HTTP 400 saving all-day calendar events in TUI (hey-sdk bug)

[drchp]

Summary

Saving an all-day calendar event in hey tui (or via hey event edit) fails with:

Save failed: Form request failed (HTTP 400)

Timed events and creating new all-day events work; editing all-day events fails.

Root cause

Upstream bug in hey-sdk updateEventValues: empty StartTime/EndTime pointers are sent as starts_at_time=:00 and ends_at_time=:00, which HEY rejects.

Fix PR: basecamp/hey-sdk#131

Reproduce

hey event add "All day test" --starts-on 2026-08-31 --json
hey event edit <id> --title "edited" --json
# {"ok":false,"error":"Form request failed (HTTP 400)","code":"api"}

Same in hey tui: create or select an all-day event, edit, Ctrl+S.

Workaround

Edit all-day events in the HEY web app until hey-cli picks up a fixed hey-sdk release.

Fix

Bump github.com/basecamp/hey-sdk/go after basecamp/hey-sdk#131 merges.