refactor: remove dead code, extract shared agent options, optimize flake

- Remove dead overlays/default.nix (flake defines overlays inline)
- Remove orphaned overlays/mods/{beads,n8n}.nix (never imported)
- Remove docs/packages/notesmd-cli.md (package doesn't exist)
- Extract externalSkills submodule to shared-options.nix (eliminates
  ~100 lines of duplication across opencode/claude-code/pi modules)
- Fix lib output: use nixpkgs.lib directly instead of instantiating
  a full nixpkgs just to get lib
- Add lib unit tests to flake checks
- Update stale comment in coding-rules.nix

.gitignore

@@ -43,3 +43,5 @@ flake.lock.bak
 .sidecar-start.sh
 .sidecar-base
 .td-root
+.pi-lens
+.cache

AGENTS.md

@@ -1,10 +1,5 @@
 # m3ta-nixpkgs Knowledge Base
 
-## MANDATORY: Use td for Task Management
-
-You must run td usage --new-session at conversation start (or after /clear) to see current work.
-Use td usage -q for subsequent reads.
-
 **Generated:** 2026-02-14
 **Commit:** dc2f3b6
 **Branch:** master
@@ -114,8 +109,8 @@ Port management utilities. See [Port Management](#port-management).
 
 ### `lib.agents`
 
-Harness-agnostic agent management. Reads canonical `agent.toml` from the AGENTS
-flake input and renders tool-specific configs.
+Harness-agnostic agent management. Reads canonical `agent.toml` +
+`system-prompt.md` from the AGENTS flake input and renders tool-specific configs.
 
 **Functions:**
 
@@ -124,17 +119,18 @@ flake input and renders tool-specific configs.
 | `loadCanonical { agentsInput }` | Load canonical agents from AGENTS flake |
 | `renderForOpencode { pkgs, canonical, modelOverrides }` | Render to OpenCode file-based agents |
 | `renderForClaudeCode { pkgs, canonical, modelOverrides }` | Render to Claude Code agents + settings.json |
-| `renderForPi { pkgs, canonical }` | Render to Pi AGENTS.md + SYSTEM.md |
-| `renderForTool { pkgs, agentsInput, tool, modelOverrides }` | Dispatch to correct renderer |
-| `shellHookForTool { pkgs, agentsInput, tool, modelOverrides }` | Generate devShell shellHook |
+| `renderForPi { pkgs, canonical, modelOverrides, primaryAgent }` | Render to Pi AGENTS.md + SYSTEM.md + agents/ |
+| `renderForTool { pkgs, agentsInput, tool, modelOverrides }` | Dispatch to correct renderer by tool name |
+| `shellHookForTool { pkgs, agentsInput, tool, modelOverrides }` | Generate devShell shellHook (symlinks rendered files) |
 
 ### `lib.coding-rules`
 
-Coding rules injection (renamed from `lib.opencode-rules`). The old name still works.
+Coding rules injection. Generates `coding-rules.json` + symlinks rules from
+the AGENTS repository. The old `lib.opencode-rules` name still works.
 
 | Function | Purpose |
 |----------|--------|
-| `mkCodingRules { agents, languages, concerns, frameworks }` | Generate rules config + shellHook |
+| `mkCodingRules { agents, languages, concerns, frameworks, rulesDir }` | Generate rules config + shellHook. `rulesDir` defaults to `.opencode-rules` |
 | `mkOpencodeRules` | Backward-compat alias for `mkCodingRules` |
 
 ## PORT MANAGEMENT
@@ -188,38 +184,34 @@ Types: `feat`, `fix`, `docs`, `style`, `refactor`, `chore`
 
 ## Task Management
 
-This project uses **td** for tracking tasks across AI coding sessions.
-Run `td usage --new-session` at conversation start to see current work.
-Use `td usage -q` for subsequent reads.
+**td** is an optional task-tracking package. See `docs/packages/td.md` for details.
 
-**Quick reference:**
+## Agent System Architecture
 
-- `td usage --new-session` - Start new session and view tasks
-- `td usage -q` - Quick view of current tasks (subsequent reads)
-- `td version` - Check version
+The agent system uses harness-agnostic canonical definitions stored as
+`agent.toml` + `system-prompt.md` in the AGENTS repository. Renderers in
+`lib/agents.nix` transform these into tool-specific configs at build time.
 
-For full workflow details, see the [td documentation](./docs/packages/td.md).
+### How it works
 
-## MIGRATION: Agent System (OpenCode → Canonical TOML)
+1. **Canonical definitions** live in the AGENTS repo as `agent.toml` files
+   (one per agent) with shared fields: name, description, mode, systemPrompt,
+   permissions, skills.
+2. **`loadCanonical`** reads all agent definitions from the AGENTS flake input.
+3. **Renderers** produce tool-specific output:
+   - `renderForOpencode` → `*.md` files with YAML frontmatter for `.opencode/agents/`
+   - `renderForClaudeCode` → `.claude/agents/*.md` + `.claude/settings.json` with permission rules
+   - `renderForPi` → `AGENTS.md`, `SYSTEM.md`, `agents/*.md` for Pi's subagent format
+4. **`renderForTool`** dispatches to the correct renderer by tool name
+   (`"opencode"`, `"claude-code"`, or `"pi"`).
+5. **`shellHookForTool`** generates a devShell shellHook that symlinks rendered
+   files into the project directory.
+6. **HM modules** in `modules/home-manager/coding/agents/` handle per-tool
+   Home Manager integration.
 
