feat: add display kiosk host

apps/api/src/module-display-routes.ts

@@ -0,0 +1,203 @@
+import type { EkklesiaPrincipal } from "@ekklesia/contracts";
+import type { ModuleUiPublicationRegistry, PublishableModuleDisplay } from "@ekklesia/core/modules";
+import type { Context, Hono } from "hono";
+import {
+  type AuthorizationMiddlewareOptions,
+  getAuthorizedPrincipal,
+  requirePermission,
+} from "./authorization-middleware.js";
+import { createDisplayHostAssets, type DisplayHostAssets } from "./display-host-assets.js";
+import { moduleApiBaseUrl } from "./module-http-routes.js";
+import { moduleRealtimeBaseUrl } from "./module-realtime-routes.js";
+import { grantedModulePermissionIds } from "./module-ui-inventory.js";
+import { moduleDisplayUiArtifactUrl } from "./module-ui-routes.js";
+
+/** Host-owned namespaces. Neither can collide with module HTTP routes, all of which live under
+ * `/api/v1/modules/<module-id>`, and neither string enters the module-facing UI ABI. */
+export const MODULE_DISPLAY_DESCRIPTOR_PREFIX = "/api/v1/module-displays";
+export const MODULE_DISPLAY_PAGE_PREFIX = "/display";
+export const DISPLAY_HOST_SCRIPT_PATH = "/assets/ekklesia-display/app.js";
+
+export function moduleDisplayPageUrl(moduleId: string): string {
+  return `${MODULE_DISPLAY_PAGE_PREFIX}/${encodeURIComponent(moduleId)}`;
+}
+
+export function moduleDisplayDescriptorUrl(moduleId: string): string {
+  return `${MODULE_DISPLAY_DESCRIPTOR_PREFIX}/${encodeURIComponent(moduleId)}`;
+}
+
+/** The portable facts a browser host needs to mount this module's one display artifact. It mirrors
+ * the primary UI descriptor while naming the role explicitly, so a host cannot accidentally load a
+ * management artifact into a signage route. No outer Ekklesia route or filesystem path crosses the
+ * boundary. */
+export interface HostModuleDisplayDescriptor {
+  readonly id: string;
+  readonly version: string;
+  readonly display: { readonly url: string };
+  readonly api: { readonly baseUrl: string };
+  readonly realtime: { readonly baseUrl: string };
+  readonly permissions: readonly string[];
+}
+
+export interface HostModuleDisplayResource {
+  readonly module: HostModuleDisplayDescriptor;
+}
+
+export interface ModuleDisplayRoutesOptions extends AuthorizationMiddlewareOptions {
+  /** The same immutable, eligible/running publication registry used for artifact bytes. */
+  readonly moduleUi: ModuleUiPublicationRegistry;
+  /** Omitted only when the registry contains no display entrypoints. Production reads the exact
+   * surface-owned files before binding and supplies their frozen contents here. */
+  readonly assets?: DisplayHostAssets;
+}
+
+/** A composition error, detected before any display route is registered. Carries no module id,
+ * permission id, path, or package location. */
+export class ModuleDisplayConfigurationError extends Error {
+  constructor() {
+    super("The module display host configuration is inconsistent.");
+    this.name = "ModuleDisplayConfigurationError";
+    this.stack = `${this.name}: ${this.message}`;
+    Object.freeze(this);
+  }
+}
+
+function displayFailure(c: Context): Response {
+  c.header("Cache-Control", "no-store");
+  return c.json({ code: "AUTHORIZATION_EVALUATION_FAILED" }, 503);
+}
+
+/** RFC 9110 weak comparison for a GET/HEAD `If-None-Match` precondition. */
+function etagMatches(headerValue: string | undefined, etag: string): boolean {
+  if (headerValue === undefined) {
+    return false;
+  }
+  if (headerValue.trim() === "*") {
+    return true;
+  }
+  return headerValue.split(",").some((candidate) => {
+    const value = candidate.trim();
+    return (value.startsWith("W/") ? value.slice(2) : value) === etag;
+  });
+}
+
+/** Copies and validates injected assets before registering any route. Production's loader already
+ * creates this exact shape, while this check keeps a test/composition caller from pairing mutable
+ * bytes with a stale validator. */
+function snapshotAssets(input: DisplayHostAssets): DisplayHostAssets {
+  try {
+    const snapshot = createDisplayHostAssets(input.html, input.script);
+    if (snapshot.scriptEtag !== input.scriptEtag) {
