opencode-copilot-plugin

opencode-copilot-plugin

An OpenCode plugin that brings GitHub Copilot's custom instruction and skill system into OpenCode. If you already have Copilot instruction or skill files set up, they work in OpenCode with no changes.

Install

Add the plugin to your opencode.json:

{
  "$schema": "https://opencode.ai/config.json",
  "plugin": ["opencode-copilot-plugin"]
}

OpenCode installs npm plugins automatically at startup — no separate install step needed.

Supported features

Custom instructions

• Repo-wide — .github/copilot-instructions.md is injected into every session automatically.
• Path-specific — .github/instructions/**/*.instructions.md files are injected when the LLM accesses files matching their applyTo glob frontmatter field.
• Global path-specific — ~/.copilot/instructions/**/*.instructions.md works the same as project path-specific instructions but applies across all workspaces.

Skills

• Project-local — .github/skills/<name>/SKILL.md
• User-global — ~/.copilot/skills/<name>/SKILL.md
• When at least one skill exists at startup, a copilot_skill tool is registered so the LLM can load skills on demand.
• Local skills shadow global skills of the same name.

Hooks

Executes Copilot hook scripts at key lifecycle points in each agent session. Hook scripts receive JSON on stdin and can approve, deny, or request confirmation for tool calls.

• Project-local — .github/hooks/*.json
• User-global — ~/.copilot/hooks/*.json
• Project hooks run before global hooks for each hook type.

Supported hook types:

Hook type	When it fires
sessionStart	When a new session is created
sessionEnd	When a session is deleted
userPromptSubmitted	When a new user message is received
preToolUse	Before each tool call — can block execution
postToolUse	After each successful tool call
agentStop	When the agent finishes responding (session goes idle)
errorOccurred	When a session error occurs

Hook configuration files use the same format as GitHub Copilot hooks:

{
  "version": 1,
  "hooks": {
    "preToolUse": [
      {
        "type": "command",
        "bash": "./scripts/security-check.sh",
        "cwd": ".",
        "timeoutSec": 15
      }
    ]
  }
}

preToolUse permission decisions: If a hook script outputs {"permissionDecision":"deny","permissionDecisionReason":"..."}, the tool call is blocked. If it outputs {"permissionDecision":"ask","permissionDecisionReason":"..."}, the agent is instructed to confirm with the user before retrying — on the next identical tool call (same tool and arguments), that specific hook is bypassed.

Tool name mapping: Hook scripts receive Copilot-equivalent tool names (view instead of read, create instead of write) so existing scripts work unmodified.

Platform note: Only bash commands are executed. powershell commands are silently skipped on macOS/Linux.

No hot-reload: Hook files are loaded once when the plugin initialises. Changes to hook files require an OpenCode restart to take effect.

Hot-reload

Instruction files and skill directories are re-parsed automatically when they change on disk — no OpenCode restart required. Hook files are the exception — see note above.

License

MIT © Brandon Burrus