spec: should `ParseTemporalCalendarString` AO accept strings such as `"2026-01[u-ca=gregory]"` or `"01-01[u-ca=gregory]"`?

[fabon-f]

EDIT: I misunderstood the actual problem, edited the issue comment completely.

As far as I read the spec, "2026-01" is a valid string for TemporalTimeString, because it can be parsed as Time (hour and minute without :) followed by negative DateTimeUTCOffset (i.e. T20:26:00-01:00). Similarly "01-01" can be parsed as well as "T01:00-01:00".

This format is explicitly rejected in ToTemporalTime (because it matches to AmbiguousTemporalTimeString), but not in ParseTemporalCalendarString and ParseTemporalTimeZoneString. Is this an intended behavior?

// error in SpiderMonkey and V8, but the reference polyfill returns `PlainDate` with Gregorian calendar
Temporal.Now.plainDateISO().withCalendar('01-01[u-ca=gregory]')