Overview

tallow ships with 52 built-in extensions that handle everything from tool output rendering to multi-agent coordination. Extensions aren’t plugins bolted on — they’re the primary way tallow’s features are implemented.

What extensions can do

Extensions have full access to tallow’s runtime:

• Register tools — give the LLM new capabilities
• Render TUI widgets — status bars, task boards, progress indicators
• Hook lifecycle events — intercept tool calls, turn completions, errors
• Register commands — add /slash commands for users
• Inject context — modify the system prompt dynamically
• Compose with each other — one extension can enhance another

Categories

Every extension has a category property in its extension.json manifest. The docs sidebar and the installer group extensions by these categories:

Note: Some extensions provide both LLM-callable tools and UI features. For example, the tasks extension provides a task board UI and a manage_tasks tool that lets the AI manage tasks programmatically.

Category	Count	What’s in it
Tools	19	bash, edit, read, write, cd, web_fetch, web_search, subagent, teams, tasks, agent-commands, ask-user-question, background-task, output-styles, theme-selector, MCP adapter, session-memory, wezterm-pane-control
UI & Display	6	custom footer, git status, tool display, minimal skill display, session-namer, random-spinner
Commands	7	command-prompt, command-expansion, context-fork, file-reference, health, shell-interpolation, skill-commands
Utilities	6	cheatsheet, context-usage, debug, init, show-system-prompt, read-tool-enhanced
Integrations	3	lifecycle hooks, claude-bridge, worktree
Language Support	1	LSP
Context	1	context-files
Dev	1	upstream-check
Aliases	1	/clear → /new
Core	1	_icons (internal icon registry)

Catalog and selection

Use the catalog command to inspect extensions before enabling them:

tallow extensions          # default table output
tallow extensions --json   # machine-readable catalog
tallow extensions tasks    # detail view for one extension ID

Invocation	Output
tallow extensions	Human-friendly table (default)
tallow extensions --json	Full JSON payload for scripts/CI
tallow extensions <id>	Expanded metadata for a single extension

Catalog output is driven by each extension manifest, including whenToUse, capabilities, and permissionSurface.

For least-privilege startup, explicitly select only what you need:

tallow --extensions-only --extension tasks --extension lsp

Repeat --extension <selector> to compose the exact extension set.

How extensions are loaded

All bundled extensions ship with tallow and are loaded automatically — no separate installation step. Just run tallow.

Extensions load from multiple sources in this order:

1. Bundled — shipped in the tallow package’s extensions/ directory
2. User global — ~/.tallow/extensions/
3. Project local — .tallow/extensions/

If a user extension has the same directory name as a bundled extension, the user version overrides the bundled one. tallow prints a notice at startup when this happens.

Disabling extensions

The installer lets you disable extension groups. Under the hood, disabled extension names are stored in settings.json:

{
  "disabledExtensions": ["git-status", "cheatsheet"]
}

You can also pass --no-extensions on the CLI to disable all extensions for a session.

Creating your own

See Creating Extensions for the full guide on building custom extensions.