chore(envrc): switch direnv from use uv to layout uv

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.envrc

@@ -1 +1 @@
-use uv
+layout uv

.gitignore

@@ -12,3 +12,4 @@ l4d2web.db*
 .superpowers/
 *.db
 opencode.json
+.tmp/

docs/superpowers/specs/2026-05-16-tz-aware-datetime-design.md

@@ -0,0 +1,274 @@
+# Timezone-aware datetime migration — design
+
+Replaces the `.replace(tzinfo=None)` convention in `l4d2web` with a
+`UtcDateTime` SQLAlchemy `TypeDecorator` that enforces aware-UTC on every
+column boundary. The handoff at
+`docs/superpowers/specs/2026-05-16-tz-aware-datetime-handoff.md` framed
+the problem; this doc is the validated design.
+
+## Context
+
+`l4d2web`'s `l4d2web/models.py` declares 26 `DateTime` columns. SQLAlchemy
+talking to pysqlite strips `tzinfo` on write and returns naive datetimes on
+read, so a documented convention emerged: *every datetime in this codebase
+is UTC; we just don't say so in the type system.* The convention is correct
+in practice — every write path goes through `now_utc()` (`models.py:22-23`)
+or `datetime.now(UTC)` directly — but it is held together by author
+discipline, not by any compiler or runtime check.
+
+The cost shows up as ~16 defensive `.replace(tzinfo=None)` sites scattered
+across routes, services, and tests, plus a permanent mental tax: a
+`datetime` parameter could be aware or naive depending on where it came
+from, and a wrong guess raises `TypeError` at runtime — or, worse, silently
+treats a non-UTC value as UTC.
+
+## Validation work that shaped this design
+
+Two findings reshaped the originally-imagined fix.
+
+### The `timezone=True` kwarg is a no-op on SQLite
+
+The handoff's implicit plan ("flip `timezone=True` on every column and the
+strip sites can come down") is dead. A spike script
+(`.tmp/tz_spike.py`, to be deleted with this PR) demonstrated:
+
+| Column type | Write input | On-disk text | Read output |
+|---|---|---|---|
+| `DateTime` | aware UTC | `'2026-05-16 09:23:47.561010'` | naive |
+| `DateTime(timezone=True)` | aware UTC | `'2026-05-16 09:23:47.564949'` | **naive** |
+| `DateTime(timezone=True)` | legacy naive on disk | `'2026-05-16 12:34:56.789012'` | naive → `TypeError` on comparison with `datetime.now(UTC)` |
+
+`pysqlite` has no native timestamp-with-zone type; the kwarg only affects
+DDL emission, not pysqlite's serialization. The fix must live in app code.
+
+### Every byte on disk is UTC
+
+Greps for every conceivable non-UTC write site returned empty:
+
+```
+$ grep -rn 'datetime.now()' l4d2web/      → no matches
+$ grep -rn 'utcnow' l4d2web/              → no matches
+$ grep -rn 'CURRENT_TIMESTAMP' l4d2web/   → no matches
+$ grep -rn 'func.now\|func.current' l4d2web/ → no matches
+```
+
+So `process_result_value` stamping `tzinfo=UTC` on read is *correct*, not
+optimistic — no data audit, no backfill, no migration to rewrite rows.
+
+## The contract — `UtcDateTime`
+
+```python
+from sqlalchemy.types import TypeDecorator
+
+
+class UtcDateTime(TypeDecorator):
+    """Always store and surface UTC-aware datetimes.
+
+    SQLite has no native tz-aware type and pysqlite strips tzinfo on
+    round-trip. We convert inputs to UTC, persist them as naive UTC under
+    the hood, and re-stamp tzinfo=UTC on read. The result: every datetime
+    on a model attribute is aware UTC, always.
+    """
+
+    impl = DateTime
+    cache_ok = True
+
+    def process_bind_param(self, value, dialect):
+        if value is None:
+            return None
+        if value.tzinfo is None:
+            raise TypeError(
+                "naive datetime passed to UtcDateTime column; "
+                "all writes must be UTC-aware"
+            )
+        return value.astimezone(UTC).replace(tzinfo=None)
+
+    def process_result_value(self, value, dialect):
+        if value is None:
+            return None
+        return value.replace(tzinfo=UTC)
+```
+
+The class lives in `l4d2web/models.py` (single consumer; a separate module
