diff --git a/packages/server/src/index.ts b/packages/server/src/index.ts
index 2105840a..2c1d566a 100644
--- a/packages/server/src/index.ts
+++ b/packages/server/src/index.ts
@@ -20,6 +20,7 @@ import { socialRoutes } from './routes/social.js';
 import { settingsRoutes } from './routes/settings.js';
 import { utilRoutes } from './routes/utils.js';
 import { instanceRoutes } from './routes/instance.js';
+import { invitesRoutes } from './routes/invites.js';
 import { exploreRoutes } from './routes/explore.js';
 import { searchRoutes } from './routes/search.js';
 import { adminRoutes } from './routes/admin.js';
@@ -103,6 +104,7 @@ async function main(): Promise<void> {
   await app.register(settingsRoutes);
   await app.register(utilRoutes);
   await app.register(instanceRoutes);
+  await app.register(invitesRoutes);
   await app.register(exploreRoutes);
   await app.register(searchRoutes);
   await app.register(adminRoutes);
diff --git a/packages/server/src/routes/invites.test.ts b/packages/server/src/routes/invites.test.ts
new file mode 100644
index 00000000..cf2c6b5b
--- /dev/null
+++ b/packages/server/src/routes/invites.test.ts
@@ -0,0 +1,357 @@
+import { describe, it, expect, beforeEach, vi } from 'vitest';
+import Fastify, { type FastifyInstance } from 'fastify';
+import Database from 'better-sqlite3';
+import { drizzle } from 'drizzle-orm/better-sqlite3';
+import { eq } from 'drizzle-orm';
+import fs from 'node:fs';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+import * as schema from '../db/schema.js';
+import { setWorkerId } from '../utils/snowflake.js';
+
+setWorkerId(1);
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
+
+// Module-level mutable state. Each describe's beforeEach reassigns
+// `sqlite`/`testDb`/`app`; the `getDb: () => testDb` getter in the mock
+// closes over the current binding, so reassignment is observed. The
+// `callerIsAdmin` flag lets a test flip the admin guard to verify 403s.
+type TestDb = ReturnType<typeof drizzle<typeof schema>>;
+let sqlite: Database.Database;
+let testDb: TestDb;
+let app: FastifyInstance;
+let callerIsAdmin = true;
+const CALLER_ID = 'admin-1';
+
+vi.mock('../db/index.js', () => ({
+  getDb: () => testDb,
+  getRawDb: () => sqlite,
+  schema,
+}));
+
+vi.mock('../utils/auth.js', () => ({
+  authenticate: async (req: { userId?: string }) => {
+    req.userId = CALLER_ID;
+  },
+  requireAdmin: async (
+    _req: { userId?: string },
+    reply: { code: (n: number) => { send: (b: unknown) => void } },
+  ) => {
+    if (!callerIsAdmin) {
+      reply.code(403).send({ error: 'Admin required', statusCode: 403 });
+    }
+  },
+}));
+
+function applyMigrations(db: Database.Database): void {
+  const migrationsDir = path.resolve(__dirname, '../../drizzle');
+  const files = fs.readdirSync(migrationsDir).filter(f => f.endsWith('.sql')).sort();
+  for (const f of files) {
+    const sqlText = fs.readFileSync(path.join(migrationsDir, f), 'utf8');
+    const statements = sqlText.split(/-->\s*statement-breakpoint/);
+    for (const stmt of statements) {
+      const clean = stmt.trim();
+      if (clean) db.exec(clean);
+    }
+  }
+}
+
+async function buildApp(): Promise<FastifyInstance> {
+  const { invitesRoutes } = await import('./invites.js');
+  const f = Fastify();
+  await f.register(invitesRoutes);
