diff --git a/.kilo/plans/888.md b/.kilo/plans/888.md
deleted file mode 100644
index 19c4130..0000000
--- a/.kilo/plans/888.md
+++ /dev/null
@@ -1,83 +0,0 @@
-# Implementation Plan: Job 888 — Admin Area General Settings (event window validation)
-
-## Status
-NOT YET IMPLEMENTED. Two negative-case defects remain in the admin General settings form:
-
-1. **Backend (`backend/src/modules/admin/dto/general.dto.ts:10-11`)** — the `eventStartUtc` / `eventEndUtc` fields are typed `z.union([z.literal(''), z.string().datetime({...})])`. Empty strings bypass validation and overwrite a previously valid event schedule with `''`. The docs at `docs/api/admin.md:48-53` and `docs/guides/admin-general-settings.md` describe this empty-allowed behaviour, but the Job explicitly requires the empty case to be rejected so the prior schedule is preserved.
-2. **Frontend (`frontend/src/app/features/admin/general.component.ts:109-125`)** — the cross-field `endBeforeStart` error and the per-field `general-eventEnd-error` are both gated on `form.controls.eventEndUtc.touched`. When the user simply types a value the field-level @if may not render visibly, and the End input has no `aria-invalid`, `aria-describedby`, `title`, or `validity.validationMessage` binding, so a disabled Save button leaves the user with no visible cue.
-
-The plan below fixes both defects and re-enables existing positive paths. No schema migration is required.
-
-## 1. Architectural Reconnaissance
-
-- **Codebase style & conventions:**
-  - **Backend:** NestJS 10, TypeScript strict, zod schemas under `backend/src/modules/<module>/dto/<module>.dto.ts` consumed via `ZodValidationPipe` (`backend/src/common/pipes/zod-validation.pipe.ts`). Errors are raised through `ApiError.validation(...)` returning `{ code: 'VALIDATION_FAILED', message, details: [{path, message}] }` with HTTP 400 (`backend/src/common/errors/api-error.ts`).
-  - **Frontend:** Angular 17+ standalone components with `ChangeDetectionStrategy.OnPush`, reactive forms (`ReactiveFormsModule`), and explicit signal wrappers (`Value`, `Invalid`, `TouchedOrDirty`) for inline error messaging (see `general.component.ts:200-257`). Templates use `@if` blocks with `data-testid` hooks tested in `tests/frontend/admin-general-pure.spec.ts`.
-  - **Pure helpers:** `frontend/src/app/features/admin/general.pure.ts` exports all validation/message helpers and is the only place to mutate when changing field-level rules; the component imports them.
-
-- **Data Layer:** SQLite (`better-sqlite3`) with a `setting` key/value table (`docs/database/auth-settings.md`). `AdminGeneralService.updateSettings` (`backend/src/modules/admin/general.service.ts:61-74`) writes each `eventStartUtc` / `eventEndUtc` value through `SettingsService.set`. No schema migration is needed for this Job.
-
-- **Test Framework & Structure:** Jest (`ts-jest`) with two projects (backend / frontend) configured in `tests/jest.config.js`. Tests live under `tests/backend/**` and `tests/frontend/**`. The repo-root `npm test` (alias of `jest --config tests/jest.config.js`) runs everything. Backend tests boot the full Nest app via `Test.createTestingModule({ imports: [AppModule] })` and use `request.agent` + CSRF (`tests/backend/csrf-client.ts`); frontend tests are pure-function specs under `tests/frontend/admin-general-pure.spec.ts` — no DOM, no UI. New tests must follow the same single-command layout.
-
-- **Required Tools & Dependencies:** No new packages. The required tools (Node 20+, npm workspaces, `jest`, `ts-jest`, `better-sqlite3`) are already declared in `package.json` and bootstrapped by `setup.sh`. The implementer does not need to install anything new.
-
-## 2. Impacted Files
-
-- **To Modify:**
-  - `backend/src/modules/admin/dto/general.dto.ts` — tighten the `eventStartUtc` / `eventEndUtc` zod union so empty strings are rejected with the per-field message; leave `superRefine` end-after-start check in place.
-  - `frontend/src/app/features/admin/general.component.ts` — extend the Event end `<input>` bindings to surface `aria-invalid`, `aria-describedby`, `title`, and `validity.validationMessage` whenever the form is in the `endBeforeStart` invalid state; ensure the inline `general-endBeforeStart` and `general-eventEnd-error` blocks render as soon as the cross-field validator fires (not only after `touched`); mirror the same logic symmetrically on the Event start side for completeness.
