Migrate TODO implementations to generated candidate bindings

checked-package.nix

@@ -0,0 +1,13 @@
+# The caller has compiled this package and its exact recursive candidate graph.
+# No credentials, mutable references, or workspace-wide unrelated schema enter
+# the package derivation. Ordinary #server builds are not promotion evidence.
+{ source, schema, generator, packageRevisionId, system ? builtins.currentSystem }:
+let
+  package = builtins.getFlake ("path:" + source);
+  checked = package.quixosPackages.${system}.checkedServer or
+    (throw "Package ${packageRevisionId} lacks checkedServer. Upgrade its Nix helper and adopt generated implementation bindings before cutover.");
+in checked {
+  inherit packageRevisionId;
+  schema = builtins.path { path = /. + schema; name = "candidate-package-bindings.json"; };
+  generator = builtins.storePath generator;
+}

quixos-package-helpers.nix

@@ -539,6 +539,7 @@ EOF
       # An exact, compiler-produced BindingSchema JSON artifact and a backend.
       # Other language helpers can consume the same schema with their own generator/runtime.
       bindings ? null,
+      bindingOptions ? { },
       # A dedicated entrypoint calling SDK serveMigration; never start the
       # normal package server in the isolated migration execution boundary.
       migrationEntrypoint ? null,
@@ -550,6 +551,8 @@ EOF
     }:
     flake-utils.lib.eachDefaultSystem (
       system:
+      let
+        outputsFor = candidateBindings:
         let
         pkgs = import nixpkgs { inherit system; };
         lib = pkgs.lib;
@@ -580,7 +583,8 @@ EOF
               attrs
           );
 
-        bindingConfig = if bindings == null then null else callOption bindings;
+        bindingConfig = if candidateBindings != null then candidateBindings
+          else if bindings == null then null else callOption bindings;
         bindingSchema = if bindingConfig == null then null else bindingConfig.schema or (mkQxBindingSchema {
           inherit pkgs;
           protocol = bindingConfig.generator;
@@ -589,14 +593,14 @@ EOF
           resources = bindingConfig.resources or [ ];
         });
         bindingOutput = if bindingConfig == null then "src/gen/qx.ts" else bindingConfig.output or "src/gen/qx.ts";
-        bindingOptions = if bindingConfig == null then null else
+        bindingOptionsFile = if bindingConfig == null then null else
-          pkgs.writeText "qx-typescript-options.json" (builtins.toJSON (bindingConfig.options or { }));
+          pkgs.writeText "qx-typescript-options.json" (builtins.toJSON (bindingConfig.options or bindingOptions));
         bindingCommand = if bindingConfig == null then "" else ''
           mkdir -p ${lib.escapeShellArg (dirOf bindingOutput)}
           ${bindingConfig.generator}/bin/quixos-codegen-ts \
             ${lib.escapeShellArg (toString bindingSchema)} \
             ${lib.escapeShellArg bindingConfig.packageRevisionId} \
-            ${lib.escapeShellArg bindingOutput} ${bindingOptions}
+            ${lib.escapeShellArg bindingOutput} ${bindingOptionsFile}
         '';
         generateBindings = pkgs.writeShellApplication {
           name = "qx-generate-bindings";
@@ -742,7 +746,14 @@ EOF
           # Explicit command keeps shell entry free of source mutations.
           shellHook = devShellHookBase + callOption devShellHook;
         };
-      } // maybeServerOutputs
+      } // maybeServerOutputs;
+      in (outputsFor null) // {
+        # The workspace supplies a compiler-produced schema for the exact
+        # candidate graph. Standalone builds may use checked-in authoring types,
+        # but only this build path regenerates and witnesses candidate contracts.
+        quixosPackages.checkedServer = { schema, generator, packageRevisionId }:
+          (outputsFor { inherit schema generator packageRevisionId; }).packages.server;
+      }
     );
 in
 {