Command Registry

The command registry (internal/registry/) manages built-in slash commands, custom user commands, and skill commands. It publishes CommandsChangedEvent on the event bus so the TUI and Web UI can keep their autocomplete lists in sync.

Architecture

internal/registry/
├── registry.go  - Registry struct, Command type, discovery, bus integration
└── sources.go   - Built-in command definitions

internal/chat/commands/
└── commands.go  - Custom commands loaded from markdown files

Registry

type Registry struct {
    // ...
}

func New(bus *eventbus.Bus) *Registry
func (r *Registry) Discover() error
func (r *Registry) Commands() []Command
func (r *Registry) All() []Command
func (r *Registry) Register(cmd Command) error
func (r *Registry) Unregister(name string)
func (r *Registry) Publish()
func (r *Registry) Close()

Command Type

type Command struct {
    Name        string   // e.g., "/model", "/skill:my-skill"
    Label       string   // human-readable label
    Description string
    AcceptsArgs bool
    Source      string   // "builtin", "user", "project", "skill", "extension"
}

Lifecycle

1. New(bus) - Creates the registry with a bus client named "registry".
2. Discover() - Discovers all command sources: built-in, custom, skills, extensions.
3. Publish() - Publishes CommandsChangedEvent on the bus so clients update completions.
4. Register(cmd) - Manually register a command (used by plugins).
5. Unregister(name) - Remove a command (used when plugins unload).

Built-in Commands

Defined in internal/registry/sources.go. These are the core slash commands:

Command	Description
/model	Switch the active model
/system	View or edit the system prompt
/temperature	Set sampling temperature
/max-tokens	Set max completion tokens
/reset	Reset the session
/reasoning	Toggle reasoning visibility or set effort
/refresh	Refresh the models.dev catalog
/sessions	List saved sessions
/export	Export session as JSONL
/help	Show command help
/debug	Toggle debug mode
/provider	Toggle a provider on/off, or /provider login <name> for OAuth
/quit	Exit tau

Custom Commands

Custom commands are loaded from markdown files in two locations:

• User commands: ~/.config/tau/commands/ - user-global custom commands.
• Project commands: .tau/commands/ - project-local custom commands.

Command File Format

Custom commands are defined in .md files with YAML frontmatter:

---
name: my-command
description: Does something useful
arguments:
  - name: target
    description: What to operate on
    required: true
---

# My Command

Command body with instructions for the agent...

Commands are loaded by LoadCustomCommands() in internal/chat/commands/commands.go and registered in the registry with "user:" or "project:" prefixes.

Naming Convention

• User commands: "user:path/to/command" (colon-separated path segments).
• Project commands: "project:path/to/command".
• Skill commands: "skill:<skill-name>".

Skill Commands

Skills that declare command frontmatter are automatically registered as commands with the "skill:" prefix. See Skills for details.

Extension Commands

Plugin slash commands are registered by the plugin manager and prefixed with "plugin:<name>:". See Plugin SDK.

Events

CommandsChangedEvent

type CommandsChangedEvent struct {
    Commands []CommandRef
}

Published on the event bus whenever the command set changes (plugins loaded/unloaded, commands discovered/refreshed). The TUI and Web UI subscribe to this event to update their autocomplete lists.

App Integration

In internal/app/run.go, the registry is created and wired:

commandRegistry := commandreg.New(bus)
commandRegistry.Discover()

// Build initial command refs for the TUI and Web UI
initialCommands := commandRefsFromRegistry(commandRegistry.All())

The registry is passed to the coordinator, which uses it for command routing (e.g., /model → handleUpdate()).