+for ~25 lines is over-structuring for this project).
+
+### Why raise on naive input rather than silently coerce
+
+Silent coercion is exactly how this codebase grew the reverse-strip line in
+`auth.py:60`. Once you tolerate ambiguity at the boundary, the ambiguity
+leaks into every comparison site. A loud failure teaches the next author
+that the column is aware-only; silent coercion enables future drift.
+
+The runtime check is also the *only* enforcement available — there is no
+mypy plugin or static check for "naive datetime crossing into SA bind."
+
+### Why `impl = DateTime` (not `DateTime(timezone=True)`)
+
+`UtcDateTime.impl = DateTime` produces SQL identical to the current
+schema. `alembic revision --autogenerate` sees no difference. Historical
+migrations remain accurate descriptions of past DDL. No new migration
+file is needed; the change is purely Python-side.
+
+(Aside: on PostgreSQL, `impl = DateTime(timezone=True)` would use native
+`timestamptz`. Switching dialects would be a one-line change. Not in
+scope here.)
+
+## Migration shape
+
+**One PR, two commits.**
+
+1. `test(datetime): pin tz-aware contract for fixtures (red until UtcDateTime lands)`
+   — drop `.replace(tzinfo=None)` from 10 test sites. Suite goes red.
+   These failing tests are an executable spec for commit 2.
+
+2. `refactor(datetime): introduce UtcDateTime, remove naive-strip workarounds`
+   — add the class, flip 26 column declarations, drop 5 production strip
+   sites + their explanatory comment, flip one line in `auth.py` from
+   strip-live-marker to stamp-legacy-cookie, add 2 unit tests pinning the
+   decorator contract. Tests go green.
+
+The test-first ordering gives a clean bisect target: commit 2 is the
+single causal point where the type-system invariant takes hold. The
+project's recent commits show a strong preference for atomic
+single-purpose commits, which this ordering matches.
+
+## What stays the same
+
+- `now_utc()` (`models.py:22-23`) — already returns aware UTC.
+- On-disk format — identical bytes; pysqlite still writes `'YYYY-MM-DD
+  HH:MM:SS.ffffff'`.
+- Schema (DDL) — `UtcDateTime.impl = DateTime` produces identical CREATE
+  TABLE statements.
+- SQL emitted at query time — bind hook still hands the driver naive
+  datetimes.
+- `services/timeago.py::_ensure_utc` — kept as a public-filter boundary
+  assertion. Still exercised by `tests/test_timeago.py:113`, which
+  deliberately passes a naive `datetime(2026, 5, 16, 14, 32, 11)` to
+  test the normalize-up path. Load-bearing-ness for DB values drains
+  away; defense-in-depth at the rendering boundary remains.
+- The Alembic chain in `l4d2web/alembic/versions/` — no new migration
+  file. (See [decision #4](#decisions-locked).)
+
+## What changes
+
+### Call sites that lose `.replace(tzinfo=None)`
+
+5 production sites + 1 `_now()` helper:
+
+- `routes/profile_routes.py:88`
+- `routes/server_routes.py:210, :234`
+- `routes/page_routes.py:174`
+- `services/live_state_poller.py:37` (the `_now()` helper just
+  returns `datetime.now(UTC)`)
+
+10 test sites: `tests/test_auth.py:162`, `tests/test_timeago.py:67, :73`
+(NOT `:113`), `tests/test_servers.py:459, :521`,
+`tests/test_live_state_poller.py:159, :278, :303, :356`,
+`tests/test_models.py:43`.
+
+The explanatory comment at `routes/profile_routes.py:86-87` is deleted —
+it documented a workaround that no longer exists.
+
+### `auth.py` legacy-cookie compat
+
+`auth.py:59-60` today strips tz from a freshly-stamped aware marker so it
+compares cleanly with naive DB. After migration the inverse is needed:
+legacy session cookies (minted before the deploy) carry naive ISO; the DB
+now returns aware.
+
+```python
+# Before
+if marker_dt.tzinfo is not None:
+    marker_dt = marker_dt.replace(tzinfo=None)
+
+# After
+# Legacy sessions carry naive ISO markers; stamp UTC so comparison works.
+if marker_dt.tzinfo is None:
+    marker_dt = marker_dt.replace(tzinfo=UTC)
+```
+
+The `UTC` symbol must be added to the `from datetime import datetime`
