Sync: preserve Pressable metadata in reconciliation fallback

[gcsecsey]

Related issues

• Fixes STU-1944
• Related to STU-1977

How AI was used in this PR

Claude investigated the issue, helped reduce it against WPCom with a test Pressable site, and implemented the fix.

Proposed Changes

When the Sync tab loads, Studio refreshes connected-site metadata from page 1 of /me/sites and fetches any connected site missing from that page individually via rest/v1.1 /sites/{id}. The single-site endpoint never returns hosting_provider_guess or environment_type, these are wpcom decorations that exist only on the /me/sites endpoints, even when explicitly requested via fields. Because Pressable support is derived from hosting_provider_guess, a successful fallback response reclassified a known Pressable site as unsupported (and could misfile staging sites), and reconciliation persisted that downgrade. Accounts with more than one page of sites, eg. the 80-site agency in STU-1977, hit this on every Sync tab load.

• The supplemental fetch now falls back to the stored connected site's isPressable / staging metadata when the response lacks those fields, instead of recomputing sync support from incomplete data.
• Deletion and permission changes are still detected from the response, only the missing provider metadata is preserved, so a genuinely deleted site or lost permissions still downgrade correctly.
• A jetpack counterpart (adding hosting_provider_guess/environment_type to the single-site endpoint) is being prepared separately, this guard protects all reconciliation paths regardless.

Testing Instructions

1. Run the unit tests: npm test -- apps/studio/src/modules/sync/lib/tests/build-supplemental-sync-site.test.ts
2. Manual verification (the bug needs a connected Pressable site that is NOT on page 1 of /me/sites):
   • Temporarily lower perPage in apps/studio/src/stores/sync/wpcom-sites.ts to force the fallback:

   diff --git a/apps/studio/src/stores/sync/wpcom-sites.ts b/apps/studio/src/stores/sync/wpcom-sites.ts
   index 602cf0afc..0d98bd509 100644
   --- a/apps/studio/src/stores/sync/wpcom-sites.ts
   +++ b/apps/studio/src/stores/sync/wpcom-sites.ts
   @@ -97,7 +97,9 @@ export const wpcomSitesApi = createApi( {
                                   search?: string;
                           }
                   >( {
   -                       queryFn: async ( { connectedSiteIds, page = 1, perPage = 20, search } ) => {
   +                       queryFn: async ( { connectedSiteIds, page = 1, perPage = 1, search } ) => {
                                   const wpcomClient = getWpcomClient();
                                   if ( ! wpcomClient ) {
                                           return { error: { status: 401, data: 'Not authenticated' } };

   • Connect a local site to a Pressable site
   • Reload the Sync tab
   • Before this change: the connected site shows "appears to be deleted or is currently unreachable" and its stored record flips to syncSupport: "unsupported", isPressable: false in ~/.studio/app.json. After: it stays recognized as a connected Pressable site and remains syncable.

trunk	this branch

Pre-merge Checklist

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

[wpmobilebot]

📊 Performance Test Results

Comparing c947ee1 vs trunk

app-size

Metric	trunk	c947ee1	Diff	Change
App Size (Mac)	1345.24 MB	1345.25 MB	+0.00 MB	⚪ 0.0%

site-editor

Metric	trunk	c947ee1	Diff	Change
load	736 ms	1071 ms	+335 ms	🔴 45.5%

site-startup

Metric	trunk	c947ee1	Diff	Change
siteCreation	6460 ms	6505 ms	+45 ms	⚪ 0.0%
siteStartup	2392 ms	2394 ms	+2 ms	⚪ 0.0%

---

Results are median values from multiple test runs.

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

[katinthehatsite]

this could be a possible refactor for clarity:

  const effectiveSite =                                                                                       
        site.hosting_provider_guess === undefined && storedSite?.isPressable                                  
                ? { ...site, hosting_provider_guess: 'pressable' as const }                                   
                : site;

[gcsecsey]

Good call, applied in 9c803c8 👍

[katinthehatsite]

I think the changes make sense and look good, I came to a similar conclusion while checking the issue.

I left one minor comment

[katinthehatsite]

As a sidenote: I don't have the right type of setup to test this manually but I reviewed the code visually and ran the tests