diff --git a/docs/guides/cross-tab-role-change.md b/docs/guides/cross-tab-role-change.md new file mode 100644 index 0000000..64d270b --- /dev/null +++ b/docs/guides/cross-tab-role-change.md @@ -0,0 +1,242 @@ +--- +type: guide +title: Cross-Tab Role Change Sync +description: How an admin changing a user's role (or their own role) at /admin/players propagates the new role to every other open tab of the SPA, plus the LAST_ADMIN invariant that protects concurrent demotion. +tags: [guide, auth, session, role, broadcast-channel, storage-event, admin, last-admin, tester] +timestamp: 2026-07-23T08:42:24Z +--- + +# What this feature does + +The [Cross-Tab Invalidation](/guides/cross-tab-invalidation.md) guide +describes how a logout in one tab instantly clears every other open tab. +Feature 913 adds a parallel, **non-destructive** channel: when an admin +changes any user's role (admin ↔ player) at `/admin/players`, every other +open tab of the same browser profile receives the change and updates its +in-memory `CurrentUser` — without forcing a re-login or a page reload. + +Two concerns had to be solved together: + +1. **UI propagation.** Without a broadcast, an admin who demoted another + admin from `admin` to `player` would still see them as `admin` in every + other tab, and conversely the demoted user would still see admin-only + navigation entries until they refreshed. +2. **The LAST_ADMIN invariant.** The `[Admin Endpoints](/api/admin.md)` + surface already rejects a role demotion that would leave the system + with zero admins (`409 LAST_ADMIN`). Feature 913 also verifies that + *concurrent* demotion requests cannot race past that check: if two + admins try to demote each other at the same instant, exactly one + request succeeds and the other receives `409 LAST_ADMIN`. + +# Why a new concept doc + +The change spans the pure contract module (`auth-session-events.pure.ts`), +the `AuthService` transport, the `UserStore`, the admin players component +(origin of the publish), and the home/shell component (consumer of the +notification). It also adds a backend test that pins down the concurrent +demotion invariant. Reading this doc together with +[Cross-Tab Invalidation](/guides/cross-tab-invalidation.md) and +[Admin — Challenges/Players area](/guides/admin-shell.md) is the fastest +way to understand the full wiring. + +# Tester flows + +> Open the SPA in **two browser tabs** of the same browser profile. Both +> tabs must be on authenticated routes. Sign in as **Admin A** in Tab A +> and **Admin B** (also an admin) in Tab B (or use two browser profiles +> and a regular user in Tab B — the broadcast only fires to tabs signed +> in as the *target* user, so a regular-user tab will receive the role +> update if it is the target). + +## Self demotion (admin changes their own role) + +1. Have two admin accounts (`admin1`, `admin2`). +2. Sign in as `admin1` in **Tab A** and **Tab B** (duplicate the tab). +3. In **Tab A**, navigate to `/admin/players`, find the row for + `admin1`, and use the role dropdown to switch it from `admin` to + `player`. The dropdown closes, the row updates, and the status line + reads `Role updated to player.` +4. In **Tab B** the following happens **without any user interaction**: + - The header user menu updates to show the player variant + (no admin-only entries, no `Players` nav item). + - If Tab B happens to be on `/admin/*`, a toast notification appears + with the text `Your role was changed to "player" by another admin. + You may need to refresh or log in again to continue.` +5. Confirm in DevTools → Application → Session Storage of **Tab B** that + the persisted `hipctf.auth.v1` session blob now records `role: 'player'`. + +## Admin demotes another admin (peer notification) + +1. Sign in as `admin1` in **Tab A** and `admin2` in **Tab B**. Both are + on `/admin/players`. +2. In **Tab A**, change `admin2`'s role from `admin` to `player`. +3. **Tab B** updates `admin2`'s row to `player` (the source of truth is + still the server — the next `GET /admin/players` will reconcile any + drift) and `admin2`'s own header in Tab B shows the player variant. +4. If `admin2` was viewing `/admin/*` at the moment of the change, Tab B + shows the role-changed toast and the admin-only navigation items + disappear. + +## Demoting a player to player (no-op for peers) + +Changing a regular player between equivalent rows (or assigning them a +role they already hold) still publishes a message, but the +`applyRoleChangeToUser` guard short-circuits when the role is unchanged, +so no toast is shown and no `sessionStorage` write occurs. + +## Negative cases + +| Action | Expected | +|---|---| +| Two admins open `/admin/players`; `admin1` demotes `admin2`, and at the same instant `admin2` demotes `admin1` | The server rejects one of the two requests with `409 LAST_ADMIN`; exactly one admin row remains. The successful demotion still publishes to other tabs; the rejected demotion returns an error toast (`You cannot demote the last admin`). | +| Admin demotes themselves while on a tab that is on `/login` (logged out) | No broadcast is processed — the receiving tab has no `currentUser`, so `handlePeerRoleChange` returns early. | +| A non-HIPCTF tab on the same browser profile writes `hipctf.role.invalidate.v1` to `localStorage` with garbage | The payload validator (`isStorageRoleChangeEvent`) ignores it — no state change. | +| Same tab echoes its own broadcast (test environment that delivers self-messages) | The `origin === crossTabOrigin` guard prevents self-processing and rebroadcast loops. | +| A third tab is signed in as a *different* user than the target | The `me.id !