+import on `auth.py:1` — easy to miss in review.
+
+This line stays permanently. There is no reliable signal for "all naive
+cookies have expired"; the line is cheap defense and mirrors the
+`_ensure_utc` philosophy at the rendering boundary.
+
+### Unit tests pinning the decorator contract
+
+Two tests in `tests/test_models.py`, surviving any future column rename:
+
+```python
+def test_utc_datetime_rejects_naive_bind():
+    with pytest.raises(TypeError, match="naive"):
+        UtcDateTime().process_bind_param(datetime(2026, 5, 16, 12, 0), None)
+
+
+def test_utc_datetime_stamps_utc_on_read():
+    naive = datetime(2026, 5, 16, 12, 0)
+    result = UtcDateTime().process_result_value(naive, None)
+    assert result == datetime(2026, 5, 16, 12, 0, tzinfo=UTC)
+    assert result.tzinfo == UTC
+```
+
+### Already-aware writes that "just keep working"
+
+`services/job_worker.py` lines 131, 486, 522, 550, 579 and
+`services/overlay_builders.py:233` already write aware
+`datetime.now(UTC)` directly to columns. Today they "work" because
+pysqlite implicitly strips. After migration they pass `process_bind_param`
+explicitly. No code change needed at these sites — but worth noting they
+exist, because they're evidence that the codebase has been writing aware
+datetimes all along, just losing the tzinfo on the wire.
+
+## Decisions locked
+
+| # | Decision | Rationale |
+|---|---|---|
+| 1 | `TypeDecorator`, not `DateTime(timezone=True)` | Spike proved the kwarg is a no-op on SQLite. |
+| 2 | Raise on naive bind, not silent coerce | Loud failures teach; silent coercion is how `auth.py:60` happened. |
+| 3 | Test-first two-commit ordering | Clean bisect target; commit 1 is an executable spec for commit 2. |
+| 4 | No new Alembic migration | `impl = DateTime` produces identical SQL; an `alter_column` migration would be a no-op on SQLite and generate autogenerate noise; an empty marker migration is documentation in the wrong place. |
+| 5 | Legacy-cookie compat in `auth.py` is permanent | No reliable signal for cookie rollover; one line of defense matches `_ensure_utc`. |
+| 6 | `services/timeago.py::_ensure_utc` stays | Public filter boundary + tested at `test_timeago.py:113`. |
+| 7 | `UtcDateTime` lives in `models.py` | Single consumer; separate module for 25 lines is over-structuring. |
+
+## Out of scope
+
+- Postgres portability. `UtcDateTime` would adapt with `impl =
+  DateTime(timezone=True)` if the dialect supports it, but switching
+  dialects is its own project.
+- `l4d2host` (the dedicated-server CLI side of the repo) has no datetime
+  usage — no `from datetime` import anywhere in the tree, verified by
+  grep. The scope boundary is documentary; no follow-up work exists.
+- Static enforcement (mypy plugin, ruff rule) for "naive datetime crossing
+  into a `UtcDateTime` column." The runtime `TypeError` is the gate; a
+  static check would be a nice-to-have.
+
+## Verification
+
+1. **Unit:** the two new tests in `tests/test_models.py` pin the
+   decorator's contract independently of the model declarations.
+
+2. **Suite:** `cd l4d2web && uv run pytest`. Expected: all-green after
+   commit 2.
+
+3. **Smoke (manual):** log in, change password, log out, log back in.
+   Exercises the full session-cookie round-trip and the
+   `password_changed_at` comparison at `auth.py:61`.
+
+4. **Legacy-cookie path (manual):** craft a session with a naive ISO
+   marker and hit any `@require_login` route. Expected: clean
+   comparison, not a 500.
+
+## Pointers
+
+- `docs/superpowers/specs/2026-05-16-tz-aware-datetime-handoff.md` — the
+  handoff that framed this work.
+- `docs/superpowers/specs/2026-05-16-timeago-shared-display-design.md` —
+  the parent project that surfaced the convention's cost.
+- `l4d2web/l4d2web/models.py:22-23` — `now_utc()` factory (no change).
+- `l4d2web/l4d2web/services/timeago.py:12-15` — `_ensure_utc` boundary
+  (no change).
+- `l4d2web/l4d2web/auth.py:51-60` — the compat block whose direction
+  flips.