-  - `frontend/src/app/features/admin/general.pure.ts` — make the inline-error messages for `endBeforeStart` and `invalidDatetime` available as exports if they are not already (they are inline strings today; centralise to keep the template clean). Optionally tighten `isoDatetimeValidator` to keep treating empty as invalid client-side so the UI can also block Save when Start/End are blank after the fix — see "Open Question" below.
-  - `tests/backend/admin-validation.spec.ts` — add focused negative-case tests for the general-settings endpoint: empty `eventEndUtc` rejected with HTTP 400, malformed string rejected with HTTP 400, end ≤ start rejected with HTTP 400; plus a positive test that confirms valid ISO-8601 values persist unchanged.
-  - `tests/frontend/admin-general-pure.spec.ts` — add a small `invalidDatetime` regression asserting that `isoDatetimeValidator({ value: '' })` returns `{ invalidDatetime: true }` (if we choose to flip client validation to match backend) — see Open Question.
-
-- **To Create:**
-  - `tests/backend/admin-general-event-window.spec.ts` — dedicated spec for the new negative cases; uses the same Nest-app fixture pattern as `tests/backend/admin-general-service.spec.ts` but focuses on PUT validation only.
-
-## 3. Proposed Changes
-
-### Backend
-
-1. **Tighten the zod schema** in `backend/src/modules/admin/dto/general.dto.ts`:
-   - Replace each `eventStartUtc` / `eventEndUtc` field from `z.union([z.literal(''), z.string().datetime({ message: '...' })])` to `z.string().datetime({ message: '... must be a valid ISO-8601 datetime' })` directly. The empty-string alternative is what allowed `eventEndUtc=''` to overwrite a valid schedule (Job negative case 1).
-   - Keep the `superRefine` rule that emits `eventEndUtc must be strictly after eventStartUtc` on `path: ['eventEndUtc']` when both values are parseable and `end <= start`.
-   - The error envelope remains `{ code: 'VALIDATION_FAILED', message: 'Request validation failed', details: [{path, message}] }` (HTTP 400), emitted by `ZodValidationPipe` (`backend/src/common/pipes/zod-validation.pipe.ts:9-15`) — no pipe changes needed.
-
-2. **Persist only on success:** nothing to change in `AdminGeneralService.updateSettings` itself; because `ZodValidationPipe` throws before the handler is called, the prior schedule is preserved automatically on rejected payloads (the SettingsService is never touched).
-
-3. **Docs reconciliation (non-blocking):** update `docs/api/admin.md:48-53` and `docs/guides/admin-general-settings.md` sentences that say "empty strings are allowed" so the docs reflect that Start/End are now required (it is OK if the docs lag the change; the Job is authoritative).
-
-### Frontend
-
-1. **Update `general.pure.ts`** to keep the validator surface aligned with the new backend:
-   - If we choose to also reject empty strings client-side (recommended — keeps UI feedback consistent with backend), change `isoDatetimeValidator` so `''` returns `{ invalidDatetime: true }` instead of `null`. If we keep empty-allowed client-side, then `datetimeMessage` must still show a helpful message on `''` so the field stays consistent with the disabled Save button.
-   - Expose a `endBeforeStartMessage` helper that returns `'Event end must be after event start.'` so the template renders it from one source.
-
-2. **Update `general.component.ts`** for the Event End input and surrounding @if blocks (lines 109-125):
-   - Bind `[attr.aria-invalid]` and `[attr.aria-describedby]` on the End `<input>` to a new `showEventEndCrossFieldError` computed that is true whenever the form has `errors.endBeforeStart`. Also bind `[attr.title]` to the message string and `[attr.validity.validationMessage]` is not directly supported by Angular — instead, surface a `data-error-message` attribute or render a hidden `<span class="sr-only">` so screen readers can announce it.
-   - Render the `general-endBeforeStart` block whenever `endBeforeStart` is present (drop the `touched` gate so the user sees the error the moment they leave End ≤ Start). Keep `general-eventEnd-error` rendering only for `invalidDatetime` cases.
-   - Symmetrically, for Event start, render the `general-eventStart-error` whenever `invalidDatetime` is on the control (today it is correctly shown when the input becomes dirty AND invalid).
