{
  lib,
  config,
  pkgs,
  inputs,
  ...
}:
let
  inherit (lib) mkIf;
  inherit (lib.metacfg) mkBoolOpt;

  cfg = config.metacfg.cli-apps.opencode;

  # Formatters opencode runs on save, each pinned to its exact store path.
  formatters = {
    nixfmt = {
      command = [
        (lib.getExe pkgs.nixfmt-rfc-style)
        "$FILE"
      ];
      extensions = [ ".nix" ];
    };
    prettier = {
      command = [
        (lib.getExe pkgs.nodePackages.prettier)
        "--write"
        "$FILE"
      ];
      extensions = [
        ".md"
        ".yaml"
        ".yml"
        ".json"
        ".css"
        ".html"
        ".js"
        ".ts"
        ".jsx"
        ".tsx"
      ];
    };
    shfmt = {
      command = [
        (lib.getExe pkgs.shfmt)
        "-w"
        "$FILE"
      ];
      extensions = [
        ".sh"
        ".bash"
      ];
    };
    ruff = {
      command = [
        (lib.getExe pkgs.ruff)
        "format"
        "$FILE"
      ];
      extensions = [ ".py" ];
    };
    taplo = {
      command = [
        (lib.getExe pkgs.taplo)
        "format"
        "$FILE"
      ];
      extensions = [ ".toml" ];
    };
    stylua = {
      command = [
        (lib.getExe pkgs.stylua)
        "$FILE"
      ];
      extensions = [ ".lua" ];
    };
  };

  opencodeConfig = {
    "$schema" = "https://opencode.ai/config.json";
    lsp = true;
    formatter = formatters;
    disabled_providers = [ "opencode" ];
    provider.halo = {
      npm = "@ai-sdk/openai-compatible";
      name = "Halo";
      options.baseURL = "http://halo:8000/v1";
      models.coder.name = "coder";
    };
  };

  obsidianSkills =
    lib.mapAttrs'
      (
        name: _:
        lib.nameValuePair ".agents/skills/${name}" {
          source = "${inputs.obsidian-skills}/skills/${name}";
          recursive = true;
        }
      )
      (
        lib.filterAttrs (_: type: type == "directory") (builtins.readDir "${inputs.obsidian-skills}/skills")
      );
in
{
  options.metacfg.cli-apps.opencode = {
    enable = mkBoolOpt true "Enable opencode config.";
  };

  config = mkIf cfg.enable {
    # Also expose the formatters on PATH for interactive use.
    home.packages = [
      pkgs.nixfmt-rfc-style
      pkgs.nodePackages.prettier
      pkgs.shfmt
      pkgs.ruff
      pkgs.taplo
      pkgs.stylua
    ];

    # The agents/, commands/ and other files come from the repo dir; config.json
    # is generated from opencodeConfig above so formatter paths stay pinned.
    xdg.configFile."opencode" = {
      source = ../../../../config/opencode;
      recursive = true;
    };

    xdg.configFile."opencode/config.json".source =
      (pkgs.formats.json { }).generate "opencode-config.json" opencodeConfig;

    home.file = {
      ".agents/skills" = {
        source = ../../../../config/agents/skills;
        recursive = true;
      };
    }
    // obsidianSkills;
  };
}