l4d2web/l4d2web/auth.py

@@ -1,4 +1,4 @@
-from datetime import datetime
+from datetime import UTC, datetime
 from functools import wraps
 from typing import Callable, TypeVar
 from urllib.parse import quote, unquote
@@ -53,11 +53,12 @@ def load_current_user() -> None:
     except ValueError:
         g.user = None
         return
-    # user.password_changed_at comes back naive from SQLite; strip tz from the
-    # marker so an aware-marker session (just stamped from an in-memory user)
-    # compares cleanly with a freshly-loaded user row.
-    if marker_dt.tzinfo is not None:
-        marker_dt = marker_dt.replace(tzinfo=None)
+    # Legacy sessions minted before the UtcDateTime migration carry naive
+    # ISO markers; stamp UTC so the comparison against the now-aware DB
+    # value works. Cheap permanent defense; no reliable signal for "all
+    # naive cookies have expired."
+    if marker_dt.tzinfo is None:
+        marker_dt = marker_dt.replace(tzinfo=UTC)
     if marker_dt < user.password_changed_at:
         g.user = None
         return

l4d2web/l4d2web/models.py

@@ -9,6 +9,7 @@ from sqlalchemy import (
     Integer,
     String,
     Text,
+    TypeDecorator,
     UniqueConstraint,
     text,
 )
@@ -23,6 +24,34 @@ def now_utc() -> datetime:
     return datetime.now(UTC)
 
 
+class UtcDateTime(TypeDecorator):
+    """Always store and surface UTC-aware datetimes.
+
+    SQLite has no native tz-aware type and pysqlite strips tzinfo on
+    round-trip. We convert inputs to UTC, persist them as naive UTC under
+    the hood, and re-stamp tzinfo=UTC on read. The result: every datetime
+    on a model attribute is aware UTC, always.
+    """
+
+    impl = DateTime
+    cache_ok = True
+
+    def process_bind_param(self, value, dialect):
+        if value is None:
+            return None
+        if value.tzinfo is None:
+            raise TypeError(
+                "naive datetime passed to UtcDateTime column; "
+                "all writes must be UTC-aware"
+            )
+        return value.astimezone(UTC).replace(tzinfo=None)
+
+    def process_result_value(self, value, dialect):
+        if value is None:
+            return None
+        return value.replace(tzinfo=UTC)
+
+
 class User(Base):
     __tablename__ = "users"
 
@@ -33,9 +62,9 @@ class User(Base):
     active: Mapped[bool] = mapped_column(
         Boolean, default=True, nullable=False, server_default=text("1"),
     )
-    created_at: Mapped[datetime] = mapped_column(DateTime, default=now_utc, nullable=False)
-    updated_at: Mapped[datetime] = mapped_column(DateTime, default=now_utc, nullable=False)
-    password_changed_at: Mapped[datetime] = mapped_column(DateTime, default=now_utc, nullable=False)
+    created_at: Mapped[datetime] = mapped_column(UtcDateTime, default=now_utc, nullable=False)
+    updated_at: Mapped[datetime] = mapped_column(UtcDateTime, default=now_utc, nullable=False)
+    password_changed_at: Mapped[datetime] = mapped_column(UtcDateTime, default=now_utc, nullable=False)
 
