Cortex Plugin Development Guide

Welcome to the Cortex Plugin System! This guide provides comprehensive documentation for developing plugins that extend Cortex functionality.

The plugin system is under active development. Sections describing the WebAssembly runtime and the full capability model document where the system is heading; cortex plugin already manages installation, enablement and the development workflow today.

Managing plugins
Introduction
Plugin Architecture
Plugin Manifest
Capabilities and Permissions
WASM Runtime
Host Functions
Development Workflow
Related Documentation

Managing plugins

cortex plugin list                    # alias: ls
cortex plugin list --enabled
cortex plugin install <name>          # alias: add
cortex plugin show <name>             # alias: info
cortex plugin enable <name>
cortex plugin disable <name>
cortex plugin remove <name>           # aliases: rm, uninstall

Developing one:

cortex plugin new my-plugin           # alias: create
cortex plugin dev --watch             # hot reload while you work
cortex plugin build
cortex plugin validate                # alias: check
cortex plugin publish --dry-run

In the TUI, /plugins manages them without leaving the session.

Introduction

The Cortex plugin system allows developers to extend the CLI with custom functionality including:

Custom Commands: Add new slash commands
Hook Handlers: Intercept and modify tool execution, chat messages, UI rendering, and more
Custom Widgets: Add UI elements to the TUI
Keyboard Bindings: Register custom key combinations
Event Handling: React to system events

Plugins are written in Rust and compiled to WebAssembly (WASM), providing cross-platform compatibility and sandboxed execution.

Plugin Architecture

Plugin Types

Type	Description	Location
WASM	WebAssembly-based plugins for cross-platform compatibility	`~/.cortex/plugins/` or `.cortex/plugins/`
Native	Dynamic libraries (.so, .dylib, .dll) for maximum performance	Same as above
Script	Directory-based plugins with hooks.json and scripts	Same as above

Plugin Locations

Plugins are discovered from two locations:

User Plugins: ~/.cortex/plugins/ - Available across all projects
Project Plugins: .cortex/plugins/ - Project-specific plugins

Plugin Lifecycle

┌─────────────┐     ┌─────────────┐     ┌──────────────┐     ┌────────────┐
│  Discovery  │ ──▶ │   Loading   │ ──▶ │ Registration │ ──▶ │ Initialize │
└─────────────┘     └─────────────┘     └──────────────┘     └────────────┘
                                                                    │
                                                                    ▼
┌─────────────┐     ┌─────────────┐                          ┌────────────┐
│  Shutdown   │ ◀── │  Unloading  │ ◀────────────────────────│   Active   │
└─────────────┘     └─────────────┘                          └────────────┘

Discovery: Plugins are found in plugin directories
Loading: Manifest is loaded and validated
Registration: Plugin is registered with the manager
Initialize: Plugin's init() function is called
Active: Plugin receives hook calls
Shutdown: Plugin's shutdown() function is called on exit

Plugin Manifest (plugin.toml)

Every plugin requires a plugin.toml manifest file. Here's a complete reference:

# ============================================================================
# Plugin Metadata
# ============================================================================
[plugin]
id = "my-awesome-plugin"           # Unique identifier (alphanumeric, hyphens, underscores)
name = "My Awesome Plugin"         # Human-readable name
version = "1.0.0"                  # Semantic version (required)
description = "Plugin description" # What your plugin does
authors = ["Your Name <email>"]    # List of authors
homepage = "https://github.com/..." # Plugin homepage/repository
license = "MIT"                    # License identifier
min_cortex_version = "1.0.0"       # Minimum Cortex version required
keywords = ["utility", "tools"]    # Keywords for discovery

# ============================================================================
# Capabilities (what your plugin can do)
# ============================================================================
capabilities = [
    "commands",    # Provide custom commands
    "hooks",       # Register hooks
    "events",      # Handle events
    "tools",       # Provide tools (MCP-style)
    "formatters",  # Provide formatters
    "themes",      # Provide custom themes
    "config",      # Access configuration
    "filesystem",  # Access file system (with permissions)
    "shell",       # Execute shell commands (with permissions)
    "network"      # Make network requests (with permissions)
]

# ============================================================================
# Permissions (what resources your plugin needs)
# ============================================================================
permissions = [
    { read_file = { paths = ["**/*.rs", "**/*.toml"] } },
    { write_file = { paths = [".cortex/plugins/my-plugin/**"] } },
    { execute = { commands = ["cargo", "rustc"] } },
    { network = { domains = ["api.example.com", "registry.npmjs.org"] } },
    { environment = { vars = ["HOME", "PATH"] } },
    { config = { keys = ["theme", "model"] } },
    "clipboard",       # Access clipboard
    "notifications"    # Show notifications
]