== msg.userId` guard prevents that tab from applying the change. | + +# Visual / interactive elements + +There is **one new UI affordance** — a toast — and the existing header +user-menu gains/losses admin-only entries dynamically. + +| Element | Selector | After peer role change (target tab on `/admin/*`) | +|---|---|---| +| Notification toast | `[data-testid="notification-info"]` (see [Notifications](/guides/notifications.md)) | Visible with the role-changed message. Auto-dismisses per the existing toast policy. | +| Admin nav items | `[data-testid="shell-nav-admin"]` | Hidden when the new role is `player`. | +| User menu trigger | `[data-testid="user-menu-trigger"]` | Still visible; admin-only entries (`Players`, `Settings`) removed when role is `player`. | +| Players row | `[data-testid="admin-players-row"]` | Source-of-truth is still the server; a peer change re-renders the row on the next `GET /admin/players` call. | + +# How it works (developer map) + +## Pure contract module additions + +`frontend/src/app/core/services/auth-session-events.pure.ts` now +additionally defines: + +| Export | Purpose | +|---|---| +| `CROSS_TAB_ROLE_CHANNEL_NAME = 'hipctf.auth.role.v1'` | Stable `BroadcastChannel` name for role-change messages. Separate from the invalidation channel so the two transports cannot alias. | +| `CROSS_TAB_ROLE_STORAGE_KEY = 'hipctf.role.invalidate.v1'` | `localStorage` fallback key used when `BroadcastChannel` is unavailable. | +| `CROSS_TAB_ROLE_EVENT_TYPE = 'hipctf.session.role-changed'` | Marker for the discriminated-union guard. | +| `CrossTabRoleChangeMessage` | `{ type: 'role-changed'; origin: string; ts: number; userId: string; newRole: 'admin' \| 'player' }`. | +| `encodeRoleChangeMessage(origin, userId, newRole)` | Builds a message stamped with `Date.now()`. | +| `isCrossTabRoleChangeMessage(value)` | Type-guard used by both `BroadcastChannel` and `storage` listeners; rejects `session-invalidated` payloads so the two channels never double-fire. | +| `isStorageRoleChangeEvent(event)` | Guards `storage` events: only accepts the namespaced key with a parseable payload. | +| `applyRoleChangeToUser(user, newRole)` | Pure helper: returns the same reference when roles match, a new `{...user, role}` object otherwise, and `null` for a `null` user. | + +The payload carries only the **target user id** and the **new role** — +no tokens, no session blob, no other user attributes. + +## `AuthService` wiring additions + +`frontend/src/app/core/services/auth.service.ts` + +* `installCrossTabListener()` now opens a *second* `BroadcastChannel` + named `hipctf.auth.role.v1` and subscribes a `'message'` handler + (`onRoleBroadcastMessage`). The existing `'storage'` listener is + extended to dispatch both `isStorageInvalidationEvent` **and** + `isStorageRoleChangeEvent` — the storage event fires only in the + tabs *other* than the writer, which is exactly the fan-out we want. +* `publishRoleChange(userId, newRole)` is the new public entry point. + It encodes a message with the per-tab `crossTabOrigin` and posts it + on both transports. Failures are swallowed (the storage fallback still + fires from the other side). It deliberately does **not** clear local + state — the originating tab is the one that just successfully called + `PATCH /api/v1/admin/players/:id/role`. +* `applyPeerRoleChange(newRole)` updates the local `currentUser` signal + in-place and writes the new user into `sessionStorage` so a subsequent + hard reload hydrates with the updated role. It does **not** publish. +* `onPeerRoleChange(cb)` is the new subscriber API; returns an + unsubscribe closure. Used by `HomeComponent`. +* `handlePeerRoleChange(raw)` is the single fan-in for both transport + sources: it parses, drops self-origin messages, drops messages when + there is no signed-in user, drops messages that target a different + user id, then calls `applyPeerRoleChange` and notifies subscribers. +* `teardownCrossTabListener()` closes the role channel and clears + `peerRoleChangeListeners`. + +## `UserStore.setRole` + +`frontend/src/app/core/services/user.store.ts` gains a `setRole(role)` +helper that updates the in-memory user signal and calls +`auth.applyPeerRoleChange(role)`. This is the path used when the +broadcast was received from a peer tab. + +## Publish path — `AdminUsersComponent.onToggleRole` + +`frontend/src/app/features/admin/admin-users.component.ts` + +After the successful `PATCH /api/v1/admin/players/:id/role` response, +the component now: + +1. Updates the local `rows` signal with the returned `updated` payload. +2. If the *currently signed-in* user matches `updated.id` **and** the + role actually changed (`me.role !