fix: do not assign weekday that contradicts the computed relative date

[spokodev]

Problem

A parse of [weekday] [in N weeks] returns a result whose reported weekday contradicts the date it computed. The weekday says one day, the date is another.

Repro (timezone-explicit so it is not a DST artifact):

const chrono = require("chrono-node");
const ref = new Date("2026-06-24T12:00:00Z"); // Wednesday
const res = chrono.parse("Saturday in 3 weeks", ref)[0];

res.start.knownValues;       // { weekday: 6, day: 15, month: 7, year: 2026 } (weekday 6 = Saturday)
res.start.date();            // 2026-07-15T12:00:00.000Z  -> 2026-07-15 is a WEDNESDAY
res.start.isCertain("weekday"); // true
res.start.get("weekday");    // 6 (Saturday), contradicts the Wednesday date

ref (Wed 2026-06-24) + 3 weeks is 2026-07-15, a Wednesday, but the result still carries weekday: 6 (Saturday) from the original "Saturday" token. The result reports a weekday that disagrees with its own date.

Over a sweep of reference dates x {Saturday, Sunday, Monday, Friday} x {in 1/2/3 weeks}, the large majority of certain-weekday results were inconsistent this way. It also reproduces with within, in N days, and a next prefix.

Cause

MergeWeekdayComponentRefiner exists to merge a weekday that labels an explicit date, for example Sunday 12/7/2014 or Tuesday, January 10. Its shouldMergeResults only checks nextResult.start.isCertain("day"), which a relative-offset result such as in 3 weeks also satisfies. The merge then fires and mergeResults overwrites the weekday with the original token, even though ParsingComponents.createRelativeFromReference had already resolved the correct day-of-week for the offset date.

Fix

Skip the merge when the next result is a relative-offset date (it carries the result/relativeDate tag). A relative-offset date already resolves its own day-of-week, so there is no weekday to label. The legitimate case, a weekday in front of an explicitly stated date, is unchanged: those results have no result/relativeDate tag and still merge exactly as before (including the existing behavior where a user-stated weekday is preserved over the computed date, e.g. Tuesday, January 10 in en_month_name_middle_endian.test.ts).

Tests

Added test/en/en_weekday_relative_consistency.test.ts asserting that any result reporting a certain weekday matches the day-of-week of its computed date. It fails on master (weekday 6 on a Wednesday date) and passes with this change. The full existing suite stays green (615 tests) under default TZ, TZ=UTC, and TZ=America/New_York.

[wanasit]

Thanks for the fix. Added one small comment.

[coveralls]

coverage: 92.859%. remained the same — spokodev:fix/weekday-relative-date-consistency into wanasit:master

[spokodev]

Thanks @wanasit. The inline comment isn't showing on my end, which usually means it's still in a pending review that hasn't been submitted. Could you submit it so the note surfaces? I'll address it right away.

[wanasit]

Having a new test file just for this one case is too fragmented.
Could this test be included in the weekday or relative time testing?

[spokodev]

Moved the case into en_merging_relative_dates.test.ts and deleted the standalone file. That suite already covers the merge-weekday-onto-relative-date path this fixes, so it fits there. No worries on the delay.

[wanasit]

Thanks @wanasit. The inline comment isn't showing on my end, which usually means it's still in a pending review that hasn't been submitted. Could you submit it so the note surfaces? I'll address it right away.

Ops. Sorry.