Expose queueing/scheduled time in the Gantt Chart

[smyjt]

Adds queued_dttm to the Gantt chart so users can see how long tasks spent waiting in the queue before execution started.

Changes:

• Backend: Added queued_dttm scheduled_dttmfield to GanttTaskInstance datamodel and SQL queries (both TaskInstance and TaskInstanceHistory)
• Frontend: Renders a separate queue segment on the Gantt bar (from queued_dttm scheduled_dttm to start_date) using the existing queued and scheduled state color
• OpenAPI spec regenerated via scripts/in_container/run_generate_openapi_spec.py
• TypeScript types regenerated via npm run codegen
• Tests updated and a new test added to verify queued_dttm/scheduled_dttm is returned

This mirrors the Airflow 2 Gantt chart behavior which was missing in Airflow 3.

closes: #63356

---

Was generative AI tooling used to co-author this PR?

• Yes — Claude Sonnet 4.6

Generated-by: Claude Sonnet 4.6 following the guidelines

[boring-cyborg]

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[bbovenzi]

Great! Can you provide screenshots of the queued time showing up in the chart?

[smyjt]

Great! Can you provide screenshots of the queued time showing up in the chart?

Does this look good?

[pierrejeambrun]

Nice, should we also handle a scheduled segment? Based on scheduled_dttm ?

[smyjt]

Nice, should we also handle a scheduled segment? Based on scheduled_dttm ?

Will add that too.

[smyjt]

@pierrejeambrun @bbovenzi
I have added both scheduled and queued segment in the gantt chart
Visually, scheduled uses zinc and queued uses stone, which was hard for me to differentiate for a task instance considering the durations are in ms, but I have verified that it is working.

[pierrejeambrun]

Looking good.

Do you mind fixing the CI.

I agree those are hard to dissociate, but are not directly related to this PR. A great follow up PR would be to suggest another default color for those states to have a better contrast. @smyjt

[smyjt]

Rebased after taking latest pull, all checks are passing locally

[smyjt]

Hi, can you help me with how to run these CI pipeline tests locally that are failing, I ran the pre-commit command without any error

[pierrejeambrun]

Looks good but on some task groups / tasks, when transition states are close enough (I think < 1s) all bars are stacked on top of each others and we cannot see schedules or queued.

Screen.Recording.2026-03-18.at.17.51.38.mov

[pierrejeambrun]

CI failures seems unrelated. Please rebase and lets try again. Usually the github logs show the breeze command that is running for the particular step. (All CI checks are breeze commands locally reproducible)

[smyjt]

Looks good but on some task groups / tasks, when transition states are close enough (I think < 1s) all bars are stacked on top of each others and we cannot see schedules or queued.

Should we change anything for this?