feat(content): eager invalidation and optimistic lock for cqrs

M4: ADR-038 Eager Invalidation + ADR-039 Optimistic Lock

- EagerInvalidationService: Redis DEL after MySQL commit

- Cache key conventions for textbook/chapter/kp/question

- Version header check (If-Match/X-Expected-Version) on write endpoints

- 409 Conflict on version mismatch

- All write endpoints return updatedAt timestamp

services/content/src/chapters/chapters.controller.ts

@@ -3,17 +3,20 @@ import {
   Controller,
   Delete,
   Get,
+  Headers,
   Param,
   Post,
   Put,
 } from "@nestjs/common";
 import { ChaptersService } from "./chapters.service.js";
+import type { ChapterWriteResult } from "./chapters.service.js";
 import type { Chapter } from "./chapters.schema.js";
 import {
   Permissions,
   RequirePermission,
 } from "../middleware/permission.guard.js";
 import { createChapterSchema, updateChapterSchema } from "./chapters.dto.js";
+import { extractExpectedVersion } from "../shared/cache/version-header.js";
 
 @Controller("chapters")
 export class ChaptersController {
@@ -23,7 +26,7 @@ export class ChaptersController {
   @RequirePermission(Permissions.CONTENT_CHAPTER_CREATE)
   async create(
     @Body() body: unknown,
-  ): Promise<{ success: true; data: { id: string } }> {
+  ): Promise<{ success: true; data: ChapterWriteResult }> {
     const input = createChapterSchema.parse(body);
     const result = await this.service.createChapter(input);
     return { success: true, data: result };
@@ -52,18 +55,24 @@ export class ChaptersController {
   async update(
     @Param("id") id: string,
     @Body() body: unknown,
-  ): Promise<{ success: true; data: { success: true } }> {
+    @Headers("if-match") ifMatch?: string,
+    @Headers("x-expected-version") xExpectedVersion?: string,
+  ): Promise<{ success: true; data: ChapterWriteResult }> {
     const input = updateChapterSchema.parse(body);
-    await this.service.updateChapter(id, input);
-    return { success: true, data: { success: true } };
+    const expectedVersion = extractExpectedVersion(ifMatch, xExpectedVersion);
+    const result = await this.service.updateChapter(id, input, expectedVersion);
+    return { success: true, data: result };
   }
 
   @Delete(":id")
   @RequirePermission(Permissions.CONTENT_CHAPTER_DELETE)
   async remove(
     @Param("id") id: string,
+    @Headers("if-match") ifMatch?: string,
+    @Headers("x-expected-version") xExpectedVersion?: string,
   ): Promise<{ success: true; data: { success: true } }> {
-    await this.service.deleteChapter(id);
+    const expectedVersion = extractExpectedVersion(ifMatch, xExpectedVersion);
+    await this.service.deleteChapter(id, expectedVersion);
     return { success: true, data: { success: true } };
   }
 }