+      throw new ModuleDisplayConfigurationError();
+    }
+    return snapshot;
+  } catch {
+    throw new ModuleDisplayConfigurationError();
+  }
+}
+
+async function describeDisplay(
+  options: ModuleDisplayRoutesOptions,
+  principal: EkklesiaPrincipal,
+  display: PublishableModuleDisplay,
+): Promise<HostModuleDisplayResource> {
+  return {
+    module: {
+      api: { baseUrl: moduleApiBaseUrl(display.moduleId) },
+      display: { url: moduleDisplayUiArtifactUrl(display) },
+      id: display.moduleId,
+      permissions: await grantedModulePermissionIds(
+        options.evaluator,
+        principal,
+        display.permissions,
+      ),
+      realtime: { baseUrl: moduleRealtimeBaseUrl(display.moduleId) },
+      version: display.version,
+    },
+  };
+}
+
+function mountDisplay(
+  app: Hono,
+  options: ModuleDisplayRoutesOptions & { readonly assets: DisplayHostAssets },
+  display: PublishableModuleDisplay,
+): void {
+  // The permission comes from an already-validated manifest/publication record. A request selects
+  // neither the permission nor the artifact; it can only hit this exact pre-composed route.
+  const requireDisplayPermission = requirePermission(options, display.displayPermission);
+
+  app.get(moduleDisplayPageUrl(display.moduleId), requireDisplayPermission, () => {
+    return new Response(options.assets.html, {
+      headers: {
+        "Cache-Control": "no-store",
+        "Content-Type": "text/html; charset=utf-8",
+        "X-Content-Type-Options": "nosniff",
+      },
+      status: 200,
+    });
+  });
+
+  app.get(moduleDisplayDescriptorUrl(display.moduleId), requireDisplayPermission, async (c) => {
+    c.header("Cache-Control", "no-store");
+    c.header("Vary", "Origin, Cookie");
+    try {
+      return c.json(await describeDisplay(options, getAuthorizedPrincipal(c), display), 200);
+    } catch {
+      return displayFailure(c);
+    }
+  });
+}
+
+/**
+ * Mounts one stable page and one descriptor route per eligible, running display declaration.
+ *
+ * There is deliberately no display inventory in this pass. A management UI may need one later,
+ * but a bookmarked TV needs only its version-independent page URL. Unknown, dashboard-only,
+ * disabled, and dependency-blocked modules have no registered route and collapse into the
+ * application's ordinary sanitized 404.
+ *
+ * The page is an inert, module-agnostic shell: its bytes contain no module id and its one absolute
+ * script URL cannot be rebased by a deep `/display/<id>` path. The browser reads the validated id
+ * from its outer URL, requests the permission-gated descriptor, and only then imports the exact
+ * versioned display artifact that the server supplied.
+ */
+export function mountModuleDisplayRoutes(app: Hono, options: ModuleDisplayRoutesOptions): void {
+  const displays = options.moduleUi.listDisplays();
+  if (displays.length === 0) {
+    return;
+  }
+  if (!options.assets) {
+    throw new ModuleDisplayConfigurationError();
+  }
+  const assets = snapshotAssets(options.assets);
+  for (const display of displays) {
+    if (!options.registry.has(display.displayPermission)) {
+      throw new ModuleDisplayConfigurationError();
+    }
+  }
+
+  // One fixed host bundle, never a directory and never a request-selected package file. Like module
+  // artifact bytes, fetching this platform code grants no authority; the page and descriptor are
+  // where identity and the module-owned display permission are enforced.
+  app.get(DISPLAY_HOST_SCRIPT_PATH, (c) => {
+    if (etagMatches(c.req.header("if-none-match"), assets.scriptEtag)) {
+      return new Response(null, {
+        headers: { "Cache-Control": "no-cache", ETag: assets.scriptEtag },
+        status: 304,
+      });
+    }
+    return new Response(assets.script, {
+      headers: {
+        "Cache-Control": "no-cache",
+        "Content-Type": "text/javascript; charset=utf-8",
+        ETag: assets.scriptEtag,
+        "X-Content-Type-Options": "nosniff",
+      },
+      status: 200,
+    });
+  });
+
+  for (const display of displays) {
+    mountDisplay(app, { ...options, assets }, display);
+  }
+}