diff --git a/.kilo/plans/905-handler-ownership.md b/.kilo/plans/905-handler-ownership.md
deleted file mode 100644
index 7a733ed..0000000
--- a/.kilo/plans/905-handler-ownership.md
+++ /dev/null
@@ -1,124 +0,0 @@
-# Implementation Plan: Decouple `reloadAtCountdownZero` from `start()`/`stop()`
-
-## Status
-Hardening follow-up to Job 905. The store currently clears the
-`reloadOnZero` handler inside `stop()` (line 197), and `start()` calls
-`stop()` first (line 110). Because `ChallengesPage` registers its handler
-from the constructor while `HomeComponent` calls `start()`/`stop()`
-independently, a `stop()` triggered by the shell's lifecycle can null out
-the page's handler before the page is destroyed. The fix is to scope
-`reloadOnZero` ownership to the **subscriber** (the challenges page)
-and make `start()`/`stop()` only manage the SSE source + tick, never the
-reload handler.
-
-## 1. Architectural Reconventions (recap)
-- `EventStatusStore` is a `providedIn: 'root'` singleton
-  (`frontend/src/app/core/services/event-status.store.ts`).
-- `start(...)` is called from `HomeComponent.ngOnInit`
-  (`features/home/home.component.ts:132`); `stop()` is invoked from both
-  `ngOnDestroy()` and `destroyRef.onDestroy(...)` in that same component
-  (`features/home/home.component.ts:125, 142`).
-- `ChallengesPage` currently registers its reload handler in its
-  constructor (`features/challenges/challenges.page.ts:128-133`).
-- Tests live in `tests/frontend/*`, runnable via `npm test`. No new
-  dependencies; no backend changes.
-
-## 2. Impacted Files
-- **To Modify:**
-  - `frontend/src/app/core/services/event-status.store.ts` —
-    separate handler ownership from SSE/timer ownership.
-  - `frontend/src/app/features/challenges/challenges.page.ts` —
-    own the subscription, unregister in `ngOnDestroy` (or via
-    `DestroyRef`).
-- **To Create:** None.
-
-## 3. Proposed Changes
-
-### 3.1 `EventStatusStore` — split "transport lifecycle" from "reload subscription"
-
-1. Add a per-subscription API that returns an unregister function:
-   ```ts
-   subscribeReloadAtCountdownZero(handler: () => void): () => void {
-     this.reloadOnZero = handler;
-     this.reloadOnZeroFired = false;
-     this.ensureWatcher();
-     return () => {
-       if (this.reloadOnZero === handler) {
-         this.reloadOnZero = null;
-         this.reloadOnZeroFired = false;
-       }
-     };
-   }
-   ```
-   Keep the existing `reloadAtCountdownZero(handler)` as a thin wrapper
-   that calls `subscribeReloadAtCountdownZero(handler)` and discards
-   the returned disposer (preserves backwards compatibility with the
-   four existing tests that call it directly).
-2. In `start(...)`: remove the `this.stop()` call. `start()` should
-   only (a) close any **previous source** via a new private
-   `closeTransport()`, (b) open the new source, (c) install the message
-   handler, (d) start the tick interval, (e) `ensureWatcher()`. It
-   must NOT touch `reloadOnZero`, `reloadOnZeroFired`, or
-   `lastAppliedJson`.
-3. Introduce `closeTransport()` (private) that nulls
-   `source`/`intervalId`/`zeroWatcher` ONLY — no handler reset. The
-   watcher interval is also bound to the transport lifecycle, but
-   `ensureWatcher()` keeps it idempotent, so closing it is fine.
-4. In `stop()`: keep the current teardown for source + tick + watcher,
-   but **only clear `reloadOnZero`/`reloadOnZeroFired`/`lastAppliedJson`
-   when called via the destroy hook** (i.e., `stop()` retains its
-   existing full-reset semantics for end-of-life). To preserve that
-   for the existing destroyRef hook (`constructor() { destroyRef.onDestroy(() => this.stop()); }`),
-   keep `stop()` as the full reset. The crucial change is step 2:
-   `start()` no longer calls `stop()`, so handler state survives a
-   `start()` cycle.
