Session Logger Plugin for OpenCode

A JSONL session event logger plugin for OpenCode. Logs chat messages and tool executions as structured JSONL files, organized by session.

Inspired by opencode-plugin-simple-memory by Kris Nicolov.

Setup

1. Add the plugin to your OpenCode config:

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

2. Enable logging via the logger_set tool or configuration file.

Configuration

The plugin supports its own config files:

• Global defaults: ~/.config/opencode/logger.json
• Per-project override: .opencode/logger.json

Project config overrides global config.

Example:

{
  "logger": {
    "enabled": true,
    "scopes": [],
    "dir": "${project}/.agent-session-logs"
  }
}

Supported placeholders:

• ${home}
• ${project} (workspace/project root)
• ${workspace} (alias of ${project})
• ${date}
• ${env:VAR_NAME}

Tools

Tool	Description
logger_set	Enable/disable logger and set scope filters
logger_status	Show active logger configuration

Log Structure

Logs are organized by session:

.agent-session-logs/
  2026-03-20-fix-auth-bug/
    main.jsonl              # Main session events
    explore-ses_abc.jsonl   # Subagent events
    codex-ses_def.jsonl     # Another subagent

Each line is a JSON object with fields like:

{
  "ts": "2026-03-20T10:00:00.000Z",
  "event": "chat_message",
  "session_id": "ses_main",
  "parent_session_id": null,
  "root_session_id": "ses_main",
  "agent": "main",
  "message_id": "msg_1",
  "model": { "providerID": "anthropic", "modelID": "claude-opus-4" }
}

Events Logged

• chat_message — Chat messages with model info and parts
• tool_execute_before — Tool call with args (before execution)
• tool_execute_after — Tool result with output (after execution)

Local Development

git clone https://github.com/frankhommers/opencode-plugin-logger.git
cd opencode-plugin-logger
bun install

Point your OpenCode config to the local checkout:

{
  "$schema": "https://opencode.ai/config.json",
  "plugin": ["file:///absolute/path/to/opencode-plugin-logger"]
}