-The agent system was migrated from embedded `agents.json` to harness-agnostic
-canonical `agent.toml` + `system-prompt.md` in the AGENTS repo. Renderers in
-`lib/agents.nix` generate tool-specific configs.
+### Key files in this repo
 
-### What changed in this repo
-
-- **`lib/agents.nix`**: New — 3 renderers (OpenCode, Claude Code, Pi) + dispatcher + shellHook
-- **`lib/coding-rules.nix`**: Renamed from `opencode-rules.nix`, `mkCodingRules` replaces `mkOpencodeRules`
-- **`modules/home-manager/coding/agents/`**: New — per-tool HM sub-modules
-- **`modules/home-manager/coding/opencode.nix`**: Slimmed — no longer handles agents/skills/context
-- **`flake.nix`**: Exports new `agents` HM module
-
-### What the user must do
-
-See `modules/home-manager/AGENTS.md` for the full migration guide. Summary:
-
-1. Move `agentsInput`/`externalSkills` from `coding.opencode` to `coding.agents.opencode`
-2. Add `modelOverrides` with previously hardcoded model strings
-3. Run `home-manager switch`
-4. Remove legacy `agents.json` + `prompts/*.txt` from AGENTS repo
-5. Remove `lib.agentsJson` backward-compat bridge from AGENTS `flake.nix`
+- `lib/agents.nix` — renderers, dispatcher, shellHook generator
+- `lib/coding-rules.nix` — coding rules injection (`mkCodingRules`)
+- `modules/home-manager/coding/agents/` — per-tool HM sub-modules (opencode, claude-code, pi)
+- `modules/home-manager/coding/opencode.nix` — OpenCode HM module (slimmed, agents handled separately)

CHANGELOG.md

@@ -0,0 +1,107 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+The format is based on [Keep a Changelog](https://keepachangelog.com/).
+
+## [Unreleased]
+
+### Changed
+- Remove duplicate opencode-rules.nix (backward-compat alias preserved)
+- Tool-agnostic naming in coding-rules lib internals
+- Remove redundant overlay entries for non-existent flake inputs
+- Remove redundant 'additions' overlay (identical to 'default')
+
+### Removed
+- Dead overlay entries for non-existent flake inputs
+
+## [0.4.0] - 2026-04-15
+
+### Added
+- Pi-agent wrapper with systemd sandbox and per-host-user policy
+- Containerized Pi agent
+- `lib.agents.nix` with loadCanonical, renderers (OpenCode, Claude Code, Pi), and shellHook
+- `lib.coding-rules` helper for per-project rule injection (renamed from opencode-rules)
+- Home Manager modules for coding agents: `claude-code`, `opencode`, `pi`
+- Agents rework with canonical TOML format and harness-agnostic renderers
+- `vibetyper` and `eigent` packages
+- `openspec` package
+- `basecamp-cli` package
+- `openshell` package (0.0.14 through 0.0.23)
+- `openwork` package
+- Opencode config moved into m3ta-nixpkgs
+- Opencode dev shell with mkCodingRules demo
+
+### Changed
+- OpenCode flake input updated through v1.1.65 to v1.3.6
+- Switched from local opencode package to upstream flake input
+- Removed opencode-desktop (awaiting upstream fix), later re-enabled
+- Nix eval warnings resolved
+- Flake inputs updated throughout
+
+### Fixed
+- Pi settings sync
+- Remove openwork sidecars in preFixup to prevent .opencode-wrapped conflict
+- Remove sidecar binaries from openwork $out/bin to fix buildEnv conflict
+- Vibetyper .desktop entry
+- Opencode module formatting
+- Formatting opencode module
+
+## [0.3.0] - 2026-02-20
+
+### Added
+- `notesmd-cli` package with flake checks
+- `sidecar` and `td` packages
+- `opencode-desktop` package with Wayland support
+- `mem0` package (1.0.2 through 1.0.9)
+- `kestracli` / `kestractl` package (1.0.0 to 1.2.2)
+
+### Changed
+- Nix-update CI workflow optimized with caching and parallel processing
+- Restructured n8n version handling for nix-update compatibility
+- Switched formatter from nixpkgs-fmt to alejandra
+- Replace local opencode with upstream flake input v1.1.27
+
+### Fixed
+- n8n build error
+- n8n pnpm hash
+- n8n update script
+- Gitea runner opencode.url flake input
+- nix-update workflow: YAML syntax, jobs indentation, PR body formatting
+- Arithmetic increment failing with set -e in nix-update workflow
+- Removed magic-nix-cache-action causing platform mapping error
+- Opencode bun version requirement patched to match upstream lockfile
+- Deprecated opencode update logic removed
+- nix fmt without arg in workflow
+- Extra Lua config renamed initLua
+- Stt-ptt use pkill for better process management
+
+## [0.2.0] - 2026-01-13
+
+### Added
+- Gitea Actions workflow for automated package updates with nix-update
+- `n8n`, `beads`, and `opencode` packages
+- `stt-ptt` package with auto-language detection
+- `rofi-project-opener` for rofi-based project launching
+- Hierarchical AGENTS.md knowledge base
+- Dev shell structure with python and devops shells
+- Port management modules (NixOS + Home Manager)
+- Port helper library (`lib/ports.nix`)
+
+### Changed
+- Beads updated through v0.49.1
+- N8n updated through v2.8.1
+- Opencode updated through v1.1.18
+- Documentation expanded with comprehensive patterns and HM module docs
+
+### Fixed
+- Python env version fix for marimo
+
+## [0.1.0] - 2025-10-04
+
+### Added
+- Initial flake setup with packages, overlays, modules, and shells
+- NixOS and Home Manager module infrastructure
+- `lib/` shared utilities
+- `overlays/mods/` for package modifications
+- `templates/` for new packages/modules
+- `examples/` for usage documentation