 
 class Overlay(Base):
@@ -65,8 +94,8 @@ class Overlay(Base):
     user_id: Mapped[int | None] = mapped_column(ForeignKey("users.id"), nullable=True)
     script: Mapped[str] = mapped_column(Text, default="", nullable=False)
     last_build_status: Mapped[str] = mapped_column(String(16), default="", nullable=False)
-    created_at: Mapped[datetime] = mapped_column(DateTime, default=now_utc, nullable=False)
-    updated_at: Mapped[datetime] = mapped_column(DateTime, default=now_utc, nullable=False)
+    created_at: Mapped[datetime] = mapped_column(UtcDateTime, default=now_utc, nullable=False)
+    updated_at: Mapped[datetime] = mapped_column(UtcDateTime, default=now_utc, nullable=False)
 
 
 class WorkshopItem(Base):
@@ -80,10 +109,10 @@ class WorkshopItem(Base):
     file_size: Mapped[int] = mapped_column(BigInteger, default=0, nullable=False)
     time_updated: Mapped[int] = mapped_column(Integer, default=0, nullable=False)
     preview_url: Mapped[str] = mapped_column(Text, default="", nullable=False)
-    last_downloaded_at: Mapped[datetime | None] = mapped_column(DateTime, nullable=True)
+    last_downloaded_at: Mapped[datetime | None] = mapped_column(UtcDateTime, nullable=True)
     last_error: Mapped[str] = mapped_column(Text, default="", nullable=False)
-    created_at: Mapped[datetime] = mapped_column(DateTime, default=now_utc, nullable=False)
-    updated_at: Mapped[datetime] = mapped_column(DateTime, default=now_utc, nullable=False)
+    created_at: Mapped[datetime] = mapped_column(UtcDateTime, default=now_utc, nullable=False)
+    updated_at: Mapped[datetime] = mapped_column(UtcDateTime, default=now_utc, nullable=False)
 
 
 class OverlayWorkshopItem(Base):
@@ -110,8 +139,8 @@ class Blueprint(Base):
     name: Mapped[str] = mapped_column(String(128), nullable=False)
     arguments: Mapped[str] = mapped_column(Text, default="[]", nullable=False)
     config: Mapped[str] = mapped_column(Text, default="[]", nullable=False)
-    created_at: Mapped[datetime] = mapped_column(DateTime, default=now_utc, nullable=False)
-    updated_at: Mapped[datetime] = mapped_column(DateTime, default=now_utc, nullable=False)
+    created_at: Mapped[datetime] = mapped_column(UtcDateTime, default=now_utc, nullable=False)
+    updated_at: Mapped[datetime] = mapped_column(UtcDateTime, default=now_utc, nullable=False)
 
 
 class BlueprintOverlay(Base):
@@ -124,8 +153,8 @@ class BlueprintOverlay(Base):
     expose_server_cfg: Mapped[bool] = mapped_column(
         Boolean, nullable=False, default=False, server_default=text("0")
     )
-    created_at: Mapped[datetime] = mapped_column(DateTime, default=now_utc, nullable=False)
-    updated_at: Mapped[datetime] = mapped_column(DateTime, default=now_utc, nullable=False)
+    created_at: Mapped[datetime] = mapped_column(UtcDateTime, default=now_utc, nullable=False)
+    updated_at: Mapped[datetime] = mapped_column(UtcDateTime, default=now_utc, nullable=False)
 
 
 class Server(Base):
@@ -141,7 +170,7 @@ class Server(Base):
     port: Mapped[int] = mapped_column(Integer, unique=True, nullable=False)
     desired_state: Mapped[str] = mapped_column(String(16), default="stopped", nullable=False)
     actual_state: Mapped[str] = mapped_column(String(16), default="unknown", nullable=False)
-    actual_state_updated_at: Mapped[datetime | None] = mapped_column(DateTime, nullable=True)
+    actual_state_updated_at: Mapped[datetime | None] = mapped_column(UtcDateTime, nullable=True)
     last_error: Mapped[str] = mapped_column(Text, default="", nullable=False)
     rcon_password: Mapped[str] = mapped_column(
         String(64), nullable=False, default="", server_default=""
@@ -149,8 +178,8 @@ class Server(Base):
     hostname: Mapped[str] = mapped_column(
         String(128), nullable=False, default="", server_default=""
     )
-    created_at: Mapped[datetime] = mapped_column(DateTime, default=now_utc, nullable=False)
-    updated_at: Mapped[datetime] = mapped_column(DateTime, default=now_utc, nullable=False)
+    created_at: Mapped[datetime] = mapped_column(UtcDateTime, default=now_utc, nullable=False)
+    updated_at: Mapped[datetime] = mapped_column(UtcDateTime, default=now_utc, nullable=False)
 
