Config Inheritance

Basic idea

Use extends to compose configs and keep them DRY.

{
  "extends": ["~/.hatago/base.json", "./team.json"],
  "mcpServers": {
    "local": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-filesystem", "."]
    }
  }
}

Rules

Multiple parents are supported: "extends": ["./base1.json", "./base2.json"]
Paths support ~ (home), relative, and absolute
Deep merge: child values override parent values
Remove inherited env vars by setting null

Env override example

{
  "extends": "~/.hatago/global.json",
  "mcpServers": {
    "github": {
      "env": {
        "GITHUB_TOKEN": "${WORK_GITHUB_TOKEN}",
        "DEBUG": null
      }
    }
  }
}

Verify behavior

hatago serve --stdio --config ./hatago.config.json --verbose

Troubleshooting

Circular extends

Break the cycle and ensure each file appears once in the chain.

File not found

Check path correctness, ~ expansion, and relative path base (current file).

Unexpected merge results

Remember child overrides parent. Inspect the effective config with --verbose and review logs.