home-manager/modules/programs/claude-code.nix

{
  config,
  lib,
  pkgs,
  ...
}:
let
  cfg = config.programs.claude-code;
  jsonFormat = pkgs.formats.json { };
in
{
  meta.maintainers = [ lib.maintainers.khaneliman ];

  options.programs.claude-code = {
    enable = lib.mkEnableOption "Claude Code, Anthropic's official CLI";

    package = lib.mkPackageOption pkgs "claude-code" { nullable = true; };

    finalPackage = lib.mkOption {
      type = lib.types.package;
      readOnly = true;
      internal = true;
      description = "Resulting customized claude-code package.";
    };

    settings = lib.mkOption {
      inherit (jsonFormat) type;
      default = { };
      example = {
        theme = "dark";
        permissions = {
          allow = [
            "Bash(git diff:*)"
            "Edit"
          ];
          ask = [ "Bash(git push:*)" ];
          deny = [
            "WebFetch"
            "Bash(curl:*)"
            "Read(./.env)"
            "Read(./secrets/**)"
          ];
          additionalDirectories = [ "../docs/" ];
          defaultMode = "acceptEdits";
          disableBypassPermissionsMode = "disable";
        };
        model = "claude-3-5-sonnet-20241022";
        hooks = {
          PreToolUse = [
            {
              matcher = "Bash";
              hooks = [
                {
                  type = "command";
                  command = "echo 'Running command: $CLAUDE_TOOL_INPUT'";
                }
              ];
            }
          ];
          PostToolUse = [
            {
              matcher = "Edit|MultiEdit|Write";
              hooks = [
                {
                  type = "command";
                  command = "nix fmt $(jq -r '.tool_input.file_path' <<< '$CLAUDE_TOOL_INPUT')";
                }
              ];
            }
          ];
        };
        statusLine = {
          type = "command";
          command = "input=$(cat); echo \"[$(echo \"$input\" | jq -r '.model.display_name')] 📁 $(basename \"$(echo \"$input\" | jq -r '.workspace.current_dir')\")\"";
          padding = 0;
        };
        includeCoAuthoredBy = false;
      };
      description = "JSON configuration for Claude Code settings.json";
    };

    agents = lib.mkOption {
      type = lib.types.attrsOf (lib.types.either lib.types.lines lib.types.path);
      default = { };
      description = ''
        Custom agents for Claude Code.
        The attribute name becomes the agent filename, and the value is either:
        - Inline content as a string with frontmatter
        - A path to a file containing the agent content with frontmatter
        Agents are stored in .claude/agents/ directory.
      '';
      example = lib.literalExpression ''
        {
          code-reviewer = '''
            ---
            name: code-reviewer
            description: Specialized code review agent
            tools: Read, Edit, Grep
            ---

            You are a senior software engineer specializing in code reviews.
            Focus on code quality, security, and maintainability.
          ''';
          documentation = ./agents/documentation.md;
        }
      '';
    };

    commands = lib.mkOption {
      type = lib.types.attrsOf (lib.types.either lib.types.lines lib.types.path);
      default = { };
      description = ''
        Custom commands for Claude Code.
        The attribute name becomes the command filename, and the value is either:
        - Inline content as a string
        - A path to a file containing the command content
        Commands are stored in .claude/commands/ directory.
      '';
      example = lib.literalExpression ''
        {
          changelog = '''
            ---
            allowed-tools: Bash(git log:*), Bash(git diff:*)
            argument-hint: [version] [change-type] [message]
            description: Update CHANGELOG.md with new entry
            ---
            Parse the version, change type, and message from the input
            and update the CHANGELOG.md file accordingly.
          ''';
          fix-issue = ./commands/fix-issue.md;
          commit = '''
            ---
            allowed-tools: Bash(git add:*), Bash(git status:*), Bash(git commit:*)
            description: Create a git commit with proper message
            ---
            ## Context

            - Current git status: !`git status`
            - Current git diff: !`git diff HEAD`
            - Recent commits: !`git log --oneline -5`

            ## Task

            Based on the changes above, create a single atomic git commit with a descriptive message.
          ''';
        }
      '';
    };

    hooks = lib.mkOption {
      type = lib.types.attrsOf lib.types.lines;
      default = { };
      description = ''
        Custom hooks for Claude Code.
        The attribute name becomes the hook filename, and the value is the hook script content.
        Hooks are stored in .claude/hooks/ directory.
      '';
      example = {
        pre-edit = ''
          #!/usr/bin/env bash
          echo "About to edit file: $1"
        '';
        post-commit = ''
          #!/usr/bin/env bash
          echo "Committed with message: $1"
        '';
      };
    };

    memory = {
      text = lib.mkOption {
        type = lib.types.nullOr lib.types.lines;
        default = null;
        description = ''
          Inline memory content for CLAUDE.md.
          This option is mutually exclusive with memory.source.
        '';
        example = ''
          # Project Memory

