docs(core): fix ComponentRegistry singleton example in README

packages/core/README.md's Component Registry snippet taught
`new ComponentRegistry()`, but ComponentRegistry is an exported singleton
instance, not a class -- packages/core/dist/registry/Registry.d.ts declares
`export declare const ComponentRegistry: Registry<any>`. The #5138 doc-snippet
type gate measures this as TS2351: This expression is not constructable.
README ships to npm inside the package's `files`, so a reader who copied the
snippet got a compile error.

Drops the `new`, calls ComponentRegistry.register/get directly on the
singleton, and adds one line stating it is the process-level shared instance
SchemaRenderer resolves every `type` against -- the same wording
packages/components/README.md was given in #5160, kept consistent across
both READMEs.

Updates the UNGATED_DOCS ledger entry for packages/core/README.md in
scripts/check-doc-snippet-types.mjs: TS2351x1 is dropped from the reason
text now that the diagnostic is gone (measured before/after against the
built dist/*.d.ts). The entry is not deleted -- the document's remaining
TS2339x2 pair is a separate, pre-existing defect out of scope here, tracked
as #5257.

Fixes #5258

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RV6yuVCxymHYE16PL9vQkE

Author: claude

.changeset/core-readme-registry-singleton-5258.md

@@ -0,0 +1,27 @@
+---
+'@object-ui/core': patch
+---
+
+Fix `packages/core/README.md`'s Component Registry example, which taught
+`new ComponentRegistry()` against an exported singleton **instance**, not a
+class — the built `packages/core/dist/registry/Registry.d.ts` declares
+`export declare const ComponentRegistry: Registry<any>`, so the snippet did
+not compile (`TS2351: This expression is not constructable`, measured by the
+objectui#5138 doc-snippet type gate). A reader who copied it got a compile
+error; if `new ComponentRegistry()` had compiled it would have produced a
+second, empty registry nothing renders from, the more expensive half of the
+mistake.
+
+The snippet now calls `ComponentRegistry.register(...)` /
+`ComponentRegistry.get(...)` directly on the singleton, with one line stating
+it is the process-level shared instance `SchemaRenderer` resolves every
+`type` against — the same wording `packages/components/README.md` was given
+in objectui#5160, kept consistent across both READMEs. Readers who want their
+own isolated registry still have `Registry` itself, separately exported as a
+real class.
+
+`scripts/check-doc-snippet-types.mjs`'s `UNGATED_DOCS` entry for
+`packages/core/README.md` is updated to match: `TS2351x1` is dropped from its
+reason text now that the diagnostic is gone. The entry is not deleted — the
+document's remaining `TS2339x2` pair (a different, pre-existing defect) is
+out of scope for this change; it's tracked as objectui#5257.

packages/core/README.md

@@ -46,11 +46,14 @@ const mySchema: PageNodeSchema = {
 ```typescript
 import { ComponentRegistry } from '@object-ui/core'
 
-const registry = new ComponentRegistry()
-registry.register('button', buttonMetadata)
-const metadata = registry.get('button')
+ComponentRegistry.register('button', buttonMetadata)
+const metadata = ComponentRegistry.get('button')
 ```
 
+`ComponentRegistry` is a process-level singleton exported by `@object-ui/core`;
+`SchemaRenderer` resolves every `type` against it, so a component registered
+here is renderable from schema anywhere in the app.
+
 ### Data Scope
 
 `DataScopeManager` owns the named scopes a component tree reads from, and

scripts/check-doc-snippet-types.mjs

@@ -246,7 +246,7 @@ const UNGATED_DOCS = {
   'packages/components/README.md':
     '1 undefined-name diagnostic(s) — blocks continue an earlier block, or use ambient names the page never defines',
   'packages/core/README.md':
-    '5 undefined-name diagnostic(s) — blocks continue an earlier block, or use ambient names the page never defines; plus TS2339x2 TS2351x1 — candidate real defects, un-triaged',
+    '5 undefined-name diagnostic(s) — blocks continue an earlier block, or use ambient names the page never defines; plus TS2339x2 — candidate real defects, un-triaged',
   'packages/data-objectstack/README.md':
     '10 parse diagnostic(s) — blocks fenced `ts` that are bare object literals or elided bodies; 41 undefined-name diagnostic(s) — blocks continue an earlier block, or use ambient names the page never defines',
   'packages/fields/README.md':