slashCommand

Declare a command the user types inside a chat session. The `id` is the name typed after the slash, `description` is the line shown in the typeahead, and `argumentHint` is the placeholder for whatever the user types after the name. The handler receives that text, or `undefined` when the user typed nothing, plus a context carrying the AI session the command was typed into. Use this instead of `command` when the behavior belongs to a conversation and needs the session. Use `command` when it belongs to the workbench and runs from the palette. Use `tool` when the model, not the user, should decide to run it. Slash commands go in the same top-level `commands` array as palette commands.