create-extension

Create Extension Workflow

Use the create_extension MCP tool to create a fully-wired TD extension:

create_extension(
    parent_path='/path/to/parent',
    class_name='MyFeatureExt',
    name='MyFeature',           # Optional: COMP name
    code='...',                 # Optional: initial Python code
    promote=True,               # Optional: promote extension methods
    ext_name='MyFeature',       # Optional: extension name
    ext_index=0                 # Optional: extension index
)

This creates: baseCOMP + text DAT + extension wiring, initialized and ready to use.

Wiring by hand: the Extension Object parameter is a constant-mode Str par whose VALUE is Python (par.ext0object.val = "op('./MyFeatureExt').module.MyFeatureExt(me)" -- the Extensions page is the ext sequence on 2025 builds: ext0object, ext0name, ext0promote; there is no extension1). Never set its .expr: the extension comes back None with extensionsReady True and errors() empty; the only trace is a SyntaxError ... Context:(Extension 1) on scriptErrors() (get_op_errors kind: 'script').

Extension Lifecycle Methods

Always implement these in your extension class:

class MyFeatureExt:
    def __init__(self, ownerComp: COMP) -> None:
        self.ownerComp = ownerComp

    def onDestroyTD(self) -> None:
        """Called on old instance before TD reinitializes. Clean up callbacks, timers, etc."""
        pass

    def onInitTD(self) -> None:
        """Called at end of frame after init. Safe to access other extensions and cooked network."""
        pass

Naming Convention

Extension classes and source DATs must follow the NameExt convention:

• Class: MyFeatureExt
• DAT: MyFeatureExt (matches class name)

Three Namespace Tiers

TD promotes every capitalized member -- methods and class constants alike. There is no per-member opt-out, so the capital letter is the access modifier. Pick the tier by who calls it: