feat(packages): add g3

Pinned commit: upstream has no tags. Ships g3 and g3-studio.

Closes nix-overlay-ikz

README.md

@@ -20,6 +20,7 @@ A custom Nix overlay and flake providing additional packages not found in upstre
 | `freebuff` | The world's strongest free coding agent | AI Coding Agents |
 | `freetoken` | Local MoE-offload LLM inference runtime with OpenAI- and Anthropic-compatible APIs | AI Inference |
 | `graphify` | Turn any folder of code, docs, papers, images, or videos into a queryable knowledge graph | AI Coding Agents |
+| `g3` | AI coding agent that writes code and executes commands, with multi-provider LLM support, context compaction, and desktop automation | AI Coding Agents |
 | `haivemind` | Multi-model AI consensus, aggregation, and fusion runner for popular AI CLIs | AI Coding Agents |
 | `hipengine` | ROCm-native local LLM inference engine with torch-free runtime for AMD RDNA GPUs | AI Inference |
 | `marmel` | Autonomous agentic coding assistant with Manager + specialist subagent orchestration over any OpenAI-compatible LLM backend | AI Coding Agents |
@@ -155,6 +156,7 @@ nix-overlay/
 │   ├── freebuff/               # Free coding agent (Codebuff)
 │   ├── freetoken/             # Local MoE inference runtime (NVIDIA CUDA)
 │   ├── graphify/               # Knowledge graph generator for code folders
+│   ├── g3/                     # AI coding agent (g3 + g3-studio)
 │   ├── haivemind/              # Multi-model AI consensus runner
 │   ├── hipengine/              # ROCm-native LLM inference engine for AMD GPUs
 │   ├── kubernetes-mcp-server/  # MCP server for Kubernetes and OpenShift

packages/g3/default.nix

@@ -0,0 +1,5 @@
+{
+  pkgs,
+  ...
+}:
+pkgs.callPackage ./package.nix { }

packages/g3/package.nix

@@ -0,0 +1,95 @@
+{
+  lib,
+  stdenv,
+  rustPlatform,
+  fetchFromGitHub,
+  pkg-config,
+  openssl,
+  cmake,
+  libx11,
+  libxtst,
+  llvmPackages,
+}:
+
+rustPlatform.buildRustPackage rec {
+  pname = "g3";
+  # Upstream has no git tags or releases; pin main and let nix-update
+  # track the branch. Version shape matches nix-update --version=branch=main
+  # for a tagless repository (package version is 0.1.0 upstream).
+  version = "0.1.0-unstable-2026-09-06";
+
+  src = fetchFromGitHub {
+    owner = "dhanji";
+    repo = "g3";
+    rev = "9793144520d290a9ea621a06cf7d8322e6fa4a35";
+    hash = "sha256-s4QlOah7ffoFjiTw2nO/SbCbvIRxr4HB/3pOpQpGWRM=";
+  };
+
+  # Cargo.lock has a git dependency (tree-sitter-haskell); cargoHash /
+  # fetchCargoVendor covers registry + git sources.
+  cargoHash = "sha256-6dvN4//NNuo9s5QzTcrxYiNkxP0Ivysg6f1F9soFrL4=";
+
+  nativeBuildInputs = [
+    pkg-config
+    cmake
+    # llama-cpp-sys-2 runs bindgen, which needs libclang.
+    llvmPackages.libclang
+  ];
+
+  buildInputs = [
+    openssl
+    libx11
+    libxtst
+  ];
+
+  # bindgen (via llama-cpp-sys-2) needs libclang and the C library headers.
+  env = {
+    LIBCLANG_PATH = "${llvmPackages.libclang.lib}/lib";
+    BINDGEN_EXTRA_CLANG_ARGS = "-isystem ${lib.getDev stdenv.cc.libc}/include";
+  };
+
+  # Root package only builds/installs its own bins; studio is a sibling
+  # workspace member. Match upstream install.sh: ship g3 and studio
+  # (renamed to g3-studio).
+  cargoBuildFlags = [
+    "-p"
+    "g3"
+    "-p"
+    "studio"
+  ];
+  cargoInstallFlags = [
+    "-p"
+    "g3"
+    "-p"
+    "studio"
+  ];
+
+  # Provider and computer-control tests need network, LLM credentials, and a
+  # display; not runnable in the Nix sandbox.
+  doCheck = false;
+
+  # Upstream install.sh names the companion workspace manager g3-studio.
+  postInstall = ''
+    mv "$out/bin/studio" "$out/bin/g3-studio"
+  '';
+
+  passthru = {
+    category = "AI Coding Agents";
+    updateScript = [
+      "nix-update"
+      "--flake"
+      ".#g3"
+      "--version=branch=main"
+    ];
+  };
+
+  meta = with lib; {
+    description = "AI coding agent that writes code and executes commands, with multi-provider LLM support, context compaction, and desktop automation";
+    homepage = "https://github.com/dhanji/g3";
+    # Cargo.toml declares MIT; the repository ships no LICENSE file.
+    license = licenses.mit;
+    sourceProvenance = with sourceTypes; [ fromSource ];
+    mainProgram = "g3";
+    platforms = platforms.unix;
+  };
+}