build every agent from the agent-base template

Delete nix/templates/ruth.nix, the ruth nixosConfiguration, module and
toplevel, the hive-c0re managerToplevel option, and the meta flake's
isManager switch with lifecycle::MANAGER_NAME. Every agent, ruth
included, now builds from nix/templates/agent.nix. The template's only
content beyond agent.nix was docs.enable = mkDefault true; docs.enable
is off by default for every agent and ruth's own agent.nix turns it on.

Refs #5377

nix/agent-modules/default.nix

@@ -1,7 +1,6 @@
 # Shared scaffolding for every hyperhive harness container.
-# `../templates/agent.nix` and `../templates/ruth.nix` both import
-# agents use the same service unit regardless of which entry-point
-# they came from.
+# `../templates/agent.nix`, the one entry point every agent builds from,
+# imports it.
 #
 # This is the core module: container plumbing (boot/nix/nixpkgs),
 # base tooling, and the cross-cutting `services.hyperhive.agent.icon` option. Each

nix/agent-modules/docs.nix

@@ -14,9 +14,8 @@
     via `claude --add-dir`, so the markdown is readable at
     `$HIVE_DOCS_DIR/`, and appends a single pointer sentence to the agent's
     system prompt so it knows the docs exist (see
-    `hive-agent::prompt::render`). Default-on for the root/manager agent
-    (see `../templates/ruth.nix`), off elsewhere; any agent can flip it from its
-    `agent.nix`.
+    `hive-agent::prompt::render`). Off by default for every agent; an agent
+    turns it on from its `agent.nix`.
   '';
 
   options.services.hyperhive.agent.docs.source = lib.mkOption {

nix/agent-modules/packages.nix

@@ -1,6 +1,6 @@
 # The hyperhive-built packages the harness modules consume, threaded
 # in explicitly as an option — no overlay. The flake's
-# `nixosModules.{agent-base,ruth}` set this to the flake's own package
+# `nixosModules.agent-base` sets this to the flake's own package
 # outputs via `lib.mkDefault`, so a per-agent override of an
 # individual key still wins.
 { lib, ... }:
@@ -15,8 +15,8 @@
       `hive-forge`, `hive-forge-notify`, `hive-github-notify`,
       `hive-matrix-daemon`,
       `hive-metric`, `hive-screen-mcp`) plus the `assets`, `frontend`,
-      `reference-docs` and `claude-plugins` trees. Wired by the flake's agent-base/ruth
-      nixosModules to `hyperhive.packages.<system>.*`; override an
+      `reference-docs` and `claude-plugins` trees. Wired by the flake's agent-base
+      nixosModule to `hyperhive.packages.<system>.*`; override an
       individual key per-agent to swap in a patched binary.
     '';
   };

nix/host-modules/hive-c0re/default.nix

@@ -189,7 +189,7 @@ in
     # above for the rationale.
     environment.etc."hyperhive/serve.json".text = serveConfigJson;
 
-    # Pull the per-container toplevels into the host system closure.
+    # Pull the agent-base toplevel into the host system closure.
     # `system.extraDependencies` adds paths to the system build
     # without referencing them at runtime — nixos-rebuild fetches /
     # builds them, they end up in /nix/store, and the first
@@ -197,7 +197,6 @@ in
     # do. Gated because the closure is sizeable and pinned to x86_64.
     system.extraDependencies = lib.optionals cfg.preBuildAgentTemplates [
       cfg.agentBaseToplevel
-      cfg.managerToplevel
     ];
 
     # Unprivileged coordinator user. hive-c0re runs as this user;

nix/host-modules/hive-c0re/options.nix

@@ -10,6 +10,12 @@
   ...
 }:
 {
+  imports = [
+    (lib.mkRemovedOptionModule [ "services" "hyperhive" "c0re" "managerToplevel" ] ''
+      Every agent, ruth included, builds from `agentBaseToplevel`. Remove this definition.
+    '')
+  ];
+
   options.services.hyperhive.c0re = {
     package = lib.mkOption {
       type = lib.types.package;
@@ -92,14 +98,6 @@
         enabled.
       '';
     };
-    managerToplevel = lib.mkOption {
-      type = lib.types.package;
-      defaultText = lib.literalExpression "hyperhive.packages.x86_64-linux.ruth-toplevel";
-      description = ''
-        Pre-built manager (ruth) container system closure — see
-        `agentBaseToplevel`.
-      '';
-    };
     nixpkgsFlake = lib.mkOption {
       type = lib.types.str;
       default = "path:${pkgs.path}";
@@ -176,8 +174,8 @@
       default = false;
       example = true;
       description = ''
-        Pre-fetch the per-container system closures (agent-base +
-        manager toplevels) into the host's /nix/store as part of this
+        Pre-fetch the agent-base container system closure, which every
+        agent builds from, into the host's /nix/store as part of this
         host's NixOS build, instead of letting the first agent spawn
         do all the work.
 

nix/packages/default.nix

@@ -273,7 +273,7 @@ in
   # is exposed too since it's independently useful/inspectable.
   inherit swagger-ui-dist swagger-ui-theme;
 
-  # Pre-built per-container system closures. Exposed as packages
+  # Pre-built system closure every agent container builds from. Exposed as a package
   # so operators can `nix build .#agent-base-toplevel` (or wire
   # them into their host system closure via the
   # `preBuildAgentTemplates` option on the hive-c0re module —
@@ -283,13 +283,12 @@ in
   # when the meta evaluator goes to build the container.
   #
   # nixosConfigurations are pinned to x86_64-linux (nixos-
-  # containers only run native arch), so these toplevels are
+  # containers only run native arch), so this toplevel is
   # only useful on an x86_64-linux host — flake check across
-  # systems still tolerates evaluating them on aarch64 because
-  # they're plain derivations, but `nix build` from a non-x86
+  # systems still tolerates evaluating it on aarch64 because
+  # it's a plain derivation, but `nix build` from a non-x86
   # host would only succeed via a remote x86 builder.
   agent-base-toplevel = self.nixosConfigurations.agent-base.config.system.build.toplevel;
-  ruth-toplevel = self.nixosConfigurations.ruth.config.system.build.toplevel;
 
   # Auto-generated nix options reference for hyperhive.
   # `docs` bundles host + swarm + deploy + agent pages into one tree;

nix/templates/ruth.nix

@@ -1,14 +0,0 @@
-{ lib, ... }:
-{
-  # Entry-point for the privileged root agent (ruth). Referenced from
-  # `flake.nix` (`nixosConfigurations.ruth`) and the meta-flake's
-  # `applied/ruth/flake.nix`.
-  imports = [ ../agent-modules ];
-
-  # The root/manager bootstraps a fresh hive, so it gets the hyperhive
-  # reference docs made available by default (readable at
-  # `$HIVE_DOCS_DIR/`, added via `claude --add-dir`). `mkDefault` so a
-  # manager's own `agent.nix` can still turn it off. Other agents default
-  # off.
-  services.hyperhive.agent.docs.enable = lib.mkDefault true;
-}