Worksheet Components

Worksheet components implement the WorksheetComponent subtrait, which pins the associated types for trait object usage.

WorksheetComponent Subtrait

trait WorksheetComponent: Component<Metadata = (), Output = WorksheetElement> {
    fn id(&self) -> &'static str;
    fn name(&self) -> &'static str;
    fn description(&self) -> &'static str;
    fn icon(&self) -> &'static str;
}

Child metadata is () — worksheet components do not receive spatial metadata from their placement. Each component compiles to a single WorksheetElement. A blanket impl covers any TypedComponent with matching types, so you only implement TypedComponent.

Built-in Components

Component	Key	Description
`SheetHeaderComponent`	`"sheet_header"`	Page header with title, class name, name/date fields
`SectionHeadingComponent`	`"section_heading"`	Section divider with title and colored accent
`QuestionComponent`	`"question"`	Question with prompt, answer area, type, difficulty
`GoalsComponent`	`"goals"`	Success criteria checklist
`AnswerGridComponent`	`"answer_grid"`	Grid of answer options in columns
`ActivityComponent`	`"activity"`	Free-form activity content

Compile Flow

Each component implements TypedComponent and receives a typed properties struct:

#[derive(modality_core::ComponentProperties)]
pub struct QuestionProps {
    #[property(key = "questionText", name = "Question")]
    pub question_text: String,

    #[property(key = "questionNumber", name = "Number", default = "1")]
    pub question_number: i32,

    #[property(key = "questionType", name = "Type")]
    pub question_type: QuestionType,

    #[property(name = "Answers", description = "JSON-encoded answer options")]
    pub answers: String,

    #[property(key = "answerBoxHeight", name = "Answer Box Height", default = "80")]
    pub answer_box_height: f64,

    // ...
}

impl TypedComponent for QuestionComponent {
    type Properties = QuestionProps;
    type Metadata = ();
    type Output = WorksheetElement;

    fn id() -> &'static str { "question" }
    fn name() -> &'static str { "Question" }
    fn description() -> &'static str { "Question with prompt, answers, and answer area" }
    fn icon() -> &'static str { "help_outline" }

    fn compile(&self, props: &QuestionProps, _meta: &())
        -> Result<WorksheetElement, CompileError>
    {
        Ok(WorksheetElement::Question(QuestionElement { /* ... */ }))
    }
}

The blanket Component impl handles HashMap extraction automatically — TypedComponent::compile() always receives typed props.

Component Registration

Components register via inventory::submit! and are resolved by key:

inventory::submit!(WorksheetComponentEntry(&QuestionComponent));

Overview — struct, types, compilation flow
Intents — all dispatchable commands
Component — the core trait all components implement
Properties — property schema and value system
Typed Component Properties RFC — design rationale for typed component properties

Worksheet Components