refactor: simplify shared config contracts

modules/features/meta.nix

@@ -27,6 +27,13 @@ let
 
   hasRequiredScopedEmail = scope: user: scopeEmailCount scope user == 1;
 
+  scopeEmailAddress =
+    scope: user:
+    let
+      emails = lib.filter (email: email.scope == scope) (builtins.attrValues user.emails);
+    in
+    if emails == [ ] then "" else (builtins.head emails).address;
+
   primaryEmailFallback = {
     address = "";
     primary = false;
@@ -125,6 +132,22 @@ let
           type = sourceControlScopeType;
           default = "personal";
         };
+
+        scopes = lib.mkOption {
+          type = lib.types.attrsOf (
+            lib.types.submodule (
+              { ... }:
+              {
+                options.email = lib.mkOption {
+                  type = lib.types.str;
+                  readOnly = true;
+                };
+              }
+            )
+          );
+          readOnly = true;
+          description = "Derived source-control identities keyed by scope.";
+        };
       };
     }
   );
@@ -149,10 +172,6 @@ let
           type = lib.types.str;
         };
 
-        terminalPackagePath = lib.mkOption {
-          type = lib.types.listOf lib.types.str;
-        };
-
         nixosConfigurationPath = lib.mkOption {
           type = lib.types.str;
           default = "${config.homeDirectory}/.config/nixos";
@@ -174,7 +193,12 @@ let
         };
       };
 
-      config.primaryEmail = primaryEmail;
+      config = {
+        primaryEmail = primaryEmail;
+        sourceControl.scopes = lib.genAttrs (requiredSourceControlScopes config) (scope: {
+          email = scopeEmailAddress scope config;
+        });
+      };
     }
   );