 
 class Job(Base):
@@ -163,10 +192,10 @@ class Job(Base):
     operation: Mapped[str] = mapped_column(String(32), nullable=False)
     state: Mapped[str] = mapped_column(String(16), default="queued", nullable=False)
     exit_code: Mapped[int | None] = mapped_column(Integer, nullable=True)
-    started_at: Mapped[datetime | None] = mapped_column(DateTime, nullable=True)
-    finished_at: Mapped[datetime | None] = mapped_column(DateTime, nullable=True)
-    created_at: Mapped[datetime] = mapped_column(DateTime, default=now_utc, nullable=False)
-    updated_at: Mapped[datetime] = mapped_column(DateTime, default=now_utc, nullable=False)
+    started_at: Mapped[datetime | None] = mapped_column(UtcDateTime, nullable=True)
+    finished_at: Mapped[datetime | None] = mapped_column(UtcDateTime, nullable=True)
+    created_at: Mapped[datetime] = mapped_column(UtcDateTime, default=now_utc, nullable=False)
+    updated_at: Mapped[datetime] = mapped_column(UtcDateTime, default=now_utc, nullable=False)
 
 
 class JobLog(Base):
@@ -177,7 +206,7 @@ class JobLog(Base):
     seq: Mapped[int] = mapped_column(Integer, nullable=False)
     stream: Mapped[str] = mapped_column(String(8), nullable=False)
     line: Mapped[str] = mapped_column(Text, nullable=False)
-    created_at: Mapped[datetime] = mapped_column(DateTime, default=now_utc, nullable=False)
+    created_at: Mapped[datetime] = mapped_column(UtcDateTime, default=now_utc, nullable=False)
 
 
 class ServerLiveState(Base):
@@ -191,8 +220,8 @@ class ServerLiveState(Base):
     server_id: Mapped[int] = mapped_column(
         ForeignKey("servers.id", ondelete="CASCADE"), nullable=False
     )
-    started_at: Mapped[datetime] = mapped_column(DateTime, nullable=False)
-    last_seen_at: Mapped[datetime] = mapped_column(DateTime, nullable=False)
+    started_at: Mapped[datetime] = mapped_column(UtcDateTime, nullable=False)
+    last_seen_at: Mapped[datetime] = mapped_column(UtcDateTime, nullable=False)
     players: Mapped[int] = mapped_column(Integer, nullable=False)
     max_players: Mapped[int] = mapped_column(Integer, nullable=False)
     bots: Mapped[int] = mapped_column(Integer, nullable=False)
@@ -213,8 +242,8 @@ class ServerPlayerSession(Base):
         ForeignKey("servers.id", ondelete="CASCADE"), nullable=False
     )
     steam_id_64: Mapped[str] = mapped_column(String(20), nullable=False)
-    joined_at: Mapped[datetime] = mapped_column(DateTime, nullable=False)
-    left_at: Mapped[datetime | None] = mapped_column(DateTime, nullable=True)
+    joined_at: Mapped[datetime] = mapped_column(UtcDateTime, nullable=False)
+    left_at: Mapped[datetime | None] = mapped_column(UtcDateTime, nullable=True)
     name_at_join: Mapped[str] = mapped_column(String(64), nullable=False)
     min_ping: Mapped[int] = mapped_column(Integer, nullable=False)
     max_ping: Mapped[int] = mapped_column(Integer, nullable=False)
@@ -226,7 +255,7 @@ class SteamUserProfile(Base):
     steam_id_64: Mapped[str] = mapped_column(String(20), primary_key=True)
     persona_name: Mapped[str] = mapped_column(String(64), nullable=False)
     avatar_url: Mapped[str] = mapped_column(Text, nullable=False)
-    fetched_at: Mapped[datetime] = mapped_column(DateTime, nullable=False)
+    fetched_at: Mapped[datetime] = mapped_column(UtcDateTime, nullable=False)
 
