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On a UTC+3 install every AMS humidity reading and every archive was
stamped three hours ahead of when it happened. Bambuddy stores naive
timestamps that hold UTC and the frontend's parseUTCDate reads an
offsetless timestamp as UTC, so the display added the offset to a value
that was already local.
The Python side has honoured that contract since #504. The reporter's
timestamps were not written by Python. Around ninety-six columns take
their value from server_default=func.now() and the migration DDL carries
another forty-nine on DEFAULT CURRENT_TIMESTAMP -- the database fills
those, and on PostgreSQL now() is a timestamptz, so storing it into a
timestamp without time zone casts it through the session TimeZone. A
Postgres container started with TZ=Europe/Istanbul bakes that zone into
postgresql.conf at initdb, and every defaulted column then receives local
wall-clock. recorded_at is the clearest case: nothing in the codebase
ever assigns it, so its value is entirely whatever the database decided.
Connections now carry timezone=UTC, which makes the cast a no-op whatever
the server is set to. Measured through the real engine factory against a
live PostgreSQL, a session on the reporter's configuration stored +10800s
and the fixed one +0s. Pinning the session was preferred over a hundred
and forty-five individual edits partly for its size but mostly because
half of those sites are raw DDL that no model-level change can reach.
SQLite needed nothing and gets nothing: its CURRENT_TIMESTAMP is UTC by
definition and it has no session timezone to get wrong, which is why this
survived two years of timezone fixes without showing itself. That also
makes it the reference -- the change moves Postgres onto SQLite's
behaviour rather than introducing a third convention -- so the SQLite
behaviour is now pinned by a test instead of being assumed. asyncpg is
the documented driver and takes the setting in its startup packet; any
other Postgres driver gets the same setting the libpq way, so a psycopg
URL does not fail at connect on a keyword asyncpg alone accepts.
Rows already written are deliberately left alone. The inverse cast is
computable and DST-correct, but it cannot be applied safely: created_at
is assigned explicitly on some paths and defaulted on others, an install
that began on SQLite holds correct and shifted rows side by side, and
nothing distinguishes them after the fact. Timestamps are right from the
upgrade forward and history keeps the times it was given.
One related mismatch goes with it, because fixing the database side alone
would have made it start lying on exactly the installs this repairs. The
support package's oldest_pending_age_seconds subtracted a naive local
clock from a naive UTC column, with a comment claiming it was UTC; on the
reporter's install the two errors cancelled. It reported a job queued
five minutes ago as three hours old east of Greenwich and a negative age
west of it. The two AMS and printer-sensor retention cutoffs move to the
same utcnow_naive helper -- correct in value already, but deprecated in
3.12 and emitting warnings on every sweep.