Fusion setup

This skill configures the Fusion agent team (a main agent, a sidekick executor, an explore searcher, and optional specialists) by writing the user's GLOBAL opencode config at ~/.config/opencode/ (on Windows: %USERPROFILE%\.config\opencode\). It does not require cloning any repository.

opencode resolves that directory as $XDG_CONFIG_HOME/opencode/ when XDG_CONFIG_HOME is set and non-empty, falling back to ~/.config/opencode/ otherwise. Every ~/.config/opencode/... path below means that resolved directory. The bundled installer in Step 4 works this out itself, so the normal flow needs no special handling; only the manual fallback in Step 4b and the verification in Step 5 need you to resolve it by hand. Installing into ~/.config/opencode/ on a machine with a different XDG_CONFIG_HOME writes a tree opencode never reads - the install looks successful and Fusion silently never loads.

What Fusion is

Fusion splits work across agents with asymmetric permissions:

• build (main, primary): a strong model that plans, makes judgment calls, and reviews. It CANNOT edit files, search the codebase, or run arbitrary shell. Its only path to changing files is delegating to the sidekick via the task tool.
• plan (primary): plan mode - the same planning brain as build. Produces a reviewed plan and delegates exploration, but does not execute; switch to build to carry it out. Overrides opencode's built-in plan agent so plan mode stays Fusion-aware.
• sidekick (subagent): a cheaper, fast model with full edit and broad bash access (direct git commit/git push and common wrappers are denied as defense-in-depth - committing stays with the main agent). It executes precise specs handed to it by the main agent.
• explore (subagent): a cheap model used for read-only codebase exploration.
• research (subagent): read-only external research - web search and docs. No edit access.
• design (subagent): frontend/UI implementation. Loads design skills, edits files, runs the dev/build tooling.
• reviewer (subagent): critiques a plan before implementation and audits a diff before commit (correctness, scope, security). Read-only plus lint/test; no edit access.
• vision (subagent): reads images/screenshots the main model cannot see and reports them as text. Only needed when the main model lacks image input.