fix(migration): フラット .md ファイル対応と slug 計算修正

旧 utcode.net の projects コンテンツは 2 形式混在:
- A: projects/<slug>/index.md (例: coursemate/index.md)
- B: projects/hackathon/<date>/<slug>.md (例: hackathon/2023-08-17/call-paper.md)

`findMarkdownFiles` が index.md/index.mdx 縛りで形式 B 9 件 (call-paper,
denigma, music-app, todo, bowling, shift-syncer, typing-script, gemmit,
hack-shooter) を silent に取りこぼしていた。articles 側の挙動を維持するため
pattern オプション ("index" | "all") を追加し、projects/images だけ "all" に。

slug 計算 `basename(dirname(file))` も形式 B では日付になり衝突するため、
ファイル名が index.{md,mdx} なら親ディレクトリ名、それ以外なら拡張子除いた
ファイル名、という分岐を `deriveProjectSlug` に切り出した。

migrate-images.server.ts にも同じ 2 つのバグがあったので併せて修正。

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: aster-void

src/lib/server/services/migration/helpers.server.test.ts

@@ -0,0 +1,34 @@
+import { describe, expect, test } from "bun:test";
+import { deriveProjectSlug } from "./helpers.server";
+
+describe("deriveProjectSlug", () => {
+  // Form A: <slug>/index.md
+  test("returns parent dir name for index.md", () => {
+    expect(deriveProjectSlug("/repo/contents/projects/coursemate/index.md")).toBe("coursemate");
+  });
+
+  test("returns parent dir name for index.mdx", () => {
+    expect(deriveProjectSlug("/repo/contents/projects/coursemate/index.mdx")).toBe("coursemate");
+  });
+
+  // Form B: hackathon/<date>/<slug>.md
+  test("returns file basename for flat .md (regression: 9 projects silently skipped)", () => {
+    expect(deriveProjectSlug("/repo/contents/projects/hackathon/2023-08-17/call-paper.md")).toBe(
+      "call-paper",
+    );
+  });
+
+  test("returns file basename for flat .mdx", () => {
+    expect(deriveProjectSlug("/repo/contents/projects/hackathon/2024-01-01/hack-shooter.mdx")).toBe(
+      "hack-shooter",
+    );
+  });
+
+  test("disambiguates siblings under same date dir", () => {
+    const a = deriveProjectSlug("/repo/contents/projects/hackathon/2023-08-17/denigma.md");
+    const b = deriveProjectSlug("/repo/contents/projects/hackathon/2023-08-17/music-app.md");
+    expect(a).toBe("denigma");
+    expect(b).toBe("music-app");
+    expect(a).not.toBe(b);
+  });
+});

src/lib/server/services/migration/helpers.server.ts

@@ -2,7 +2,7 @@
  * Helper functions for migration
  */
 import { readdir, stat } from "node:fs/promises";
-import { extname, join } from "node:path";
+import { basename, dirname, extname, join } from "node:path";
 import * as v from "valibot";
 import { parse as parseYaml } from "yaml";
 import type { ProjectCategory } from "$lib/shared/models/schema";
@@ -24,7 +24,20 @@ export function parseFrontmatter<T>(
   return { frontmatter, body: bodyStr.trim() };
 }
 
-export async function findMarkdownFiles(basePath: string): Promise<string[]> {
+/**
+ * Walk `basePath` and collect markdown files.
+ *
+ * - `pattern: "index"` (default): only `index.md` / `index.mdx`. Used for the
+ *   directory-per-entry layout (members, articles, project form A like
+ *   `coursemate/index.md`).
+ * - `pattern: "all"`: every `.md` / `.mdx`. Used for project form B
+ *   (`hackathon/<date>/<slug>.md`) where multiple flat files share a parent
+ *   directory. See migrate-projects.server.ts for slug derivation.
+ */
+export async function findMarkdownFiles(
+  basePath: string,
+  pattern: "index" | "all" = "index",
+): Promise<string[]> {
   const files: string[] = [];
   async function walk(dir: string): Promise<void> {
     try {
@@ -33,7 +46,7 @@ export async function findMarkdownFiles(basePath: string): Promise<string[]> {
         const fullPath = join(dir, entry.name);
         if (entry.isDirectory()) {
           await walk(fullPath);
-        } else if (entry.name === "index.md" || entry.name === "index.mdx") {
+        } else if (matchesPattern(entry.name, pattern)) {
           files.push(fullPath);
         }
       }
@@ -45,6 +58,36 @@ export async function findMarkdownFiles(basePath: string): Promise<string[]> {
   return files.sort();
 }
 