-
-3. **Save gating remains:** `[disabled]="submitting() || form.invalid"` keeps Save disabled while any of (a) the inline per-field validators, (b) the cross-field `endBeforeStart`, or (c) the page-title required/blank validator are in error. No change needed.
-
-### Open Question (please confirm before implementation)
-
-The current docs intentionally allow empty Start/End so the event window can be cleared (`general.pure.ts:69-72`, `docs/api/admin.md:48-53`). The Job description says empty strings should be rejected (negative case 1). I am interpreting the Job as the source of truth and proposing we **reject empty strings** in both backend and client. If instead the intent is to keep `''` valid but reject "malformed-but-not-empty" strings, the backend fix becomes a no-op (it already does that) and only the UI changes are needed. Please confirm before implementation begins.
-
-## 4. Test Strategy
-
-- **Target backend test file:** new `tests/backend/admin-general-event-window.spec.ts`. Reuses `tests/backend/csrf-client.ts`, follows the exact pattern from `tests/backend/admin-validation.spec.ts:16-46` (boots `AppModule`, registers first admin, primes CSRF, then exercises `PUT /api/v1/admin/general/settings` via `request.agent`).
-- **Target frontend test file:** `tests/frontend/admin-general-pure.spec.ts`. Add only the helper-level assertions (e.g., `isoDatetimeValidator({ value: '' })` returns `{ invalidDatetime: true }`) — no DOM rendering tests. The existing pattern uses plain `describe` / `it` with assertions on function returns.
-- **Mocking strategy:** No new mocks. The backend spec uses the real `AppModule` against `:memory:` SQLite (set via `process.env.DATABASE_PATH = ':memory:'` at the top of the file, mirroring `admin-validation.spec.ts:1-3`). Auth uses `register-first-admin` + login + CSRF — already idempotent because the database is in-memory and the test creates exactly one admin in `beforeAll`.
-- **Cases to cover (minimal & focused):**
-  1. **Backend negative — empty Event End** ⇒ `PUT /settings` with `eventEndUtc: ''` returns HTTP 400 and the per-field message, and a follow-up `GET /settings` shows `eventEndUtc` unchanged.
-  2. **Backend negative — empty Event Start** ⇒ symmetric to (1).
-  3. **Backend negative — malformed datetime** ⇒ `PUT /settings` with `eventEndUtc: 'not-a-date'` returns HTTP 400 and `'eventEndUtc must be a valid ISO-8601 datetime'`.
-  4. **Backend negative — end ≤ start** ⇒ valid Start + `End === Start` returns HTTP 400 with `'eventEndUtc must be strictly after eventStartUtc'`.
-  5. **Backend positive — valid window** ⇒ well-formed `2026-08-15T10:30:00.000Z` / `2026-08-20T18:45:00.000Z` persists and is round-tripped unchanged.
-  6. **Frontend pure** — assert `isoDatetimeValidator('')` returns the invalid sentinel (if we choose to flip empty to invalid client-side).
-  7. **Frontend pure** — assert the new `endBeforeStartMessage` helper returns the canonical string.
-- **Single command:** `npm test` from `/repo` runs the full suite. Frontend and backend can also be run separately via `npm run test:backend` / `npm run test:frontend` (already in `package.json`).
-
-## 5. Persistent Project Data (/data)
-
-Not applicable to this Job. No mock data, seed files, or shared assets are produced or consumed by the bug fix. Tests boot against `:memory:` SQLite, which is sufficient.
diff --git a/.kilo/plans/889.md b/.kilo/plans/889.md
new file mode 100644
index 0000000..35507fd
--- /dev/null
+++ b/.kilo/plans/889.md
@@ -0,0 +1,258 @@
+# Implementation Plan: Job 889 — Admin Area General Settings and Categories 1.07
+
+## Status
+NOT FULLY IMPLEMENTED. Two residual defects remain after Job 888:
+
+1. **Categories SQL** — `backend/src/modules/admin/categories.service.ts:30-37` uses
+   `createQueryBuilder('c').orderBy('LOWER(c.abbreviation)', 'ASC').addOrderBy('c.abbreviation', 'ASC').getMany()`.
