Implemented phase 1 for the POC prototype in the Website service.

Services/Website/Sources/App/Extensions/App+Build.swift

@@ -11,8 +11,8 @@ import WebsiteLibrary
 /// Reads the log level, server name, static files location, minimum response size to compress, and security headers from the configuration, then assembles
 /// the router, server configuration, and logger. It warns when the localization catalog cannot be read, since pages would serve raw localization keys.
 /// It also builds the persistence driver, registers its migrations, and attaches the `Fluent` service so it starts
-/// and stops alongside the HTTP server; the ephemeral in-memory backend is migrated on startup, while a PostgreSQL backend is migrated out of
-/// band (so a shared database is never migrated on boot).
+/// and stops alongside the HTTP server; the ephemeral in-memory backend is migrated here, before the landing page reads its listings, while a
+/// PostgreSQL backend is migrated out of band (so a shared database is never migrated on boot).
 /// - Parameter reader: the configuration reader the values are read from.
 /// - Returns: the configured application, ready to run as a service.
 /// - Throws: a ``ConfigError`` when a `database.*` key holds an unrecognized token, or an error when the persistence service cannot be built
@@ -46,6 +46,15 @@ func application(
 
     await prepareDB(for: fluent)
 
+    // The in-memory backend is recreated on every launch, so it is migrated — and seeded — before the landing page
+    // reads its listings. The PostgreSQL backend is left untouched: a shared database is migrated out of band to avoid
+    // multi-instance races.
+    if case .inMemory = driver {
+        try await fluent.migrate()
+    }
+
+    let repository = CatalogueRepository(fluent: fluent)
+
     var app = Application(
         router: router(
             staticFilesPath: reader.staticFilesPath,
@@ -60,7 +69,12 @@ func application(
             // building both against an empty host.
             siteOrigin: reader.siteOrigin.isEmpty ? nil : reader.siteOrigin,
             logLevel: reader.logLevel,
-            probe: Probe(fluent: fluent)
+            probe: Probe(fluent: fluent),
+            repository: repository,
+            listings: await homeListings(
+                from: repository,
+                logger: logger
+            )
         ),
         configuration: ApplicationConfiguration(
             reader: reader.scoped(to: "http")
@@ -70,14 +84,6 @@ func application(
 
     app.addServices(fluent)
 
-    // The in-memory backend is recreated on every launch, so it is migrated on startup. The PostgreSQL backend is
-    // left untouched here: a shared database is migrated out of band to avoid multi-instance races.
-    if case .inMemory = driver {
-        app.beforeServerStarts {
-            try await fluent.migrate()
-        }
-    }
-
     return app
 }
 
@@ -121,6 +127,26 @@ func migration(
 /// The request context type the application serves its routes with.
 private typealias AppRequestContext = WebsiteRequestContext
 
+/// Reads the listings the landing page shows, once: the page is rendered at startup and cached.
+///
+/// A catalogue that cannot be read — a PostgreSQL backend not migrated yet — leaves the page without its rows rather than failing the launch.
+/// - Parameters:
+///   - repository: the repository the listings are read through.
+///   - logger: the logger the failure is reported to.
+/// - Returns: the landing page's listings, or none when the catalogue cannot be read.
+private func homeListings(
+    from repository: CatalogueRepository,
+    logger: Logger
+) async -> HomeListings {
+    do {
+        return .init(from: try await repository.listings())
+    } catch {
+        logger.warning("Catalogue is unreadable; the landing page will show no listings: \(error)")
+
+        return .init()
+    }
+}
+
 /// Builds the application's logger.
 /// - Parameters:
 ///   - serverName: the label applied to the logger.
@@ -156,6 +182,8 @@ private func logger(
 ///   - siteOrigin: the public origin the pages derive their canonical URLs and language alternates from, or `nil` to omit them.
 ///   - logLevel: the level the request-logging middleware logs at.
 ///   - probe: the probe consulted by the `HealthController` readiness route.
+///   - repository: the repository the `CatalogueController` reads the shops and listings through.
+///   - listings: the listings the landing page shows in its rows.
 /// - Returns: the configured router.
 private func router(
     staticFilesPath: String,
@@ -168,7 +196,9 @@ private func router(
     securityHeaders: SecurityHeadersMiddleware<AppRequestContext>.Configuration,
     siteOrigin: String?,
     logLevel: Logger.Level,
-    probe: Probe
+    probe: Probe,
+    repository: CatalogueRepository,
+    listings: HomeListings
 ) -> Router<AppRequestContext> {
     // HEAD siblings are generated for every GET route, so uptime monitors and crawlers probing with HEAD requests get
     // the page's status and headers instead of a 404.
@@ -204,6 +234,12 @@ private func router(
         RootController<AppRequestContext>(
             assetVersion: assetVersion,
             siteOrigin: siteOrigin,
+            analytics: analytics,
+            listings: listings
+        )
+        CatalogueController<AppRequestContext>(
+            repository: repository,
+            assetVersion: assetVersion,
             analytics: analytics
         )
         HealthController<AppRequestContext>(