docs/packages/notesmd-cli.md

@@ -1,117 +0,0 @@
-# notesmd-cli
-
-Obsidian CLI (Community) - Interact with Obsidian in the terminal.
-
-## Description
-
-notesmd-cli is a command-line interface for interacting with Obsidian, the popular knowledge management and note-taking application. It allows you to create, search, and manipulate notes directly from the terminal.
-
-## Features
-
-- 📝 **Note Creation**: Create new notes from the command line
-- 🔍 **Search**: Search through your Obsidian vault
-- 📂 **Vault Management**: Interact with your vault structure
-- 🔗 **WikiLink Support**: Work with Obsidian's WikiLink format
-- 🏷️ **Tag Support**: Manage and search by tags
-- ⚡ **Fast**: Lightweight Go binary with no external dependencies
-
-## Installation
-
-### Via Overlay
-
-```nix
-{pkgs, ...}: {
-  environment.systemPackages = with pkgs; [
-    notesmd-cli
-  ];
-}
-```
-
-### Direct Reference
-
-```nix
-{pkgs, ...}: {
-  environment.systemPackages = with pkgs; [
-    inputs.m3ta-nixpkgs.packages.${pkgs.system}.notesmd-cli
-  ];
-}
-```
-
-### Run Directly
-
-```bash
-nix run git+https://code.m3ta.dev/m3tam3re/nixpkgs#notesmd-cli
-```
-
-## Usage
-
-### Basic Commands
-
-```bash
-# Show help
-notesmd-cli --help
-
-# Create a new note
-notesmd-cli new "My Note Title"
-
-# Search notes
-notesmd-cli search "search term"
-
-# List notes
-notesmd-cli list
-```
-
-### Working with Vaults
-
-```bash
-# Specify vault path
-notesmd-cli --vault /path/to/vault new "Note Title"
-
-# Open a note in Obsidian
-notesmd-cli open "Note Name"
-```
-
-### Advanced Usage
-
-```bash
-# Search with tags
-notesmd-cli search --tag "project"
-
-# Append to existing note
-notesmd-cli append "Note Name" "Additional content"
-```
-
-## Configuration
-
-### Environment Variables
-
-- `OBSIDIAN_VAULT`: Default vault path
-
-### Command Line Options
-
-Run `notesmd-cli --help` for a complete list of options.
-
-## Build Information
-
-- **Version**: 0.3.0
-- **Language**: Go
-- **License**: MIT
-- **Source**: [GitHub](https://github.com/Yakitrak/notesmd-cli)
-- **Vendor Hash**: null (no external dependencies)
-
-## Platform Support
-
-- Linux
-- macOS (Unix systems)
-
-## Notes
-
-- No vendor dependencies (pure Go stdlib)
-- The binary is named `notesmd-cli` (not `notesmd`)
-- This is the community CLI, not the official Obsidian CLI
-
-## Related
-
-- [Obsidian](https://obsidian.md) - The Obsidian application
-- [Adding Packages](../guides/adding-packages.md) - How to add new packages
-- [Quick Start](../QUICKSTART.md) - Getting started guide

flake.nix

@@ -56,13 +56,6 @@
           inputs = inputs;
         };
 
-      # Individual overlays for more granular control
-      additions = final: prev:
-        import ./pkgs {
-          pkgs = final;
-          inputs = inputs;
-        };
-
       modifications = final: prev: import ./overlays/mods {inherit prev;};
     };
 
@@ -84,10 +77,7 @@
     };
 
     # Library functions - helper utilities for your configuration
-    lib = forAllSystems (system: let
-      pkgs = pkgsFor system;
-    in
-      import ./lib {lib = pkgs.lib;});
+    lib = forAllSystems (system: import ./lib {lib = nixpkgs.lib;});
 
