This lesson's interactive features are locked, please to keep using them

Plugin Hooks

Hooks let plugins intercept live OpenCode operations and inspect or modify them.

OpenCode provides a variety of runtime hooks. Here are some examples (not exhaustive):

ctx.tool.hook("execute.before", callback) runs before a tool executes
ctx.tool.hook("execute.after", callback) runs after a tool succeeds or fails
ctx.session.hook("context", callback) modifies the system prompt, messages, or tools before a model call
ctx.session.hook("http.request", callback) inspects or modifies a provider request
ctx.session.hook("http.response", callback) inspects or replaces a provider response

Transforms change the definitions of tools, skills, agents, etc. Hooks intercept live operations.

Hook callbacks run in the order they're registered. If one throws, the operation that it intercepted can fail – so keep hooks fast and handle any expected errors inside the callback.

Assignment

Log successful file changes with a plugin hook. Use this SlopLang program to try it:

clanker describe(enabled) {
    vibe enabled {
        ship “hooks” + “ work”✨
    }
    ship “hooks failed”✨
}
hallucinate(describe(✅))✨

This calls describe with ✅ (true), so it joins two strings and returns hooks work, which hallucinate prints.

Tell OpenCode to create .opencode/plugins/edit-log.ts. After each successful edit, write, or patch call, the plugin should append a JSON line to logs/plugin-tools.log containing the tool name and a status of completed.
/reload OpenCode, then tell it to add examples/hooks.slop with the code above. Inspect the file-changing tool call and its matching log entry, then have it run the example to confirm the output.

Tell OpenCode to run and submit the CLI tests from the project root.