Bundle Types

echidna supports 8 bundle types, each providing a different template for ChimeraX extension development.

Available Types

Type	Description	Use Case
command	Command-only bundle (default)	Add new commands to ChimeraX
tool	Qt-based GUI tool	Create a dockable panel with Qt widgets
tool-html	HTML-based GUI tool	Create a dockable panel with HTML/JS UI
format	File format reader/writer	Add support for new file formats
fetch	Network database fetcher	Fetch data from online databases
selector	Chemical subgroup selector	Define custom atom/residue selectors
preset	Visualization presets	Create reusable visualization styles
cpp	C/C++ extension bundle	Bundle with native C++ code

Selecting a Type

Use the --type (or -t) flag with echi init:

echi init --type command my-tool       # Default
echi init --type tool my-gui-tool
echi init --type tool-html my-html-tool
echi init --type format my-format
echi init --type fetch my-fetcher
echi init --type selector my-selector
echi init --type preset my-preset
echi init --type cpp my-native-ext

Type Details

command (default)

Registers a new command in ChimeraX. This is the most common bundle type.

Generated files:

• src/__init__.py - Bundle initialization, command registration
• src/cmd.py - Command implementation

Example use cases: Adding data analysis commands, automation scripts, custom workflows.

tool

Creates a dockable GUI panel using Qt widgets. Use this for interactive tools that need native desktop UI elements.

Generated files:

• src/__init__.py - Bundle initialization, tool registration
• src/tool.py - Tool panel implementation with Qt

Example use cases: Property inspectors, control panels, interactive editors.

tool-html

Creates a dockable GUI panel using an embedded HTML/JavaScript interface. Useful when you prefer web technologies for the UI.

Generated files:

• src/__init__.py - Bundle initialization, tool registration
• src/tool.py - Tool panel with HTML UI

Example use cases: Data dashboards, form-based tools, visualizations using web libraries.

format

Adds support for reading (and optionally writing) a new file format.

Generated files:

• src/__init__.py - Bundle initialization, format registration
• src/open.py - File reader implementation

Example use cases: Custom molecular file formats, structure databases, experimental data formats.

fetch

Registers a fetcher that downloads data from a network database.

Generated files:

• src/__init__.py - Bundle initialization, fetch registration
• src/fetch.py - Fetcher implementation

Example use cases: Database clients (PDB, UniProt, custom databases).

selector

Defines a custom selector for picking atoms, residues, or other model components.

Generated files:

• src/__init__.py - Bundle initialization, selector registration
• src/selector.py - Selector implementation

Example use cases: Chemical subgroup selectors, property-based selection.

preset

Creates reusable visualization presets that users can apply to models.

Generated files:

• src/__init__.py - Bundle initialization, preset registration
• src/preset.py - Preset implementation

Example use cases: Publication-quality styles, analysis-specific coloring schemes.

cpp

A bundle that includes C/C++ code compiled as a native extension. Uses a different source layout with the package nested under src/chimerax/.

Generated files:

• src/chimerax/<package>/__init__.py - Bundle initialization
• src/chimerax/<package>/cmd.py - Python command wrapper
• src/chimerax/<package>/_extension.cpp - C++ extension code

Example use cases: Performance-critical computations, wrapping existing C/C++ libraries.

note

C++ bundles are marked as pure = false in pyproject.toml and require a C++ compiler to build.