[EuiSuperDatePicker] Prevent time window steps from drifting by 1ms

[mgadewoll]

Summary

This PR updates EuiSuperDatePicker to fix unexpected time shifts by 1ms when using the time window buttons.

The issue was that the roundUp on dateMath.parse({date}, { roundUp: true }) results in .999ms times for relative dates like "Today". This results in a 1ms difference that's being carried across time window steps.

This update ensures that the time window range is adjusted accordingly for "inclusive" dates (ending on the last ms of the date instead of the first ms of the next date) to keep a stable ms range.

Note

A similar issue was previously resolved for absolute dates in #8985.

Why are we making this change?

🧰 Bug fix: This bug was reported to us by @KodeRad. This update ensures that the time window steps result in stable start and end date/time.

Screenshots #

scenario	before	after
step backwards	Screen.Recording.2026-03-09.at.15.11.09.mov	Screen.Recording.2026-03-09.at.15.12.53.mov
step forwards	Screen.Recording.2026-03-09.at.15.10.36.mov	Screen.Recording.2026-03-09.at.15.13.34.mov
zoom out	Screen.Recording.2026-03-09.at.15.11.37.mov	Screen.Recording.2026-03-09.at.15.14.04.mov
absolute dates	Screen.Recording.2026-03-09.at.15.24.35.mov	Screen.Recording.2026-03-09.at.15.25.26.mov

Impact to users

🟢 No updates required on consumer side.

QA

• select "Today" via the quick select menu and:
  • the date range is 00:00:00.000 - 23:59:59.999
  • verify that stepping forward on EuiSuperDatePicker time windows results in the same range of 00:00:00.000 - 23:59:59.999 for the previous day(s)
  • verify that stepping backwards on EuiSuperDatePicker time windows results in the same range of 00:00:00.000 - 23:59:59.999 for the previous day(s)
  • verify that zooming out results in start .000ms and end .999ms ranges
• Select absolute start and end dates and verify there is no regression with production when using forward/backward steps or zoom out

General checklist

• Browser QA
  • Checked in both light and dark modes
  • Checked in both MacOS and Windows high contrast modes
    • (emulate forced colors if you do not have access to a Windows machine.)
  • Checked in mobile
  • Checked in Chrome, Safari, Edge, and Firefox
  • Checked for accessibility including keyboard-only and screenreader modes
• Docs site QA
  • Added documentation
  • Props have proper autodocs (using @default if default values are missing) and playground toggles
  • Checked Code Sandbox works for any docs examples
• Code quality checklist
  • Added or updated jest and cypress tests
  • Updated visual regression tests
• Release checklist
  • A changelog entry exists and is marked appropriately
  • If applicable, added the breaking change issue label (and filled out the breaking change checklist)
  • If the changes unblock an issue in a different repo, smoke tested carefully (see Testing EUI features in Kibana ahead of time)
• Designer checklist
  • If applicable, file an issue to update EUI's Figma library with any corresponding UI changes. (This is an internal repo, if you are external to Elastic, ask a maintainer to submit this request)

[weronikaolejniczak]

Thank you for fixing the issue, Lene! I tested the solution, I see no 1ms drift or any regression 🟢 I have a couple of nits only.

Testing notes

Stepping backwards & forwards

Absolute dates

Zoom in & out

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: 8d0b839
• Documentation website
• Storybook

History

• 💚 Build #2907 succeeded 274dab8

cc @mgadewoll

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: 8d0b839

cc @mgadewoll