diff --git a/README.md b/README.md
index cb513bf7..a2f48896 100644
--- a/README.md
+++ b/README.md
@@ -78,6 +78,16 @@ manager container, and auto-rebuilds any container whose hyperhive
 rev goes stale. `claude-code` is unfree — hyperhive scopes the
 whitelist to itself, nothing for the operator to set.
 
+Optional: set `services.hive-c0re.preBuildAgentTemplates = true;`
+to pre-fetch the per-container system closures into your host's
+/nix/store as part of `nixos-rebuild`. First-agent-spawn then
+completes in seconds instead of minutes (no nixpkgs/claude-code
+fetch on the critical path), at the cost of a few GB extra in your
+system closure. Off by default (the toplevels are pinned to
+`x86_64-linux`, so non-x86 hosts would otherwise force a cross-build).
+Alternatively warm the store manually:
+`nix build github:vinzenz/hyperhive#agent-base-toplevel`.
+
 ## Agent configuration
 
 Per-agent settings live in each agent's `agent.nix` and are synced to
diff --git a/flake.nix b/flake.nix
index fa26a6db..792bf2fb 100644
--- a/flake.nix
+++ b/flake.nix
@@ -69,6 +69,24 @@
           frontend = pkgs.callPackage ./nix/frontend.nix {
             branding-svg = ./branding/hyperhive.svg;
           };
+          # Pre-built per-container system closures. Exposed as packages
+          # 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 —
+          # see nix/modules/hive-c0re.nix). Speeds up the first agent
+          # spawn dramatically because the heavy lifting (nixpkgs +
+          # claude-code + hive-ag3nt binary) is already in the store
+          # when the meta evaluator goes to build the container.
+          # Closes #97.
+          #
+          # nixosConfigurations are pinned to x86_64-linux (nixos-
+          # containers only run native arch), so these toplevels are
+          # 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
+          # host would only succeed via a remote x86 builder.
+          agent-base-toplevel = self.nixosConfigurations.agent-base.config.system.build.toplevel;
+          manager-toplevel = self.nixosConfigurations.manager.config.system.build.toplevel;
         }
       );
 
@@ -117,6 +135,15 @@
           hyperhivePackage = system: self.packages.${system}.default;
           hyperhiveFrontend = system: self.packages.${system}.frontend;
           hyperhiveFlake = "${self}";
+          # Per-container toplevels — wired into `system.extraDependencies`
+          # when `services.hive-c0re.preBuildAgentTemplates` is on so the
+          # host system closure pre-fetches the heavy build inputs (#97).
+          # Defined only for x86_64-linux because nixosConfigurations are
+          # hardcoded to that system; the option's default keeps the
+          # extra deps gated so aarch64 hosts don't accidentally pull
+          # them in via cross-build.
+          agentBaseToplevel = self.packages.x86_64-linux.agent-base-toplevel;
+          managerToplevel = self.packages.x86_64-linux.manager-toplevel;
         };
         hive-forge = ./nix/modules/hive-forge.nix;
         # Convenience alias: one import covers the full hyperhive host
diff --git a/nix/modules/hive-c0re.nix b/nix/modules/hive-c0re.nix
index 9d77eb57..467a5f7e 100644
--- a/nix/modules/hive-c0re.nix
+++ b/nix/modules/hive-c0re.nix
@@ -2,6 +2,8 @@
   hyperhivePackage,
   hyperhiveFrontend,
   hyperhiveFlake,
+  agentBaseToplevel,
+  managerToplevel,
 }:
 {
   pkgs,
@@ -71,6 +73,32 @@ in
         approval needed.
       '';
     };
+    preBuildAgentTemplates = lib.mkOption {
+      type = lib.types.bool;
+      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
+        host's NixOS build, instead of letting the first agent spawn
+        do all the work. Closes #97.
+
+        Enabling this adds roughly the full nixpkgs runtime closure +
+        claude-code + the harness binary to your system closure size
+        (low single-digit GB), but the first `nixos-container start`
+        for any agent then completes in seconds instead of minutes
+        because nothing's left to fetch.
+
+        Off by default because the toplevels are pinned to
+        `x86_64-linux` (nixos-containers run native arch). Enabling
+        on an aarch64 host would force nix to build the x86 closure
+        via cross or a remote builder, which is rarely what you want.
+        Flip to `true` on an x86_64 host when you care more about
+        first-spawn latency than host store size — or just
+        `nix build ${hyperhiveFlake}#agent-base-toplevel` once
+        manually to warm the store.
+      '';
+    };
     contextWindowTokens = lib.mkOption {
       type = lib.types.attrsOf lib.types.int;
       default = {
@@ -104,6 +132,17 @@ in
       pkgs.git
     ];
 
+    # Pull the per-container toplevels into the host system closure
+    # (#97). `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
+    # nixos-container update + start for an agent has nothing left to
+    # do. Gated because the closure is sizeable and pinned to x86_64.
+    system.extraDependencies = lib.optionals cfg.preBuildAgentTemplates [
+      agentBaseToplevel
+      managerToplevel
+    ];
+
     # Dashboard + per-container web UIs share the host's network namespace and
     # need their ports reachable. Dashboard: `cfg.dashboardPort` (default 7000).
     # Manager: 8000. Sub-agents: 8100..8999 (deterministic hash; see