fix(gottext): write a bare wall clock time as the time it names

gottext/CHANGELOG.md

@@ -10,6 +10,7 @@ from CI.
 ### Fixed
 
 - `mismatched` reads the tags a message carries, so a translation that adds, drops, renames or repeats one is named.
+- `formatTime` writes a bare wall clock time, such as `09:30`, as the time it names for every reader, instead of Invalid Date.
 
 ## [0.8.0] - 2026-11-02
 

gottext/src/format.ts

@@ -8,6 +8,9 @@ let named: string | undefined
 /** CALENDAR_DAY is the shape of a bare calendar day, such as 2026-09-01. */
 const CALENDAR_DAY = /^\d{4}-\d{2}-\d{2}$/
 
+/** WALL_CLOCK is the shape of a bare wall clock time, such as 09:30. */
+const WALL_CLOCK = /^\d{2}:\d{2}$/
+
 /** DAY is how a date is written unless the caller asks otherwise. */
 const DAY: Intl.DateTimeFormatOptions = { day: '2-digit', month: '2-digit', year: 'numeric' }
 
@@ -68,11 +71,17 @@ export function formatDate(at: Date | string, options: Intl.DateTimeFormatOption
 
 /**
  * Returns a moment as a time of day in the format locale.
- * @param at - The moment, or the text a server stored.
+ * @param at - The moment, the text a server stored, or a bare wall clock time.
  * @returns The time, such as 09:05, empty when there is no moment.
  */
 export function formatTime(at: Date | string): string {
-	return at === '' ? '' : new Date(at).toLocaleTimeString(formatLocale(), CLOCK)
+	if (at === '') {
+		return ''
+	}
+	if (typeof at === 'string' && WALL_CLOCK.test(at)) {
+		return new Date(`1970-01-01T${at}Z`).toLocaleTimeString(formatLocale(), { ...CLOCK, timeZone: 'UTC' })
+	}
+	return new Date(at).toLocaleTimeString(formatLocale(), CLOCK)
 }
 
 /**

gottext/test/format.test.ts

@@ -62,6 +62,33 @@ test('writes a time as two digit hours and minutes on the es-ES clock', () => {
 	expect(formatTime('2026-09-30T09:05:00Z')).toBe('09:05')
 })
 
+test('writes a bare wall clock time as the time it names in every time zone', () => {
+	rememberFormatLocale('es-ES')
+	vi.stubEnv('TZ', 'America/Los_Angeles')
+
+	expect(formatTime('09:30')).toBe('09:30')
+	expect(formatTime('21:05')).toBe('21:05')
+	expect(formatTime('00:00')).toBe('00:00')
+	expect(formatTime('23:59')).toBe('23:59')
+})
+
+test('writes a bare wall clock time on the en-US clock as the time it names', () => {
+	rememberFormatLocale('en-US')
+	vi.stubEnv('TZ', 'Asia/Tokyo')
+
+	expect(formatTime('09:30')).toBe('09:30 AM')
+	expect(formatTime('21:05')).toBe('09:05 PM')
+	expect(formatTime('00:00')).toBe('12:00 AM')
+})
+
+test('writes a timestamp a server stored on the reader clock, with or without a zone', () => {
+	rememberFormatLocale('es-ES')
+	vi.stubEnv('TZ', 'America/Los_Angeles')
+
+	expect(formatTime('2026-09-30T09:05:00Z')).toBe('02:05')
+	expect(formatTime('2026-09-30T09:05')).toBe('09:05')
+})
+
 test('writes nothing for an absent moment', () => {
 	rememberFormatLocale('es-ES')