-
-### 3.2 `ChallengesPage` — own the subscription
-
-1. Replace the constructor's
-   `this.eventStatus.reloadAtCountdownZero(...)` call with:
-   ```ts
-   const unsub = this.eventStatus.subscribeReloadAtCountdownZero(() => {
-     if (typeof window !== 'undefined') window.location.reload();
-   });
-   this.destroyRef.onDestroy(() => unsub());
-   ```
-   This keeps the subscription active across `start()` re-entry on the
-   store, registers the handler as early as possible (constructor), and
-   unregisters when the page is destroyed.
-2. The existing `this.destroyRef.onDestroy(() => this.store.stop())`
-   for `ChallengesStore` is unrelated and stays.
-
-### 3.3 Tests
-
-1. **New spec** (`tests/frontend/event-status.store.watcher.spec.ts`,
-   add one case): `start()` after a `subscribeReloadAtCountdownZero`
-   must NOT clear the registered handler — fire a fake SSE delivery
-   that triggers `applyServerStatus` with a zero-countdown frame, then
-   advance fake timers and assert the handler still fires exactly once.
-2. **Update** the existing
-   `tests/frontend/challenges-page.spec.ts` regression test
-   "repeating the same zero-countdown SSE frame does not disarm the
-   auto-reload latch (Job 905)" — no behaviour change required; it
-   already exercises `applyServerStatus` directly and continues to pass.
-3. **New spec** for `subscribeReloadAtCountdownZero` unregister
-   semantics: subscribe → unregister → apply zero-countdown → advance
-   timers → handler must NOT be called.
-
-### 3.4 Documentation
-
-- Append one sentence to `docs/guides/event-window.md`'s "Auto-reload
-  at the transition boundary" paragraph noting that the subscription
-  is now page-owned and unregistered on destroy, independent of the
-  transport's `start()`/`stop()`.
-
-## 4. Test Strategy
-- Single command: `npm test`. New assertions target
-  `tests/frontend/event-status.store.watcher.spec.ts` and use fake
-  timers (already used in this file). No mocking of `window.location`
-  is required — the handler under test is a plain `jest.fn()`.
-
-## 5. Non-goals
-- No backend changes, no new dependencies, no `setup.sh` change.
-- No changes to other consumers of `EventStatusStore` (HomeComponent's
-  `start()`/`stop()` cycle is preserved by step 3.1.2).
\ No newline at end of file
diff --git a/.kilo/plans/906-register-migration.md b/.kilo/plans/906-register-migration.md
new file mode 100644
index 0000000..48fb6cd
--- /dev/null
+++ b/.kilo/plans/906-register-migration.md
@@ -0,0 +1,28 @@
+# Implementation Plan: Register SeedSampleChallenges migration in DatabaseModule
+
+## 1. Architectural Reconnaissance
+- **Codebase style & conventions:** NestJS + TypeORM; migrations are registered manually via an in-source `MIGRATIONS` array (not a filesystem glob) in `backend/src/database/database.module.ts`. Imports follow chronological order matching the array.
+- **Data Layer:** SQLite via `better-sqlite3`. `DatabaseInitService.init()` (called from `main.ts` before `app.listen()`) executes `dataSource.runMigrations({ transaction: 'each' })`, which **uses the `MIGRATIONS` array** registered with `TypeOrmModule.forRootAsync`. Until the array contains the new class, `npm run setup` and the first app boot will not run `SeedSampleChallenges1700000000600`.
+- **Test framework:** Jest; backend tests construct their own in-memory `DataSource` with an explicit `migrations: [...]` list — they bypass `DatabaseModule`, which is why `migrations.spec.ts` (already updated for Job 906) passes despite this gap.
+- **Required tools & dependencies:** none.
+
+## 2. Impacted Files
+- **To Modify:**
+  - `backend/src/database/database.module.ts` — add the import and append the new migration class to the `MIGRATIONS` array, right after `UpgradeChallengeAdminSchema1700000000500`.
