Substrate marshals deadline.due_date as time.Date(...,0,0,0,0,UTC), so the
JSON arrives as "YYYY-MM-DDT00:00:00Z" — UTC midnight, no real time. Feeding
that into new Date() + toLocaleTimeString() produced "02:00" in CEST,
"01:00" in CET, "20:00 the day before" in EST, etc.
Pattern A: don't render time for date-only fields.
- Centralised the date/time formatters used by the views shapes into
frontend/src/client/views/format.ts. parseDateOnly recognises both
"YYYY-MM-DD" and the substrate's "YYYY-MM-DDT00:00:00Z" form; formatDate
formats those in UTC so the day matches the source day in every timezone.
- shape-cards.ts: per-row time slot is empty for deadlines when the day is
already in the heading (groupBy=day). Falls back to formatDate when
groupBy=week|none. Bucketing now anchors date-only inputs to UTC so a
deadline can't slip into the previous day in negative-offset zones.
- shape-list.ts: formatRelative is kind-aware — deadlines reduce to
day-precision ("morgen" / "in 3 Tagen") instead of leaking hour math
("in 2h") off the UTC midnight.
- Appointments and other timestamped sources are untouched.
- format.test.ts: regression coverage in CEST / PST / UTC. 14 tests pass.
f90bfeda9b