          ## Current Task
          Implementing enhanced claude-code module for home-manager.

          ## Key Files
          - claude-code.nix: Main module implementation
        '';
      };

      source = lib.mkOption {
        type = lib.types.nullOr lib.types.path;
        default = null;
        description = ''
          Path to a file containing memory content for CLAUDE.md.
          This option is mutually exclusive with memory.text.
        '';
        example = lib.literalExpression "./claude-memory.md";
      };
    };

    agentsDir = lib.mkOption {
      type = lib.types.nullOr lib.types.path;
      default = null;
      description = ''
        Path to a directory containing agent files for Claude Code.
        Agent files from this directory will be symlinked to .claude/agents/.
      '';
      example = lib.literalExpression "./agents";
    };

    commandsDir = lib.mkOption {
      type = lib.types.nullOr lib.types.path;
      default = null;
      description = ''
        Path to a directory containing command files for Claude Code.
        Command files from this directory will be symlinked to .claude/commands/.
      '';
      example = lib.literalExpression "./commands";
    };

    hooksDir = lib.mkOption {
      type = lib.types.nullOr lib.types.path;
      default = null;
      description = ''
        Path to a directory containing hook files for Claude Code.
        Hook files from this directory will be symlinked to .claude/hooks/.
      '';
      example = lib.literalExpression "./hooks";
    };

    mcpServers = lib.mkOption {
      type = lib.types.attrsOf jsonFormat.type;
      default = { };
      description = "MCP (Model Context Protocol) servers configuration";
      example = {
        github = {
          type = "http";
          url = "https://api.githubcopilot.com/mcp/";
        };
        filesystem = {
          type = "stdio";
          command = "npx";
          args = [
            "-y"
            "@modelcontextprotocol/server-filesystem"
            "/tmp"
          ];
        };
        database = {
          type = "stdio";
          command = "npx";
          args = [
            "-y"
            "@bytebase/dbhub"
            "--dsn"
            "postgresql://user:pass@localhost:5432/db"
          ];
          env = {
            DATABASE_URL = "postgresql://user:pass@localhost:5432/db";
          };
        };
        customTransport = {
          type = "websocket";
          url = "wss://example.com/mcp";
          customOption = "value";
          timeout = 5000;
        };
      };
    };
  };

  config = lib.mkIf cfg.enable {
    assertions = [
      {
        assertion = cfg.mcpServers == { } || cfg.package != null;
        message = "`programs.claude-code.package` cannot be null when `mcpServers` is configured";
      }
      {
        assertion = !(cfg.memory.text != null && cfg.memory.source != null);
        message = "Cannot specify both `programs.claude-code.memory.text` and `programs.claude-code.memory.source`";
      }
      {
        assertion = !(cfg.agents != { } && cfg.agentsDir != null);
        message = "Cannot specify both `programs.claude-code.agents` and `programs.claude-code.agentsDir`";
      }
      {
        assertion = !(cfg.commands != { } && cfg.commandsDir != null);
        message = "Cannot specify both `programs.claude-code.commands` and `programs.claude-code.commandsDir`";
      }
      {
        assertion = !(cfg.hooks != { } && cfg.hooksDir != null);
        message = "Cannot specify both `programs.claude-code.hooks` and `programs.claude-code.hooksDir`";
      }
    ];

    programs.claude-code.finalPackage =
      let
        makeWrapperArgs = lib.flatten (
          lib.filter (x: x != [ ]) [
            (lib.optional (cfg.mcpServers != { }) [
              "--add-flags"
              "--mcp-config ${jsonFormat.generate "claude-code-mcp-config.json" { inherit (cfg) mcpServers; }}"
            ])
          ]
        );

        hasWrapperArgs = makeWrapperArgs != [ ];
      in
      if hasWrapperArgs then
        pkgs.symlinkJoin {
          name = "claude-code";
          paths = [ cfg.package ];
          nativeBuildInputs = [ pkgs.makeWrapper ];
          postBuild = ''
            wrapProgram $out/bin/claude ${lib.escapeShellArgs makeWrapperArgs}
          '';
          inherit (cfg.package) meta;
        }
      else
        cfg.package;

    home = {
      packages = lib.mkIf (cfg.package != null) [ cfg.finalPackage ];

      file = {
        ".claude/settings.json" = lib.mkIf (cfg.settings != { }) {
          source = jsonFormat.generate "claude-code-settings.json" (
            cfg.settings
            // {
              "$schema" = "https://json.schemastore.org/claude-code-settings.json";
            }
          );
        };

        ".claude/CLAUDE.md" = lib.mkIf (cfg.memory.text != null || cfg.memory.source != null) (
          if cfg.memory.text != null then { text = cfg.memory.text; } else { source = cfg.memory.source; }
        );

        ".claude/agents" = lib.mkIf (cfg.agentsDir != null) {
          source = cfg.agentsDir;
          recursive = true;
        };

        ".claude/commands" = lib.mkIf (cfg.commandsDir != null) {
          source = cfg.commandsDir;
          recursive = true;
        };

        ".claude/hooks" = lib.mkIf (cfg.hooksDir != null) {
          source = cfg.hooksDir;
          recursive = true;
        };
      }
      // lib.mapAttrs' (
        name: content:
        lib.nameValuePair ".claude/agents/${name}.md" (
          if lib.isPath content then { source = content; } else { text = content; }
        )
      ) cfg.agents
      // lib.mapAttrs' (
        name: content:
        lib.nameValuePair ".claude/commands/${name}.md" (
          if lib.isPath content then { source = content; } else { text = content; }
        )
      ) cfg.commands
      // lib.mapAttrs' (
        name: content:
        lib.nameValuePair ".claude/hooks/${name}" {
          text = content;
        }
      ) cfg.hooks;
    };
  };
}