pi-coding-agent: add module

modules/misc/news/2026/06/2026-06-02_12-00-00.nix

@@ -0,0 +1,15 @@
+{ config, ... }:
+{
+  time = "2026-06-02T12:00:00+00:00";
+  condition = config.programs.pi-coding-agent.enable;
+  message = ''
+    A new module is available: `programs.pi-coding-agent`.
+
+    The module supports declarative configuration of Pi Coding Agent
+    including settings, keybindings, models, and global context
+    (AGENTS.md).
+
+    For MCP server support, use the existing `programs.mcp` module
+    which writes to `~/.config/mcp/mcp.json`.
+  '';
+}

modules/programs/pi-coding-agent.nix

@@ -0,0 +1,223 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+let
+  inherit (lib)
+    literalExpression
+    mkEnableOption
+    mkIf
+    mkOption
+    mkPackageOption
+    ;
+
+  cfg = config.programs.pi-coding-agent;
+
+  jsonFormat = pkgs.formats.json { };
+
+  isPathLike =
+    content:
+    lib.isPath content
+    || (builtins.isString content && lib.hasPrefix "${builtins.storeDir}/" content)
+    || lib.isDerivation content;
+
+  upstreamConfigDir = "${config.home.homeDirectory}/.pi/agent";
+
+  packageWithExtraPackages =
+    if cfg.package != null && cfg.extraPackages != [ ] then
+      pkgs.symlinkJoin {
+        inherit (cfg.package) meta;
+        name = "${lib.getName cfg.package}-wrapped-${lib.getVersion cfg.package}";
+        paths = [ cfg.package ];
+        preferLocalBuild = true;
+        nativeBuildInputs = [ pkgs.makeWrapper ];
+        postBuild = ''
+          wrapProgram $out/bin/pi \
+            --suffix PATH : ${lib.makeBinPath cfg.extraPackages}
+        '';
+      }
+    else
+      cfg.package;
+in
+{
+  meta.maintainers = with lib.hm.maintainers; [ semi710 ];
+
+  options.programs.pi-coding-agent = {
+    enable = mkEnableOption "pi-coding-agent";
+
+    package = mkPackageOption pkgs "pi-coding-agent" { nullable = true; };
+
+    extraPackages = mkOption {
+      type = with lib.types; listOf package;
+      default = [ ];
+      example = literalExpression "[ pkgs.nodejs pkgs.bun ]";
+      description = ''
+        Extra packages available to Pi Coding Agent.
+        These are added to the PATH of the wrapped pi binary.
+
+        Needed for packages installed by pi (e.g.
+        {command}`npm:@termdraw/pi` requires {command}`npm` and
+        {command}`bun`).
+      '';
+    };
+
+    configDir = mkOption {
+      type = lib.types.str;
+      default = upstreamConfigDir;
+      defaultText = literalExpression ''"''${config.home.homeDirectory}/.pi/agent"'';
+      example = literalExpression ''"''${config.xdg.configHome}/pi/agent"'';
+      description = ''
+        Directory holding Pi Coding Agent's configuration files.
+
+        Defaults to {file}`~/.pi/agent`, matching the upstream
+        {command}`pi` CLI default. The {env}`PI_CODING_AGENT_DIR`
+        environment variable is exported automatically whenever the
+        directory differs from this default so the CLI reads
+        configuration from the same location.
+      '';
+    };
+
+    settings = mkOption {
+      inherit (jsonFormat) type;
+      default = { };
+      example = {
+        defaultProvider = "anthropic";
+        defaultModel = "claude-sonnet-4-20250514";
+        defaultThinkingLevel = "medium";
+        theme = "dark";
+        packages = [
+          "npm:@termdraw/pi"
+          "npm:pi-mcp-adapter"
+        ];
+        compaction = {
+          enabled = true;
+          reserveTokens = 16384;
+          keepRecentTokens = 20000;
+        };
+        retry = {
+          enabled = true;
+          maxRetries = 3;
+        };
+        enabledModels = [
+          "claude-*"
+          "gpt-4o"
+        ];
+      };
+      description = ''
+        Configuration written to
+        {file}`~/.pi/agent/settings.json`.
+        See <https://pi.dev/docs/latest/settings> for the
+        documentation.
+      '';
+    };
+
+    keybindings = mkOption {
+      inherit (jsonFormat) type;
+      default = { };
+      example = {
+        "tui.editor.cursorUp" = [
+          "up"
+          "ctrl+p"
+        ];
+        "tui.editor.cursorDown" = [
+          "down"
+          "ctrl+n"
+        ];
+        "tui.editor.deleteWordBackward" = [
+          "ctrl+w"
+          "alt+backspace"
+        ];
+      };
+      description = ''
+        Keybindings configuration written to
+        {file}`~/.pi/agent/keybindings.json`.
+        See <https://pi.dev/docs/latest/keybindings> for the
+        documentation.
+      '';
+    };
+
+    models = mkOption {
+      inherit (jsonFormat) type;
+      default = { };
+      example = {
+        providers = {
+          ollama = {
+            baseUrl = "http://localhost:11434/v1";
+            api = "openai-completions";
+            apiKey = "ollama";
+            models = [ { id = "llama3.1:8b"; } ];
+          };
+        };
+      };
+      description = ''
+        Custom model providers written to
+        {file}`~/.pi/agent/models.json`.
+
+        Each provider entry may contain `baseUrl`,
+        `api`, `apiKey`, `compat`, and a `models`
+        list with `id`, `name`, `reasoning`, etc.
+
+        See <https://pi.dev/docs/latest/models> for the
+        documentation.
+      '';
+    };
+
+    context = mkOption {
+      type = lib.types.either lib.types.lines lib.types.path;
+      default = "";
+      description = ''
+        Global context for Pi Coding Agent.
+
+        The value is either:
+        - Inline content as a string
+        - A path to a file containing the content
+
+        The configured content is written to
+        {file}`AGENTS.md` inside
+        {option}`programs.pi-coding-agent.configDir`
+        (default {file}`~/.pi/agent/AGENTS.md`).
+      '';
+      example = literalExpression "./pi-context.md";
+    };
+  };
+
+  config = mkIf cfg.enable {
+    home = {
+      packages = mkIf (packageWithExtraPackages != null) [
+        packageWithExtraPackages
+      ];
+
+      sessionVariables = lib.mkIf (cfg.configDir != upstreamConfigDir) {
+        PI_CODING_AGENT_DIR = cfg.configDir;
+      };
+
+      file = lib.mkMerge [
+        (mkIf (cfg.settings != { }) {
+          "${cfg.configDir}/settings.json".source =
+            jsonFormat.generate "pi-coding-agent-settings.json" cfg.settings;
+        })
+
+        (mkIf (cfg.keybindings != { }) {
+          "${cfg.configDir}/keybindings.json".source =
+            jsonFormat.generate "pi-coding-agent-keybindings.json" cfg.keybindings;
+        })
+
+        (mkIf (cfg.models != { }) {
+          "${cfg.configDir}/models.json".source =
+            jsonFormat.generate "pi-coding-agent-models.json" cfg.models;
+        })
+
+        (
+          if isPathLike cfg.context then
+            { "${cfg.configDir}/AGENTS.md".source = cfg.context; }
+          else
+            (mkIf (cfg.context != "") {
+              "${cfg.configDir}/AGENTS.md".text = cfg.context;
+            })
+        )
+      ];
+    };
+  };
+}

