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+# User Management UI Redesign — Design
+
+Date: 2026-08-12
+Status: Approved (brainstorming 2026-08-12)
+
+## Goal
+
+The admin user-management UI (`UserManagementSection.tsx`, embedded in
+`AccountDialog`) is a plain list with native `<input>`/`<select>` elements and
+`window.prompt`/`window.confirm` interactions. Redesign it in place to match
+the rest of the app's visual quality and interaction patterns.
+
+Decisions locked in during brainstorming:
+
+- **Scope:** in-place beautification + interaction upgrade. The section stays
+  inside `AccountDialog`; no standalone admin page.
+- **Features:** unchanged — list, create, promote/demote, reset password,
+  delete. No new backend capabilities.
+- **Layout:** list rows with avatar + role badge + a `⋯` actions dropdown;
+  "Add user" becomes a header button that opens a dialog.
+- **i18n:** all copy goes through next-intl (zh + en), replacing the current
+  hardcoded English strings.
+
+## Current state
+
+`src/app/components/UserManagementSection.tsx` renders:
+
+- a `<ul>` of users with three small outline buttons per row (Promote/Demote,
+  Password, Delete),
+- a persistent bottom form (two native inputs + native `<select>` + Create
+  button) for adding users,
+- `window.prompt` for password reset and `window.confirm` for deletion,
+- hardcoded English copy despite the app shipping zh/en i18n.
+
+Available shadcn/ui primitives in `src/components/ui/`: `button`, `dialog`,
+`dropdown-menu`, `input`, `label`, `select`, `skeleton`, `scroll-area` —
+everything needed; no new dependencies.
+
+## Components
+
+### 1. Reworked `UserManagementSection`
+
+Same file, same props (`{ self: string }`), same fetch logic and API calls.
+
+**Header row:** section title + user count (`3 users`), and a primary-size-sm
+"Add user" button on the right that opens the create dialog.
+
+**User rows** replace the `<ul>` styling:
+
+- Left: circular avatar (`size-8 rounded-full bg-accent`) showing the
+  username's first letter, uppercased.
+- Middle: username (`font-medium truncate`), a role badge, and a `(you)`
+  marker for the self row. Badges: admin = `bg-primary/10 text-primary`,
+  user = `bg-accent text-muted-foreground`; shared badge markup extracted to a
+  small `RoleBadge` inline component.
+- Right: `DropdownMenu` triggered by a ghost icon button (`⋯`,
+  `aria-label` = "Actions for {username}") with items:
+  - "Make admin" / "Make user" (label depends on current role),
+  - "Reset password",
+  - "Delete" — `text-destructive`, separated by `DropdownMenuSeparator`,
+    hidden on the self row.
+- Rows get `hover:bg-accent/50` and consistent `px-3 py-2` rhythm.
+
+**States:**
+
+- Loading: three `Skeleton` rows (`size-8` circle + two bars) instead of the
+  "Loading users…" text.
+- Empty: centered muted placeholder line.
+- Error: existing `role="alert"` destructive paragraph, restyled into the
+  section header area.
+
+**Scrolling:** the list is wrapped in the existing `scroll-area` with a max
+height so the dialog doesn't grow unbounded with many users.
+
+### 2. Three dialogs (all using `dialog.tsx`)
+
+Managed by local state in `UserManagementSection`:
+
+- **`CreateUserDialog`** — fields: username (`input.tsx` + `label.tsx`),
+  password (`type="password"`, hint "8–256 characters"), role (`select.tsx`).
+  Submit disabled until username matches the backend pattern
+  (`/^[A-Za-z0-9][A-Za-z0-9._-]{0,63}$/`) and password ≥ 8 chars. API errors
+  render inline above the footer (destructive text), not just as a toast.
+  On success: toast + close + refresh.
+- **`ResetPasswordDialog`** — single password field + hint, targeted at one
+  user; title includes the username. Replaces `window.prompt`.
+- **`DeleteUserDialog`** — confirmation with the username repeated in the
+  body; confirm button is `variant="destructive"`. Replaces
+  `window.confirm`.
+
+Only one dialog is open at a time; each receives `open`, `onOpenChange`, and
+the target user (create dialog: none).
+
+### 3. i18n
+
+New namespace `userManagement` in
+`src/i18n/messages/{zh,en}/userManagement.ts`, registered in both `index.ts`
+files (spread like the existing modules). Keys cover: section title, user
+count (ICU plural), badges, `(you)`, menu items, all three dialogs (titles,
+descriptions, labels, hints, submit/cancel), empty/loading states, and success
+toasts. Component calls `useTranslations("userManagement")`.
+
+## Data flow
+
+Unchanged: `GET /api/auth/users`, `POST /api/auth/users`,
+`PATCH/DELETE /api/auth/users/[username]`. The existing `run()` helper
+(busy-flag + toast + refresh) is kept; dialogs layer on top of it and surface
+API errors inline before dismissing.
+
+## Error handling
+
+- Client-side validation mirrors server rules (username pattern, password
+  8–256) so most errors never hit the network.
+- Server errors (e.g. last-admin guard on demote/delete) show both in the
+  open dialog (inline) and via the existing `errorToast("users.manage", …)`.
+- The self row hides Delete; demoting/deleting the last admin remains a
+  server-enforced rule — the UI does not try to predict it.
+
+## Testing
+
+Vitest + Testing Library, following existing `*.test.ts(x)` conventions:
+
+- List rendering: rows, badges, self marker, Delete hidden for self.
+- Create dialog: validation gating (bad username, short password), successful
+  submit calls the right endpoint and closes.
+- Menu actions: promote/demote label flips with role; reset password and
+  delete open their dialogs with the right username.
+- Delete flow: cancel does nothing; confirm sends DELETE and refreshes.
+- Loading skeleton and empty states render.
+
+Fetch is mocked at the `fetch` boundary, as in existing component tests.
+
+## Out of scope
+
+- Backend changes of any kind.
+- A standalone `/users` page, search/filter/pagination, avatar uploads,
+  disable/enable accounts.
+- Restyling `AccountDialog` itself beyond what the section needs.