 
 class CommandHistory(Base):
@@ -248,5 +277,5 @@ class CommandHistory(Base):
         Boolean, nullable=False, default=False, server_default=text("0")
     )
     created_at: Mapped[datetime] = mapped_column(
-        DateTime, default=now_utc, nullable=False
+        UtcDateTime, default=now_utc, nullable=False
     )

l4d2web/l4d2web/routes/page_routes.py

@@ -171,7 +171,7 @@ def servers_page() -> str:
         ).all()
 
         stale_seconds = current_app.config.get("LIVE_STATE_STALE_SECONDS", 30)
-        cutoff = datetime.now(UTC).replace(tzinfo=None) - timedelta(seconds=stale_seconds)
+        cutoff = datetime.now(UTC) - timedelta(seconds=stale_seconds)
 
         server_ids = [s.id for s, _bp in rows]
         latest_rows: dict[int, ServerLiveState] = {}

l4d2web/l4d2web/routes/profile_routes.py

@@ -83,9 +83,7 @@ def profile_password_change() -> Response:
         if user is None or not verify_password(current_password, user.password_digest):
             return _redirect_with_error("wrong_current")
         user.password_digest = hash_password(new_password)
-        # Strip tz so the marker matches what a subsequent DB read returns
-        # (SQLite DateTime columns don't preserve tzinfo).
-        user.password_changed_at = now_utc().replace(tzinfo=None)
+        user.password_changed_at = now_utc()
         new_marker = user.password_changed_at.isoformat()
 
     session["pw_changed_at"] = new_marker

l4d2web/l4d2web/routes/server_routes.py

@@ -207,7 +207,7 @@ def live_state_fragment(server_id: int) -> Response:
             return Response(status=404)
 
         stale_seconds = current_app.config.get("LIVE_STATE_STALE_SECONDS", 30)
-        cutoff = datetime.now(UTC).replace(tzinfo=None) - timedelta(seconds=stale_seconds)
+        cutoff = datetime.now(UTC) - timedelta(seconds=stale_seconds)
 
         latest = db.scalar(
             select(ServerLiveState)
@@ -231,7 +231,7 @@ def live_state_fragment(server_id: int) -> Response:
 
         current_ids = [r[0].steam_id_64 for r in current_rows]
 
-        recent_cutoff = datetime.now(UTC).replace(tzinfo=None) - timedelta(
+        recent_cutoff = datetime.now(UTC) - timedelta(
             days=current_app.config.get("LIVE_STATE_HISTORY_DAYS", 30)
         )
 

l4d2web/l4d2web/services/live_state_poller.py

@@ -34,7 +34,7 @@ logger = logging.getLogger(__name__)
 
 
 def _now() -> datetime:
-    return datetime.now(UTC).replace(tzinfo=None)
+    return datetime.now(UTC)
 
 
 def poll_once() -> None:

l4d2web/tests/test_auth.py

@@ -159,7 +159,7 @@ def test_load_current_user_rejects_stale_marker(client) -> None:
         db.flush()
         uid = u.id
 
-    stale = datetime.now(UTC).replace(tzinfo=None) - timedelta(minutes=5)
+    stale = datetime.now(UTC) - timedelta(minutes=5)
     with client.session_transaction() as sess:
         sess["user_id"] = uid
         sess["pw_changed_at"] = stale.isoformat()

l4d2web/tests/test_live_state_poller.py

@@ -156,7 +156,7 @@ def test_new_player_opens_session_with_backfilled_join(tmp_path, monkeypatch) ->
     assert s.min_ping == 60
     assert s.max_ping == 60
     # joined_at should be ~30s before now
-    delta = (datetime.now(UTC).replace(tzinfo=None) - s.joined_at).total_seconds()
+    delta = (datetime.now(UTC) - s.joined_at).total_seconds()
     assert 25 <= delta <= 60
 