+   `getMany()` auto-selects every column mapped on `CategoryEntity`, including
+   `created_at` and `updated_at` (added by migration
+   `1700000000200-AddCategoryTimestampsAndUniqueAbbrev`). The
+   `InitSchema1700000000000` migration (`backend/src/database/migrations/1700000000000-InitSchema.ts:28-37`)
+   creates the `category` table **without** those columns and relies on the
+   200-migration to add them at startup. On any database where the 200-migration
+   has not yet run (e.g. when an older pre-1.06 DB is hit before migrations
+   resolve, or when tests / fresh clones initialise the schema out of order),
+   SQLite raises `SqliteError: no such column: c.created_at` and the Categories
+   section on `/admin/general` (which embeds `AdminCategoriesComponent`) renders
+   the error to the admin. The fix is to make the `category` table include
+   `created_at` and `updated_at` in its initial `CREATE TABLE` and keep the 200
+   migration as a no-op `if (!names.has(...))` ALTER for pre-existing DBs.
+
+2. **Event End equal-to-start field-level message** — `frontend/src/app/features/admin/general.pure.ts:41-51`
+   already returns `{ endBeforeStart: true }` when `e <= s`, and
+   `frontend/src/app/features/admin/general.component.ts:123-128` renders the
+   `general-endBeforeStart` element whenever `eventEndCrossFieldError()` is true.
+   However the message lives in a **separate** `data-testid="general-endBeforeStart"`
+   div instead of inside the per-field error region
+   `data-testid="general-eventEnd-error"` that the Job (and `docs/guides/admin-general-settings.md`)
+   describe as the canonical "field-level validation message" for the Event End
+   input. The Job explicitly states: *"no visible message inside the field-level
+   error region (e.g., `[data-testid=general-eventEnd-error]`)"*. The fix is to
+   funnel the cross-field `endBeforeStart` message into `general-eventEnd-error`
+   (and surface it via `aria-invalid` / `aria-describedby` / `title` on the
+   input) so it is rendered as the Event End field's own validation message.
+
+## 1. Architectural Reconnaissance
+
+- **Codebase style & conventions:**
+  - **Backend:** NestJS 10, TypeScript strict, TypeORM 0.3.20 over
+    `better-sqlite3`. Migrations live under
+    `backend/src/database/migrations/` and are wired through
+    `DatabaseModule.MIGRATIONS` (`backend/src/database/database.module.ts:31-36`)
+    and run on bootstrap by `DatabaseInitService.init()` (`backend/src/database/database-init.service.ts:26-54`).
+    Entities are auto-selected from `DatabaseModule.ENTITIES` and must remain
+    in sync with the SQL schema produced by the migrations.
+  - **Frontend:** Angular 17+ standalone components with
+    `ChangeDetectionStrategy.OnPush`, reactive forms, and the `Value` /
+    `Invalid` / `TouchedOrDirty` signal trio for inline error messaging
+    (see `general.component.ts:204-321`). Pure validation / message helpers
+    live in `frontend/src/app/features/admin/general.pure.ts` and are
+    unit-tested under `tests/frontend/admin-general-pure.spec.ts`.
+  - **Error envelopes:** backend emits
+    `{ code: 'VALIDATION_FAILED', message, details: [{path, message}] }` via
+    `ZodValidationPipe` (`backend/src/common/pipes/zod-validation.pipe.ts:9-15`)
+    for `400`s; `ApiError` helpers live in `backend/src/common/errors/api-error.ts`.
+
+- **Data Layer:** SQLite (`better-sqlite3`) database file at
+  `process.env.DATABASE_PATH` (default `/data/hipctf/db.sqlite`). The
+  `category` table is created by `InitSchema1700000000000` and seeded /
+  amended by `SeedSystemData1700000000100`,
+  `AddCategoryTimestampsAndUniqueAbbrev1700000000200`, and
+  `UpdateSystemCategoryKeys1700000000300`. The
+  `CategoryEntity` (`backend/src/database/entities/category.entity.ts`) is
+  the single source of truth for the column names that TypeORM will SELECT
+  via `getMany()`.
+
+- **Test Framework & Structure:** Jest (`ts-jest`) with two projects
+  (`backend` and `frontend`) configured in `tests/jest.config.js`. Tests
+  live in `tests/backend/**/*.spec.ts` and `tests/frontend/**/*.spec.ts`
+  and run with a single command `npm test` from the repo root (already in
+  `package.json:scripts.test`). Backend tests typically boot the real
+  `AppModule` against `:memory:` SQLite via
+  `process.env.DATABASE_PATH = ':memory:'`; frontend tests are pure
+  function specs that never touch the DOM. New tests must follow the same
+  layout.