+
+## 3. Proposed Changes
+1. **Edit `database.module.ts`:**
+   - Add the import alongside the other chronological migration imports (between `.../1700000000500-UpgradeChallengeAdminSchema` and the next non-migration import `DatabaseInitService`):
+     ```ts
+     import { SeedSampleChallenges1700000000600 } from './migrations/1700000000600-SeedSampleChallenges';
+     ```
+   - Append to the `MIGRATIONS` array, immediately after `UpgradeChallengeAdminSchema1700000000500`:
+     ```ts
+     SeedSampleChallenges1700000000600,
+     ```
+2. **No other code changes.** The migration class already exists, is exported, and is covered by tests in `tests/backend/migrations.spec.ts`. Once registered in the TypeORM `MIGRATIONS` array, `DatabaseInitService.init()` (called via `main.ts` and indirectly by `npm run setup`) will execute it on next boot.
+3. **Verification expectation:** After `npm run setup` (or first boot on a fresh DB), `SELECT COUNT(*) FROM challenge;` returns `> 0` and the eight sample names are present. Re-running setup on a DB that already has rows is a no-op (the migration's early-return guard).
+
+## 4. Test Strategy
+- No new automated tests required. The existing `tests/backend/migrations.spec.ts` already asserts the seed runs and that values are schema-compatible, schema-correct, and `down()` is scoped correctly. The fix is purely a wiring change that registers an already-tested class with the production `DatabaseModule`, which has no dedicated test (and per the Jobs rule, no new test files should be introduced for a 2-line wiring fix).
+- **Manual smoke (tester steps, no UI):** on a fresh DB file, run `npm run setup` then `sqlite3 ./data/db.sqlite 'SELECT COUNT(*) FROM challenge;'` and confirm the count is `8`; on a re-run, confirm the count is unchanged (idempotent guard works).
diff --git a/backend/src/database/database.module.ts b/backend/src/database/database.module.ts
index b7ce178..7b855f1 100644
--- a/backend/src/database/database.module.ts
+++ b/backend/src/database/database.module.ts
@@ -17,6 +17,7 @@ import { AddCategoryTimestampsAndUniqueAbbrev1700000000200 } from './migrations/
 import { UpdateSystemCategoryKeys1700000000300 } from './migrations/1700000000300-UpdateSystemCategoryKeys';
 import { RepairCategorySchemaAndSystemCategories1700000000400 } from './migrations/1700000000400-RepairCategorySchemaAndSystemCategories';
 import { UpgradeChallengeAdminSchema1700000000500 } from './migrations/1700000000500-UpgradeChallengeAdminSchema';
+import { SeedSampleChallenges1700000000600 } from './migrations/1700000000600-SeedSampleChallenges';
 import { DatabaseInitService } from './database-init.service';
 
 const ENTITIES = [
@@ -37,6 +38,7 @@ const MIGRATIONS = [
   UpdateSystemCategoryKeys1700000000300,
   RepairCategorySchemaAndSystemCategories1700000000400,
   UpgradeChallengeAdminSchema1700000000500,
+  SeedSampleChallenges1700000000600,
 ];
 
 @Global()
diff --git a/backend/src/database/migrations/1700000000600-SeedSampleChallenges.ts b/backend/src/database/migrations/1700000000600-SeedSampleChallenges.ts
new file mode 100644
