plugin-calendar: authoring events on a calendar-view node crashes the component — the SDUI action object overwrites the computed CalendarEvent array #4433

Measured by the #4425 phase-1 DOM-leak sweep gate. This one is not a DOM leak — it is a crash, found because the sweep plants the same canary set on every target and this target refused to render.

The defect

packages/plugin-calendar/src/calendar-view-renderer.tsx computes a CalendarEvent[] from schema.data, passes it as events, and then spreads the remaining props after it:

return (
  CalendarView
    className={className}
    events={events}
    onEventClick={handleEventClick}
    {...props}
  /
);

SchemaRenderer forwards a node's events key as a prop (it is not on the renderer's strip list). So an SDUI node that authors events — the ordinary action metadata of AGENTS.md section 4, legal on any node — has its { onClick: [...] } object land on the events prop, replacing the array. CalendarView then iterates it and throws.

Measured, in isolation

events alone, nothing else authored:

{ "type": "plugin-calendar:calendar-view", "id": "n",
  "events": { "onClick": [{ "action": "navigate" }] } }

renders the error boundary, not the calendar:

Component "plugin-calendar:calendar-view" failed to render
events is not iterable

The same node without events renders the real calendar (role="region" aria-label="Calendar"), and so does one carrying every other canary. So events is the sole trigger — this is not a side effect of the sweep's other canaries.

Why this is worse than the leaks filed alongside it

#4431 and #4432 put junk attributes on the DOM. This one takes the whole component down: a perfectly spec-legal node loses its calendar and shows an error card instead. A prop-name collision between injected SDUI metadata and a component's own prop is a different failure mode from the leak class, and a whitelist at the spread site would close it as a side effect — one more input for #4425 phase 2.

Interaction with the gate

The sweep renders plugin-calendar:calendar-view without the events canary, recorded in the gate as CALENDAR_VIEW_OMITS with the reason, because a crashing render produces a tidy error-boundary DOM with no leaked attributes and would otherwise read as a clean pass. The omission is not silent: the gate carries a dedicated case pinning this crash, so it cannot regress unnoticed. Fixing it turns that case red, and both halves — the omission and the pin — come out in the same change, putting events back into the sweep for this target.

Generated by Claude Code