tests/modules/programs/pi-coding-agent/context-empty.nix

@@ -0,0 +1,9 @@
+{
+  programs.pi-coding-agent = {
+    enable = true;
+    context = "";
+  };
+  nmt.script = ''
+    assertPathNotExists home-files/.pi/agent/AGENTS.md
+  '';
+}

tests/modules/programs/pi-coding-agent/context-inline.md

@@ -0,0 +1,4 @@
+# Global Pi Context
+
+Always use TypeScript strict mode.
+Follow the project's existing code style.

tests/modules/programs/pi-coding-agent/context-inline.nix

@@ -0,0 +1,16 @@
+{
+  programs.pi-coding-agent = {
+    enable = true;
+    context = ''
+      # Global Pi Context
+
+      Always use TypeScript strict mode.
+      Follow the project's existing code style.
+    '';
+  };
+  nmt.script = ''
+    assertFileExists home-files/.pi/agent/AGENTS.md
+    assertFileContent home-files/.pi/agent/AGENTS.md \
+      ${./context-inline.md}
+  '';
+}

tests/modules/programs/pi-coding-agent/context-path.nix

@@ -0,0 +1,11 @@
+{
+  programs.pi-coding-agent = {
+    enable = true;
+    context = ./context-inline.md;
+  };
+  nmt.script = ''
+    assertFileExists home-files/.pi/agent/AGENTS.md
+    assertFileContent home-files/.pi/agent/AGENTS.md \
+      ${./context-inline.md}
+  '';
+}

tests/modules/programs/pi-coding-agent/custom-config-dir.nix

@@ -0,0 +1,11 @@
+{
+  programs.pi-coding-agent = {
+    enable = true;
+    configDir = "/home/testuser/.config/pi/agent";
+  };
+  nmt.script = ''
+    # Verify env var is set for non-default configDir
+    assertFileRegex home-path/etc/profile.d/hm-session-vars.sh \
+      'PI_CODING_AGENT_DIR'
+  '';
+}

