T3 Code: skills not loading when using OpenCode provider models

Problem

Skills are completely unavailable in T3 Code when using OpenCode provider models (Aion, via OpenRouter, etc.), even though:

• ✅ Skills work perfectly with Claude and Codex provider models in T3 Code
• ✅ Skills work perfectly in the standalone OpenCode harness
• ✅ Superpowers plugin is installed and configured

When switching to an opencode model in T3 Code, the /skill command is unavailable and the skill list is empty in folders.

Root Cause

T3 Code is missing plugin configuration for OpenCode provider models.

Plugins in ~/.claude/plugins/cache/ contain harness-specific configuration directories:

• .claude-plugin/ — Claude Code
• .codex-plugin/ — Codex provider
• .cursor-plugin/ — Cursor IDE
• .opencode/ — Standalone OpenCode harness (different from T3 Code's opencode driver)
• .kimi-plugin/, .pi/ — Other providers
• .t3-plugin/ — MISSING for T3 Code

When T3 Code attempts to load a plugin with an OpenCode model, it looks for .t3-plugin/ configuration. This directory doesn't exist, so plugin loading fails silently.

Why .opencode/ Isn't Enough

The .opencode/ directory exists in plugins but is configured for the standalone OpenCode binary (~/.opencode/bin/opencode), which is a separate application from T3 Code. The T3 Code application has an 'opencode driver' provider that uses a different plugin API than the standalone OpenCode binary. These are not interchangeable.

Steps to Reproduce

1. Open T3 Code
2. Switch to any OpenCode provider model (e.g., Aion-3.0 via OpenRouter)
3. Try to use skills (e.g., /skill, /brainstorm, etc.)
4. Expected: Skills available
5. Actual: Skills unavailable; 'no skills available' or similar message

Workaround (User-Applied)

Temporary fix available: Added .t3-plugin/ directories to plugins in ~/.claude/plugins/cache/ with Codex-compatible plugin configuration. This requires manual intervention for each plugin.

Proposed Solution

Create .t3-plugin/ directories in all plugins from the Claude marketplace. T3 Code should:

1. Recognize OpenCode models as a supported provider configuration
2. Look for .t3-plugin/ configuration directory for OpenCode models
3. Load skills from the shared skills/ directory using T3 Code's skill discovery API

This mirrors the current pattern:

• Claude models → .claude-plugin/
• Codex models → .codex-plugin/
• OpenCode models → .t3-plugin/ (new)
• Cursor IDE → .cursor-plugin/

Impact

• Affects all skills: superpowers, feature-dev, code-review, and any third-party skills
• High-value issue: Users may not realize OpenCode models in T3 Code are less capable without skills
• Easy to fix: Requires adding plugin configuration directories

Environment

• T3 Code: Current version
• OpenCode provider: OpenRouter (Aion models)
• OS: macOS
• Affected plugins: All 10+ marketplace plugins

---

Note: This issue is distinct from OpenCode harness skills support. OpenCode harness works fine; this is specific to T3 Code's OpenCode driver.