Headers field not being respected

Hello,

thanks for the updates! I just updated to the most recent version (0.5.1) and it fixed some of my styling issues! However, sadly it introduced a new kind of issue: The header field in the YAML is not being respected.

Code

show-today: true
headers:
  - month
start: 2025-11-01
end: 2026-08-31
tasks:
  - name: Exposé
    start: 2025-11-01
    end: 2026-01-31

#import "@preview/gantty:0.5.1": gantt

= Timeline

#gantt(yaml("gantt.yaml"))

Result

Expected

The resulting gantt should only show the month, not include the weeks. If I add year (out of curiosity) it is not respected as well. The header will always show month and week.

Here are the results from a prior version. I would expect something similar.

0.3.0

show-today: true
viewport-snap: month
headers:
  - month
  - year
start: 2025-11-01
end: 2026-08-31
taskgroups:
  - name: Exposé
    tasks:
    - start: 2025-11-01
      end: 2026-01-31
      name: example task
milestones:
  - name: Exposé Abgabe
    date: 2026-01-31
  - name: Projektplan Abgabe
    date: 2026-02-28
  - name: Zwischenpräsentation
    date: 2026-05-15
  - name: Abschlusspräsentation
    date: 2026-08-31