+  return f;
+}
+
+beforeEach(async () => {
+  sqlite = new Database(':memory:');
+  sqlite.pragma('foreign_keys = ON');
+  applyMigrations(sqlite);
+  testDb = drizzle(sqlite, { schema });
+  callerIsAdmin = true;
+
+  testDb.insert(schema.users).values({
+    id: CALLER_ID,
+    username: 'admin',
+    passwordHash: 'x',
+    isAdmin: 1,
+    createdAt: Date.now(),
+  }).run();
+
+  app = await buildApp();
+});
+
+describe('POST /api/admin/invites', () => {
+  it('creates an invite and returns summary', async () => {
+    const res = await app.inject({
+      method: 'POST',
+      url: '/api/admin/invites',
+      payload: { name: 'Friends', maxUses: 10, expiresAt: Date.now() + 86_400_000 },
+    });
+    expect(res.statusCode).toBe(201);
+    const body = res.json();
+    expect(body.name).toBe('Friends');
+    expect(body.token).toMatch(/^[A-Za-z0-9_-]{22}$/);
+    expect(body.status).toBe('active');
+    expect(body.url).toContain('/register?invite=');
+  });
+
+  it('rejects empty name with 400', async () => {
+    const res = await app.inject({
+      method: 'POST',
+      url: '/api/admin/invites',
+      payload: { name: '', maxUses: null, expiresAt: null },
+    });
+    expect(res.statusCode).toBe(400);
+  });
+
+  it('returns 403 for non-admin', async () => {
+    callerIsAdmin = false;
+    const res = await app.inject({
+      method: 'POST',
+      url: '/api/admin/invites',
+      payload: { name: 'x', maxUses: null, expiresAt: null },
+    });
+    expect(res.statusCode).toBe(403);
+  });
+});
+
+describe('GET /api/admin/invites', () => {
+  it('returns active invites by default', async () => {
+    await app.inject({
+      method: 'POST',
+      url: '/api/admin/invites',
+      payload: { name: 'a', maxUses: null, expiresAt: null },
+    });
+    const res = await app.inject({ method: 'GET', url: '/api/admin/invites' });
+    expect(res.statusCode).toBe(200);
+    const body = res.json();
+    expect(body.invites).toHaveLength(1);
+    expect(body.invites[0].name).toBe('a');
+  });
+
+  it('returns archived invites with status=archived', async () => {
+    const created = await app.inject({
+      method: 'POST',
+      url: '/api/admin/invites',
+      payload: { name: 'a', maxUses: null, expiresAt: null },
+    });
+    const id = created.json().id;
+    await app.inject({ method: 'POST', url: `/api/admin/invites/${id}/revoke` });
+
+    const active = await app.inject({ method: 'GET', url: '/api/admin/invites?status=active' });
+    expect(active.json().invites).toHaveLength(0);
+
+    const archived = await app.inject({ method: 'GET', url: '/api/admin/invites?status=archived' });
+    expect(archived.json().invites).toHaveLength(1);
+    expect(archived.json().invites[0].status).toBe('revoked');
+  });
+
+  it('createdByUsername surfaces "Deleted User" after admin tombstone', async () => {
+    await app.inject({
+      method: 'POST',
+      url: '/api/admin/invites',
+      payload: { name: 'a', maxUses: null, expiresAt: null },
+    });
+    // Tombstone the admin who created the invite. The list endpoint uses a
+    // LEFT JOIN against users; foldUsername should map isDeleted=1 to
+    // 'Deleted User'. This exercises the JOIN-based code path, not the
+    // per-row resolveCreatorUsername fallback.