tests/modules/programs/pi-coding-agent/default.nix

@@ -0,0 +1,10 @@
+{
+  pi-coding-agent-settings = ./settings.nix;
+  pi-coding-agent-empty-settings = ./empty-settings.nix;
+  pi-coding-agent-keybindings = ./keybindings.nix;
+  pi-coding-agent-context-inline = ./context-inline.nix;
+  pi-coding-agent-context-path = ./context-path.nix;
+  pi-coding-agent-context-empty = ./context-empty.nix;
+  pi-coding-agent-custom-config-dir = ./custom-config-dir.nix;
+  pi-coding-agent-models = ./models.nix;
+}

tests/modules/programs/pi-coding-agent/empty-settings.nix

@@ -0,0 +1,9 @@
+{
+  programs.pi-coding-agent = {
+    enable = true;
+    settings = { };
+  };
+  nmt.script = ''
+    assertPathNotExists home-files/.pi/agent/settings.json
+  '';
+}

tests/modules/programs/pi-coding-agent/keybindings.json

@@ -0,0 +1,14 @@
+{
+  "tui.editor.cursorDown": [
+    "down",
+    "ctrl+n"
+  ],
+  "tui.editor.cursorUp": [
+    "up",
+    "ctrl+p"
+  ],
+  "tui.editor.deleteWordBackward": [
+    "ctrl+w",
+    "alt+backspace"
+  ]
+}

tests/modules/programs/pi-coding-agent/keybindings.nix

@@ -0,0 +1,24 @@
+{
+  programs.pi-coding-agent = {
+    enable = true;
+    keybindings = {
+      "tui.editor.cursorUp" = [
+        "up"
+        "ctrl+p"
+      ];
+      "tui.editor.cursorDown" = [
+        "down"
+        "ctrl+n"
+      ];
+      "tui.editor.deleteWordBackward" = [
+        "ctrl+w"
+        "alt+backspace"
+      ];
+    };
+  };
+  nmt.script = ''
+    assertFileExists home-files/.pi/agent/keybindings.json
+    assertFileContent home-files/.pi/agent/keybindings.json \
+      ${./keybindings.json}
+  '';
+}

tests/modules/programs/pi-coding-agent/models.json

@@ -0,0 +1,14 @@
+{
+  "providers": {
+    "litellm": {
+      "api": "openai-completions",
+      "apiKey": "ollama",
+      "baseUrl": "http://localhost:11434/v1",
+      "models": [
+        {
+          "id": "llama3.1:8b"
+        }
+      ]
+    }
+  }
+}

tests/modules/programs/pi-coding-agent/models.nix

@@ -0,0 +1,20 @@
+{
+  programs.pi-coding-agent = {
+    enable = true;
+    models = {
+      providers = {
+        litellm = {
+          baseUrl = "http://localhost:11434/v1";
+          api = "openai-completions";
+          apiKey = "ollama";
+          models = [ { id = "llama3.1:8b"; } ];
+        };
+      };
+    };
+  };
+  nmt.script = ''
+    assertFileExists home-files/.pi/agent/models.json
+    assertFileContent home-files/.pi/agent/models.json \
+      ${./models.json}
+  '';
+}

tests/modules/programs/pi-coding-agent/settings.json

@@ -0,0 +1,19 @@
+{
+  "compaction": {
+    "enabled": true,
+    "keepRecentTokens": 20000,
+    "reserveTokens": 16384
+  },
+  "defaultModel": "claude-sonnet-4-20250514",
+  "defaultProvider": "anthropic",
+  "defaultThinkingLevel": "medium",
+  "enabledModels": [
+    "claude-*",
+    "gpt-4o"
+  ],
+  "retry": {
+    "enabled": true,
+    "maxRetries": 3
+  },
+  "theme": "dark"
+}

tests/modules/programs/pi-coding-agent/settings.nix

@@ -0,0 +1,29 @@
+{
+  programs.pi-coding-agent = {
+    enable = true;
+    settings = {
+      defaultProvider = "anthropic";
+      defaultModel = "claude-sonnet-4-20250514";
+      defaultThinkingLevel = "medium";
+      theme = "dark";
+      compaction = {
+        enabled = true;
+        reserveTokens = 16384;
+        keepRecentTokens = 20000;
+      };
+      retry = {
+        enabled = true;
+        maxRetries = 3;
+      };
+      enabledModels = [
+        "claude-*"
+        "gpt-4o"
+      ];
+    };
+  };
+  nmt.script = ''
+    assertFileExists home-files/.pi/agent/settings.json
+    assertFileContent home-files/.pi/agent/settings.json \
+      ${./settings.json}
+  '';
+}