OpenCode System Prompt Logger

OpenCode plugin that logs the system prompt for debugging and inspection.

What it does

Every time you send a message in OpenCode, this plugin intercepts the system prompt before it's sent to the LLM and logs it. This is useful for:

• Debugging – understanding what instructions the AI is receiving
• Inspecting AGENTS.md – verifying your custom instructions are being loaded
• Development – testing changes to system prompts or agent configurations

Installation

Add the plugin to your opencode.json or opencode.jsonc:

{
  "plugin": ["opencode-system-prompt-logger"]
}

The plugin will be automatically installed and loaded when OpenCode starts.

Usage

Once installed, the system prompt will be logged every time you send a message. The log entry includes:

• Session ID
• Provider ID and model ID
• Full system prompt content (multiple prompts are separated by -----)

The plugin logs using OpenCode's structured logging system. See the example:

INFO  2026-01-01T08:00:00 +1ms service=system-prompt-logger sessionID=ses_abc123 providerID=opencode modelID=gpt-5-nano
You are a title generator. You output ONLY a thread title. Nothing else.
...

To determine the logs location:

opencode debug paths

Requirements

• OpenCode >= 1.1.37

License

See the LICENSE file for details.