feat(shell): make module pages first-class top-level routes

Module pages move from `/modules/<id>` to `/<module-id>` (`/signage`),
beside `/settings` and `/account`, so the implementation concept
"module" never appears in a user-facing address. ADR 0057 is rewritten
to match.

- Core reserves the top-level names the platform actually serves today
  (`account`, `api`, `assets`, `display`, `settings`), and discovery
  refuses a module that declares one with `MODULE_ID_RESERVED`. That
  covers startup, `modules:validate`, and package verification. Tests in
  `apps/api` hold the set to every top-level route the API registers and
  every page the shell interprets.
- The API serves the Dashboard page at `/<module-id>` and below only for
  modules discovered with a Dashboard UI, enabled or not: a disabled
  module's bookmark still opens the Dashboard, which says it is
  unavailable. An arbitrary root path such as
  `/definitely-not-a-real-module` stays the sanitized 404.
- Both reference proxies forward every top-level path shaped like a
  module id and let the API decide; the split Dashboard hostname still
  refuses `/api`, `/display`, and `/assets`. Installing a module needs no
  proxy change.
- `/<module-id>/<page>` is already served and forwarded, so a later
  module sub-page contract needs no routing or deployment change; the
  shell shows "Page not found" there until it exists.
- The deploy smoke checks a module's address before install, while
  installed, while disabled, after removal, and after reinstall, plus
  unknown names and the old `/modules/…` form through the real proxy.

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

core/src/modules/discovery.ts

@@ -9,6 +9,7 @@ import {
   safeParseModuleManifest,
   semanticVersionSchema,
 } from "@ekklesia/contracts";
+import { isReservedModuleId } from "./reserved-ids.js";
 
 export const MODULE_MANIFEST_FILENAME = "ekklesia.module.json";
 
@@ -39,6 +40,7 @@ export type ModuleDiscoveryIssueCode =
   | "MODULE_ENTRYPOINT_INVALID"
   | "MODULE_ENTRYPOINT_MISSING"
   | "MODULE_ID_DUPLICATE"
+  | "MODULE_ID_RESERVED"
   | "MODULE_MANIFEST_INVALID"
   | "MODULE_MANIFEST_MISSING"
   | "MODULE_PACKAGE_INVALID"
@@ -614,6 +616,18 @@ async function scanModuleDirectory(
     });
   }
 
+  if (isReservedModuleId(manifest.id)) {
+    // A module's Dashboard page is `/<module-id>` (ADR 0057), in the same URL space as the
+    // platform's own top-level namespaces.
+    issues.push({
+      code: "MODULE_ID_RESERVED",
+      message: `Module ID ${manifest.id} is reserved: the platform uses /${manifest.id} for its own pages and routes.`,
+      moduleDirectory: directoryName,
+      moduleId: manifest.id,
+      path: "id",
+    });
+  }
+
   const artifacts = await resolveEntrypoints(moduleDirectory, directoryName, manifest, issues);
   if (!artifacts) {
     return undefined;

core/src/modules/index.ts

@@ -13,6 +13,7 @@ export * from "./module-package-host.js";
 export * from "./module-package-verification.js";
 export * from "./permissions.js";
 export * from "./realtime.js";
+export * from "./reserved-ids.js";
 export * from "./runtime.js";
 export * from "./schema-discovery.js";
 export * from "./ui-publication.js";

core/src/modules/reserved-ids.ts

@@ -0,0 +1,33 @@
+/**
+ * Top-level names the platform owns, which therefore can never be a module id (ADR 0057).
+ *
+ * Every module with a Dashboard UI is addressed at `/<module-id>`, beside the platform's own
+ * top-level namespaces in one URL space. A module called `settings` would collide with the
+ * Dashboard's Settings pages, and one called `api` with the API itself. This is the complete set the
+ * platform serves today, not a guess at what it might want later:
+ *
+ * - `api` — the API: identity, principal, health, Core resources, module routes, module UI artifacts,
+ *   display descriptors, and realtime (`/api/…`);
+ * - `assets` — the Dashboard's and display host's scripts (`/assets/ekklesia-dashboard/…`,
+ *   `/assets/ekklesia-display/…`);
+ * - `display` — the display host's pages and service worker (`/display/…`);
+ * - `settings` and `account` — the Dashboard's own Settings and account areas.
+ *
+ * `apps/api` holds the list to the routes it actually registers, and to the Dashboard namespaces the
+ * shell interprets, so a new top-level platform route cannot be added without reserving it here.
+ * Reserving a name is a breaking change for any installation with a module of that id, so the set
+ * grows only deliberately.
+ */
+export const RESERVED_MODULE_IDS = Object.freeze([
+  "account",
+  "api",
+  "assets",
+  "display",
+  "settings",
+] as const);
+
+const reserved: ReadonlySet<string> = new Set(RESERVED_MODULE_IDS);
+
+export function isReservedModuleId(moduleId: string): boolean {
+  return reserved.has(moduleId);
+}

core/tests/module-discovery.test.ts

@@ -4,8 +4,10 @@ import path from "node:path";
 import { afterEach, describe, expect, it } from "vitest";
 import {
   discoverModules,
+  isReservedModuleId,
   ModuleDiscoveryError,
   type ModuleDiscoveryIssueCode,
+  RESERVED_MODULE_IDS,
 } from "../src/modules/index.js";
 
 interface ModuleFixtureOptions {
@@ -271,6 +273,52 @@ describe("module discovery", () => {
     );
   });
 
+  it("rejects a module whose id is one of the platform's reserved top-level names (ADR 0057)", async () => {
+    // Every module with a Dashboard UI is addressed at `/<module-id>`, so an id equal to a
+    // platform-owned top-level namespace would collide with the API, the display host, a host
+    // script, or a Dashboard page.
+    expect(RESERVED_MODULE_IDS).toEqual(["account", "api", "assets", "display", "settings"]);
+    expect(Object.isFrozen(RESERVED_MODULE_IDS)).toBe(true);
+
+    for (const id of RESERVED_MODULE_IDS) {
+      const modulesDirectory = await createModulesDirectory();
+      await createModule(modulesDirectory, id);
+
+      const error = await discoveryError(modulesDirectory);
+
+      expect(error.issues, id).toEqual([
+        expect.objectContaining({
+          code: "MODULE_ID_RESERVED",
+          moduleDirectory: id,
+          moduleId: id,
+          path: "id",
+        }),
+      ]);
+    }
+  });
+
+  it("accepts ids that merely resemble a reserved name", async () => {
+    const modulesDirectory = await createModulesDirectory();
+    for (const id of ["settings-sync", "my-account", "displays", "api-docs"]) {
+      await createModule(modulesDirectory, id);
+    }
+
+    const modules = await discoverModules({
+      moduleSdkVersion: "0.1.0",
+      modulesDirectory,
+      platformVersion: "0.1.0",
+    });
+
+    expect(modules.map((module) => module.manifest.id).sort()).toEqual([
+      "api-docs",
+      "displays",
+      "my-account",
+      "settings-sync",
+    ]);
+    expect(isReservedModuleId("settings")).toBe(true);
+    expect(isReservedModuleId("settings-sync")).toBe(false);
+  });
+
   it("enforces platform and Module SDK compatibility", async () => {
     const modulesDirectory = await createModulesDirectory();
     await createModule(modulesDirectory, "future", {