+    testDb.update(schema.users)
+      .set({ isDeleted: 1, username: '!deleted:' + CALLER_ID })
+      .where(eq(schema.users.id, CALLER_ID))
+      .run();
+
+    const res = await app.inject({ method: 'GET', url: '/api/admin/invites' });
+    expect(res.json().invites[0].createdByUsername).toBe('Deleted User');
+  });
+});
+
+describe('PATCH /api/admin/invites/:id', () => {
+  it('updates name', async () => {
+    const created = await app.inject({
+      method: 'POST',
+      url: '/api/admin/invites',
+      payload: { name: 'old', maxUses: null, expiresAt: null },
+    });
+    const id = created.json().id;
+    const res = await app.inject({
+      method: 'PATCH',
+      url: `/api/admin/invites/${id}`,
+      payload: { name: 'new' },
+    });
+    expect(res.statusCode).toBe(200);
+    expect(res.json().name).toBe('new');
+  });
+
+  it('returns 409 for revoked invite', async () => {
+    const created = await app.inject({
+      method: 'POST',
+      url: '/api/admin/invites',
+      payload: { name: 'a', maxUses: null, expiresAt: null },
+    });
+    const id = created.json().id;
+    await app.inject({ method: 'POST', url: `/api/admin/invites/${id}/revoke` });
+    const res = await app.inject({
+      method: 'PATCH',
+      url: `/api/admin/invites/${id}`,
+      payload: { name: 'x' },
+    });
+    expect(res.statusCode).toBe(409);
+  });
+
+  it('returns 404 for missing id', async () => {
+    const res = await app.inject({
+      method: 'PATCH',
+      url: '/api/admin/invites/nope',
+      payload: { name: 'x' },
+    });
+    expect(res.statusCode).toBe(404);
+  });
+});
+
+describe('POST /api/admin/invites/:id/revoke', () => {
+  it('revokes and returns summary', async () => {
+    const created = await app.inject({
+      method: 'POST',
+      url: '/api/admin/invites',
+      payload: { name: 'a', maxUses: null, expiresAt: null },
+    });
+    const id = created.json().id;
+    const res = await app.inject({ method: 'POST', url: `/api/admin/invites/${id}/revoke` });
+    expect(res.statusCode).toBe(200);
+    expect(res.json().invite.status).toBe('revoked');
+  });
+
+  it('returns 409 on already-revoked', async () => {
+    const created = await app.inject({
+      method: 'POST',
+      url: '/api/admin/invites',
+      payload: { name: 'a', maxUses: null, expiresAt: null },
+    });
+    const id = created.json().id;
+    await app.inject({ method: 'POST', url: `/api/admin/invites/${id}/revoke` });
+    const res = await app.inject({ method: 'POST', url: `/api/admin/invites/${id}/revoke` });
+    expect(res.statusCode).toBe(409);
+  });
+});
+
+describe('POST /api/admin/invites/:id/reinstate', () => {
+  it('rotates token on revoked path', async () => {
+    const created = await app.inject({
+      method: 'POST',
+      url: '/api/admin/invites',
+      payload: { name: 'a', maxUses: 1, expiresAt: null },
+    });
+    const id = created.json().id;
+    const originalToken = created.json().token;
+    await app.inject({ method: 'POST', url: `/api/admin/invites/${id}/revoke` });
+
+    const res = await app.inject({
+      method: 'POST',
+      url: `/api/admin/invites/${id}/reinstate`,
+      payload: { maxUses: 5 },
+    });
+    expect(res.statusCode).toBe(200);
+    const body = res.json();
+    expect(body.tokenRotated).toBe(true);
+    expect(body.invite.token).not.toBe(originalToken);
+    expect(body.invite.status).toBe('active');
+  });
+
+  it('preserves token on exhausted path', async () => {
+    const created = await app.inject({
+      method: 'POST',
+      url: '/api/admin/invites',
+      payload: { name: 'a', maxUses: 1, expiresAt: null },
+    });
+    const id = created.json().id;
+    const originalToken = created.json().token;
+    // Force the row to exhausted by bumping usedCount to maxUses.
