feat: gate every surface on CoeditingRegistry (INV-10) — commenting ranges re-assigned on gate change (spec §6.4 v0.2.1)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/attributionController.ts

@@ -21,6 +21,7 @@ import { minimizeReplace, PendingEditRegistry } from "./pendingEdits";
 import type { VersionGuard } from "./versionGuard";
 import { isAuthorable } from "./workspacePath";
 import type { AuthorSpan } from "./trackChangesModel";
+import type { CoeditingRegistry } from "./coeditingRegistry";
 
 /** Test-facing snapshot of live attribution state for a document. */
 export interface RenderedSpan {
@@ -69,6 +70,7 @@ export class AttributionController implements vscode.Disposable {
     private readonly store: SidecarRouter,
     private readonly rootDir: string | undefined,
     private readonly guard: VersionGuard,
+    private readonly registry: CoeditingRegistry,
   ) {
     this.disposables.push(this.statusItem, this.output, this.applyEmitter);
     this.disposables.push(
@@ -104,6 +106,7 @@ export class AttributionController implements vscode.Disposable {
   /** Load the sidecar and re-resolve every attribution (live span | orphan). */
   loadAll(document: vscode.TextDocument): void {
     if (!this.isTracked(document)) return;
+    if (!this.registry.isCoediting(document.uri)) return;
     const docPath = this.keyOf(document);
     const s = this.state(docPath);
     const artifact = this.store.load(docPath);
@@ -145,6 +148,7 @@ export class AttributionController implements vscode.Disposable {
 
   private onDidChange(e: vscode.TextDocumentChangeEvent): void {
     if (!this.isTracked(e.document) || e.contentChanges.length === 0) return;
+    if (!this.registry.isCoediting(e.document.uri)) return;
     const docPath = this.keyOf(e.document);
     if (!e.document.isDirty && this.matchesDisk(e.document)) {
       // Disk sync (revert / external reload): buffer now equals the file on