a0-development

Create a class inheriting from Tool in helpers.tool, implement the async execute() method returning a Response, and place it in a plugin's tools/ directory. You must also add a matching agent.system.tool.<name>.md prompt fragment so the agent knows how to use it.

Create a Python file named _NN_name.py under extensions/python/<hook_point>/, subclassing Extension from helpers.extension. The numeric prefix controls execution order, and hook points include agent_init, before_main_llm_call, tool_execute_before, and monologue_end.

Plugins are the primary extension mechanism, bundling tools, extensions, prompts, and API endpoints into one package. Extensions are individual lifecycle hooks that can also live standalone, but the framework recommends packaging new capabilities as plugins.

Place user code under /a0/usr/: plugins in usr/plugins/, agent profiles in usr/agents/, skills in usr/skills/, and extensions in usr/extensions/. Everything under /a0/usr/ is user-space and survives framework updates.

Profiles inherit prompts from the default profile, and placing a file with the same name in the profile's prompts/ directory overrides it. The framework searches profile-specific directories first, then plugins, then core prompts, using the first match found.