Ban handwritten re-exports

eslint.config.mjs

@@ -46,6 +46,17 @@ const removedChatStateEscapeHatchRestrictions = [
     message: "Use a named ChatAction instead of reintroducing the generic state patch escape hatch.",
   },
 ];
+const handWrittenReExportRestrictions = [
+  {
+    selector: "ExportNamedDeclaration[source.value]",
+    message: "Do not add hand-written re-exports. Import from the owning module directly unless this file is an explicit public boundary.",
+  },
+  {
+    selector: "ExportAllDeclaration[source.value]",
+    message:
+      "Do not add hand-written export-all barrels. Import from the owning module directly unless this file is an explicit public boundary.",
+  },
+];
 const chatSignalAdapterRestrictions = [
   {
     selector: "ImportDeclaration[source.value='@preact/signals']",
@@ -209,6 +220,7 @@ const appServerClientProjectionTypeRestrictions = [
   },
 ];
 const baseSourceSyntaxRestrictions = [
+  ...handWrittenReExportRestrictions,
   ...removedChatStateEscapeHatchRestrictions,
   ...generatedAppServerThreadImportRestrictions,
   ...appServerClientProjectionTypeRestrictions,
@@ -295,7 +307,11 @@ export default defineConfig([
     files: ["tests/**/*.{ts,tsx}"],
     rules: {
       ...testTypeScriptRelaxations,
-      ...restrictedSyntaxRule([...generatedAppServerThreadImportRestrictions, ...chatSignalAdapterRestrictions]),
+      ...restrictedSyntaxRule([
+        ...handWrittenReExportRestrictions,
+        ...generatedAppServerThreadImportRestrictions,
+        ...chatSignalAdapterRestrictions,
+      ]),
     },
   },
   {

tests/scripts/eslint-config.test.ts

@@ -101,6 +101,46 @@ export const status = signal("idle");
     expect(messages).toContain("no-restricted-syntax");
   });
 
+  it("reports hand-written named re-exports", async () => {
+    const messages = await lintSource(
+      "src/shared/text/preview.ts",
+      `
+export { shortThreadId } from "../id/thread-id";
+export type { Thread } from "../../domain/threads/model";
+`,
+    );
+
+    expect(messages.filter((message) => message === "no-restricted-syntax")).toHaveLength(2);
+  });
+
+  it("reports hand-written export-all barrels", async () => {
+    const messages = await lintSource(
+      "src/shared/text/preview.ts",
+      `
+export * from "../id/thread-id";
+`,
+    );
+
+    expect(messages).toContain("no-restricted-syntax");
+  });
+
+  it("allows local exports from owning modules", async () => {
+    const messages = await lintSource(
+      "src/shared/text/preview.ts",
+      `
+const limit = 80;
+
+export function truncate(value: string): string {
+  return value.slice(0, limit);
+}
+
+export { limit };
+`,
+    );
+
+    expect(messages).not.toContain("no-restricted-syntax");
+  });
+
   it("reports non-turn app-server protocol imports outside app-server", async () => {
     const messages = await lintSource(
       "src/features/chat/application/pending-requests/pending-request-actions.ts",