An inbox between two members — conversations, per-person unread marks,
photos, blocking. Not live chat: that needs a connection held open per
signed-in member, which the sync workers cannot do.
Membership of the conversation is the whole access rule and is checked on
every hit, answering 404 rather than 403 so a member cannot tell a
conversation that is not theirs from one that does not exist. A picture
in a private message is checked the same way: on the board being signed
in is enough, here it is nowhere near.
Blocking is symmetric. One row stops both directions, and you can only
lift your own. A block that silenced only the blocked person would leave
the blocker writing freely, which is a megaphone rather than a safety
feature. Enforced in the handlers, with a test that posts from a page
held open from before the block.
Erasing a member deletes their private messages, both sides, and their
pictures off disk. A thread outlives its author because other people
replied; a two-party exchange has no remainder, and keeping half of
erased correspondence is what erasure exists to prevent. The guard added
in c9c549e did its job: it failed the moment the new tables landed and
named all four columns.
The part that needed care: schema.sql is all CREATE TABLE IF NOT EXISTS,
so it can add a table and nothing else. Every change so far happened to
be a new table. Letting an attachment belong to a message is not — and
SQLite cannot do it in place, because the table carries a CHECK
constraint and there is no DROP CONSTRAINT. Verified before building on
it: ALTER TABLE ADD COLUMN succeeds and the next insert is refused.
So migrations.py, numbered steps recorded in PRAGMA user_version, run
after the schema so a fresh database finds its work already done. Step 1
rebuilds attachments the documented way. Tested against a database built
in the old shape with rows in it, because a migration tested only on a
fresh database is tested against the one case it was never needed for —
including that the rebuilt CHECK is as strict as the one it replaced.
229 tests.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NizVpJ2dwzCbjCrTLCjeHn
5ab9e3cab5