events with channel: studio-cli.

Follow-up (issue DoD, not code)

Each event and all its eventprops (including the wrapper-attached common props) still need registering via the Tracks Registration tool — documentation/CI integrity, separate from ingestion.

Pre-merge Checklist

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

[wpmobilebot]

📊 Performance Test Results

Comparing 06737ca vs trunk

app-size

Metric	trunk	06737ca	Diff	Change
App Size (Mac)	1405.26 MB	1405.27 MB	+0.00 MB	⚪ 0.0%

site-editor

Metric	trunk	06737ca	Diff	Change
load	1072 ms	1043 ms	29 ms	⚪ 0.0%

site-startup

Metric	trunk	06737ca	Diff	Change
siteCreation	7532 ms	7555 ms	+23 ms	⚪ 0.0%
siteStartup	2865 ms	2868 ms	+3 ms	⚪ 0.0%

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Results are median values from multiple test runs.

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