     # Development shells for various programming environments
     # Usage: nix develop .#<shell-name>
@@ -111,6 +101,9 @@
           ${pkgs.alejandra}/bin/alejandra --check ${./.}
           touch $out
         '';
+        # Lib unit tests
+        lib-agents = import ./tests/lib/agents-test.nix;
+        lib-coding-rules = import ./tests/lib/coding-rules-test.nix;
       });
 
     # Templates for creating new packages/modules

lib/coding-rules.nix

@@ -1,4 +1,4 @@
-# Opencode rules management utilities
+# Coding rules management utilities
 #
 # This module provides functions to configure Opencode agent rules across
 # multiple projects. Rules are defined in the AGENTS repository and can be
@@ -26,7 +26,7 @@
 #
 # The shellHook creates:
 #   - A `.opencode-rules/` symlink pointing to the AGENTS repository rules directory
-#   - An `opencode.json` file with a $schema reference and instructions list
+#   - A `coding-rules.json` file with a $schema reference and instructions list
 #
 # The instructions list contains paths relative to the project root, all prefixed
 # with `.opencode-rules/`, making them portable across different project locations.
@@ -46,7 +46,7 @@
   #
   # Returns:
   #   An attribute set containing:
-  #     - shellHook: Bash code to create symlink and opencode.json
+  #     - shellHook: Bash code to create symlink and coding-rules.json
   #     - instructions: List of rule file paths (relative to project root)
   #
   # Example:
@@ -82,9 +82,8 @@
     ],
     frameworks ? [],
     extraInstructions ? [],
+    rulesDir ? ".opencode-rules",
   }: let
-    rulesDir = ".opencode-rules";
-
     # Build instructions list by mapping concerns, languages, frameworks to their file paths
     # All paths are relative to project root via the rulesDir symlink
     instructions =
@@ -93,8 +92,8 @@
       ++ (map (f: "${rulesDir}/frameworks/${f}.md") frameworks)
       ++ extraInstructions;
 
-    # Generate JSON configuration for Opencode
-    opencodeConfig = {
+    # Generate JSON configuration for coding rules
+    rulesConfig = {
       "$schema" = "https://opencode.ai/config.json";
       inherit instructions;
     };
@@ -102,15 +101,15 @@
     inherit instructions;
 
     # Shell hook to set up rules in the project
-    # Creates a symlink to the AGENTS rules directory and generates opencode.json
+    # Creates a symlink to the AGENTS rules directory and generates coding-rules.json
     shellHook = ''
       # Create/update symlink to AGENTS rules directory
       ln -sfn ${agents}/rules ${rulesDir}
 
-      # Generate opencode.json configuration file
-      cat > opencode.json <<'OPENCODE_EOF'
-      ${builtins.toJSON opencodeConfig}
-      OPENCODE_EOF
+      # Generate coding-rules.json configuration file
+      cat > coding-rules.json <<'RULES_EOF'
+      ${builtins.toJSON rulesConfig}
+      RULES_EOF
     '';
   };
 

modules/home-manager/coding/agents/claude-code.nix

@@ -3,7 +3,9 @@
   lib,
   pkgs,
   ...
-}:
+}: let
+  shared = import ./shared-options.nix {inherit lib;};
+in
   with lib; let
     cfg = config.coding.agents.claude-code;
     mcpCfg = config.programs.mcp or null;
@@ -11,34 +13,22 @@ in {
     options.coding.agents.claude-code = {
       enable = mkEnableOption "Claude Code agent management via canonical agent.toml definitions";
 
-    agentsInput = mkOption {
-      type = types.nullOr types.anything;
-      default = null;
-      description = ''
+      agentsInput = shared.mkAgentsInputOption ''
         The `agents` flake input (your personal AGENTS repo).
         When set, agents are rendered from canonical agent.toml files
         and symlinked to ~/.claude/agents/.
       '';
-    };
 
-    modelOverrides = mkOption {
-      type = types.attrsOf types.str;
-      default = {};
-      description = ''
-        Per-agent model overrides. Maps agent slug to model alias or ID.
-        Example: { chiron = "claude-sonnet-4-20250514"; }
-      '';
-      example = literalExpression ''
-        {
-          chiron = "claude-sonnet-4-20250514";
-          "chiron-forge" = "claude-sonnet-4-20250514";
-        }
-      '';
-    };
+      modelOverrides = shared.mkModelOverridesOption;
+
+      externalSkills = shared.externalSkillsOption;
 
       mcpServers = mkOption {
         type = types.attrsOf types.anything;
-      default = if mcpCfg != null then mcpCfg.servers else {};
+        default =
+          if mcpCfg != null
+          then mcpCfg.servers
+          else {};
         defaultText = literalExpression "config.programs.mcp.servers";
         description = ''
           MCP server configurations for Claude Code.
@@ -82,6 +72,15 @@ in {
         source = "${rendered}/.claude/agents";
       };
 