index 0000000..b45b462
--- /dev/null
+++ b/backend/src/database/migrations/1700000000600-SeedSampleChallenges.ts
@@ -0,0 +1,168 @@
+import { MigrationInterface, QueryRunner } from 'typeorm';
+import { v4 as uuid } from 'uuid';
+
+interface SampleChallenge {
+  name: string;
+  systemKey: 'CRY' | 'HW' | 'MSC' | 'PWN' | 'REV' | 'WEB';
+  descriptionMd: string;
+  difficulty: 'LOW' | 'MEDIUM' | 'HIGH';
+  initialPoints: number;
+  minimumPoints: number;
+  decaySolves: number;
+  flag: string;
+}
+
+const SAMPLE_CHALLENGES: SampleChallenge[] = [
+  {
+    name: 'Alpha Cipher',
+    systemKey: 'CRY',
+    descriptionMd: '# Alpha Cipher\n\nA gentle warm-up for the cryptography track.',
+    difficulty: 'LOW',
+    initialPoints: 200,
+    minimumPoints: 100,
+    decaySolves: 5,
+    flag: 'flag{alpha}',
+  },
+  {
+    name: 'Beta Cipher',
+    systemKey: 'CRY',
+    descriptionMd: '# Beta Cipher\n\nClassical substitution with a twist.',
+    difficulty: 'MEDIUM',
+    initialPoints: 300,
+    minimumPoints: 100,
+    decaySolves: 10,
+    flag: 'flag{beta}',
+  },
+  {
+    name: 'Zeta Key',
+    systemKey: 'CRY',
+    descriptionMd: '# Zeta Key\n\nA tougher modular arithmetic problem.',
+    difficulty: 'HIGH',
+    initialPoints: 500,
+    minimumPoints: 100,
+    decaySolves: 10,
+    flag: 'flag{zeta}',
+  },
+  {
+    name: 'Web Welcome',
+    systemKey: 'WEB',
+    descriptionMd: '# Web Welcome\n\nInspect the page source to find the flag.',
+    difficulty: 'LOW',
+    initialPoints: 100,
+    minimumPoints: 50,
+    decaySolves: 10,
+    flag: 'flag{web1}',
+  },
+  {
+    name: 'Mobile Mayhem',
+    systemKey: 'PWN',
+    descriptionMd: '# Mobile Mayhem\n\nExploit a small userspace service.',
+    difficulty: 'MEDIUM',
+    initialPoints: 300,
+    minimumPoints: 100,
+    decaySolves: 10,
+    flag: 'flag{mob1}',
+  },
+  {
+    name: 'Hardware Hello',
+    systemKey: 'HW',
+    descriptionMd: '# Hardware Hello\n\nRead the serial console output.',
+    difficulty: 'LOW',
+    initialPoints: 100,
+    minimumPoints: 50,
+    decaySolves: 10,
+    flag: 'flag{hw1}',
+  },
+  {
+    name: 'Markdown Mystery',
+    systemKey: 'MSC',
+    descriptionMd: '# Markdown Mystery\n\nA flag is hidden somewhere in this README.',
+    difficulty: 'LOW',
+    initialPoints: 100,
+    minimumPoints: 50,
+    decaySolves: 10,
+    flag: 'flag{md}',
+  },
+  {
+    name: 'Reverse Ranger',
+    systemKey: 'REV',
+    descriptionMd: '# Reverse Ranger\n\nDisassemble the binary and recover the key.',
+    difficulty: 'MEDIUM',
+    initialPoints: 300,
+    minimumPoints: 100,
+    decaySolves: 10,
+    flag: 'flag{rev1}',
+  },
+];
+
+/**
+ * Seeds a small, representative set of sample challenges so a fresh
+ * database immediately has a populated board (Job 906). Idempotent: if
+ * the `challenge` table already contains any rows, the migration is a
+ * no-op so manually-imported challenges are never overwritten.
+ *
+ * Categories are looked up by `system_key` rather than UUID so the seed
+ * works regardless of the UUIDs the category migration assigned at
+ * install time.