+
+- **Required Tools & Dependencies:** No new packages. Node 20+, npm
+  workspaces, `jest`, `ts-jest`, `better-sqlite3`, `@nestjs/typeorm`,
+  and `@nestjs/common` are all already declared and bootstrapped by
+  `setup.sh` (`setup.sh:1-19`). No `setup.sh` change is required for
+  this Job.
+
+## 2. Impacted Files
+
+- **To Modify:**
+  - `backend/src/database/migrations/1700000000000-InitSchema.ts` —
+    add `"created_at"` and `"updated_at"` columns to the initial
+    `CREATE TABLE "category"` so the columns exist from the very first
+    migration; preserve the `description` and `icon_path` defaults.
+  - `frontend/src/app/features/admin/general.component.ts` —
+    extend the Event End `general-eventEnd-error` element so it also
+    renders the cross-field `endBeforeStart` message when no
+    per-field `invalidDatetime` error is present; keep
+    `general-endBeforeStart` as a redundant/legacy visual element only
+    if it is already asserted in tests (see Test Strategy); bind
+    `[attr.aria-invalid]` / `[attr.aria-describedby]` / `[attr.title]`
+    on the Event End `<input>` to the merged state.
+  - `frontend/src/app/features/admin/general.pure.ts` — add a tiny
+    helper (e.g. `eventEndFieldError(fieldErrors, crossField)`) that
+    returns the right human-readable string for the merged Event End
+    field error, so the template can read it from a single source.
+  - `tests/frontend/admin-general-pure.spec.ts` — add focused unit
+    assertions for the new helper (equal-to-start and end-before-start
+    cases).
+  - `tests/backend/migrations.spec.ts` — add a focused assertion that
+    running `InitSchema1700000000000` against an empty database
+    produces a `category` table that contains a `created_at` column
+    (and `updated_at`). This locks the SQL schema in place so the
+    Categories endpoint can never regress to the
+    `no such column: c.created_at` state.
+  - `docs/guides/admin-general-settings.md` — clarify that the
+    Event End inline error region (`general-eventEnd-error`) is the
+    canonical place where the end-before-start message surfaces.
+
+- **To Create:**
+  - None required. Existing test files are sufficient.
+
+## 3. Proposed Changes
+
+### 1. Database / Schema Migration
+
+1. **Update `InitSchema1700000000000`** at
+   `backend/src/database/migrations/1700000000000-InitSchema.ts:28-37` so
+   the `category` `CREATE TABLE` includes `created_at` and `updated_at`
+   columns from the very first migration:
+   ```sql
+   CREATE TABLE IF NOT EXISTS "category" (
+     "id" TEXT PRIMARY KEY,
+     "system_key" TEXT,
+     "name" TEXT NOT NULL,
+     "abbreviation" TEXT NOT NULL,
+     "description" TEXT NOT NULL DEFAULT '',
+     "icon_path" TEXT NOT NULL DEFAULT '',
+     "created_at" TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%fZ','now')),
+     "updated_at" TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%fZ','now'))
+   );
+   ```
+   Mirror the `strftime('%Y-%m-%dT%H:%M:%fZ','now')` default already used
+   for `user.created_at` (line 17) and `challenge.created_at` (line 54) so
+   newly-inserted rows get a sane timestamp without a follow-up
+   UPDATE-pass.
+
+2. **Keep `AddCategoryTimestampsAndUniqueAbbrev1700000000200`
+   unchanged.** Its `if (!names.has('created_at'))` /
+   `if (!names.has('updated_at'))` guards (`backend/src/database/migrations/1700000000200-AddCategoryTimestampsAndUniqueAbbrev.ts:8-20`)
+   make the ALTER a no-op for fresh databases and still patch
+   older pre-1.06 databases that lack the columns. No changes needed
+   to `down()` either — the down() drops the columns, which is the
+   correct mirror of `up()`.
+
+3. **Keep `UpdateSystemCategoryKeys1700000000300` unchanged.** Its
+   `INSERT` already lists `created_at` and `updated_at`
+   (`backend/src/database/migrations/1700000000300-UpdateSystemCategoryKeys.ts:51`).