+      # Skills (merged from personal AGENTS repo + optional external skills)
+      home.file.".claude/skills" = mkIf (cfg.agentsInput != null) {
+        source = cfg.agentsInput.lib.mkOpencodeSkills {
+          inherit pkgs;
+          customSkills = "${cfg.agentsInput}/skills";
+          externalSkills = shared.mapExternalSkills cfg.externalSkills;
+        };
+      };
+
       # Rendered settings.json with permissions + MCP servers
       home.file.".claude/settings.json" = mkIf (settingsJson != null) {
         source = "${settingsJson}";

modules/home-manager/coding/agents/opencode.nix

@@ -3,80 +3,30 @@
   lib,
   pkgs,
   ...
-}:
-with lib; let
-  cfg = config.coding.agents.opencode;
-in {
+}: let
+  shared = import ./shared-options.nix {inherit lib;};
+in
+  with lib; {
     options.coding.agents.opencode = {
       enable = mkEnableOption "OpenCode agent management via canonical agent.toml definitions";
 
-    agentsInput = mkOption {
-      type = types.nullOr types.anything;
-      default = null;
-      description = ''
+      agentsInput = shared.mkAgentsInputOption ''
         The `agents` flake input (your personal AGENTS repo).
         When set, agents are rendered from canonical agent.toml files
         and symlinked to ~/.config/opencode/agents/.
       '';
+
+      modelOverrides = shared.mkModelOverridesOption;
+
+      externalSkills = shared.externalSkillsOption;
     };
 
-    modelOverrides = mkOption {
-      type = types.attrsOf types.str;
-      default = {};
-      description = ''
-        Per-agent model overrides. Maps agent slug to model string.
-        Example: { chiron = "anthropic/claude-sonnet-4"; }
-      '';
-      example = literalExpression ''
-        {
-          chiron = "anthropic/claude-sonnet-4";
-          "chiron-forge" = "anthropic/claude-sonnet-4";
-        }
-      '';
-    };
-
-    externalSkills = mkOption {
-      type = types.listOf (types.submodule {
-        options = {
-          src = mkOption {
-            type = types.anything;
-            description = "Flake input pointing to a skills repository root.";
-          };
-          skillsDir = mkOption {
-            type = types.str;
-            default = "skills";
-            description = ''
-              Subdirectory inside src that contains skill folders.
-            '';
-          };
-          selectSkills = mkOption {
-            type = types.nullOr (types.listOf types.str);
-            default = null;
-            description = ''
-              List of skill names to cherry-pick from this source.
-              null means include every skill found in skillsDir.
-            '';
-          };
-        };
-      });
-      default = [];
-      description = ''
-        External skill sources passed to mkOpencodeSkills.
-        Each entry maps directly to an element of the externalSkills
-        list accepted by the AGENTS flake's lib.mkOpencodeSkills.
-      '';
-      example = literalExpression ''
-        [
-          { src = inputs.skills-anthropic; selectSkills = [ "claude-api" ]; }
-          { src = inputs.skills-vercel; }
-        ]
-      '';
-    };
-  };
-
-  config = mkIf cfg.enable {
+    config = mkIf config.coding.agents.opencode.enable {
       # Rendered agent files symlinked to ~/.config/opencode/agents/
-    xdg.configFile."opencode/agents" = mkIf (cfg.agentsInput != null) {
+      xdg.configFile."opencode/agents" = let
+        cfg = config.coding.agents.opencode;
+      in
+        mkIf (cfg.agentsInput != null) {
           source = (import ../../../../lib {inherit lib;}).agents.renderForOpencode {
             inherit pkgs;
             canonical = cfg.agentsInput.lib.loadAgents;
@@ -85,28 +35,34 @@ in {
         };
 
       # Skills (merged from personal AGENTS repo + optional external skills)
-    xdg.configFile."opencode/skills" = mkIf (cfg.agentsInput != null) {
+      xdg.configFile."opencode/skills" = let
+        cfg = config.coding.agents.opencode;
+      in
+        mkIf (cfg.agentsInput != null) {
           source = cfg.agentsInput.lib.mkOpencodeSkills {
             inherit pkgs;
             customSkills = "${cfg.agentsInput}/skills";
-        externalSkills =
-          map (
-            entry:
-              {inherit (entry) src skillsDir;}
-              // optionalAttrs (entry.selectSkills != null) {inherit (entry) selectSkills;}
-          )
-          cfg.externalSkills;
+            externalSkills = shared.mapExternalSkills cfg.externalSkills;
           };
         };
 
