Add pi coding agent tool + settings

- package pi-coding-agent with a vendored lockfile
- add pi to toolchain and expose settings file via tmpfiles
- seed pi defaults to match local model choices

Tests: nix build --no-link --impure --expr 'let pkgs = import <nixpkgs> {}; in pkgs.callPackage ./nix/tools/pi-coding-agent.nix {}'

clawdinator/pi-settings.json

@@ -0,0 +1,9 @@
+{
+  "defaultProvider": "openai-codex",
+  "defaultModel": "gpt-5.2-codex",
+  "defaultThinkingLevel": "xhigh",
+  "enabledModels": [
+    "openai-codex/gpt-5.2-codex",
+    "anthropic/claude-opus-4-5"
+  ]
+}

nix/modules/clawdinator.nix

@@ -523,6 +523,10 @@ in
         - **clawdinator-gh-refresh** — mint GitHub App token + refresh GH auth (no sudo).
       '';
     };
+    environment.etc."clawdinator/pi-settings.json" = {
+      mode = "0644";
+      source = ../../clawdinator/pi-settings.json;
+    };
     environment.etc."stunnel/efs.conf" = lib.mkIf cfg.memoryEfs.enable {
       mode = "0644";
       text = ''
@@ -578,6 +582,9 @@ in
 
     systemd.tmpfiles.rules = [
       "d ${cfg.stateDir} 0750 ${cfg.user} ${cfg.group} - -"
+      "d ${cfg.stateDir}/.pi 0750 ${cfg.user} ${cfg.group} - -"
+      "d ${cfg.stateDir}/.pi/agent 0750 ${cfg.user} ${cfg.group} - -"
+      "L+ ${cfg.stateDir}/.pi/agent/settings.json - - - - /etc/clawdinator/pi-settings.json"
       "d ${workspaceDir} 0750 ${cfg.user} ${cfg.group} - -"
       "d ${logDir} 0750 ${cfg.user} ${cfg.group} - -"
       "d ${ghConfigDir} 0750 ${cfg.user} ${cfg.group} - -"

nix/tools/clawdinator-tools.nix

@@ -1,4 +1,7 @@
 { pkgs }:
+let
+  piCodingAgent = pkgs.callPackage ./pi-coding-agent.nix {};
+in
 {
   packages = [
     pkgs.bash
@@ -11,6 +14,7 @@
     pkgs.ripgrep
     pkgs.nodejs_22
     pkgs.pnpm_10
+    piCodingAgent
     pkgs.util-linux
     pkgs.nfs-utils
     pkgs.stunnel
@@ -22,6 +26,7 @@
     { name = "bash"; description = "Shell runtime for CLAWDINATOR scripts."; }
     { name = "gh"; description = "GitHub CLI for repo + PR inventory."; }
     { name = "openclaw-gateway"; description = "CLAWDINATOR runtime (Clawbot gateway)."; }
+    { name = "pi"; description = "Pi coding agent CLI."; }
     { name = "git"; description = "Repo sync + ops."; }
     { name = "curl"; description = "HTTP requests."; }
     { name = "jq"; description = "JSON processing."; }

nix/tools/pi-coding-agent.nix

@@ -0,0 +1,17 @@
+{ pkgs }:
+pkgs.buildNpmPackage {
+  pname = "pi-coding-agent";
+  version = "0.50.1";
+
+  src = pkgs.fetchurl {
+    url = "https://registry.npmjs.org/@mariozechner/pi-coding-agent/-/pi-coding-agent-0.50.1.tgz";
+    hash = "sha256-39tkNCz+h0CjvkAjnWJELsMpeg9HCr4S+y3teNQP8A8=";
+  };
+
+  postPatch = ''
+    cp ${../vendor/pi-coding-agent/package-lock.json} package-lock.json
+  '';
+
+  npmDepsHash = "sha256-xCHoy5xKeUl/ouowPqyHVlq/zjNTPygxy9af8jItC/w=";
+  dontNpmBuild = true;
+}