Unsupported Diagram type "Gantt"

[bender316]

Opus created a plan which included a gantt chart:

mermaid
gantt
    title Phase 2 Execution Timeline
    dateFormat  YYYY-MM-DD

    section Frontend Track
    Task 1: TanStack Query migration      :t1, 2026-07-21, 5d
    Task 4: Icon & dependency cleanup      :t4, 2026-07-21, 1d
    Task 5: Console.log purge              :t5, after t4, 1d

    section Backend Track
    Task 2: Split db/models.go by domain   :t2, 2026-07-21, 1d
    Task 3: Seed.go → JSON fixtures        :t3, after t2, 2d
    Task 6: Standardize handler errors     :t6, after t3, 2d

if I display the artifact in Antigravity CLI it just shows "📊 Diagram (unsupported type)" and the "source code" of the chart.