feat: VersionGuard — newer-major sidecars are read-only with one warning (F5 SLICE-2, INV-16/PUC-4, #14)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/extension.ts

@@ -5,6 +5,7 @@ import { ThreadController } from "./threadController";
 import { AttributionController } from "./attributionController";
 import { ProposalController } from "./proposalController";
 import { buildFingerprint } from "./anchorer";
+import { VersionGuard } from "./versionGuard";
 
 const CHANNEL_NAME = "Cowriting (Cline SDK)";
 
@@ -12,6 +13,7 @@ export interface CowritingApi {
   threadController: ThreadController;
   attributionController: AttributionController;
   proposalController: ProposalController;
+  versionGuard: VersionGuard;
 }
 
 export function activate(context: vscode.ExtensionContext): CowritingApi | undefined {
@@ -67,15 +69,18 @@ export function activate(context: vscode.ExtensionContext): CowritingApi | undef
     return undefined;
   }
   const store = new CoauthorStore(root);
-  const threadController = new ThreadController(store, root);
+  // F5 (INV-16): one shared guard — newer-major sidecars are read-only, one
+  // warning per doc across the three co-owning controllers.
+  const versionGuard = new VersionGuard(store);
+  const threadController = new ThreadController(store, root, versionGuard);
   context.subscriptions.push(threadController);
 
   // --- F3: live attribution (Feature #6) ---
-  const attributionController = new AttributionController(store, root);
+  const attributionController = new AttributionController(store, root, versionGuard);
   context.subscriptions.push(attributionController);
 
   // --- F4: propose/accept (Feature #12) ---
-  const proposalController = new ProposalController(store, attributionController, root);
+  const proposalController = new ProposalController(store, attributionController, root, versionGuard);
   context.subscriptions.push(proposalController);
 
   // One SHARED sidecar watcher for both controllers; self-writes are
@@ -228,7 +233,7 @@ export function activate(context: vscode.ExtensionContext): CowritingApi | undef
   vscode.workspace.textDocuments.forEach(renderIfOpen);
   context.subscriptions.push(vscode.workspace.onDidOpenTextDocument(renderIfOpen));
 
-  return { threadController, attributionController, proposalController };
+  return { threadController, attributionController, proposalController, versionGuard };
 }
 
 export function deactivate(): void {