+
+4. No need to touch `CategoryEntity`
+   (`backend/src/database/entities/category.entity.ts`) — its current
+   `@Column('text', { name: 'created_at', default: '' })` and
+   `@Column('text', { name: 'updated_at', default: '' })` annotations
+   match the columns we are guaranteeing.
+
+### 2. Backend Logic & APIs
+
+No controller / service logic changes are required. With the schema
+fix, `AdminCategoriesService.list()` at
+`backend/src/modules/admin/categories.service.ts:30-37` will resolve
+`c.created_at` and `c.updated_at` and return rows that satisfy the
+existing `CategoryView` shape used by the front-end.
+
+If desired, the controller surface can stay untouched
+(`backend/src/modules/admin/admin-categories.controller.ts:30-34`) —
+no new endpoint is needed.
+
+### 3. Frontend UI Integration
+
+1. **Update `frontend/src/app/features/admin/general.pure.ts`** to
+   expose a small `eventEndFieldMessage(controlErrors, crossField)` pure
+   helper that returns the canonical Event End field error string:
+
+   | `controlErrors?.['invalidDatetime']` | `form.errors?.['endBeforeStart']` | Returned message                                         |
+   |---------------------------------------|-----------------------------------|----------------------------------------------------------|
+   | `true`                                | any                               | `"Event end must be a valid ISO-8601 datetime."`         |
+   | falsy                                | `true`                            | `"Event end must be after event start."`                 |
+   | falsy                                | falsy                             | `null`                                                   |
+
+   This mirrors the existing `datetimeMessage` pattern and keeps the
+   template a thin consumer.
+
+2. **Update `frontend/src/app/features/admin/general.component.ts`**:
+
+   - Replace the current `@if (showEventEndError())` /
+     `@if (eventEndCrossFieldError())` pair (lines 123-128) with a single
+     `eventEndFieldMessage` consumer that always renders inside the
+     `data-testid="general-eventEnd-error"` element. When both
+     validators are off, the element is absent.
+   - Bind `[attr.aria-invalid]` to `true` when
+     `eventEndFieldMessage(...)` is non-null, otherwise null.
+   - Bind `[attr.aria-describedby]` to `"general-eventEnd-error"` and
+     bind `[attr.title]` to the resolved message string in that same
+     case.
+   - Drop the separate `general-endBeforeStart` block **only after**
+   confirming no existing test asserts on it (a quick search of
+   `tests/frontend` shows it is only mentioned in
+   `tests/frontend/admin-general-pure.spec.ts` as a value assertion on
+   the constant `endBeforeStartMessage`, not as a DOM query). If a test
+   asserts on the element, keep it as a redundant duplicate or update
+   the test.
+
+3. **Do not change** the form-level validator at
+   `general.pure.ts:41-51` — it already returns `{ endBeforeStart: true }`
+   for both `e < s` and `e === s`. The Job requirement is purely a
+   rendering fix.
+
+## 4. Test Strategy
+
+- **Target backend test file:** `tests/backend/migrations.spec.ts` (new
+  spec). Add a focused `describe('InitSchema creates category with
+  created_at + updated_at columns')` that:
+  - Boots `AppModule` against `:memory:` SQLite.
+  - Calls `dataSource.runMigrations({ transaction: 'each' })`.
+  - Queries `PRAGMA table_info("category")` and asserts the returned
+    names contain both `created_at` and `updated_at`.
+  - Sanity-checks that `AdminCategoriesService.list()` returns an array
+    (length ≥ 6 seeded system rows) without throwing — this is the
+    regression test that prevents the user-visible
+    `no such column: c.created_at` error from coming back.
+
+- **Target backend test file:** `tests/backend/admin-categories-service.spec.ts`
+  (extend). Add one `it('list() succeeds against the migrated schema and
+  returns seeded rows')` that runs after the existing CRUD specs. The
+  existing tests already use `synchronize: true` which would have masked
+  the bug; the new test should rely on the **migrations** path so it
+  actually exercises the schema the production app uses.
+
+- **Target frontend test file:** `tests/frontend/admin-general-pure.spec.ts`
+  (extend). Add a `describe('eventEndFieldMessage')` block with three
+  focused cases:
+  1. Returns the ISO message when `invalidDatetime` is set, even if
+     `endBeforeStart` is also set.
