feat(secrets): pre-host ${secret:} config expander (ScadaBridge G-4 T2)

src/ZB.MOM.WW.ScadaBridge.Host/Program.cs

@@ -1,3 +1,4 @@
+using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.DependencyInjection.Extensions;
 using Microsoft.Extensions.Options;
 using ZB.MOM.WW.Auth.ApiKeys.DependencyInjection;
@@ -26,6 +27,10 @@ using ZB.MOM.WW.ScadaBridge.Security;
 using ZB.MOM.WW.ScadaBridge.SiteCallAudit;
 using ZB.MOM.WW.ScadaBridge.TemplateEngine;
 using ZB.MOM.WW.ScadaBridge.Transport;
+using ZB.MOM.WW.Secrets.Abstractions;
+using ZB.MOM.WW.Secrets.Configuration;
+using ZB.MOM.WW.Secrets.DependencyInjection;
+using ZB.MOM.WW.Secrets.Sqlite;
 using ZB.MOM.WW.Telemetry;
 using Serilog;
 
@@ -42,6 +47,20 @@ var configuration = new ConfigurationBuilder()
     .AddCommandLine(args)
     .Build();
 
+// Expand ${secret:...} config references before any validator/binder sees them (Layer A).
+// Throwaway provider — disposed here, shares no singletons with the host container.
+#pragma warning disable ASP0000 // deliberate throwaway container
+await using (var secretsProvider = new ServiceCollection()
+    .AddZbSecrets(configuration, "Secrets")
+    .BuildServiceProvider())
+#pragma warning restore ASP0000
+{
+    await secretsProvider.GetRequiredService<SqliteSecretsStoreMigrator>().MigrateAsync(default);
+    var resolver = secretsProvider.GetRequiredService<ISecretResolver>();
+    await new SecretReferenceExpander(resolver)
+        .ExpandConfigurationAsync(configuration, default);
+}
+
 // Full startup validation — fail fast before any DI or actor system setup
 StartupValidator.Validate(configuration);
 

src/ZB.MOM.WW.ScadaBridge.Host/appsettings.json

@@ -9,6 +9,12 @@
       }
     }
   },
+  "Secrets": {
+    "SqlitePath": "scadabridge-secrets.db",
+    "MasterKey": { "Source": "Environment", "EnvVarName": "ZB_SECRETS_MASTER_KEY" },
+    "RunMigrationsOnStartup": true,
+    "ResolveCacheTtl": "00:00:30"
+  },
   "Serilog": {
     "Using": [
       "Serilog.Sinks.Console",