feat(mcpedia): Phase 3 — async indexing (BullMQ), git-sync webhook, revisions, MCP Resources

- packages/queue: ioredis singleton + BullMQ Queue/Worker (prefix mcpedia:
  on shared imrnes Redis :6379); apps/worker runs startWorker()
- @mcpedia/core: indexContentFile/runFullIndex (single indexing entry point
  shared by script/worker/hook) + revision.service (list/get/restore)
- document_revisions table (migration 0002) — snapshots only on body change
- apps/api: POST /hooks/reindex + /hooks/index webhooks; tRPC revisions,
  getRevision, restoreRevision, jobStatus, queueStatus
- apps/mcp: register MCP Resources mcpedia://docs{/,+slug/chunks/revisions}
  ({+slug} RFC6570 reserved expansion for slugs containing /)
- apps/mcp zod pinned to ^4 to match MCP SDK 1.30 compiled types
  (resolves registerTool TS2589/ShapeOutput skew)
- scripts/enqueue.ts one-shot job enqueue helper; indexer refactored to runFullIndex
- PHASES.md/README/.env.example/docs updated

packages/core/src/revision.service.ts

@@ -0,0 +1,116 @@
+import { db } from "@mcpedia/db";
+import { documents, documentRevisions, documentChunks } from "@mcpedia/db/schema";
+import { eq, desc, and, sql } from "drizzle-orm";
+import { toMeta } from "./row-map";
+import type { DocumentMeta } from "@mcpedia/types";
+
+export interface RevisionSummary {
+  id: string;
+  slug: string;
+  revisionNo: number;
+  title: string;
+  reason: string;
+  createdAt: string;
+  bodyLength: number;
+}
+
+/** List revisions for a slug, newest first. */
+export async function listRevisions(
+  slug: string,
+  limit = 20,
+): Promise<RevisionSummary[]> {
+  const [doc] = await db
+    .select({ id: documents.id })
+    .from(documents)
+    .where(eq(documents.slug, slug));
+  if (!doc) return [];
+
+  const rows = await db
+    .select({
+      id: documentRevisions.id,
+      slug: documentRevisions.slug,
+      revisionNo: documentRevisions.revisionNo,
+      title: documentRevisions.title,
+      reason: documentRevisions.reason,
+      createdAt: documentRevisions.createdAt,
+      bodyLength: sql<number>`length(${documentRevisions.body})`,
+    })
+    .from(documentRevisions)
+    .where(eq(documentRevisions.documentId, doc.id))
+    .orderBy(desc(documentRevisions.revisionNo))
+    .limit(limit);
+
+  return rows.map((r) => ({
+    id: r.id,
+    slug: r.slug,
+    revisionNo: r.revisionNo,
+    title: r.title,
+    reason: r.reason,
+    createdAt: r.createdAt.toISOString(),
+    bodyLength: r.bodyLength,
+  }));
+}
+
+/** Fetch a single revision's full body. */
+export async function getRevision(
+  id: string,
+): Promise<{ id: string; revisionNo: number; body: string; meta: unknown } | null> {
+  const [row] = await db
+    .select({
+      id: documentRevisions.id,
+      revisionNo: documentRevisions.revisionNo,
+      body: documentRevisions.body,
+      meta: documentRevisions.meta,
+    })
+    .from(documentRevisions)
+    .where(eq(documentRevisions.id, id));
+  if (!row) return null;
+  return {
+    id: row.id,
+    revisionNo: row.revisionNo,
+    body: row.body,
+    meta: row.meta,
+  };
+}
+
+/** Restore a revision: write its body+metadata back into the live `documents` row. */
+export async function restoreRevision(
+  id: string,
+): Promise<{ slug: string; documentId: string } | null> {
+  const [rev] = await db
+    .select({
+      id: documentRevisions.id,
+      documentId: documentRevisions.documentId,
+      slug: documentRevisions.slug,
+      title: documentRevisions.title,
+      body: documentRevisions.body,
+      meta: documentRevisions.meta,
+    })
+    .from(documentRevisions)
+    .where(eq(documentRevisions.id, id));
+  if (!rev) return null;
+
+  const m = rev.meta as {
+    type?: string;
+    section?: string;
+    status?: string;
+    author?: string;
+    tags?: string[];
+  };
+
+  await db
+    .update(documents)
+    .set({
+      title: rev.title,
+      type: (m.type as any) ?? "documentation",
+      section: (m.section as any) ?? "docs",
+      status: (m.status as any) ?? "published",
+      author: m.author ?? "",
+      tags: m.tags ?? [],
+      body: rev.body,
+      updatedAt: new Date(),
+    })
+    .where(eq(documents.id, rev.documentId));
+
+  return { slug: rev.slug, documentId: rev.documentId };
+}