agent: pull in and allow claude-code only for the claude runtime

nix/agent-modules/default.nix

@@ -41,6 +41,10 @@ let
     queue option. Remove the setting.
   '';
 
+  # Only a claude-runtime agent runs the binary. ACP subagents run on the
+  # parent agent's runtime, so they need no claude either.
+  runsClaude = config.services.hyperhive.agent.runtime == "claude";
+
   # `claude` on PATH. A hive that pins a claude-code
   # (`services.hyperhive.deploy.hive-controller.claudeCodePackage`) hands its
   # store path over at container start as `HYPERHIVE_CLAUDE_CODE_PATH`, and
@@ -237,7 +241,10 @@ in
     # evaluates its own `nixpkgs` instance, so the operator's host-level
     # `nixpkgs.config.allowUnfreePredicate` does not propagate into here —
     # we have to allow it inside the container's config as well.
-    nixpkgs.config.allowUnfreePredicate = pkg: builtins.elem (pkgs.lib.getName pkg) [ "claude-code" ];
+    # Only an agent that runs claude needs it: `runtime = "acp"` never
+    # references the package, so it is neither built nor allowed there.
+    nixpkgs.config.allowUnfreePredicate =
+      pkg: runsClaude && builtins.elem (pkgs.lib.getName pkg) [ "claude-code" ];
 
     # Core tooling every agent gets. Per-bin split packages (see
     # nix/packages/default.nix + ./packages.nix) rather than the full
@@ -256,9 +263,7 @@ in
     environment.systemPackages = [
       config.services.hyperhive.agent.packages.hive-metric
     ]
-    ++ [
-      claude
-    ]
+    ++ lib.optional runsClaude claude
     ++ (with pkgs; [
       bashInteractive
       coreutils-full