feat(turbo-gen): event generator (publish mode)

Wires `pnpm turbo gen event` with publish/consume mode prompt; publish
branch generates the contract file + test and threads it through the
feature's // <gen:events> anchor. Consume branch is a stub that throws
until Task 40 lands the handler-side templates and modify-blocks.

turbo/generators/config.ts

@@ -1,4 +1,7 @@
+import { existsSync } from "node:fs";
+import { join } from "node:path";
 import type { PlopTypes } from "@turbo/gen";
+import { assertAnchors } from "./lib/anchor-validate.js";
 
 /**
  * Turbo generator: `feature`
@@ -325,6 +328,138 @@ export default function generator(plop: PlopTypes.NodePlopAPI): void {
       },
     ],
   });
+
+  /**
+   * Turbo generator: `event`
+   *
+   * Mode `publish` scaffolds an event contract under
+   * `packages/<feature>/src/events/<event-kebab>.event.ts` (+ test) and
+   * re-exports it from the feature's public surface at the `// <gen:events>`
+   * anchor. Mode `consume` (Task 40) scaffolds a handler in the consumer
+   * feature.
+   */
+  plop.setGenerator("event", {
+    description: "Scaffold an event contract (publish) or handler (consume)",
+    prompts: [
+      {
+        type: "list",
+        name: "mode",
+        message: "Mode:",
+        choices: ["publish", "consume"],
+      },
+      {
+        type: "input",
+        name: "feature",
+        message:
+          "Owning feature (kebab-case; for publish: contract package; for consume: consumer package):",
+        validate(input: string) {
+          if (!/^[a-z][a-z0-9-]*$/.test(input)) return "Must be kebab-case";
+          if (!existsSync(join(process.cwd(), "packages", input, "src"))) {
+            return `packages/${input}/src does not exist`;
+          }
+          return true;
+        },
+      },
+      {
+        type: "input",
+        name: "event",
+        message: "Event slug (dotted-kebab past tense, e.g. 'user.signed-up'):",
+        validate(input: string) {
+          if (!/^[a-z][a-z0-9-]*(\.[a-z][a-z0-9-]*)+$/.test(input)) {
+            return "Must be dotted-kebab past tense (e.g. user.signed-up)";
+          }
+          return true;
+        },
+      },
+      {
+        type: "input",
+        name: "publisher",
+        message: "Publisher feature (kebab-case; only for consume mode):",
+        when(answers: { mode: string }) {
+          return answers.mode === "consume";
+        },
+        validate(input: string, answers: { event: string }) {
+          if (!/^[a-z][a-z0-9-]*$/.test(input)) return "Must be kebab-case";
+          const eventKebab = answers.event.replace(/\./g, "-");
+          const path = join(
+            process.cwd(),
+            "packages",
+            input,
+            "src",
+            "events",
+            `${eventKebab}.event.ts`,
+          );
+          if (!existsSync(path)) {
+            return `Publisher contract not found: ${path}`;
+          }
+          return true;
+        },
+      },
+    ],
+    actions(answers) {
+      const a = answers as {
+        mode: "publish" | "consume";
+        feature: string;
+        event: string;
+        publisher?: string;
+      };
+      if (a.mode === "publish") return publishActions(a);
+      throw new Error("consume mode is wired in Task 40");
+    },
+  });
+}
+
+function publishActions(a: {
+  feature: string;
+  event: string;
+}): PlopTypes.ActionType[] {
+  const eventKebab = a.event.replace(/\./g, "-");
+  const indexPath = `packages/${a.feature}/src/index.ts`;
+  return [
+    () => {
+      assertAnchors(process.cwd(), indexPath, ["// <gen:events>"]);
+      return `Anchors verified in ${indexPath}`;
+    },
+    {
+      type: "add",
+      path: `packages/${a.feature}/src/events/${eventKebab}.event.ts`,
+      templateFile: "templates/event/publish/event.ts.hbs",
+      data: { event: a.event, feature: a.feature, eventKebab },
+    },
+    {
+      type: "add",
+      path: `packages/${a.feature}/src/events/${eventKebab}.event.test.ts`,
+      templateFile: "templates/event/publish/event.test.ts.hbs",
+      data: { event: a.event, feature: a.feature, eventKebab },
+    },
+    {
+      type: "modify",
+      path: indexPath,
+      pattern: /\/\/ <gen:events>/,
+      template: `// <gen:events>\nexport {\n  {{camelCase event}}Event,\n  {{camelCase event}}EventSchema,\n  type {{pascalCase event}}Event,\n} from "./events/{{kebabCase event}}.event";`,
+      data: { event: a.event },
+    },
+    () => printPublishNextSteps(a),
+  ];
+}
+
+function printPublishNextSteps(a: { feature: string; event: string }): string {
+  const eventKebab = a.event.replace(/\./g, "-");
+  return [
+    "",
+    "─────────────────────────────────────────────────────────────",
+    `Event ${a.feature}.${a.event} contract scaffolded.`,
+    "",
+    "Next steps (manual):",
+    `  1. Fill in the schema in packages/${a.feature}/src/events/${eventKebab}.event.ts`,
+    `  2. Pick a use case in packages/${a.feature}/src/application/use-cases/ that should publish.`,
+    `     - Add 'bus: IEventBus' to the factory signature.`,
+    `     - Call 'await bus.publish(${camel(a.event.replace(/\./g, "-"))}Event, payload)' after success.`,
+    `     - Update the use case's DI binding to inject the bus.`,
+    `  3. Verify: pnpm --filter @repo/${a.feature} lint typecheck test`,
+    "─────────────────────────────────────────────────────────────",
+    "",
+  ].join("\n");
 }
 
 // Local helpers used inside the printNextSteps action — Plop's helpers aren't