docs(comments): correct comments the cuts left stale

The registration language is read today (preferences.language, the mail language); the Modal and
the players order against popovers through layerStack, not the FloatingTree; the upload's auth
dependency is current_user; the module of access tests covers onboarding and access, not only the
canonical email. The dev proxy's WebSocket upgrade served the removed messages socket and goes; the
test compose header says a pure-logic run needs SIFTLODE_TEST_REQUIRE_DB=0; the speed measure no
longer reports an unreachable database as "no share link".

backend/app/routes/auth.py

@@ -298,8 +298,9 @@ class EmailPasswordIn(BaseModel):
     # The language the sign-up page was in. Captured at registration because it is the ONLY moment
     # the choice exists anywhere the server can see: it lives in the browser until an account does,
     # and a preference nobody recorded cannot be backfilled later (as `google_email` showed: those
-    # rows still read NULL until each user signs in again). Nothing reads it yet; the bilingual
-    # mail templates will.
+    # rows still read NULL until each user signs in again). It is stored as the account's
+    # `preferences["language"]`, which the UI starts in and every mail to the account is written in
+    # (`mailtext.lang_for_user` / `lang_for_email`).
     lang: str | None = None
 
 

backend/docker-compose.test.yml

@@ -1,7 +1,8 @@
 # DB-backed pytest lane: an ephemeral Postgres + the test image, wired together so the
 # `db` fixture (tests/conftest.py) has a real database. The whole thing is throwaway — the pg data
-# lives in tmpfs (RAM) and nothing is persisted. The pure-logic lane still runs WITHOUT this file
-# (plain `docker run … python -m pytest` — DB tests skip when no Postgres is reachable).
+# lives in tmpfs (RAM) and nothing is persisted. A pure-logic run without this file is possible but
+# must say so: `docker run -e SIFTLODE_TEST_REQUIRE_DB=0 … python -m pytest` (without it, a missing
+# Postgres fails the run instead of skipping the DB tests).
 #
 #   docker compose -f backend/docker-compose.test.yml up --build --abort-on-container-exit \
 #     --exit-code-from test

backend/tests/test_review_round.py

@@ -1,10 +1,13 @@
-"""Review round — the invariants the canonical-email work's own review found unpinned.
+"""The onboarding and access invariants a review of that work found unpinned.
 
 Every test here corresponds to a defect a reviewer could still introduce with the whole suite green:
-a mail whose body never renders in any test, an activation that only works for the exact spelling, a
-"we already wrote to them" stamp for a mail that was dropped, an env allow-list that answers a
-different question than the gate it backs, and the address pre-emption that the order-independent
-gates' argument covered only while the address stayed unverified.
+a mail whose body never renders in some language, a link lifetime described in the wrong unit, a
+registration that rewrites an existing password or kills a link already in flight, an activation
+that only works for the exact spelling, a "we already wrote to them" stamp for a mail that was
+dropped, an env allow-list that answers a different question than the gate it backs, a reset or
+resend that reports success it did not have, and a throttle that leaks whether an account exists.
+Approval's password revoke was called redundant because `password_login` refuses an unverified
+account; that holds only until the address is verified, which is what the tests on pre-emption pin.
 """
 
 from datetime import datetime, timedelta, timezone