Summary

The FlutterFlow AI MCP cannot author Calendar.onSelectedDateChanged.

The DSL's WidgetState(widgetName, property) expression — the documented way to read a widget's runtime value — explicitly excludes Calendar and exposes only value, text, and currentIndex (WidgetStateProperty enum). value is hard-coded to a closed list of widget types (Toggle, Checkbox, Dropdown, Slider, RadioGroup, PinCode) and throws if used against a Calendar.

The underlying proto clearly supports this — the editor produces actions that read Calendar's selected date — but the DSL surface doesn't expose the variable source/operation tree needed to construct one, and there is no documented example to reverse-engineer from.

Repro

In a FlutterFlow project, attempt the following via the flutterflow_ai DSL:

app.editPage('Daily', (page) {
  page.ensureActions(
    page.findByName('Calendar'),
    triggerType: FFActionTriggerType.ON_DATE_SELECTED,
    actions: [
      SetState('selectedDay', WidgetState('Calendar', WidgetStateProperty.value)),
    ],
  );
});

Result: Throws at compile time:

StateError: WidgetState(Calendar, value) requires a Toggle, Checkbox, Dropdown, Slider, RadioGroup, or PinCode target.

Source: .flutterflow/sdk/flutterflow_ai/lib/src/dsl/compiler.dart:7651-7663 (_widgetValueTypeForDslWidget).

Why this matters

This is a normal binding that any builder can do in two clicks in the FF editor:

Calendar → Actions → On Selected Date Changed → Update Page State → field = Calendar Widget State → Selected Date → Start Date

Every Calendar-on-a-page workflow needs it: filtering a list by day, navigating between days, querying date-scoped data. There's no DSL workaround short of writing raw protobuf, which:

1. Has no documented example to crib from anywhere in references/, docs api-surface, or docs ui.
2. Requires guessing the FFVariableSource / FFBaseVariable.widgetState shape for a non-action widget value (the existing FFWidgetStateVariable_ActionVariableType enum covers UPLOAD_DATA_URL, DATE_PICKER, TIMER_*, etc. — nothing for Calendar).
3. Will silently break with any future schema rev because it's bypassing the typed surface.

Environment

• flutterflow_ai SDK version: latest as of 2026-05-18
• DSL files: dsl/edit.dart