       # Static config dirs from AGENTS repo
-    xdg.configFile."opencode/context" = mkIf (cfg.agentsInput != null) {
+      xdg.configFile."opencode/context" = let
+        cfg = config.coding.agents.opencode;
+      in
+        mkIf (cfg.agentsInput != null) {
           source = "${cfg.agentsInput}/context";
         };
-    xdg.configFile."opencode/commands" = mkIf (cfg.agentsInput != null) {
+      xdg.configFile."opencode/commands" = let
+        cfg = config.coding.agents.opencode;
+      in
+        mkIf (cfg.agentsInput != null) {
           source = "${cfg.agentsInput}/commands";
         };
-    xdg.configFile."opencode/prompts" = mkIf (cfg.agentsInput != null) {
+      xdg.configFile."opencode/prompts" = let
+        cfg = config.coding.agents.opencode;
+      in
+        mkIf (cfg.agentsInput != null) {
           source = "${cfg.agentsInput}/prompts";
         };
     };

modules/home-manager/coding/agents/pi.nix

@@ -3,7 +3,9 @@
   lib,
   pkgs,
   ...
-}:
+}: let
+  shared = import ./shared-options.nix {inherit lib;};
+in
   with lib; let
     cfg = config.coding.agents.pi;
     mcpCfg = config.programs.mcp or null;
@@ -22,25 +24,13 @@ in {
         '';
       };
 
-    agentsInput = mkOption {
-      type = types.nullOr types.anything;
-      default = null;
-      description = ''
+      agentsInput = shared.mkAgentsInputOption ''
         The `agents` flake input (your personal AGENTS repo).
         When set, the primary agent's system prompt is rendered as SYSTEM.md,
         all agents are listed in AGENTS.md, and subagent .md files are deployed.
       '';
-    };
 
-    modelOverrides = mkOption {
-      type = types.attrsOf types.str;
-      default = {};
-      description = ''
-        Per-agent model overrides for Pi subagents.
-        Maps agent slug to model string, e.g.:
-          { chiron = "anthropic/claude-sonnet-4"; chiron-forge = "anthropic/claude-sonnet-4"; }
-      '';
-    };
+      modelOverrides = shared.mkModelOverridesOption;
 
       primaryAgent = mkOption {
         type = types.nullOr types.str;
@@ -51,6 +41,8 @@ in {
         '';
       };
 
+      externalSkills = shared.externalSkillsOption;
+
       settings = mkOption {
         type = types.submodule {
           freeformType = types.attrsOf types.anything;
@@ -222,11 +214,12 @@ in {
         # ── Agents — pi-subagents .md files ────────────────────────────
         agentFiles
 
-      # ── Skills symlinked from AGENTS repo ──────────────────────────
+        # ── Skills symlinked from AGENTS repo + external skills ────────
         (mkIf (cfg.agentsInput != null) {
           ".pi/agent/skills".source = cfg.agentsInput.lib.mkOpencodeSkills {
             inherit pkgs;
             customSkills = "${cfg.agentsInput}/skills";
+            externalSkills = shared.mapExternalSkills cfg.externalSkills;
           };
         })
       ];

modules/home-manager/coding/agents/shared-options.nix

@@ -0,0 +1,75 @@
+# Shared option definitions for agent modules.
+# Prevents copy-pasting the externalSkills submodule across opencode/claude-code/pi.
+{lib}: let
+  inherit (lib) mkOption mkEnableOption types literalExpression;
+in {
+  # Common agentsInput option used by all agent modules.
+  mkAgentsInputOption = description: mkOption {
+    type = types.nullOr types.anything;
+    default = null;
+    inherit description;
+  };
+
+  # Common modelOverrides option.
+  mkModelOverridesOption = mkOption {
+    type = types.attrsOf types.str;
+    default = {};
+    description = ''
+      Per-agent model overrides. Maps agent slug to model string.
+      Example: { chiron = "anthropic/claude-sonnet-4"; }
+    '';
+    example = literalExpression ''
+      {
+        chiron = "anthropic/claude-sonnet-4";
+        "chiron-forge" = "anthropic/claude-sonnet-4";
+      }
+    '';
+  };
+
+  # External skills submodule — used by opencode, claude-code, and pi modules.
+  externalSkillsOption = mkOption {
+    type = types.listOf (types.submodule {
+      options = {
+        src = mkOption {
+          type = types.anything;
+          description = "Flake input pointing to a skills repository root.";
+        };
+        skillsDir = mkOption {
+          type = types.str;
+          default = "skills";
+          description = ''
+            Subdirectory inside src that contains skill folders.
+          '';
+        };
+        selectSkills = mkOption {
+          type = types.nullOr (types.listOf types.str);
+          default = null;
+          description = ''
+            List of skill names to cherry-pick from this source.
+            null means include every skill found in skillsDir.
+          '';
+        };
+      };
+    });
+    default = [];
+    description = ''
+      External skill sources passed to mkOpencodeSkills.
+      Each entry maps directly to an element of the externalSkills
+      list accepted by the AGENTS flake's lib.mkOpencodeSkills.
+    '';
+    example = literalExpression ''
+      [
+        { src = inputs.skills-anthropic; selectSkills = [ "claude-api" ]; }
+        { src = inputs.basecamp; }
+      ]
+  '';
+  };
+
+  # Helper to map externalSkills from module config to mkOpencodeSkills format.
+  mapExternalSkills = cfgEntries:
+    map (
+      entry:
+        {inherit (entry) src skillsDir;}
+        // lib.optionalAttrs (entry.selectSkills != null) {inherit (entry) selectSkills;}
+    ) cfgEntries;
+}

