refactor: use ~/.config/opencode instead of npm global prefix for plugin discovery

- Remove npm global prefix lookup (execSync npm config get prefix)
- Add user config directory: ~/.config/opencode/node_modules/
- Plugin discovery now searches: user config -> local (last wins)
- Remove unused execSync import

Author: wagnert

AGENTS.md

@@ -160,10 +160,10 @@ console.log(`${colors.green}  + ${message}${colors.reset}`);
 ### Plugin Discovery (lib/discovery.js)
 
 Plugins are discovered from two locations:
-1. **Global**: `npm config get prefix`/lib/node_modules/
+1. **User config**: `~/.config/opencode/node_modules/`
 2. **Local**: `{targetDir}/node_modules/`
 
-Priority: **last wins** (local overrides global)
+Priority: **last wins** (local overrides user)
 
 ### Plugin Types
 

lib/discovery.js

@@ -2,7 +2,7 @@
  * Plugin Discovery Module
  * 
  * Discovers OpenCode plugins from two locations (priority: last wins):
- * 1. Global: npm global prefix (npm install -g)
+ * 1. User config: ~/.config/opencode/node_modules/
  * 2. Local: {targetDir}/node_modules/
  * 
  * Each location can contain two types of packages:
@@ -13,52 +13,44 @@
 import fs from 'fs';
 import os from 'os';
 import path from 'path';
-import { execSync } from 'child_process';
 
 /**
- * Gets the npm global prefix directory.
- * This is where `npm install -g` installs packages.
+ * Gets the user config directory for OpenCode plugins.
+ * This is where user-level plugins are installed.
  * 
- * @returns {string|null} Path to npm global prefix or null if not determinable
+ * @returns {string} Path to ~/.config/opencode/node_modules
  */
-function getGlobalDir() {
-  try {
-    const prefix = execSync('npm config get prefix', { encoding: 'utf-8' }).trim();
-    return path.join(prefix, 'lib', 'node_modules');
-  } catch {
-    return null;
-  }
+function getUserConfigDir() {
+  return path.join(os.homedir(), '.config', 'opencode', 'node_modules');
 }
 
 /**
  * Discovers all available plugins from all locations.
  * 
  * Priority (last wins):
- * 1. Global: npm global prefix (npm install -g)
+ * 1. User config: ~/.config/opencode/node_modules/
  * 2. Local: {targetDir}/node_modules/
  * 
  * @param {string} targetDir - The .opencode directory (e.g., /project/.opencode)
  * @returns {Map<string, PluginDescriptor>} Map of plugin name to descriptor
  */
 export function discoverPlugins(targetDir) {
-  const globalDir = getGlobalDir();
+  const userConfigDir = getUserConfigDir();
 
   // Scan all locations (order matters: last wins)
   const allPlugins = new Map();
 
-  // 1. Global (lowest priority)
-  if (globalDir) {
-    const globalPlugins = scanLocation(globalDir, 'global');
-    for (const [name, descriptor] of globalPlugins.entries()) {
-      allPlugins.set(name, descriptor);
-    }
+  // 1. User config (lower priority)
+  const userPlugins = scanLocation(userConfigDir, 'user');
+  for (const [name, descriptor] of userPlugins.entries()) {
+    allPlugins.set(name, descriptor);
   }
 
   // 2. Local (highest priority)
   const localPlugins = scanLocation(path.join(targetDir, 'node_modules'), 'local');
   for (const [name, descriptor] of localPlugins.entries()) {
     if (allPlugins.has(name)) {
-      console.log(`  ⚠️  Plugin "${name}" found in local, overrides global`);
+      console.log(`  ⚠️  Plugin "${name}" found in local, overrides user`);
     }
     allPlugins.set(name, descriptor);
   }