fix(collab): keep the cells a doc does not own when the relay persists a row

docs/features/site-shell.md

@@ -549,7 +549,11 @@ across all their docs via a routing-group stack.
 seeds them from the stored JSON (the server is the ONLY seeder — fixed seed
 clientID, so two clients can never build divergent initial histories),
 persists each doc's update blob to `collab_documents` AND the derived row
-JSON to `data_rows`/site on a short debounce (~800 ms), applies
+JSON to `data_rows`/site on a short debounce (~800 ms) — replacing only the
+cells the doc owns (`OWNED_CELLS` in `relayPersistence.ts`: title, slug, body
+and the template cells for pages; name, slug, body, params, classIds for
+components; name, slug, body, classes for layouts), so SEO, featured media,
+and plugin cells edited elsewhere survive every relay write — applies
 roster-driven soft-deletes, and RESETS docs whose row was written outside
 the relay (`rowWriteEvents.ts`) — clients rebind and reseed. The publish
 endpoint flushes the relay first so the baked snapshot includes edits still

server/collab/relayPersistence.ts

@@ -45,6 +45,30 @@ const KIND_TABLE: Record<Exclude<CollabDocKind, 'site'>, string> = {
   layout: 'layouts',
 }
 
+/**
+ * The cells each doc kind derives from its Y doc. Every other cell on the
+ * row (SEO title and description, featured media, plugin-owned fields) is
+ * edited elsewhere and must survive a relay write untouched; an owned cell
+ * the projection no longer emits (a page that stopped being a template)
+ * is cleared.
+ */
+const OWNED_CELLS: Record<Exclude<CollabDocKind, 'site'>, readonly string[]> = {
+  page: ['title', 'slug', 'body', 'templateEnabled', 'templateTarget', 'templatePriority'],
+  component: ['name', 'slug', 'body', 'params', 'classIds'],
+  layout: ['name', 'slug', 'body', 'classes'],
+}
+
+/** The row's stored cells with the doc-owned ones replaced by what the doc derives. */
+export function mergeDerivedCells(
+  existing: Record<string, unknown> | undefined,
+  derived: Record<string, unknown>,
+  owned: readonly string[],
+): Record<string, unknown> {
+  const merged: Record<string, unknown> = { ...existing }
+  for (const key of owned) delete merged[key]
+  return { ...merged, ...derived }
+}
+
 export type DerivedWrite = 'written' | 'incomplete' | 'invalid'
 type SiteRosters = ReturnType<typeof projectSiteDoc>['rosters']
 
@@ -301,9 +325,12 @@ export function createRelayPersistence(
       slug = layoutSlugFromName(layout.name)
     }
 
+    // The doc carries only the cells the editor owns; the rest of the row
+    // was edited elsewhere and stays exactly as stored.
+    const existing = await getDataRow(db, parsed.rowId)
     await upsertDataRowDraft(
       db,
-      { id: parsed.rowId, tableId: table, cells, slug },
+      { id: parsed.rowId, tableId: table, cells: mergeDerivedCells(existing?.cells, cells, OWNED_CELLS[parsed.kind]), slug },
       null,
       { collabInternal: true },
     )

src/__tests__/server/collabRelayIntegration.test.ts

@@ -207,6 +207,32 @@ describe('collab relay integration (real server, real sockets)', () => {
     })
   })
 
+  it('keeps the cells the doc does not own when it persists the derived row', async () => {
+    const stack = await startStack()
+    const docId = `page:${stack.homeId}`
+    // SEO lives on the row, never in the doc: seed it out of band before any
+    // doc exists, then let the relay write the row from a doc edit.
+    const seeded = (await getDataRow(stack.harness.db, stack.homeId))!
+    await saveDataRowDraft(stack.harness.db, stack.homeId, {
+      cells: { ...seeded.cells, seoTitle: 'Kept title', seoDescription: 'Kept description' },
+      slug: seeded.slug,
+    })
+
+    const client = connectClient(stack)
+    const bound = client.bind(docId)
+    await bound.whenSynced
+    const rootId = treeMap(bound.doc).get('rootNodeId') as string
+    setNodeLabel(bound.doc, rootId, 'Edited in the doc')
+
+    await waitFor(async () => {
+      const row = await getDataRow(stack.harness.db, stack.homeId)
+      return row !== null && pageFromRow(row).nodes[rootId]?.label === 'Edited in the doc'
+    })
+    const row = (await getDataRow(stack.harness.db, stack.homeId))!
+    expect(row.cells.seoTitle).toBe('Kept title')
+    expect(row.cells.seoDescription).toBe('Kept description')
+  })
+
   it('refuses a read-only edit AND resets the viewer so its own screen reverts', async () => {
     const stack = await startStack()
     const docId = `page:${stack.homeId}`