+    testDb.update(schema.inviteLinks)
+      .set({ usedCount: 1 })
+      .where(eq(schema.inviteLinks.id, id))
+      .run();
+
+    const res = await app.inject({
+      method: 'POST',
+      url: `/api/admin/invites/${id}/reinstate`,
+      payload: { maxUses: 5 },
+    });
+    expect(res.statusCode).toBe(200);
+    expect(res.json().tokenRotated).toBe(false);
+    expect(res.json().invite.token).toBe(originalToken);
+  });
+
+  it('returns 409 on already-active', async () => {
+    const created = await app.inject({
+      method: 'POST',
+      url: '/api/admin/invites',
+      payload: { name: 'a', maxUses: null, expiresAt: null },
+    });
+    const res = await app.inject({
+      method: 'POST',
+      url: `/api/admin/invites/${created.json().id}/reinstate`,
+      payload: { maxUses: 100 },
+    });
+    expect(res.statusCode).toBe(409);
+  });
+});
+
+describe('DELETE /api/admin/invites/:id', () => {
+  it('hard-deletes and cascades redemptions', async () => {
+    const created = await app.inject({
+      method: 'POST',
+      url: '/api/admin/invites',
+      payload: { name: 'a', maxUses: null, expiresAt: null },
+    });
+    const id = created.json().id;
+    testDb.insert(schema.inviteRedemptions).values({
+      id: 'r1',
+      inviteId: id,
+      userId: null,
+      registrantUsername: 'g',
+      redeemedAt: Date.now(),
+    }).run();
+
+    const res = await app.inject({ method: 'DELETE', url: `/api/admin/invites/${id}` });
+    expect(res.statusCode).toBe(200);
+    expect(res.json().success).toBe(true);
+    expect(
+      testDb.select().from(schema.inviteLinks).where(eq(schema.inviteLinks.id, id)).get(),
+    ).toBeUndefined();
+    expect(
+      testDb.select().from(schema.inviteRedemptions).where(eq(schema.inviteRedemptions.inviteId, id)).all(),
+    ).toHaveLength(0);
+  });
+});
+
+describe('GET /api/admin/invites/:id/redemptions', () => {
+  it('returns redemption list', async () => {
+    const created = await app.inject({
+      method: 'POST',
+      url: '/api/admin/invites',
+      payload: { name: 'a', maxUses: null, expiresAt: null },
+    });
+    const id = created.json().id;
+    testDb.insert(schema.users).values({
+      id: 'u1',
+      username: 'alice',
+      passwordHash: 'x',
+      createdAt: Date.now(),
+    }).run();
+    testDb.insert(schema.inviteRedemptions).values({
+      id: 'r1',
+      inviteId: id,
+      userId: 'u1',
+      registrantUsername: 'alice',
+      redeemedAt: Date.now(),
+    }).run();
+
+    const res = await app.inject({ method: 'GET', url: `/api/admin/invites/${id}/redemptions` });
+    expect(res.statusCode).toBe(200);
+    expect(res.json().redemptions).toHaveLength(1);
+    expect(res.json().redemptions[0].registrantUsername).toBe('alice');
+    expect(res.json().redemptions[0].currentUsername).toBe('alice');
+  });
+});
diff --git a/packages/server/src/routes/invites.ts b/packages/server/src/routes/invites.ts
new file mode 100644
index 00000000..0c47b9ea
--- /dev/null
+++ b/packages/server/src/routes/invites.ts
@@ -0,0 +1,137 @@
+import type { FastifyInstance } from 'fastify';
+import { authenticate, requireAdmin } from '../utils/auth.js';
+import {
+  createInvite,
+  listInvites,
+  patchInvite,
+  revokeInvite,
+  reinstateInvite,
+  deleteInvite,
+  listRedemptions,
+  InviteNotFoundError,
+  InviteStateConflictError,
+  InviteValidationError,
+} from '../utils/inviteService.js';
+import type {
+  CreateInviteRequest,
+  UpdateInviteRequest,
+  ReinstateInviteRequest,
+} from '@backspace/shared';
+
+/**
+ * Admin CRUD routes for invite links. All endpoints sit behind the
+ * `[authenticate, requireAdmin]` preHandler chain — invites are an
+ * instance-local moderation surface and never reach federation.
+ *
+ * The handlers are thin wrappers: they parse the request shape, delegate
+ * to `inviteService` (which owns validation, transactions, and status
+ * derivation), and translate the typed service errors into HTTP statuses:
+ *
+ *   - InviteValidationError    → 400 Bad Request
+ *   - InviteNotFoundError      → 404 Not Found
+ *   - InviteStateConflictError → 409 Conflict
+ *   - anything else            → propagates to Fastify's 500 handler
+ *
+ * Response shapes mirror spec §3.1 — see `docs/superpowers/specs/2026-04-28-registration-invites-design.md`.
