OpenCode

Changeward adds an MCP server and a small OpenCode plugin. The plugin checks every bash tool call and blocks direct writes to your registered targets.

Verified: OpenCode 1.18 (opencode run, Claude Haiku 4.5). The agent used changeward_query → changeward_propose_change → changeward_apply_change without being told to. When forced to run a raw psql … DELETE, the plugin blocked it, and the agent offered to go through Changeward instead.

Set up

changeward connect app --dsn '${DATABASE_URL}' --env personal
changeward install opencode

opencode.json (merged with your existing config):

{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "changeward": {
      "type": "local",
      "command": ["/usr/local/bin/changeward", "mcp", "postgres", "--target", "app"],
      "environment": { "CHANGEWARD_AGENT": "opencode" },
      "enabled": true
    }
  }
}

.opencode/plugins/changeward.ts is a tool.execute.before handler. It runs changeward hook check --json "<command>" and throws, which blocks the call, on deny or ask. If the changeward binary is missing, it lets commands through rather than breaking the agent. Set CHANGEWARD_BIN to override the path.

Use it

opencode                                  # TUI
opencode run "remove customer 19, they closed their account"

Check the server with opencode mcp list. The tools appear as changeward_query, changeward_propose_change and so on.

Troubleshooting

• Plugin not loaded: OpenCode loads .opencode/plugins/*.ts from the project root. Start OpenCode from the directory that contains changeward.yaml.
• Test the decision by hand: changeward hook check --json "psql -d app -c 'DELETE FROM t'".