+  2. Returns the end-before-start message when `invalidDatetime` is
+     absent and `endBeforeStart` is set.
+  3. Returns `null` when both are absent.
+
+- **Mocking Strategy:** No new mocks. Backend spec uses the real
+  `AppModule` against `:memory:` SQLite (already the pattern in
+  `tests/backend/admin-validation.spec.ts` and
+  `tests/backend/admin-general-service.spec.ts`). Frontend spec
+  continues to assert on the pure helper return values only.
+
+- **Single command:** `npm test` from `/repo` runs the full suite
+  (already in `package.json:14`). Frontend and backend can also be run
+  separately via `npm run test:backend` / `npm run test:frontend`.
+
+## 5. Persistent Project Data (/data)
+
+Not applicable to this Job. The DB schema change is a migration; tests
+use `:memory:` SQLite and never write to `/data`. The Categories
+endpoint reads from the existing `category` table without touching
+uploaded files or any other shared asset.
\ No newline at end of file
diff --git a/backend/src/database/migrations/1700000000000-InitSchema.ts b/backend/src/database/migrations/1700000000000-InitSchema.ts
index c6c58af..a8bdd15 100644
--- a/backend/src/database/migrations/1700000000000-InitSchema.ts
+++ b/backend/src/database/migrations/1700000000000-InitSchema.ts
@@ -32,7 +32,9 @@ export class InitSchema1700000000000 implements MigrationInterface {
         "name" TEXT NOT NULL,
         "abbreviation" TEXT NOT NULL,
         "description" TEXT NOT NULL DEFAULT '',
-        "icon_path" TEXT NOT NULL DEFAULT ''
+        "icon_path" TEXT NOT NULL DEFAULT '',
+        "created_at" TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%fZ','now')),
+        "updated_at" TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%fZ','now'))
       );
     `);
     await queryRunner.query(`CREATE UNIQUE INDEX IF NOT EXISTS "uq_category_system_key" ON "category"("system_key") WHERE "system_key" IS NOT NULL;`);
diff --git a/frontend/src/app/features/admin/general.component.ts b/frontend/src/app/features/admin/general.component.ts
index 048d617..b62f607 100644
--- a/frontend/src/app/features/admin/general.component.ts
+++ b/frontend/src/app/features/admin/general.component.ts
@@ -11,6 +11,7 @@ import {
   deriveEventState,
   endAfterStartValidator,
   endBeforeStartMessage,
+  eventEndFieldMessage,
   isoDatetimeValidator,
   normalizePageTitle,
   pageTitleMessage,
@@ -114,17 +115,12 @@ import {
                 type="datetime-local"
                 formControlName="eventEndUtc"
                 data-testid="general-eventEnd"
-                [attr.aria-invalid]="showEventEndError() || eventEndCrossFieldError() ? 'true' : null"
-                [attr.aria-describedby]="(showEventEndError() || eventEndCrossFieldError())
-                  ? 'general-eventEnd-error general-endBeforeStart'
-                  : null"
-                [attr.title]="(showEventEndError() ? eventEndMessage() : eventEndCrossFieldError() ? endBeforeStartMessage : null)"
+                [attr.aria-invalid]="eventEndFieldMessageText() ? 'true' : null"
+                [attr.aria-describedby]="eventEndFieldMessageText() ? 'general-eventEnd-error' : null"
+                [attr.title]="eventEndFieldMessageText()"
               />
-              @if (showEventEndError()) {
-                <div class="field-error" id="general-eventEnd-error" data-testid="general-eventEnd-error">{{ eventEndMessage() }}</div>
-              }
-              @if (eventEndCrossFieldError()) {
-                <div class="field-error" id="general-endBeforeStart" data-testid="general-endBeforeStart">{{ endBeforeStartMessage }}</div>
+              @if (eventEndFieldMessageText(); as msg) {
+                <div class="field-error" id="general-eventEnd-error" data-testid="general-eventEnd-error">{{ msg }}</div>
               }
             </div>
 
@@ -260,9 +256,11 @@ export class AdminGeneralComponent implements OnInit {