overlays/default.nix

@@ -1,70 +0,0 @@
-{inputs, ...}: {
-  # This one brings our custom packages from the 'pkgs' directory
-  additions = final: prev:
-    (import ../pkgs {pkgs = final;})
-    # // (inputs.hyprpanel.overlay final prev)
-    // {rose-pine-hyprcursor = inputs.rose-pine-hyprcursor.packages.${prev.stdenv.hostPlatform.system}.default;};
-
-  # This one contains whatever you want to overlay
-  # You can change versions, add patches, set compilation flags, anything really.
-  # https://nixos.wiki/wiki/Overlays
-  modifications = final: prev:
-  # Import all package modifications from mods directory
-    (import ./mods/default.nix {inherit prev;})
-    // {
-      # Direct configuration overrides
-      brave = prev.brave.override {
-        commandLineArgs = "--password-store=gnome-libsecret";
-      };
-
-      # nodejs_24 = inputs.nixpkgs-stable.legacyPackages.${prev.system}.nodejs_24;
-      # paperless-ngx = inputs.nixpkgs-45570c2.legacyPackages.${prev.system}.paperless-ngx;
-      # anytype-heart = inputs.nixpkgs-9e58ed7.legacyPackages.${prev.system}.anytype-heart;
-      # trezord = inputs.nixpkgs-2744d98.legacyPackages.${prev.system}.trezord;
-      # mesa = inputs.nixpkgs-master.legacyPackages.${prev.system}.mesa;
-      # hyprpanel = inputs.hyprpanel.packages.${prev.system}.default.overrideAttrs (prev: {
-      #   version = "latest"; # or whatever version you want
-      #   src = final.fetchFromGitHub {
-      #     owner = "Jas-SinghFSU";
-      #     repo = "HyprPanel";
-      #     rev = "master"; # or a specific commit hash
-      #     hash = "sha256-l623fIVhVCU/ylbBmohAtQNbK0YrWlEny0sC/vBJ+dU=";
-      #   };
-      # });
-    };
-
-  temp-packages = final: _prev: {
-    temp = import inputs.nixpkgs-9e9486b {
-      system = final.stdenv.hostPlatform.system;
-      config.allowUnfree = true;
-    };
-  };
-
-  stable-packages = final: _prev: {
-    stable = import inputs.nixpkgs-stable {
-      system = final.stdenv.hostPlatform.system;
-      config.allowUnfree = true;
-    };
-  };
-
-  pinned-packages = final: _prev: {
-    pinned = import inputs.nixpkgs-9472de4 {
-      system = final.stdenv.hostPlatform.system;
-      config.allowUnfree = true;
-    };
-  };
-
-  locked-packages = final: _prev: {
-    locked = import inputs.nixpkgs-locked {
-      system = final.stdenv.hostPlatform.system;
-      config.allowUnfree = true;
-    };
-  };
-
-  master-packages = final: _prev: {
-    master = import inputs.nixpkgs-master {
-      system = final.stdenv.hostPlatform.system;
-      config.allowUnfree = true;
-    };
-  };
-}

overlays/mods/beads.nix

@@ -1,16 +0,0 @@
-{prev}:
-prev.beads.overrideAttrs (oldAttrs: rec {
-  version = "0.47.1";
-
-  src = prev.fetchFromGitHub {
-    owner = "steveyegge";
-    repo = "beads";
-    tag = "v${version}";
-    hash = "sha256-DwIR/r1TJnpVd/CT1E2OTkAjU7k9/KHbcVwg5zziFVg=";
-  };
-
-  vendorHash = "sha256-pY5m5ODRgqghyELRwwxOr+xlW41gtJWLXaW53GlLaFw=";
-
-  # Tests require git worktree operations that fail in Nix sandbox
-  doCheck = false;
-})

overlays/mods/default.nix

@@ -2,9 +2,6 @@
   # Package modifications
   # This overlay contains package overrides and modifications
 
-  # n8n = import ./n8n.nix {inherit prev;};
-  # beads = import ./beads.nix {inherit prev;};
-
   # Add more modifications here as needed
   # example-package = prev.example-package.override { ... };
 }

overlays/mods/n8n.nix

@@ -1,18 +0,0 @@
-{prev}:
-prev.n8n.overrideAttrs (oldAttrs: rec {
-  version = "2.4.1";
-
-  src = prev.fetchFromGitHub {
-    owner = "n8n-io";
-    repo = "n8n";
-    rev = "n8n@${version}";
-    hash = "sha256-EQP9ZI8kt30SUYE1+/UUpxQXpavzKqDu8qE24zsNifg=";
-  };
-
-  pnpmDeps = prev.pnpm_10.fetchDeps {
-    pname = oldAttrs.pname;
-    inherit version src;
-    fetcherVersion = 1;
-    hash = "sha256-Q30IuFEQD3896Hg0HCLd38YE2i8fJn74JY0o95LKJis=";
-  };
-})

