Gantt — data-struct API

v1 is data-struct only. No DSL, no parser, no builder. Future M-CHART.1 may add a builder if ergonomics demand it.

Top level

pub struct Gantt {
    pub range: DateRange,
    pub rows: Vec<Row>,
    pub bars: Vec<Bar>,
    pub people: PersonMap,
}

DateRange

Half-open [start, end). Two constructors:

DateRange::year(2026)                    // [Jan 1, Jan 1 of next year)
DateRange::from(date(2026, 2, 1)..date(2026, 3, 15))

The From<Range<Date>> impl makes inline construction ergonomic in fixtures and tests.

Row

Row::new("vec", "M-VEC")

id is the stable identifier; Bar::row_id references it. label is the string drawn in the left gutter.

Bar

Bar::new(
    "vec",
    date(2026, 2, 1)..date(2026, 3, 15),
    "Matt",
)

Bar::label and Bar::group are Option<String> and default to None. v1 stores group but does not render it.

PersonMap

let mut people = PersonMap::default();
people.insert(Person {
    name: "Matt".into(),
    color: Color::from_hex("#0072b2").unwrap(),
});

Explicit entries override the auto-assigned palette colour. Owners without an entry fall back to Theme::palette auto-assignment.

Serde

The data structs are intentionally serde-friendly — adding #[derive(Serialize, Deserialize)] later is a one-line change per struct. The first ingest format will be CSV (M-CHART.2 / follow-on ticket).

API stability

The public surface is intentionally narrow. Additive changes (more fields with Default impls, more constructors) ship at minor versions. Renames / removals trip cargo semver-checks.