Fix Universal Modder Plugin Discovery

Check the installation inside the agent you are actually using, then confirm that its Universal Modder skills are available in the current workspace. If Gemini reports a missing gemini-extension.json, compare your situation with the earlier failure below before reinstalling unrelated tools.

Example: a missing manifest

On Windows, Gemini could fail with the error prefix Configuration file not found at, followed by a temporary checkout path ending in gemini-extension.json. Issue #13 tracks the problem.

The incomplete checkout came from older symlinks in the repository, and PR #58 removed those symlinks. The issue is closed, and the normal installation route works.

The repository now contains a regular gemini-extension.json file and real skill directories. A new failure can have a different cause, so preserve its exact message rather than assuming every invisible plugin has the old symlink problem.

Step 1: use the correct installation route

A repository clone sitting elsewhere on your disk is not necessarily the workspace your agent has open. Likewise, a CLI that runs in your terminal says nothing about whether the agent loaded a skill.

Step 2: check the checkout or installed integration

For a clone-based route, confirm that the project folder is complete and that you opened that folder. The repository uses AGENTS.md, skills/, agent-visible skill directories and agent-specific MCP configuration. Check the install section of the README for the files belonging to your route.

For a plugin or extension route, inspect the agent's installed/enabled list and open a fresh session after installation. Follow that agent's page for its current commands rather than copying another agent's slash-command syntax.

If Gemini's missing-manifest error recurs with a current checkout, confirm that gemini-extension.json exists in the folder being installed. Capture the preceding clone output: a checkout error may explain why the file was never available. Do not globally change Git's symlink setting to fix it; the repository no longer relies on symlinks.

Step 3: separate skill, CLI and asset checks

After discovery, check the CLI separately:

um --version
um --help

If those commands are unavailable, use the um command not found diagnosis. If the skills and CLI work but fal authentication fails, use FAL_KEY is not set. A fal connection failure does not mean the skill files are absent.

Verify the intended skill

In a fresh session, ask the agent to identify the available Universal Modder skill and explain its first planning step without modifying a game. Confirm that it can cite the loaded skill or integration, then use a small planning request from the Universal Modder tutorial. Treat a generic answer about game modding as a sign that the plugin has not loaded.

Still not working?

Record the agent/version, operating system, install route, workspace type, exact error and whether the installed/enabled list contains the integration. Include redacted checkout output if a manifest is missing. File a new toolkit report on the GitHub issue tracker; the troubleshooting index helps classify a different failure before you send it.