pkgs/default.nix

@@ -3,6 +3,7 @@
   inputs,
   ...
 }: let
+  # Used only for flake input pass-throughs (basecamp, openspec, opencode-desktop)
   system = pkgs.stdenv.hostPlatform.system;
 in {
   # Custom packages registry

pkgs/eigent/default.nix

@@ -8,10 +8,10 @@
   nix-update-script,
 }: let
   pname = "eigent";
-  version = "0.0.89";
+  version = "0.0.90";
   src = fetchurl {
     url = "https://github.com/eigent-ai/eigent/releases/download/v${version}/Eigent-${version}.AppImage";
-    hash = "sha256-9KuiFjegfXhCu1W/FCinWX4ae/DsNPudeBcXFfW18Hc=";
+    hash = "sha256-mwCBx+D6mgGqQa8bDuUpo3h49EwFVkwasJwaYc6aXFE=";
   };
   appimageContents = appimageTools.extractType2 {inherit pname version src;};
 in

pkgs/opencode-desktop/default.nix

@@ -31,7 +31,7 @@
   # Upstream is missing outputHashes for git dependencies
   # Also fix stale npm deps hash in upstream node_modules FOD
   fixedNodeModules = opencode.node_modules.overrideAttrs {
-    outputHash = "sha256-LRhPPrOKCGUSCEWTpAxPdWKTKVNkg82WrvD25cP3jts=";
+    outputHash = "sha256-285KZ7rZLRoc6XqCZRHc25NE+mmpGh/BVeMpv8aPQtQ=";
   };
 
   opencode-desktop = rustPlatform.buildRustPackage (finalAttrs: {

tests/lib/agents-test.nix

@@ -0,0 +1,26 @@
+let
+  lib = import <nixpkgs/lib>;
+  agentsLib = (import ../../lib {inherit lib;}).agents;
+
+  # Test 1: renderForTool throws for unknown tools
+  testUnknownTool = let
+    result = builtins.tryEval (
+      agentsLib.renderForTool {
+        pkgs = {};
+        agentsInput = {};
+        tool = "unknown-tool";
+      }
+    );
+  in
+    assert result.success == false; {result = "pass";};
+
+  # Test 2: loadCanonical extracts loadAgents from input
+  testLoadCanonical = let
+    fakeInput = {lib.loadAgents = {test = {description = "test";};};};
+    result = agentsLib.loadCanonical {agentsInput = fakeInput;};
+  in
+    assert result == {test = {description = "test";};}; {result = "pass";};
+in {
+  unknown-tool-throws = testUnknownTool;
+  load-canonical = testLoadCanonical;
+}

tests/lib/coding-rules-test.nix

@@ -0,0 +1,48 @@
+let
+  lib = import <nixpkgs/lib>;
+  codingRulesLib = (import ../../lib {inherit lib;}).coding-rules;
+
+  # Test 1: instructions are generated correctly with custom rulesDir
+  testInstructions = let
+    rules = codingRulesLib.mkCodingRules {
+      agents = "/tmp/fake-agents";
+      languages = ["python"];
+      concerns = ["naming"];
+      rulesDir = ".coding-rules";
+    };
+  in
+    assert rules.instructions
+    == [
+      ".coding-rules/concerns/naming.md"
+      ".coding-rules/languages/python.md"
+    ]; {result = "pass";};
+
+  # Test 2: default rulesDir is .opencode-rules
+  testDefaultRulesDir = let
+    rules = codingRulesLib.mkCodingRules {
+      agents = "/tmp/fake-agents";
+    };
+    hasCorrectPrefix = builtins.all (s: builtins.substring 0 15 s == ".opencode-rules") rules.instructions;
+  in
+    assert hasCorrectPrefix == true; {result = "pass";};
+
+  # Test 3: backward-compat alias exists
+  testBackwardCompat = assert codingRulesLib.mkOpencodeRules == codingRulesLib.mkCodingRules; {result = "pass";};
+
+  # Test 4: shellHook contains both the symlink command and the config generation
+  testShellHook = let
+    rules = codingRulesLib.mkCodingRules {
+      agents = "/tmp/fake-agents";
+    };
+    hook = rules.shellHook;
+    hasSymlink = builtins.match ".*ln -sfn.*" hook != null;
+    hasConfigGen = builtins.match ".*coding-rules.json.*" hook != null;
+  in
+    assert hasSymlink;
+    assert hasConfigGen; {result = "pass";};
+in {
+  instructions-correct = testInstructions;
+  default-rules-dir = testDefaultRulesDir;
+  backward-compat = testBackwardCompat;
+  shell-hook = testShellHook;
+}

tests/lib/default.nix

@@ -0,0 +1,4 @@
+{
+  coding-rules = import ./coding-rules-test.nix;
+  agents = import ./agents-test.nix;
+}