Add pi-coding-agent package, simplify Go builds with unstable.buildGoModule

- Add pi-coding-agent package (v0.55.4) with multi-platform support
- Replace custom Go 1.25.6 override with nixpkgs-unstable buildGoModule
  for beads and perles builds
- Update flake inputs: beads, nixpkgs-unstable, perles
- Update vendor hashes for beads and perles
- Add pi-coding-agent to development role

packages/beads/default.nix

@@ -2,8 +2,6 @@
 # Takes src as argument so it can be called from both overlay and flake packages
 { lib
 , buildGoModule
-, fetchurl
-, go_1_25
 , git
 , pkg-config
 , icu
@@ -11,23 +9,12 @@
 , version ? "unknown"
 }:
 
-let
-  # beads' dolt deps require Go >= 1.25.6 (GOTOOLCHAIN=auto can't download in sandbox)
-  go_1_25_6 = go_1_25.overrideAttrs (old: rec {
-    version = "1.25.6";
-    src = fetchurl {
-      url = "https://go.dev/dl/go${version}.src.tar.gz";
-      hash = "sha256-WMv3ceRNdt5vVtGeM7d9dFoeSJNAkih15GWFuXXCsFk=";
-    };
-  });
-  buildGoModule_1_25_6 = buildGoModule.override { go = go_1_25_6; };
-in
-buildGoModule_1_25_6 {
+buildGoModule {
   pname = "beads";
   inherit version src;
   subPackages = [ "cmd/bd" ];
   doCheck = false;
-  vendorHash = "sha256-M+JCxrKgUxCczYzMc2czLZ/JhdVulo7dH2YLTPrJVSc=";
+  vendorHash = "sha256-OL6QGf4xSMpEbmU+41pFdO0Rrs3H162T3pdiW9UfWR0=";
   nativeBuildInputs = [ git pkg-config ];
   buildInputs = [ icu ];
   meta = with lib; {

packages/default.nix

@@ -5,4 +5,5 @@
   claude-code = pkgs.callPackage ./claude-code {};
   mcrcon-rbw = pkgs.callPackage ./mcrcon-rbw {};
   rclone-torbox-setup = pkgs.callPackage ./rclone-torbox-setup {};
+  pi-coding-agent = pkgs.callPackage ./pi-coding-agent {};
 }

packages/pi-coding-agent/default.nix

@@ -0,0 +1,79 @@
+{ lib
+, stdenv
+, fetchurl
+, patchelf
+, glibc
+, makeWrapper
+}:
+
+let
+  version = "0.55.4";
+
+  srcs = {
+    aarch64-darwin = {
+      url = "https://github.com/badlogic/pi-mono/releases/download/v${version}/pi-darwin-arm64.tar.gz";
+      sha256 = "0vsav9frvnzskk6p6j60i7klrs3m8lphhyi4c39mv2mvhpm8fkl5";
+    };
+    x86_64-darwin = {
+      url = "https://github.com/badlogic/pi-mono/releases/download/v${version}/pi-darwin-x64.tar.gz";
+      sha256 = "1377rvhsiiww1bbpgv2v46fjm7iz2smmh8g2yhm28kbsq3gwvvr0";
+    };
+    x86_64-linux = {
+      url = "https://github.com/badlogic/pi-mono/releases/download/v${version}/pi-linux-x64.tar.gz";
+      sha256 = "1wnfwnkfq5ffz6wyqyhciv4lz06bpxims0hv0dlhz0f9vliyc1md";
+    };
+    aarch64-linux = {
+      url = "https://github.com/badlogic/pi-mono/releases/download/v${version}/pi-linux-arm64.tar.gz";
+      sha256 = "00fp37hgjl40kc59jfpv189i7np53ymm037hvds6k9y2sz818wjy";
+    };
+  };
+
+  src = srcs.${stdenv.hostPlatform.system} or (throw "Unsupported system: ${stdenv.hostPlatform.system}");
+
+in stdenv.mkDerivation {
+  pname = "pi-coding-agent";
+  inherit version;
+
+  src = fetchurl {
+    inherit (src) url sha256;
+  };
+
+  sourceRoot = "pi";
+
+  # Bun standalone binaries have JS code appended after the ELF sections
+  dontStrip = true;
+  dontPatchELF = true;
+
+  nativeBuildInputs = [ makeWrapper ]
+    ++ lib.optionals stdenv.isLinux [ patchelf ];
+
+  installPhase = ''
+    runHook preInstall
+
+    # Install the full pi directory structure (binary + supporting files)
+    mkdir -p $out/lib/pi-coding-agent
+    cp -r . $out/lib/pi-coding-agent/
+
+    # Create bin wrapper that runs the binary from its lib directory
+    # (pi expects supporting files like themes and wasm relative to itself)
+    mkdir -p $out/bin
+    makeWrapper $out/lib/pi-coding-agent/pi $out/bin/pi
+
+    runHook postInstall
+  '';
+
+  # Manually patch the interpreter for bun standalone binaries on Linux
+  postFixup = lib.optionalString stdenv.isLinux ''
+    interpreter="${glibc}/lib/${if stdenv.hostPlatform.system == "aarch64-linux" then "ld-linux-aarch64.so.1" else "ld-linux-x86-64.so.2"}"
+    patchelf --set-interpreter "$interpreter" $out/lib/pi-coding-agent/pi
+  '';
+
+  meta = with lib; {
+    description = "Minimal terminal coding agent with extensible tools and session management";
+    homepage = "https://github.com/badlogic/pi-mono/tree/main/packages/coding-agent";
+    license = licenses.mit;
+    maintainers = [ ];
+    platforms = [ "aarch64-darwin" "x86_64-darwin" "x86_64-linux" "aarch64-linux" ];
+    mainProgram = "pi";
+  };
+}