feat(pi): add persistent Mosaic /goal controller (#1152)

packages/mosaic/src/commands/launch.ts

@@ -715,9 +715,15 @@ export function buildPiSkillArgs(
   return ['--no-skills', ...forcedSkillArgs];
 }
 
-function discoverPiExtension(): string[] {
-  const ext = join(MOSAIC_HOME, 'runtime', 'pi', 'mosaic-extension.ts');
-  return existsSync(ext) ? ['--extension', ext] : [];
+const PI_EXTENSION_FILES = ['mosaic-extension.ts', 'goal-extension.ts'] as const;
+
+export function discoverPiExtensionArgs(mosaicHome: string = MOSAIC_HOME): string[] {
+  const args: string[] = [];
+  for (const fileName of PI_EXTENSION_FILES) {
+    const extensionPath = join(mosaicHome, 'runtime', 'pi', fileName);
+    if (existsSync(extensionPath)) args.push('--extension', extensionPath);
+  }
+  return args;
 }
 
 // ─── Launch functions ────────────────────────────────────────────────────────
@@ -792,7 +798,7 @@ function launchRuntime(runtime: RuntimeName, args: string[], yolo: boolean): nev
       const prompt = buildRuntimePrompt('pi');
       const cliArgs = ['--append-system-prompt', prompt];
       cliArgs.push(...buildPiSkillArgs(args));
-      cliArgs.push(...discoverPiExtension());
+      cliArgs.push(...discoverPiExtensionArgs());
       if (hasMissionNoArgs) {
         cliArgs.push(missionPrompt);
       } else {