[imdreamrunner]

Exact decision needed

Which form of the weekday name Calendar's column headers show.

Existing authority searched

• component:Calendar (current, docs/specs/components/Calendar/Calendar.spec.md): FR1 says only that weekday names come from the provider locale. architecture:internationalization covers locale data but not name width. No current record settles the form.
• Code: Calendar's headers use the CLDR stand-alone short width from a generated table (Su–Sa in English). The touch date field's sheet already uses the abbreviated width (Sun–Sat).
• Open PRs: none edits the Calendar record or the weekday headers (the open Calendar fixes touch initial focus and the date-field sheets).

Decision

component:Calendar DD1: each weekday column header shows the provider locale's stand-alone abbreviated weekday name (the CLDR abbreviated width) in full, so Sun–Sat in English. FR1 points to DD1. The headers still render the short names today, so the DD1 row, Current-state impact, and a verification-map evidence gap record that as an implementation gap. This PR changes no code.

Rejected alternatives

• Cutting each name to three characters. That misnames days in locales whose abbreviations differ. It is kept as one Rejected: line in DD1.

Claim scope and non-goals

• Covers the visible header text only. The header's accessible name, typography, column width, and how an over-wide locale name lays out stay uncontracted.
• Switching the header to the abbreviated width and updating the day-name tests is a separate implementation PR.

Evidence and implementation relationship

• This is a design request. In English, two-letter names make Tu and Th, or Sa and Su, easy to confuse.
• In some catalog locales the abbreviated names are longer than three letters (from Intl/CLDR): ar and pt-PT use full words (الثلاثاء, segunda), and he (יום א׳), pl (niedz.), vi (Thứ 2), da, fr, pt, and ro also run longer.

Question for design review

@rubyycheung, could you review this? It's the 3-letter weekday change you asked for. One call is yours: in Arabic and European Portuguese the abbreviated name is a full word, and DD1 shows it in full in the narrow day column. Should those locales keep the shorter form instead?

Writing rubric results

• R1 narration: none; DD1, its implementation gap, and the Current-state impact line are in the present tense.
• R2 research in the record: none; the locale-length check stays in this description.
• R3 evidence naming a change: none; the DD1 verification row names the test cases.
• R4 rejected alternatives over one line or outside a decision: one, inside DD1, one line.
• R5 pull request or issue references remaining: none.
• R6 ruled open questions still listing options: none; no open question added.

Scope

• This PR contains specification records only.
• It records observable behavior and preserves equivalent internal implementations.
• Any named internal mechanism is intentionally public, names its dependent caller/system, and explains why an equivalent implementation would not satisfy the contract: none named.
• Verification states the evidence layer and failure signal without prescribing CI job/workflow topology.
• It records one intentional durable decision, not a rescue for a separable tagalong.
• The canonical knowledge owner, affected current claims, and overlapping open work are named; no ownership collision.
• Adjacent API, visual, accessibility, composition, and implementation facts remain outside scope unless this exact decision depends on them.
• Public text and artifacts contain no internal Meta context.

Validation

• pnpm check:knowledge: aligned
• Prettier: clean
• git diff --check: clean
• Approval groups for this change: spec and design (the Design decisions block and the record body both change)
• Rebased onto main after the Calendar record became current and moved under docs/specs/components/.

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[astracat-bot]

AI review status for this pull request.

Review status	Updated
❓ Needs maintainer input (for maintainers only)	Nov 1, 2026, 5:20 PM UTC

[github-actions]

PR Analysis Report

Current run: The current change has no visual or preview-producing scope. Visual checks are not applicable; preview links are not shown.

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[astracat-bot]

Approval waits on an owner decision. DD1 adds a weekday-header rule that no current spec on main states yet: whole abbreviated names, including full words in Arabic and European Portuguese. An engineering owner records that decision by commenting /approve-spec 986546d4aabca741c217874492d0537e4ccab3ba on this pull request, and the author may do so if they are an engineering owner. Two record fixes are needed whatever the decision:

• Calendar.spec.md line 59 still says the released default is preserved, although DD1 changes every Calendar's header text.
• The DD1 verification row tests English and one other locale, but English and the Spanish locale the current tests use both have three-letter abbreviations, so a header cut to three characters would still pass; name a locale with longer abbreviations, such as pl or pt-PT.

[Automated review]

[astracat-bot]

DD1 changes every Calendar's weekday headers from the short to the abbreviated names, with no prop to keep the short form, and line 45 already says the record departs from shipped behavior for that. This line should say so too, for example "yes, except DD1: no", naming the header change.

[imdreamrunner]

Fixed in fd7a6ba: the row now requires a locale whose abbreviated names run past three characters, such as pl or pt-PT.

[astracat-bot]

English and es-ES (the locale the existing day-name cases use) both have three-letter abbreviated names, so a header cut to three characters would pass this row. Naming a second locale with longer abbreviations, such as pl or pt-PT, makes the stated failure detectable.

[imdreamrunner]

Fixed in fd7a6ba: the row now requires a locale whose abbreviated names run past three characters, such as pl or pt-PT.

[astracat-bot]

Approval waits on a spec owner deciding DD1 as the governing spec for Calendar's weekday headers: no current spec on main states that rule yet, and it shows whole abbreviated names, including full words in Arabic and European Portuguese that overrun the 32px day column. To settle it, an engineering owner comments /approve-spec fd7a6bae09fa026c2d5f78bf8f1604a87e714465 on this pull request (the author may do so as an engineering owner), or the owners ask for a shorter form in those locales; the repository's design-decision routing also asks for a design owner's review. The two record fixes from the earlier review are in, and nothing else needs to change.

[Automated review]

[astracat-bot]

Approval waits on a spec owner deciding DD1 as the governing spec for Calendar's weekday headers: no current spec states the abbreviated-width rule yet, and it shows whole names, including full words in Arabic and European Portuguese that are wider than the 32px day column. To settle it, an engineering owner comments /approve-spec c74015220a9aa3e3ce184fc8e500fdb196f01d8a on this pull request (the author may do so as an engineering owner), or the owners ask for a shorter form in those locales; the repository's design-decision routing also asks for a design owner's review. Nothing else in the record needs to change.

[Automated review]