opencode-plugin-development

OpenCode plugin development intercepts tool execution by returning async hook functions that mutate hook input/output payloads. You register these hooks with correct YAML frontmatter naming, allowing your plugin to alter runtime behavior, inject context, and manage session-aware automation across tool workflows.

OpenCode event hooks follow a specified execution order for chat, tool execution, commands, permissions, and config events. Understanding this sequence is critical for reasoning about runtime behavior, ensuring your plugin intercepts and mutates events at the correct lifecycle stage without conflicts.

To register a custom tool in OpenCode, you define schemas using Zod-based parameter builders and shape the tool input/output, titles, and metadata. This TypeScript approach ensures strict parameter validation and reliable tool execution within your plugin architecture.

OpenCode plugin development supports managing subagent and child-session lifecycles, including TUI automation. You can orchestrate child sessions, inject context safely across turns and compaction, and automate the TUI lifecycle with progress notifications during runtime.

Context disappears after session compaction if your plugin does not correctly inject context safely across turns and compaction. Proper OpenCode plugin development requires adhering to specified hook input/output mutation rules to ensure injected context survives compaction events.

Yes, OpenCode hooks allow you to mutate LLM request parameters and headers directly. By leveraging the plugin API's event-driven behavior, your plugin can intercept requests and alter runtime parameters, enabling session-aware automation and custom agent configurations.