fix: assert unknown profiles in mkHomeConfig; move agent modules to coding/agents

- home/lib/default.nix: add assertion for unknown profile names instead of
  silently filtering them out; remove unused 'inherit (lib) optional'
- home/coding/agents/{opencode,pi}.nix: moved from home/features/coding/
  to co-locate with agents.nix (eliminating cross-directory back-references)
- home/coding/agents/agents.nix: update imports to ./opencode.nix and ./pi.nix
- home/features/coding/: remove now-dead default.nix (nothing imported it)

home/coding/agents/agents.nix

@@ -19,8 +19,8 @@ in {
 
   imports = [
     # OpenCode and Pi agent configurations
-    ../../features/coding/opencode.nix
-    ../../features/coding/pi.nix
+    ./opencode.nix
+    ./pi.nix
   ];
 
   coding.agents.skills = {

home/features/coding/default.nix

@@ -1,101 +0,0 @@
-{
-  config,
-  inputs,
-  pkgs,
-  videoDrivers,
-  ...
-}: let
-  npmGlobalPrefix = "${config.home.homeDirectory}/.npm-global";
-in {
-  home.file.".npmrc".text = ''
-    prefix=${npmGlobalPrefix}
-  '';
-  home.sessionVariables.NPM_CONFIG_PREFIX = npmGlobalPrefix;
-  imports = [
-    ./opencode.nix
-    ./pi.nix
-  ];
-
-  coding.agents.skills = {
-    agentsInput = inputs.agents;
-    externalSkills = [
-      {
-        src = inputs.skills-anthropic;
-        selectSkills = ["pdf" "docx" "frontend-design"];
-      }
-      {src = inputs.skills-vercel;}
-      {src = inputs.skills-basecamp;}
-      {src = inputs.skills-kestra;}
-    ];
-  };
-
-  programs.mcp = {
-    enable = true;
-    servers = {
-      DeepWiki = {
-        url = "https://mcp.deepwiki.com/mcp";
-      };
-      Ref = {
-        command = "bash";
-        args = ["-c" "REF_API_KEY=$(cat /run/agenix/ref-key) exec bunx ref-tools-mcp@latest"];
-      };
-      Exa = {
-        command = "bash";
-        args = ["-c" "EXA_API_KEY=$(cat /run/agenix/exa-key) exec bunx exa-mcp-server@latest tools=web_search_exa"];
-      };
-      Outline = {
-        url = "https://wiki.az-gruppe.com/mcp";
-      };
-      ContextMode = {
-        command = "bash";
-        args = ["-c" "exec bunx context-mode@latest"];
-      };
-      Honcho = {
-        command = "bash";
-        args = [
-          "-c"
-          ''exec bunx mcp-remote@latest https://mcp.honcho.dev --header "Authorization:Bearer $(cat /run/agenix/honcho-key)" --header "X-Honcho-User-Name:m3tam3re"''
-        ];
-      };
-    };
-  };
-
-  home.packages = with pkgs; [
-    agenix-cli
-    agent-browser
-    alejandra
-    bc
-    bun
-    devpod
-    #devpod-desktop
-    gnumake
-    cmake
-    (python3.withPackages (ps:
-      with ps; [
-        pip
-        uv
-        # Scientific packages
-        numba
-        numpy
-        torch
-        srt
-      ]))
-    pyrefly
-    nixd
-    nix-update
-    nodejs
-    # opencode-desktop
-    (qmd.override {
-      vulkanSupport = videoDrivers == ["amdgpu"];
-      cudaSupport = videoDrivers == ["nvidia"];
-    })
-    openshell
-    openspec
-    pi-coding-agent
-    alejandra
-    sidecar
-    tailwindcss
-    tailwindcss-language-server
-    td
-  ];
-}

home/lib/default.nix

@@ -11,8 +11,6 @@
 { lib }:
 
 let
-  inherit (lib) optional;
-
   # Infrastructure layer — nixpkgs overlays, nix-colors, m3ta-nixpkgs modules.
   # Always loaded on every host.
   commonModule = ../common;
@@ -55,6 +53,12 @@ in {
       else if context == "server" then [ contextModuleMap.server ]
       else [];
 
+    # Partition profiles into known and unknown for assertion + safe import.
+    unknownProfiles = builtins.filter
+      (profileName: ! builtins.hasAttr profileName profileModuleMap)
+      profiles;
+
+    # Only import known profiles; the assertion below catches unknowns.
     activeProfiles = builtins.filter
       (profileName: builtins.hasAttr profileName profileModuleMap)
       profiles;
@@ -76,6 +80,14 @@ in {
           "m3ta home: context must be 'desktop', 'server', or null"
           + " (got: '${contextStr}')";
       }
+      {
+        assertion = unknownProfiles == [];
+        message =
+          "m3ta home: unknown profiles requested:"
+          + " [ ${builtins.concatStringsSep " " unknownProfiles} ]."
+          + " Valid profiles are:"
+          + " [ ${builtins.concatStringsSep " " (builtins.attrNames profileModuleMap)} ]";
+      }
     ];
   };
 }