The previous version implied l4d2host has tz patterns to defer. An
inventory grep showed it has no datetime usage at all (no `from datetime`
import anywhere in the tree). Replace the bullet with the verified
finding.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Validated design for the migration framed by the 2026-05-16 handoff doc.
Two findings shaped this design: (1) DateTime(timezone=True) is a no-op
on SQLite per the round-trip spike, so the fix must live in app code;
(2) every byte on disk is provably UTC (no datetime.now() / utcnow() /
CURRENT_TIMESTAMP / func.now() anywhere), so a result-side tzinfo stamp
is correct, not optimistic.
The chosen approach: a UtcDateTime TypeDecorator that raises on naive
bind and stamps tzinfo=UTC on read. Single PR, two commits (test-first
for clean bisect). No DDL change, no Alembic migration, no on-disk
data transform.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