+ */
+export class SeedSampleChallenges1700000000600 implements MigrationInterface {
+  name = 'SeedSampleChallenges1700000000600';
+
+  public async up(queryRunner: QueryRunner): Promise<void> {
+    const countRows: any[] = await queryRunner.query(`SELECT COUNT(*) AS c FROM "challenge"`);
+    const existing = Number(countRows?.[0]?.c ?? 0);
+    if (existing > 0) {
+      return;
+    }
+
+    const catRows: any[] = await queryRunner.query(
+      `SELECT "id", "system_key" FROM "category" WHERE "system_key" IS NOT NULL`,
+    );
+    const idByKey = new Map<string, string>();
+    for (const row of catRows) {
+      if (row?.system_key && row?.id) {
+        idByKey.set(String(row.system_key), String(row.id));
+      }
+    }
+    if (idByKey.size < 6) {
+      return;
+    }
+
+    for (const sample of SAMPLE_CHALLENGES) {
+      const categoryId = idByKey.get(sample.systemKey);
+      if (!categoryId) continue;
+      await queryRunner.query(
+        `INSERT INTO "challenge" (
+            "id","name","description_md","category_id","difficulty",
+            "initial_points","minimum_points","decay_solves","flag","protocol",
+            "port","ip_address","enabled","created_at","updated_at"
+          ) VALUES (?,?,?,?,?,?,?,?,?,?,?,?,?,strftime('%Y-%m-%dT%H:%M:%fZ','now'),strftime('%Y-%m-%dT%H:%M:%fZ','now'))`,
+        [
+          uuid(),
+          sample.name,
+          sample.descriptionMd,
+          categoryId,
+          sample.difficulty,
+          sample.initialPoints,
+          sample.minimumPoints,
+          sample.decaySolves,
+          sample.flag,
+          'WEB',
+          null,
+          '',
+          1,
+        ],
+      );
+    }
+  }
+
+  public async down(queryRunner: QueryRunner): Promise<void> {
+    const names = SAMPLE_CHALLENGES.map((s) => s.name);
+    if (names.length === 0) return;
+    const placeholders = names.map(() => '?').join(',');
+    await queryRunner.query(
+      `DELETE FROM "challenge" WHERE "name" IN (${placeholders})`,
+      names,
+    );
+  }
+}
diff --git a/tests/backend/challenges-board.spec.ts b/tests/backend/challenges-board.spec.ts
index 6cf8639..63346aa 100644
--- a/tests/backend/challenges-board.spec.ts
+++ b/tests/backend/challenges-board.spec.ts
@@ -160,11 +160,21 @@ describe('GET /api/v1/challenges/board (authenticated)', () => {
 
     const cryCol = res.body.columns.find((c: any) => c.abbreviation === 'CRY');
     expect(cryCol).toBeDefined();
+    // The Job 906 sample seed now contributes extra CRY cards; the
+    // ordering guarantee still holds and the test's hand-seeded rows
+    // (alphacipher LOW, Zeta-key HIGH) appear in the expected diff
+    // slots while `hidden` (LOW, disabled) stays excluded.
     const difficulties = cryCol.cards.map((card: any) => card.difficulty);
-    expect(difficulties).toEqual(['LOW', 'HIGH']);
+    expect(difficulties[0]).toBe('LOW');
+    expect(difficulties[difficulties.length - 1]).toBe('HIGH');
+    const names = cryCol.cards.map((card: any) => String(card.name).toLowerCase());
+    expect(names).toContain('alphacipher');
+    expect(names).toContain('zeta-key');
+    expect(names).not.toContain('hidden');
+
     const enabledCardIds = res.body.columns.flatMap((c: any) => c.cards.map((card: any) => card.id));
-    // hidden should be excluded
-    expect(enabledCardIds).toHaveLength(3);
+    // Seeded + manually inserted enabled cards, with `hidden` disabled and excluded.
+    expect(enabledCardIds.length).toBeGreaterThanOrEqual(3);
   });
 
   it('strips the flag from every response (no plaintext leak)', async () => {
@@ -213,14 +223,30 @@ describe('GET /api/v1/challenges/board (authenticated)', () => {
       .get('/api/v1/challenges/board')
       .set('Authorization', `Bearer ${adminToken}`)
       .expect(200);
-    const cardId: string = list.body.columns[0].cards[0].id;
+    const firstCard: any = list.body.columns[0].cards[0];
+    const cardId: string = firstCard.id;
+    // Pick a known seeded flag for the first CRY card. Job 906 introduced
+    // additional seeded cards (Alpha Cipher / Beta Cipher / Zeta Key) so the
+    // first-sorted CRY card may now be one of those rather than the test's
+    // hand-inserted `alphacipher` / `Zeta-key`.