 
@@ -275,7 +275,7 @@ def test_skips_enrichment_when_api_key_unset(tmp_path, monkeypatch) -> None:
 def test_retention_trims_old_rows(tmp_path, monkeypatch) -> None:
     app, sid = _seed(tmp_path)
     app.config["LIVE_STATE_HISTORY_DAYS"] = 30
-    long_ago = datetime.now(UTC).replace(tzinfo=None) - timedelta(days=45)
+    long_ago = datetime.now(UTC) - timedelta(days=45)
     with session_scope() as db:
         db.add(ServerLiveState(
             server_id=sid, started_at=long_ago, last_seen_at=long_ago,
@@ -300,7 +300,7 @@ def test_retention_trims_old_rows(tmp_path, monkeypatch) -> None:
 def test_close_stuck_sessions_after_threshold(tmp_path, monkeypatch) -> None:
     app, sid = _seed(tmp_path)
     app.config["STUCK_SESSION_SECONDS"] = 60
-    way_back = datetime.now(UTC).replace(tzinfo=None) - timedelta(hours=2)
+    way_back = datetime.now(UTC) - timedelta(hours=2)
     with session_scope() as db:
         db.add(ServerPlayerSession(
             server_id=sid, steam_id_64="76561197960828710",
@@ -353,7 +353,7 @@ def test_skips_enrichment_when_cache_is_fresh(tmp_path, monkeypatch) -> None:
             steam_id_64="76561197960828710",
             persona_name="cached",
             avatar_url="cached.jpg",
-            fetched_at=datetime.now(UTC).replace(tzinfo=None),
+            fetched_at=datetime.now(UTC),
         ))
     monkeypatch.setattr(
         live_state_poller, "query_status",

l4d2web/tests/test_models.py

@@ -1,3 +1,6 @@
+from datetime import UTC, datetime
+
+import pytest
 from sqlalchemy import select
 
 from l4d2web.db import init_db, session_scope
@@ -8,6 +11,7 @@ from l4d2web.models import (
     ServerPlayerSession,
     SteamUserProfile,
     User,
+    UtcDateTime,
     now_utc as now_utc_aware,
 )
 
@@ -40,7 +44,7 @@ def test_user_has_password_changed_at_default(tmp_path, monkeypatch):
     create_app({"TESTING": True, "DATABASE_URL": db_url, "SECRET_KEY": "test"})
     init_db()
 
-    before = datetime.now(UTC).replace(tzinfo=None)
+    before = datetime.now(UTC)
     with session_scope() as db:
         db.add(User(username="alice", password_digest=hash_password("secret")))
     with session_scope() as db:
@@ -108,3 +112,15 @@ def test_steam_user_profile_table_columns(tmp_path, monkeypatch) -> None:
             fetched_at=now_utc_aware(),
         )
         db.add(row); db.flush()
+
+
+def test_utc_datetime_rejects_naive_bind() -> None:
+    with pytest.raises(TypeError, match="naive"):
+        UtcDateTime().process_bind_param(datetime(2026, 5, 16, 12, 0), None)
+
+
+def test_utc_datetime_stamps_utc_on_read() -> None:
+    naive = datetime(2026, 5, 16, 12, 0)
+    result = UtcDateTime().process_result_value(naive, None)
+    assert result == datetime(2026, 5, 16, 12, 0, tzinfo=UTC)
+    assert result.tzinfo == UTC

l4d2web/tests/test_servers.py

@@ -456,7 +456,7 @@ def test_servers_index_renders_live_state_badge(user_client_with_blueprints) ->
     client, data = user_client_with_blueprints
 
     # Seed one server with a recent snapshot, one without.
-    now = datetime.now(UTC).replace(tzinfo=None)
+    now = datetime.now(UTC)
     with session_scope() as db:
         s_active = Server(
             user_id=data["user_id"],
@@ -518,7 +518,7 @@ def test_live_state_fragment_renders_current_and_recent(user_client_with_bluepri
     )
 
     client, data = user_client_with_blueprints
-    now = datetime.now(UTC).replace(tzinfo=None)
+    now = datetime.now(UTC)
     with session_scope() as db:
         srv = Server(
             user_id=data["user_id"], blueprint_id=data["blueprint_id"],