oppi.li
source dump of claude code
1/**
2 * Format an ISO timestamp for the brief/chat message label line.
3 *
4 * Display scales with age (like a messaging app):
5 * - same day: "1:30 PM" or "13:30" (locale-dependent)
6 * - within 6 days: "Sunday, 4:15 PM" (locale-dependent)
7 * - older: "Sunday, Feb 20, 4:30 PM" (locale-dependent)
8 *
9 * Respects POSIX locale env vars (LC_ALL > LC_TIME > LANG) for time format
10 * (12h/24h), weekday names, month names, and overall structure.
11 * Bun/V8's `toLocaleString(undefined)` ignores these on macOS, so we
12 * convert them to BCP 47 tags ourselves.
13 *
14 * `now` is injectable for tests.
15 */
16export function formatBriefTimestamp(
17 isoString: string,
18 now: Date = new Date(),
19): string {
20 const d = new Date(isoString)
21 if (Number.isNaN(d.getTime())) {
22 return ''
23 }
24
25 const locale = getLocale()
26 const dayDiff = startOfDay(now) - startOfDay(d)
27 const daysAgo = Math.round(dayDiff / 86_400_000)
28
29 if (daysAgo === 0) {
30 return d.toLocaleTimeString(locale, {
31 hour: 'numeric',
32 minute: '2-digit',
33 })
34 }
35
36 if (daysAgo > 0 && daysAgo < 7) {
37 return d.toLocaleString(locale, {
38 weekday: 'long',
39 hour: 'numeric',
40 minute: '2-digit',
41 })
42 }
43
44 return d.toLocaleString(locale, {
45 weekday: 'long',
46 month: 'short',
47 day: 'numeric',
48 hour: 'numeric',
49 minute: '2-digit',
50 })
51}
52
53/**
54 * Derive a BCP 47 locale tag from POSIX env vars.
55 * LC_ALL > LC_TIME > LANG, falls back to undefined (system default).
56 * Converts POSIX format (en_GB.UTF-8) to BCP 47 (en-GB).
57 */
58function getLocale(): string | undefined {
59 const raw =
60 process.env.LC_ALL || process.env.LC_TIME || process.env.LANG || ''
61 if (!raw || raw === 'C' || raw === 'POSIX') {
62 return undefined
63 }
64 // Strip codeset (.UTF-8) and modifier (@euro), replace _ with -
65 const base = raw.split('.')[0]!.split('@')[0]!
66 if (!base) {
67 return undefined
68 }
69 const tag = base.replaceAll('_', '-')
70 // Validate by trying to construct an Intl locale — invalid tags throw
71 try {
72 new Intl.DateTimeFormat(tag)
73 return tag
74 } catch {
75 return undefined
76 }
77}
78
79function startOfDay(d: Date): number {
80 return new Date(d.getFullYear(), d.getMonth(), d.getDate()).getTime()
81}