     datetimeMessage('Event end', this.eventEndValue(), this.form.controls.eventEndUtc.errors),
   );
 
-  readonly eventEndCrossFieldError = computed(
-    () => !!this.form.errors?.['endBeforeStart'],
-  );
+  readonly eventEndFieldMessageText = computed(() => {
+    const fieldErrs = this.eventEndTouchedOrDirty() ? this.form.controls.eventEndUtc.errors : null;
+    const crossErrs = this.form.errors;
+    return eventEndFieldMessage(fieldErrs, crossErrs);
+  });
 
   constructor() {
     this.form.controls.welcomeMarkdown.valueChanges
diff --git a/frontend/src/app/features/admin/general.pure.ts b/frontend/src/app/features/admin/general.pure.ts
index 781bb32..9cede94 100644
--- a/frontend/src/app/features/admin/general.pure.ts
+++ b/frontend/src/app/features/admin/general.pure.ts
@@ -87,3 +87,16 @@ export function datetimeMessage(
 }
 
 export const endBeforeStartMessage = 'Event end must be after event start.';
+
+export function eventEndFieldMessage(
+  controlErrors: { [key: string]: unknown } | null | undefined,
+  crossFieldErrors: { [key: string]: unknown } | null | undefined,
+): string | null {
+  if (controlErrors?.['invalidDatetime']) {
+    return 'Event end must be a valid ISO-8601 datetime.';
+  }
+  if (crossFieldErrors?.['endBeforeStart']) {
+    return endBeforeStartMessage;
+  }
+  return null;
+}
diff --git a/tests/backend/migrations.spec.ts b/tests/backend/migrations.spec.ts
index 998d458..1cba788 100644
--- a/tests/backend/migrations.spec.ts
+++ b/tests/backend/migrations.spec.ts
@@ -73,4 +73,22 @@ describe('Migrations', () => {
     const restrict = fks.filter((f: any) => f.on_delete === 'RESTRICT');
     expect(restrict.length).toBeGreaterThanOrEqual(2);
   });
+
+  it('creates the category table with created_at and updated_at columns (Job 889)', async () => {
+    const cols: any[] = await dataSource.query(`PRAGMA table_info("category")`);
+    const names = new Set(cols.map((c: any) => c.name));
+    expect(names.has('created_at')).toBe(true);
+    expect(names.has('updated_at')).toBe(true);
+  });
+
+  it('lists categories without a "no such column: c.created_at" error (Job 889)', async () => {
+    const rows = await dataSource
+      .getRepository(CategoryEntity)
+      .createQueryBuilder('c')
+      .orderBy('LOWER(c.abbreviation)', 'ASC')
+      .addOrderBy('c.abbreviation', 'ASC')
+      .getMany();
+    expect(Array.isArray(rows)).toBe(true);
+    expect(rows.length).toBeGreaterThanOrEqual(6);
+  });
 });
\ No newline at end of file
diff --git a/tests/frontend/admin-general-pure.spec.ts b/tests/frontend/admin-general-pure.spec.ts
index 3d6018d..64a83c0 100644
--- a/tests/frontend/admin-general-pure.spec.ts
+++ b/tests/frontend/admin-general-pure.spec.ts
@@ -2,6 +2,7 @@ import {
   datetimeMessage,
   deriveEventState,
   endAfterStartValidator,
+  eventEndFieldMessage,
   isoDatetimeValidator,
   normalizePageTitle,
   pageTitleError,
@@ -203,3 +204,22 @@ describe('datetimeMessage', () => {
     expect(datetimeMessage('Event start', '2026-08-15T10:30:00.000Z', null)).toBeNull();
   });
 });
+
+describe('eventEndFieldMessage (Job 889)', () => {
+  const endIsoMsg = 'Event end must be a valid ISO-8601 datetime.';
+  const endBeforeMsg = 'Event end must be after event start.';
+
+  it('returns the ISO message when invalidDatetime is set, even if endBeforeStart is also set', () => {
+    expect(eventEndFieldMessage({ invalidDatetime: true }, { endBeforeStart: true })).toBe(endIsoMsg);
+  });
+
+  it('returns the end-before-start message when invalidDatetime is absent and endBeforeStart is set', () => {
+    expect(eventEndFieldMessage(null, { endBeforeStart: true })).toBe(endBeforeMsg);
+    expect(eventEndFieldMessage({}, { endBeforeStart: true })).toBe(endBeforeMsg);
+  });
+
+  it('returns null when both error sources are absent', () => {
+    expect(eventEndFieldMessage(null, null)).toBeNull();
+    expect(eventEndFieldMessage({}, {})).toBeNull();
+  });
+});