feat(blog): add bind-dev-seed binder + dev seed

Sets the canonical pattern for all 5 features. Three new files:

- src/__seeds__/dev.ts — buildDevArticles() function returning 3
  realistic articles (welcome, vertical-feature-architecture,
  wip-post) built from articleFactory with id/slug/title/status
  overrides only.
- src/di/bind-dev-seed.ts — bindDevSeedBlog() async function that
  unbinds IArticlesRepository, constructs MockArticlesRepository,
  seeds it via buildDevArticles(), and rebinds via .toConstantValue.
- src/di/bind-dev-seed.test.ts — 3 tests: populated repo, welcome
  article reachable by slug, idempotent (callable twice).

package.json adds the ./di/bind-dev-seed subpath export, parallel to
./di/bind-production.

Tests + use cases continue to construct MockArticlesRepository
directly — they never go through bindDevSeedBlog. The seed only attaches
when called explicitly at app boot.

packages/blog/package.json

@@ -8,7 +8,8 @@
     "./ui": "./src/ui/index.ts",
     "./cms": "./src/integrations/cms/index.ts",
     "./api": "./src/integrations/api/router.ts",
-    "./di/bind-production": "./src/di/bind-production.ts"
+    "./di/bind-production": "./src/di/bind-production.ts",
+    "./di/bind-dev-seed": "./src/di/bind-dev-seed.ts"
   },
   "scripts": {
     "build": "tsc --noEmit",

packages/blog/src/__seeds__/dev.ts

@@ -0,0 +1,35 @@
+import { articleFactory } from "../__factories__/article.factory.js";
+import type { Article } from "../entities/models/article.js";
+
+/**
+ * Realistic blog seed for dev mode + storybook stories.
+ *
+ * Built from `articleFactory` so factory defaults take care of the boring
+ * fields (createdAt, updatedAt, content, authorId) and we only override what
+ * makes the data look like a populated database.
+ *
+ * Lazily produced so importing this module is side-effect-free — the factory's
+ * sequence counter only advances when a binder calls `buildDevArticles()`.
+ */
+export function buildDevArticles(): Article[] {
+  return [
+    articleFactory.build({
+      id: "welcome",
+      slug: "welcome",
+      title: "Welcome to the blog",
+      status: "published",
+    }),
+    articleFactory.build({
+      id: "vertical-feature-architecture",
+      slug: "vertical-feature-architecture",
+      title: "Why vertical-feature packages",
+      status: "published",
+    }),
+    articleFactory.build({
+      id: "wip-post",
+      slug: "work-in-progress",
+      title: "A draft we haven't shipped yet",
+      status: "draft",
+    }),
+  ];
+}

packages/blog/src/di/bind-dev-seed.test.ts

@@ -0,0 +1,71 @@
+import "reflect-metadata";
+import { afterEach, beforeEach, describe, expect, it } from "vitest";
+import { bindDevSeedBlog } from "@/di/bind-dev-seed";
+import { blogContainer } from "@/di/container";
+import { BLOG_SYMBOLS } from "@/di/symbols";
+import { MockArticlesRepository } from "@/infrastructure/repositories/articles.repository.mock";
+import type { IArticlesRepository } from "@/application/repositories/articles.repository.interface";
+
+describe("bindDevSeedBlog", () => {
+  // Each test starts from the default empty-mock binding and tears down
+  // afterwards so the global blogContainer state stays clean for siblings.
+  beforeEach(() => {
+    if (blogContainer.isBound(BLOG_SYMBOLS.IArticlesRepository)) {
+      blogContainer.unbind(BLOG_SYMBOLS.IArticlesRepository);
+    }
+    blogContainer
+      .bind<IArticlesRepository>(BLOG_SYMBOLS.IArticlesRepository)
+      .to(MockArticlesRepository);
+  });
+
+  afterEach(() => {
+    if (blogContainer.isBound(BLOG_SYMBOLS.IArticlesRepository)) {
+      blogContainer.unbind(BLOG_SYMBOLS.IArticlesRepository);
+    }
+    blogContainer
+      .bind<IArticlesRepository>(BLOG_SYMBOLS.IArticlesRepository)
+      .to(MockArticlesRepository);
+  });
+
+  it("populates the repository with the dev articles", async () => {
+    await bindDevSeedBlog();
+
+    const repo = blogContainer.get<IArticlesRepository>(
+      BLOG_SYMBOLS.IArticlesRepository,
+    );
+    const all = await repo.getArticles();
+
+    expect(all.length).toBeGreaterThan(0);
+  });
+
+  it("seeds the welcome article reachable by slug", async () => {
+    await bindDevSeedBlog();
+
+    const repo = blogContainer.get<IArticlesRepository>(
+      BLOG_SYMBOLS.IArticlesRepository,
+    );
+    const welcome = await repo.getArticleBySlug("welcome");
+
+    expect(welcome).toBeDefined();
+    expect(welcome?.title).toBe("Welcome to the blog");
+    expect(welcome?.status).toBe("published");
+  });
+
+  it("is idempotent — calling twice rebuilds a fresh populated repo", async () => {
+    await bindDevSeedBlog();
+    const before = blogContainer.get<IArticlesRepository>(
+      BLOG_SYMBOLS.IArticlesRepository,
+    );
+    const beforeCount = (await before.getArticles()).length;
+
+    await bindDevSeedBlog();
+    const after = blogContainer.get<IArticlesRepository>(
+      BLOG_SYMBOLS.IArticlesRepository,
+    );
+    const afterCount = (await after.getArticles()).length;
+
+    expect(afterCount).toBe(beforeCount);
+    // It's a fresh instance — not the previous one.
+    expect(after).not.toBe(before);
+  });
+});

packages/blog/src/di/bind-dev-seed.ts

@@ -0,0 +1,30 @@
+import { blogContainer } from "./container.js";
+import { BLOG_SYMBOLS } from "./symbols.js";
+import { MockArticlesRepository } from "../infrastructure/repositories/articles.repository.mock.js";
+import { buildDevArticles } from "../__seeds__/dev.js";
+import type { IArticlesRepository } from "../application/repositories/articles.repository.interface.js";
+
+/**
+ * Replace the default empty mock with a populated one for dev mode + storybook.
+ *
+ * Call this from app boot when `USE_DEV_SEED=true`, mutually exclusive with
+ * `bindProductionBlog(config)`. Tests must NOT call this — they construct
+ * `new MockArticlesRepository()` directly and seed via factories per-test.
+ *
+ * Idempotent: safe to call multiple times; each call rebuilds a fresh
+ * populated repo and rebinds the symbol.
+ */
+export async function bindDevSeedBlog(): Promise<void> {
+  if (blogContainer.isBound(BLOG_SYMBOLS.IArticlesRepository)) {
+    blogContainer.unbind(BLOG_SYMBOLS.IArticlesRepository);
+  }
+
+  const repo = new MockArticlesRepository();
+  for (const article of buildDevArticles()) {
+    await repo.createArticle(article);
+  }
+
+  blogContainer
+    .bind<IArticlesRepository>(BLOG_SYMBOLS.IArticlesRepository)
+    .toConstantValue(repo);
+}