# ============================================================================
# Commands
# ============================================================================
[[commands]]
name = "my-command"               # Command name (without leading /)
aliases = ["mc", "myc"]           # Alternative names
description = "Does something"    # Command description
usage = "/my-command [options]"   # Usage example
category = "utility"              # Category for grouping
hidden = false                    # Hide from help listing

[[commands.args]]
name = "option"                   # Argument name
description = "An option"         # Argument description
required = false                  # Is it required?
default = "default_value"         # Default value
arg_type = "string"               # Type: string, number, boolean

# ============================================================================
# Hooks
# ============================================================================
[[hooks]]
hook_type = "tool_execute_before" # Hook type (see HOOKS.md)
priority = 50                     # Lower = runs first (default: 100)
pattern = "*.rs"                  # Optional pattern filter
function = "my_hook_handler"      # WASM function name (optional)

[[hooks]]
hook_type = "session_start"
priority = 100

# ============================================================================
# Configuration Schema
# ============================================================================
[config]
api_key = { description = "API key", type = "string", required = true }
max_items = { description = "Max items", type = "number", default = 10 }
enabled = { description = "Enable feature", type = "boolean", default = true }

[config.advanced]
description = "Advanced settings"
type = "object"
required = false

# ============================================================================
# WASM Settings
# ============================================================================
[wasm]
memory_pages = 256      # Memory limit in 64KB pages (256 = 16MB)
timeout_ms = 30000      # Execution timeout (30 seconds default)
wasi_enabled = true     # Enable WASI preview1
wasi_caps = [           # WASI capabilities
    "stdin",
    "stdout",
    "stderr",
    "env",
    "random",
    "clocks"
]

Capabilities and Permissions

Capabilities

Capabilities declare what your plugin can do:

Capability	Description
`commands`	Provide custom slash commands
`hooks`	Register hook handlers
`events`	Handle system events
`tools`	Provide MCP-style tools
`formatters`	Provide code formatters
`themes`	Provide custom themes
`config`	Access Cortex configuration
`filesystem`	Access file system (requires permissions)
`shell`	Execute shell commands (requires permissions)
`network`	Make network requests (requires permissions)

Permissions

Permissions request access to specific resources:

Permission	Description	Risk Level
`read_file`	Read files from specified paths	Medium
`write_file`	Write files to specified paths	High
`execute`	Execute specified shell commands	High
`network`	Access specified network domains	Medium
`environment`	Access environment variables	Low
`config`	Access configuration keys	Low
`clipboard`	Access clipboard	Medium
`notifications`	Show notifications	Low

WASM Runtime

Resource Limits

The WASM runtime enforces strict resource limits for security:

Resource	Limit	Description
Memory	16 MB	Maximum memory per plugin instance
CPU	10M operations	Fuel-based CPU limiting
Timeout	30 seconds	Default execution timeout
Tables	10,000 elements	Maximum table size
Instances	10	Maximum instances per plugin
Memories	1	One linear memory per instance

Memory Configuration

Memory is allocated in 64KB pages:

[wasm]
memory_pages = 256  # 256 × 64KB = 16MB (maximum)

Fuel-Based CPU Limiting

The runtime uses wasmtime's fuel mechanism to limit CPU usage. Each WASM operation consumes fuel. When fuel is exhausted, execution stops with an error.

Default fuel limit: 10,000,000 operations (approximately 10 million basic operations).

Host Functions

Plugins can call host functions to interact with Cortex. These are exposed through the cortex WASM import module.

Available Host Functions

Function	Signature	Description
`log`	`(level: i32, msg_ptr: i32, msg_len: i32)`	Log a message
`get_context`	`() -> i64`	Get execution context
`register_widget`	`(region: i32, type_ptr: i32, type_len: i32) -> i32`	Register a UI widget
`register_keybinding`	`(key_ptr: i32, key_len: i32, action_ptr: i32, action_len: i32) -> i32`	Register a keyboard binding
`show_toast`	`(level: i32, msg_ptr: i32, msg_len: i32, duration_ms: i32) -> i32`	Show a toast notification
`emit_event`	`(name_ptr: i32, name_len: i32, data_ptr: i32, data_len: i32) -> i32`	Emit a custom event