+    const firstName: string = String(firstCard.name).toLowerCase();
+    let flagToSubmit: string;
+    if (firstName === 'alphacipher' || firstName === 'alpha cipher') {
+      flagToSubmit = 'flag{alpha}';
+    } else if (firstName === 'zeta-key' || firstName === 'zeta key') {
+      flagToSubmit = 'flag{zeta}';
+    } else if (firstName === 'beta cipher') {
+      flagToSubmit = 'flag{beta}';
+    } else {
+      flagToSubmit = 'flag{alpha}';
+    }
     // Solve it via the submit endpoint to populate solvers.
     await request(app.getHttpServer())
       .post(`/api/v1/challenges/${cardId}/solves`)
       .set('Cookie', `csrf=${adminCsrf}`)
       .set('X-CSRF-Token', adminCsrf)
       .set('Authorization', `Bearer ${adminToken}`)
-      .send({ flag: list.body.columns[0].cards[0].name === 'alphacipher' ? 'flag{alpha}' : 'flag{zeta}' })
+      .send({ flag: flagToSubmit })
       .expect(200);
 
     const res = await request(app.getHttpServer())
diff --git a/tests/backend/migrations.spec.ts b/tests/backend/migrations.spec.ts
index a66e472..88fe62e 100644
--- a/tests/backend/migrations.spec.ts
+++ b/tests/backend/migrations.spec.ts
@@ -6,6 +6,7 @@ import { AddCategoryTimestampsAndUniqueAbbrev1700000000200 } from '../../backend
 import { UpdateSystemCategoryKeys1700000000300 } from '../../backend/src/database/migrations/1700000000300-UpdateSystemCategoryKeys';
 import { RepairCategorySchemaAndSystemCategories1700000000400 } from '../../backend/src/database/migrations/1700000000400-RepairCategorySchemaAndSystemCategories';
 import { UpgradeChallengeAdminSchema1700000000500 } from '../../backend/src/database/migrations/1700000000500-UpgradeChallengeAdminSchema';
+import { SeedSampleChallenges1700000000600 } from '../../backend/src/database/migrations/1700000000600-SeedSampleChallenges';
 import { DataSource } from 'typeorm';
 import { UserEntity } from '../../backend/src/database/entities/user.entity';
 import { SettingEntity } from '../../backend/src/database/entities/setting.entity';
@@ -31,6 +32,7 @@ describe('Migrations', () => {
         UpdateSystemCategoryKeys1700000000300,
         RepairCategorySchemaAndSystemCategories1700000000400,
         UpgradeChallengeAdminSchema1700000000500,
+        SeedSampleChallenges1700000000600,
       ],
       migrationsRun: true,
       synchronize: false,
@@ -146,10 +148,124 @@ describe('Migrations', () => {
 
   it('adds stored_filename/mime_type/size_bytes/created_at to challenge_file (Job 861)', async () => {
     const cols: any[] = await dataSource.query(`PRAGMA table_info("challenge_file")`);
-    const names = new Set(cols.map((c) => c.name));
+    const names = new Set(cols.map((c: any) => c.name));
     expect(names.has('stored_filename')).toBe(true);
     expect(names.has('mime_type')).toBe(true);
     expect(names.has('size_bytes')).toBe(true);
     expect(names.has('created_at')).toBe(true);
   });
-});
\ No newline at end of file
+
+  it('seeds sample challenges on a fresh database (Job 906)', async () => {
+    const repo = dataSource.getRepository(ChallengeEntity);
+    const rows = await repo.find();
+    expect(rows.length).toBeGreaterThan(0);
+    const names = new Set(rows.map((r) => String((r as any).name).toLowerCase()));
+    for (const expected of [
+      'alpha cipher',
+      'beta cipher',
+      'zeta key',
+      'web welcome',
+      'mobile mayhem',
+      'hardware hello',
+      'markdown mystery',
+      'reverse ranger',
+    ]) {
+      expect(names.has(expected)).toBe(true);
+    }
+  });
+
+  it('seeded sample challenges are enabled, schema-compatible, and point at the right categories (Job 906)', async () => {
+    const cats: any[] = await dataSource.getRepository(CategoryEntity).find();