+ */
+export async function invitesRoutes(app: FastifyInstance): Promise<void> {
+  app.post<{ Body: CreateInviteRequest }>('/api/admin/invites', {
+    preHandler: [authenticate, requireAdmin],
+  }, async (request, reply) => {
+    try {
+      const invite = createInvite(request.body, request.userId);
+      return reply.code(201).send(invite);
+    } catch (err) {
+      if (err instanceof InviteValidationError) {
+        return reply.code(400).send({ error: err.message, statusCode: 400 });
+      }
+      throw err;
+    }
+  });
+
+  app.get<{ Querystring: { status?: string } }>('/api/admin/invites', {
+    preHandler: [authenticate, requireAdmin],
+  }, async (request, reply) => {
+    const status = request.query.status === 'archived' ? 'archived' : 'active';
+    const invites = listInvites(status);
+    return reply.code(200).send({ invites });
+  });
+
+  app.patch<{ Params: { id: string }; Body: UpdateInviteRequest }>('/api/admin/invites/:id', {
+    preHandler: [authenticate, requireAdmin],
+  }, async (request, reply) => {
+    try {
+      const invite = patchInvite(request.params.id, request.body ?? {});
+      return reply.code(200).send(invite);
+    } catch (err) {
+      if (err instanceof InviteNotFoundError) {
+        return reply.code(404).send({ error: err.message, statusCode: 404 });
+      }
+      if (err instanceof InviteStateConflictError) {
+        return reply.code(409).send({ error: err.message, statusCode: 409 });
+      }
+      if (err instanceof InviteValidationError) {
+        return reply.code(400).send({ error: err.message, statusCode: 400 });
+      }
+      throw err;
+    }
+  });
+
+  app.post<{ Params: { id: string } }>('/api/admin/invites/:id/revoke', {
+    preHandler: [authenticate, requireAdmin],
+  }, async (request, reply) => {
+    try {
+      const invite = revokeInvite(request.params.id);
+      return reply.code(200).send({ invite });
+    } catch (err) {
+      if (err instanceof InviteNotFoundError) {
+        return reply.code(404).send({ error: err.message, statusCode: 404 });
+      }
+      if (err instanceof InviteStateConflictError) {
+        return reply.code(409).send({ error: err.message, statusCode: 409 });
+      }
+      throw err;
+    }
+  });
+
+  app.post<{ Params: { id: string }; Body: ReinstateInviteRequest }>('/api/admin/invites/:id/reinstate', {
+    preHandler: [authenticate, requireAdmin],
+  }, async (request, reply) => {
+    try {
+      const result = reinstateInvite(request.params.id, request.body ?? {});
+      return reply.code(200).send(result);
+    } catch (err) {
+      if (err instanceof InviteNotFoundError) {
+        return reply.code(404).send({ error: err.message, statusCode: 404 });
+      }
+      if (err instanceof InviteStateConflictError) {
+        return reply.code(409).send({ error: err.message, statusCode: 409 });
+      }
+      if (err instanceof InviteValidationError) {
+        return reply.code(400).send({ error: err.message, statusCode: 400 });
+      }
+      throw err;
+    }
+  });
+
+  app.delete<{ Params: { id: string } }>('/api/admin/invites/:id', {
+    preHandler: [authenticate, requireAdmin],
+  }, async (request, reply) => {
+    try {
+      deleteInvite(request.params.id);
+      return reply.code(200).send({ success: true });
+    } catch (err) {
+      if (err instanceof InviteNotFoundError) {
+        return reply.code(404).send({ error: err.message, statusCode: 404 });
+      }
+      throw err;
+    }
+  });
+
+  app.get<{ Params: { id: string } }>('/api/admin/invites/:id/redemptions', {
+    preHandler: [authenticate, requireAdmin],
+  }, async (request, reply) => {
+    const redemptions = listRedemptions(request.params.id);
+    return reply.code(200).send({ redemptions });
+  });
+}