diff --git a/nix/modules/hive-c0re.nix b/nix/modules/hive-c0re.nix
index be2a4574..3fba5127 100644
--- a/nix/modules/hive-c0re.nix
+++ b/nix/modules/hive-c0re.nix
@@ -15,6 +15,19 @@
 }:
 let
   cfg = config.services.hyperhive.c0re;
+
+  # Privsep splits ownership across users, so git/libgit2's dubious-
+  # ownership guard trips on legitimate cross-user reads: hive-priv (root)
+  # fetches the hive-core-owned meta/applied repos via nix, and hive-c0re
+  # (hive-core) fetches the agent-owned proposed-config repos. Both
+  # processes are trusted and can already read the files; this gitconfig
+  # only satisfies the ownership guard. libgit2 honours the literal `*`
+  # (mid-path globs aren't supported, so per-agent repos can't be listed);
+  # in practice these processes only ever touch hyperhive's own repos.
+  safeDirGitconfig = pkgs.writeText "hyperhive-safe-gitconfig" ''
+    [safe]
+    directory = *
+  '';
 in
 {
   # The forge is part of the standard install — hive-c0re mirrors
@@ -446,6 +459,11 @@ in
         # plus the `agents/` dir node itself (not its contents) so c0re can
         # still create new per-agent subdirs.
         ExecStartPre = [
+          # Install the safe.directory gitconfig at $HOME/.gitconfig
+          # (HOME = /var/lib/hyperhive) so c0re's `git fetch`/`rev-parse`
+          # against the agent-owned proposed repos pass the ownership guard.
+          # Placed before the chown below so it's chowned to hive-core too.
+          "+-${pkgs.coreutils}/bin/cp ${safeDirGitconfig} /var/lib/hyperhive/.gitconfig"
           "+-${pkgs.findutils}/bin/find /var/lib/hyperhive -mindepth 1 -maxdepth 1 -not -name agents -exec ${pkgs.coreutils}/bin/chown -R hive-core:hive-core {} +"
           "+-${pkgs.coreutils}/bin/chown hive-core:hive-core /var/lib/hyperhive/agents"
         ];
@@ -557,6 +575,11 @@ in
         ProtectSystem = "false";
         # Writable HOME for nix's caches (see environment.HOME above).
         StateDirectory = "hive-priv";
+        # nix (run here as root for `nixos-container update --flake
+        # /var/lib/hyperhive/meta#<agent>`) fetches the hive-core-owned
+        # meta/applied repos; libgit2 refuses them without safe.directory.
+        # See safeDirGitconfig above.
+        ExecStartPre = "+-${pkgs.coreutils}/bin/cp ${safeDirGitconfig} /var/lib/hive-priv/.gitconfig";
       };
     };
   };