events

# PyWry Event System — Agent Reference > **The event bus is the plumbing underneath every MCP tool.** You > rarely need to think about it — the typed tools wrap emit + wait + > state-poll for you — but when you reach for `send_event` or > interpret tool results, this is how it works. ## Event names are namespaced Every event has the form `namespace:event-name`, e.g.: - `tvchart:symbol-search` — ask the chart to open symbol search - `tvchart:state-response` — chart's reply with its current state - `tvchart:data-request` — chart asks Python for bars - `tvchart:data-response` — Python delivers bars - `toolbar:request-state` — ask a toolbar component for its value - `toolbar:state-response` — component's reply - `chat:user-message` — user typed something - `chat:ai-response` — model produced a token - `pywry:update-theme` — dark/light mode change Never emit an event with a name that doesn't match `namespace:event-name` — the framework rejects it. ## Widget IDs vs component IDs **widget_id** — identifies the top-level PyWry widget (a chart, a grid, a chat panel, a dashboard). Every MCP tool takes `widget_id` as an argument because all events route to the widget first. **componentId** — identifies a child *inside* a widget (a specific toolbar button, a marquee ticker slot, a chart pane). Component IDs are scoped to their containing widget. When you call `send_event(widget_id, event_type, data)`, the `widget_id` picks the ta...