feat(core-eslint): rule no-realtime-handler-reexport

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/core-eslint/rules/no-realtime-handler-reexport.test.js

@@ -0,0 +1,35 @@
+// packages/core-eslint/rules/no-realtime-handler-reexport.test.js
+import { RuleTester } from "eslint";
+import rule from "./no-realtime-handler-reexport.js";
+
+const tester = new RuleTester({
+  languageOptions: { ecmaVersion: 2022, sourceType: "module" },
+});
+
+tester.run("no-realtime-handler-reexport", rule, {
+  valid: [
+    // Importing a handler from inside a feature's bind-* file is allowed.
+    {
+      code: 'import { onPingHandler } from "../realtime/handlers/on-ping.handler";',
+      filename: "/repo/packages/blog/src/di/bind-production.ts",
+    },
+    // Re-exporting a channel descriptor is allowed.
+    {
+      code: 'export { presenceChannel } from "./realtime/presence.channel";',
+      filename: "/repo/packages/blog/src/index.ts",
+    },
+  ],
+  invalid: [
+    // Re-exporting a handler from any non-bind file is forbidden.
+    {
+      code: 'export { onPingHandler } from "./realtime/handlers/on-ping.handler";',
+      filename: "/repo/packages/blog/src/index.ts",
+      errors: [{ messageId: "noRealtimeHandlerReexport" }],
+    },
+    {
+      code: 'export * from "./handlers/on-ping.handler";',
+      filename: "/repo/packages/blog/src/realtime/index.ts",
+      errors: [{ messageId: "noRealtimeHandlerReexport" }],
+    },
+  ],
+});