A store registry record needs no repository

The client only ever took identity from a store repository — a slug, a name, a catalog —
and the store engine's own defaults cover everything else: the host-to-asset mapping, the
install modes, the platforms, the behaviour. So `store_repository_url` is now optional:
nullable in the schema, no presence validation, the format check only when a value is
given, and the serializer answers null rather than an empty string, because the client
branches on its absence.

Adding a store is therefore a row with two fields filled in. Given a repository the
client still reads its config.json, and that file remains the authority on how the store
behaves — the admin form and the endpoint's documentation say so.

The frontend's /stores page gains a section of its own for the graphical client on the
desktop tab: what it does, that it sets the store up itself, that it is the way in on
Windows where `curl … | sh` does not exist, and links to the releases, the repository and
the documentation — now under stores/warp-engine-client, which is where that repository
lives after the rename.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

apps/api/app/admin/stores.rb

@@ -35,8 +35,10 @@ ActiveAdmin.register Store do
       row :updated_at
     end
     para do
-      "Listed by GET /api/stores, which the desktop client reads on first run: it " \
-        "takes the config from the store repository and points it at the catalog above."
+      "Listed by GET /api/stores, which the desktop client reads on first run. With a " \
+        "store repository the client takes that config and points it at the catalog " \
+        "above; without one it uses the store engine's defaults, which need nothing " \
+        "but the name and the catalog."
     end
   end
 
@@ -45,8 +47,10 @@ ActiveAdmin.register Store do
       f.input :name, hint: "What the client shows in its store picker"
       f.input :catalog_url, hint: "Base URL of the WarpEngine catalog, e.g. https://teletypegames.org"
       f.input :store_repository_url,
-              hint: "Repository holding the store's config.json, e.g. " \
-                    "https://git.teletypegames.org/stores/ttg-desktop-store"
+              hint: "Optional. A repository holding the store's config.json, e.g. " \
+                    "https://git.teletypegames.org/stores/ttg-desktop-store. Leave it " \
+                    "empty and the client uses the engine's defaults with the name and " \
+                    "catalog above"
     end
     f.actions
   end

apps/api/app/controllers/api/stores_controller.rb

@@ -6,13 +6,19 @@ class Api::StoresController < ApiController
   api :GET, "/api/stores", "List the stores a client can install from"
   desc <<~DESC
     The registry the graphical desktop client reads on first run: which catalogs
-    exist, and where each one's store configuration lives. Public on purpose —
-    a client has nobody to log in as.
+    exist, and — where there is one — the repository holding a store's own
+    configuration. Public on purpose: a client has nobody to log in as.
+
+    A record needs a name and a catalog URL. `storeRepositoryUrl` is optional and
+    answers `null` when there is none; a client then takes identity from this
+    record and everything else from the store engine's built-in defaults, so no
+    repository has to exist for a store to be installable.
   DESC
   returns code: 200, desc: "Array of stores" do
     property :name, String, desc: "Display name of the store"
     property :catalogUrl, String, desc: "Base URL of the WarpEngine catalog it serves"
-    property :storeRepositoryUrl, String, desc: "Repository holding the store's config.json"
+    property :storeRepositoryUrl, [String, nil],
+             desc: "Repository holding the store's config.json, or null when it has none"
   end
   def index
     render json: StoreService.new.index

apps/api/app/models/store.rb

@@ -1,15 +1,22 @@
-# A store a client can install from: a WarpEngine catalog, and the repository
-# holding the store's own configuration.
+# A store a client can install from: a WarpEngine catalog, and — optionally — a
+# repository holding that store's own configuration.
 #
 # This is deliberately not part of WarpEngine. The engine serves one catalog and
 # has no business knowing which stores exist for it; the registry is a property of
 # this site, which is what the graphical client asks.
+#
+# The repository is optional because a store does not need one. A client takes
+# identity from this record — the name, the catalog and a slug derived from it —
+# and everything else from the store engine's built-in defaults. A repository is
+# still honoured when given: it remains the authority on how that store behaves,
+# which platforms it offers and where things land.
 class Store < ApplicationRecord
   URL = %r{\Ahttps?://\S+\z}
 
   validates :name, presence: true
   validates :catalog_url, presence: true, format: { with: URL, message: "must be an http(s) URL" }
-  validates :store_repository_url, presence: true, format: { with: URL, message: "must be an http(s) URL" }
+  validates :store_repository_url, format: { with: URL, message: "must be an http(s) URL" },
+                                   allow_blank: true
 
   default_scope { where(deleted_at: nil) }
 

apps/api/app/serializers/store_serializer.rb

@@ -5,5 +5,7 @@ class StoreSerializer < Blueprinter::Base
   # camelCase, as the catalog's own payloads use — one convention for a client
   # that reads both.
   field(:catalogUrl) { |store| store.catalog_url }
-  field(:storeRepositoryUrl) { |store| store.store_repository_url }
+  # Null rather than an empty string when there is no repository: the client
+  # branches on its absence, and "" is not an absence a JSON reader can trust.
+  field(:storeRepositoryUrl) { |store| store.store_repository_url.presence }
 end