Plugins

Plugins are external programs that extend mew’s capabilities. They can register tools, add slash commands, modify requests, observe events, and push UI updates. Plugins are the original extension format — the newer extension package format adds manifests, sandboxing, and consent, but bare plugins continue to work.

Where plugins live

Plugins are discovered as executable files in these directories:

1. ~/.config/mew/plugins/ (global — loads for every session)
2. .mew/plugins/ in your project directory (project-local)

Any executable file in these directories is loaded automatically on startup. Plugins are loaded in alphabetical order by filename.

Managing plugins

There’s no mew plugin install command — just copy the executable into the plugins directory:

cp my-plugin ~/.config/mew/plugins/
chmod +x ~/.config/mew/plugins/my-plugin

To disable a plugin without removing it:

mew ext disable <name>

To re-enable:

mew ext enable <name>

Disabled plugins are tracked in state.toml under disabled_plugins.

What plugins can do

• Register dynamic tools that appear in the model’s tool list
• Register slash commands that show up in autocomplete and /help
• Modify chat parameters (temperature, max_tokens, tool_choice) per turn
• Inject HTTP headers into provider requests
• Modify the system prompt before each turn
• Block or modify tool inputs before execution
• Modify tool outputs after execution
• Auto-approve or deny permissions based on custom rules
• Inject environment variables into bash commands
• Observe all provider events for telemetry and metrics
• Store per-plugin key-value data persisted to disk
• Push toast notifications to the TUI
• Render custom text content beside the input area

Consent

On first load, bare plugins prompt for full access (all hooks and host functions). Approve to grant full access, or decline to restrict the plugin to observe-only mode. In non-interactive mode, new plugins are auto-restricted to observe-only.

Your choice is persisted and remembered on subsequent loads.

Plugins vs extension packages

Feature	Bare plugins	Extension packages
Manifest	None	mew-ext.toml required
Sandbox	No	Yes (macOS)
Consent	Full-access prompt	Capability-based prompts
Install	Manual file copy	mew ext install
Discovery	plugins/ dir	extensions/ dir

Bare plugins are being superseded by extension packages. A future release will add deprecation warnings for bare plugins. See Extensions for the newer format.

For the JSON-RPC protocol, hook point reference, and host function API, see Extension System Internals.