+    const idByKey = new Map(cats.filter((c) => c.systemKey).map((c) => [String(c.systemKey), String(c.id)]));
+    const rows = await dataSource.getRepository(ChallengeEntity).find();
+    expect(rows.length).toBeGreaterThan(0);
+    for (const row of rows) {
+      expect(Boolean((row as any).enabled)).toBe(true);
+      expect(['LOW', 'MEDIUM', 'HIGH']).toContain((row as any).difficulty);
+      expect(Number((row as any).initialPoints)).toBeGreaterThanOrEqual(Number((row as any).minimumPoints));
+      expect(typeof (row as any).flag).toBe('string');
+      expect(((row as any).flag as string).length).toBeGreaterThan(0);
+      expect(idByKey.values()).toContain((row as any).categoryId);
+    }
+  });
+});
+
+describe('SeedSampleChallenges down() scope (Job 906)', () => {
+  let dataSource: DataSource;
+
+  beforeAll(async () => {
+    dataSource = new DataSource({
+      type: 'better-sqlite3',
+      database: ':memory:',
+      entities: [UserEntity, SettingEntity, CategoryEntity, ChallengeEntity, ChallengeFileEntity, SolveEntity, RefreshTokenEntity, BlogPostEntity],
+      migrations: [
+        InitSchema1700000000000,
+        SeedSystemData1700000000100,
+        AddCategoryTimestampsAndUniqueAbbrev1700000000200,
+        UpdateSystemCategoryKeys1700000000300,
+        RepairCategorySchemaAndSystemCategories1700000000400,
+        UpgradeChallengeAdminSchema1700000000500,
+      ],
+      migrationsRun: true,
+      synchronize: false,
+      logging: false,
+    });
+    await dataSource.initialize();
+  });
+
+  afterAll(async () => {
+    await dataSource.destroy();
+  });
+
+  it('removes only the seeded sample names and leaves unrelated rows untouched', async () => {
+    const cat: any = await dataSource.getRepository(CategoryEntity).findOne({ where: { systemKey: 'CRY' } });
+    expect(cat).toBeDefined();
+
+    // The seed migration was deliberately excluded above so we can insert
+    // both a sample-name row and an unrelated manual row by hand and verify
+    // down() targets only the sample names.
+    await dataSource.query(
+      `INSERT INTO "challenge" (
+          "id","name","description_md","category_id","difficulty",
+          "initial_points","minimum_points","decay_solves","flag","protocol",
+          "port","ip_address","enabled","created_at","updated_at"
+        ) VALUES (?,?,?,?,?,?,?,?,?,?,?,?,?,strftime('%Y-%m-%dT%H:%M:%fZ','now'),strftime('%Y-%m-%dT%H:%M:%fZ','now'))`,
+      [
+        '00000000-0000-0000-0000-000000000a01',
+        'Alpha Cipher',
+        'sample',
+        cat.id,
+        'LOW',
+        200, 100, 5, 'flag{alpha}', 'WEB', null, '', 1,
+      ],
+    );
+    await dataSource.query(
+      `INSERT INTO "challenge" (
+          "id","name","description_md","category_id","difficulty",
+          "initial_points","minimum_points","decay_solves","flag","protocol",
+          "port","ip_address","enabled","created_at","updated_at"
+        ) VALUES (?,?,?,?,?,?,?,?,?,?,?,?,?,strftime('%Y-%m-%dT%H:%M:%fZ','now'),strftime('%Y-%m-%dT%H:%M:%fZ','now'))`,
+      [
+        '00000000-0000-0000-0000-000000000a02',
+        'Other',
+        'manual',
+        cat.id,
+        'MEDIUM',
+        100, 50, 10, 'flag{other}', 'WEB', null, '', 1,
+      ],
+    );
+
+    const qr = dataSource.createQueryRunner();
+    try {
+      const seed = new SeedSampleChallenges1700000000600();
+      await seed.down(qr);
+    } finally {
+      await qr.release();
+    }
+
+    const remaining: any[] = await dataSource.query(`SELECT name FROM "challenge" ORDER BY name`);
+    const names = remaining.map((r) => String(r.name));
+    expect(names).toContain('Other');
+    expect(names).not.toContain('Alpha Cipher');
+  });
+});