Log Levels

Level	Value	Description
Trace	0	Detailed debugging
Debug	1	Debug information
Info	2	General information
Warn	3	Warning messages
Error	4	Error messages

UI Regions for Widgets

Region	Value	Description
Header	0	Top header area
Footer	1	Bottom footer area
SidebarLeft	2	Left sidebar
SidebarRight	3	Right sidebar
MainContent	4	Main content area
InputArea	5	User input area
Overlay	6	Overlay/modal area
StatusBar	7	Status bar
ToolOutput	8	Tool output area
MessageArea	9	Chat message area

Toast Notification Levels

Level	Value	Description
Info	0	Informational
Success	1	Success message
Warning	2	Warning message
Error	3	Error message

Example: Using Host Functions in Rust

#[link(wasm_import_module = "cortex")]
extern "C" {
    fn log(level: i32, msg_ptr: i32, msg_len: i32);
    fn register_widget(region: i32, type_ptr: i32, type_len: i32) -> i32;
    fn show_toast(level: i32, msg_ptr: i32, msg_len: i32, duration_ms: i32) -> i32;
}

fn log_info(msg: &str) {
    unsafe {
        log(2, msg.as_ptr() as i32, msg.len() as i32);
    }
}

fn register_status_widget(widget_type: &str) -> bool {
    unsafe {
        register_widget(7, widget_type.as_ptr() as i32, widget_type.len() as i32) == 0
    }
}

fn show_success_toast(msg: &str, duration_ms: i32) {
    unsafe {
        show_toast(1, msg.as_ptr() as i32, msg.len() as i32, duration_ms);
    }
}

Development Workflow

1. Create Your Plugin

# Create plugin directory
mkdir -p ~/.cortex/plugins/my-plugin
cd ~/.cortex/plugins/my-plugin

# Initialize Rust project
cargo init --lib

2. Configure Cargo.toml

[package]
name = "my-plugin"
version = "0.1.0"
edition = "2021"

[lib]
crate-type = ["cdylib"]

[profile.release]
opt-level = "s"
lto = true

3. Create plugin.toml

See the Plugin Manifest section above.

4. Build Your Plugin

# Add WASM target
rustup target add wasm32-wasi

# Build
cargo build --target wasm32-wasi --release

# Copy WASM file
cp target/wasm32-wasi/release/my_plugin.wasm plugin.wasm

5. Test Your Plugin

# Validate your plugin
cortex plugin validate .

# Test in development mode
cortex plugin dev --watch

6. Install Your Plugin

# Plugin is automatically discovered from ~/.cortex/plugins/my-plugin/
cortex plugin list

Configuration in Cortex Config

Plugins can be configured in your main Cortex config file:

[[plugins]]
name = "my-plugin"
path = "~/.cortex/plugins/my-plugin"
enabled = true
priority = 0
granted_permissions = ["read_files", "network"]

[plugins.config]
api_key = "your-api-key"
max_items = 20

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Cortex Plugin Development Guide

Table of Contents

Managing plugins

Introduction

Plugin Architecture

Plugin Types

Plugin Locations

Plugin Lifecycle

Plugin Manifest (plugin.toml)

Capabilities and Permissions

Capabilities

Permissions

WASM Runtime

Resource Limits

Memory Configuration

Fuel-Based CPU Limiting

Host Functions

Available Host Functions

Log Levels

UI Regions for Widgets

Toast Notification Levels

Example: Using Host Functions in Rust

Development Workflow

1. Create Your Plugin

2. Configure Cargo.toml

3. Create plugin.toml

4. Build Your Plugin

5. Test Your Plugin

6. Install Your Plugin

Related Documentation

Configuration in Cortex Config

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Cortex Plugin Development Guide

Table of Contents

Managing plugins

Introduction

Plugin Architecture

Plugin Types

Plugin Locations

Plugin Lifecycle

Plugin Manifest (plugin.toml)

Capabilities and Permissions

Capabilities

Permissions

WASM Runtime

Resource Limits

Memory Configuration

Fuel-Based CPU Limiting

Host Functions

Available Host Functions

Log Levels

UI Regions for Widgets

Toast Notification Levels

Example: Using Host Functions in Rust

Development Workflow

1. Create Your Plugin

2. Configure Cargo.toml

3. Create plugin.toml

4. Build Your Plugin

5. Test Your Plugin

6. Install Your Plugin

Related Documentation

Configuration in Cortex Config