Manage paired displays: themed select, reassignment, live list, no revoked clutter

Real-device review of the platform display flow found four defects in
display management:

- Shared SelectMenu in @ekklesia/ui (additive): an Ekklesia-drawn
  single choice following the WAI-ARIA select-only combobox pattern,
  replacing the native select for "Show on this screen". It has a
  themed list, a chevron inside the control, keyboard support (arrows,
  Home/End, type-ahead, Enter/Space/Tab, and Escape that closes only
  the list), pointer and touch support, and focus that stays on the
  control. It is an ek-control, so it keeps the 16px phone size.
- Newly paired displays appear without a reload. Approval doesn't
  create the display; the screen does when it claims its credential a
  few seconds later. The page now shows a "Waiting for the screen to
  connect" placeholder and refetches every second until the new display
  appears (for up to a minute), and refreshes the list every 30
  seconds.
- What a display shows can change after pairing. In the single-target
  Stage 1 model, a display's current target is its one active display
  permission, so no migration is needed.
  PUT /api/v1/devices/:id/display, with core.devices.manage, a trusted
  origin and a bounded body, revokes its other active permission rows
  (kept as history) and grants the chosen module's declared display
  permission, in one transaction on the same device. The screen notices
  within about 30 seconds: a paired device on a module page that is no
  longer set to show it goes to /display/setup instead of re-pairing,
  and /display/setup opens the new target.
- Revoked displays leave the normal list at once. Their rows stay in
  the database as history.

Each display card now shows its name, Online/Offline/Not connected yet,
"Showing: ...", last seen and paired dates, and Change and Revoke.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

apps/api/src/device-routes.ts

@@ -432,6 +432,56 @@ export function createDeviceRoutes(options: DeviceRoutesOptions): Hono {
     }
   });
 
+  /**
+   * Changes what a paired display shows (ADR 0065): `{ "moduleId": "<id>" }` for a running display
+   * module, or `{ "moduleId": null }` for nothing. The permission granted is that module's declared
+   * display permission, never one the request names. It is the same display — the same identity,
+   * name, and credential — before and after; the screen notices on its next check and opens the new
+   * module's page, or the platform's setup page, without being paired again.
+   */
+  routes.put(
+    `${DEVICES_PREFIX}/:deviceId/display`,
+    requireOrigin,
+    mutationBodyLimit,
+    requireManage,
+    async (c: Context) => {
+      const parsed = safeParseEkklesiaDeviceId(c.req.param("deviceId"));
+      const body = await readJsonObject(c);
+      if (!parsed.success || body === undefined || !("moduleId" in body)) {
+        return sanitizedFailure(c, 400, "INVALID_REQUEST");
+      }
+      let permissionId: PermissionId | undefined;
+      if (body.moduleId !== null) {
+        const moduleId = readString(body, "moduleId", 128);
+        const display = moduleId === undefined ? undefined : findDisplay(moduleId);
+        if (display === undefined) {
+          return sanitizedFailure(c, 400, "INVALID_REQUEST");
+        }
+        permissionId = display.permissionId;
+      }
+      const principal = getAuthorizedPrincipal(c);
+      if (principal.kind !== "authenticated") {
+        return sanitizedFailure(c, 403, "AUTHORIZATION_DENIED");
+      }
+      try {
+        const changed = await options.devices.setDisplayTarget({
+          changedBy: principal.userId,
+          deviceId: parsed.data,
+          now: now(),
+          permissionId,
+        });
+        if (!changed) {
+          // Unknown and revoked alike: neither is a display whose content can change.
+          return sanitizedFailure(c, 404, "NOT_FOUND");
+        }
+        noStore(c);
+        return c.json({ moduleId: body.moduleId === null ? null : body.moduleId }, 200);
+      } catch {
+        return sanitizedFailure(c, 503, "DEVICE_LOOKUP_UNAVAILABLE");
+      }
+    },
+  );
+
   routes.get(DEVICES_PREFIX, requireManage, async (c: Context) => {
     try {
       const devices = await options.devices.listDevices();