+function matchesPattern(name: string, pattern: "index" | "all"): boolean {
+  switch (pattern) {
+    case "index":
+      return name === "index.md" || name === "index.mdx";
+    case "all":
+      return name.endsWith(".md") || name.endsWith(".mdx");
+    default:
+      return pattern satisfies never;
+  }
+}
+
+/**
+ * Derive project slug from a markdown file path.
+ *
+ * Legacy content has two layouts:
+ * - Form A: `<slug>/index.md` (e.g. `coursemate/index.md`) -> parent dir name
+ * - Form B: `hackathon/<date>/<slug>.md` (e.g. `hackathon/2023-08-17/call-paper.md`) -> file basename
+ *
+ * Previously slug was always `basename(dirname(file))`, which collapsed all
+ * Form B siblings under one date dir into the same slug and silently skipped
+ * 9 projects on prod migration.
+ */
+export function deriveProjectSlug(file: string): string {
+  const filename = basename(file);
+  if (filename === "index.md" || filename === "index.mdx") {
+    return basename(dirname(file));
+  }
+  return basename(file, extname(file));
+}
+
 export function generateArticleSlug(dirPath: string): string {
   const parts = dirPath.split("/");
   const year = parts.at(-2) ?? "";

src/lib/server/services/migration/migrate-images.server.ts

@@ -11,6 +11,7 @@ import { db } from "$lib/server/drivers/db";
 import { article, member, project } from "$lib/shared/models/schema";
 import type { MigrationResult } from "$lib/shared/types/migration";
 import {
+  deriveProjectSlug,
   fileExists,
   findMarkdownFiles,
   generateArticleSlug,
@@ -165,11 +166,13 @@ export async function migrateImages(repoPath: string, log: Logger): Promise<Migr
   // Project images
   log("Processing project images...");
   const projectsPath = join(repoPath, "contents/projects");
-  const projectFiles = await findMarkdownFiles(projectsPath);
+  // Match migrate-projects.server.ts: walk all .md/.mdx so flat layouts
+  // (e.g. hackathon/<date>/<slug>.md) are picked up too.
+  const projectFiles = await findMarkdownFiles(projectsPath, "all");
 
   for (const file of projectFiles) {
     const dirPath = dirname(file);
-    const slug = basename(dirPath);
+    const slug = deriveProjectSlug(file);
 
     try {
       const content = await readFile(file, "utf-8");

src/lib/server/services/migration/migrate-projects.server.ts

@@ -2,19 +2,25 @@
  * Project migration worker
  */
 import { readFile } from "node:fs/promises";
-import { basename, dirname, join } from "node:path";
+import { dirname, join } from "node:path";
 import { eq } from "drizzle-orm";
 import { db } from "$lib/server/drivers/db";
 import { member, project, projectMember } from "$lib/shared/models/schema";
 import type { MigrationResult } from "$lib/shared/types/migration";
-import { findMarkdownFiles, type Logger, mapCategory, parseFrontmatter } from "./helpers.server";
+import {
+  deriveProjectSlug,
+  findMarkdownFiles,
+  type Logger,
+  mapCategory,
+  parseFrontmatter,
+} from "./helpers.server";
 import { processContentImages } from "./image-processor.server";
 import { ProjectFrontmatterSchema } from "./schemas.server";
 
 export async function migrateProjects(repoPath: string, log: Logger): Promise<MigrationResult> {
   log("--- Migrating Projects ---");
   const projectsPath = join(repoPath, "contents/projects");
-  const files = await findMarkdownFiles(projectsPath);
+  const files = await findMarkdownFiles(projectsPath, "all");
   log(`Found ${files.length} project files`);
 
   let created = 0;
@@ -23,7 +29,7 @@ export async function migrateProjects(repoPath: string, log: Logger): Promise<Mi
 
   for (const file of files) {
     const dirPath = dirname(file);
-    const slug = basename(dirPath);
+    const slug = deriveProjectSlug(file);
 
     try {
       const content = await readFile(file, "utf-8");