refactor: unify skills install method across all platforms

Replace platform-specific install approaches with a consistent
per-skill symlink pattern for OpenCode and Codex (both share
~/.agents/skills/), matching the OpenCode docs requirement of
<name>/SKILL.md discovery.

Changes:
- OpenCode: migrate from opencode.json plugin config to direct
  skill symlinks in ~/.agents/skills/<name>/
- Codex: replace broken bundle symlink (understand-anything/ had
  no SKILL.md at root) with individual per-skill symlinks, matching
  OpenCode exactly
- All platforms: add universal ~/.understand-anything-plugin symlink
  so understand-dashboard SKILL.md can reliably find packages/dashboard/
- All platforms: use idempotent [ -e ] || [ -L ] || ln -s guard to
  handle multi-platform installs on the same machine
- All platforms: use ln -sf and rm -f for robust re-installs and
  partial uninstalls
- understand-dashboard/SKILL.md: replace fragile dirname-based path
  resolution with a prioritized candidate loop with explicit error
  guard
- Remove orphaned .opencode/plugins/understand-anything.js and its
  build scaffolding
- Update all three README variants (en, zh-CN, ja-JP) to reflect
  new OpenCode AI-driven install method

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.opencode/INSTALL.md

@@ -2,55 +2,86 @@
 
 ## Prerequisites
 
-- [OpenCode.ai](https://opencode.ai) installed
+- Git
+- [OpenCode](https://opencode.ai) installed
 
 ## Installation
 
-Add understand-anything to the `plugin` array in your `opencode.json` (global or project-level):
+1. **Clone the repository:**
+   ```bash
+   git clone https://github.com/Lum1104/Understand-Anything.git ~/.opencode/understand-anything
+   ```
 
-```json
-{
-  "plugin": ["understand-anything@git+https://github.com/Lum1104/Understand-Anything.git"]
-}
-```
+2. **Create the skills symlinks:**
+   ```bash
+   mkdir -p ~/.agents/skills
+   # Note: if Codex's Understand-Anything is already installed, these symlinks
+   # already exist and the ln commands will safely fail — that is fine, the
+   # existing symlinks work for OpenCode too.
+   for skill in understand understand-chat understand-dashboard understand-diff understand-explain understand-onboard; do
+     ln -sf ~/.opencode/understand-anything/understand-anything-plugin/skills/$skill ~/.agents/skills/$skill
+   done
+   # Universal plugin root symlink — lets the dashboard skill find packages/dashboard/
+   # Skip if already exists (e.g. another platform was installed first)
+   [ -e ~/.understand-anything-plugin ] || [ -L ~/.understand-anything-plugin ] || ln -s ~/.opencode/understand-anything/understand-anything-plugin ~/.understand-anything-plugin
+   ```
 
-Restart OpenCode. The plugin auto-installs and registers all skills.
+   **Windows (PowerShell):**
+   ```powershell
+   New-Item -ItemType Directory -Force -Path "$env:USERPROFILE\.agents\skills"
+   $skills = @("understand","understand-chat","understand-dashboard","understand-diff","understand-explain","understand-onboard")
+   foreach ($skill in $skills) {
+     cmd /c mklink /J "$env:USERPROFILE\.agents\skills\$skill" "$env:USERPROFILE\.opencode\understand-anything\understand-anything-plugin\skills\$skill"
+   }
+   # Universal plugin root symlink
+   cmd /c mklink /J "$env:USERPROFILE\.understand-anything-plugin" "$env:USERPROFILE\.opencode\understand-anything\understand-anything-plugin"
+   ```
+
+3. **Restart OpenCode** to discover the skills.
 
 ## Verify
 
-Ask: "List available skills" — you should see understand, understand-chat, understand-dashboard, etc.
+```bash
+ls -la ~/.agents/skills/ | grep understand
+```
+
+You should see symlinks for each skill pointing into the cloned repository.
 
 ## Usage
 
+Skills activate automatically when relevant. You can also invoke directly:
+
 ```
-use skill tool to load understand-anything/understand
+use skill tool to load understand
 ```
 
 Or just ask: "Analyze this codebase and build a knowledge graph"
 
 ## Updating
 
-Restart OpenCode — the plugin re-installs from git automatically.
-
-To pin a specific version:
-
-```json
-{
-  "plugin": ["understand-anything@git+https://github.com/Lum1104/Understand-Anything.git#v1.1.1"]
-}
+```bash
+cd ~/.opencode/understand-anything && git pull
 ```
 
+Skills update instantly through the symlinks.
+
 ## Uninstalling
 
-Remove the plugin line from `opencode.json` and restart.
+```bash
+for skill in understand understand-chat understand-dashboard understand-diff understand-explain understand-onboard; do
+  rm -f ~/.agents/skills/$skill
+done
+rm ~/.understand-anything-plugin
+rm -rf ~/.opencode/understand-anything
+```
 
 ## Troubleshooting
 
 ### Skills not found
 
-1. Verify the plugin line in your `opencode.json`
-2. Check that `~/.cache/opencode/node_modules/understand-anything` exists after restart
-3. Use the `skill` tool to list discovered skills
+1. Check that the symlinks exist: `ls -la ~/.agents/skills/ | grep understand`
+2. Verify the clone succeeded: `ls ~/.opencode/understand-anything/understand-anything-plugin/skills/`
+3. Restart OpenCode
 
 ### Tool mapping
 

.opencode/plugins/understand-anything.js

@@ -1,25 +0,0 @@
-/**
- * Understand Anything plugin for OpenCode.ai
- *
- * Auto-registers the skills directory so OpenCode discovers all
- * understand-anything skills without manual symlinks or config edits.
- */
-
-import path from 'path';
-import { fileURLToPath } from 'url';
-
-const __dirname = path.dirname(fileURLToPath(import.meta.url));
-
-export const UnderstandAnythingPlugin = async ({ client, directory }) => {
-  const skillsDir = path.resolve(__dirname, '../../understand-anything-plugin/skills');
-
-  return {
-    config: async (config) => {
-      config.skills = config.skills || {};
-      config.skills.paths = config.skills.paths || [];
-      if (!config.skills.paths.includes(skillsDir)) {
-        config.skills.paths.push(skillsDir);
-      }
-    },
-  };
-};