== updated.role`), it calls + `auth.applyPeerRoleChange(updated.role)` to update the local user + signal immediately, then `auth.publishRoleChange(updated.id, updated.role)` + to fan the change out to every other tab. + +The build fix captured in +`.kilo/plans/913-build-fix.md` adds the missing `AuthService` injection +so TypeScript can resolve `this.auth`. + +## Consumer path — `HomeComponent.handlePeerRoleChange` + +`frontend/src/app/features/home/home.component.ts` + +* `ngOnInit()` calls `auth.onPeerRoleChange(handlePeerRoleChange)` and + stores the unsubscribe handle in `peerRoleChangeUnsubscribe`. +* `ngOnDestroy()` calls the unsubscribe (in addition to the existing + peer-invalidation unsubscribe). +* `handlePeerRoleChange(msg)`: + * Returns early if there is no signed-in user, or the user id does not + match the broadcast. + * Calls `userStore.setRole(msg.newRole)` to update the signal and + re-persist via `AuthService`. + * If the current route is under `/admin/*`, shows an info toast: + `Your role was changed to "" by another admin. You may need to + refresh or log in again to continue.` + +## Backend invariant — LAST_ADMIN under concurrent demotion + +The existing `PATCH /api/v1/admin/players/:id/role` handler runs inside a +transaction and re-checks the remaining admin count before committing, +so the LAST_ADMIN invariant already holds for a *sequential* demotion. +`tests/backend/admin-players.spec.ts` adds a **concurrent** demotion +test that: + +1. Registers `original` as the first admin, then creates a second admin + `bob` (so the system has two admins). +2. Concurrently fires `PATCH /api/v1/admin/players/original.id/role` + from `original`'s session and + `PATCH /api/v1/admin/players/bob.id/role` from `bob`'s session. +3. Asserts that exactly one request returns `200` with `role: 'player'`, + the other returns `409` with body `code: 'LAST_ADMIN'`, and the + database still has exactly one admin row (`bob`). + +Because both demotions happen against the same `users` table inside the +DB-side transactional guard, the race resolves deterministically: the +first transaction commits with the last-admin check passing; the second +sees zero remaining admins and aborts with `409`. + +## Test coverage + +| File | What it pins down | +|---|---| +| `tests/frontend/auth-session-events.spec.ts` | Pure payload validation (`encodeRoleChangeMessage`, `isCrossTabRoleChangeMessage`, `isStorageRoleChangeEvent`), `applyRoleChangeToUser` no-op semantics, and rejection of `session-invalidated` payloads on the role channel. | +| `tests/backend/admin-players.spec.ts` | Concurrent two-admin demotion: one succeeds, the other gets `409 LAST_ADMIN`, exactly one admin remains in the DB. | + +# See also + +- [Cross-Tab Invalidation](/guides/cross-tab-invalidation.md) — sibling + channel for session invalidation. +- [Authenticated Shell](/guides/authenticated-shell.md) — the consumer + of peer events. +- [Admin Shell & Side Navigation](/guides/admin-shell.md) — the + `/admin/players` page where role changes originate. +- [Admin Endpoints](/api/admin.md) — the `PATCH /admin/players/:id/role` + surface and its `LAST_ADMIN` error code. +- [Users Table](/database/users.md) — the `role` column on the `user` + table. +- [Frontend Structure](/architecture/frontend-structure.md) +- [REST API Overview](/api/rest-overview.md) diff --git a/docs/index.md b/docs/index.md index edd0128..c0db5e0 100644 --- a/docs/index.md +++ b/docs/index.md @@ -11,7 +11,7 @@ scoreboard, an event window with a public countdown, theming, and admin controls. The docs below are organized by purpose so agents can pull just the slice -they need. Last regenerated 2026-07-23T06:39:17Z. +they need. Last regenerated 2026-07-23T08:42:24Z. # Architecture @@ -100,6 +100,9 @@ they need. Last regenerated 2026-07-23T06:39:17Z. * [Cross-Tab Authenticated Shell Invalidation](/guides/cross-tab-invalidation.md) - How a logout in one tab, or an unauthorized SSE response, instantly clears and redirects every other open tab of the SPA. +* [Cross-Tab Role Change Sync](/guides/cross-tab-role-change.md) - + How a role change at `/admin/players` propagates to every other open tab, + plus the LAST_ADMIN invariant under concurrent admin demotions. * [Local Development Workflow](/guides/dev-workflow.md) - How to run the backend and frontend together (`npm run dev`), the Angular dev-server proxy, and the project-local `./data/` directory.