Address production-readiness review: clearer errors, safer votes, and ops hardening.

Distinguish auth/lookup failures, make votes idempotent on visible questions, bound shutdown, page admin users, LRU throttle, trusted-proxy CIDRs, avatar cleanup, versioned migrations, and session cleanup logging.

db/queries/sessions.sql

@@ -13,6 +13,6 @@ SET data = excluded.data, expiry = excluded.expiry;
 DELETE FROM sessions
 WHERE token = $1;
 
--- name: DeleteExpiredSessions :exec
+-- name: DeleteExpiredSessions :execrows
 DELETE FROM sessions
 WHERE expiry <= now();

db/queries/users.sql

@@ -15,7 +15,17 @@ WHERE username = $1;
 -- name: ListUsers :many
 SELECT id, username, name, role, avatar_url, state, created_at
 FROM users
-ORDER BY created_at ASC
+WHERE (
+  sqlc.arg(search) = ''
+  OR username ILIKE '%' || sqlc.arg(search) || '%'
+  OR name ILIKE '%' || sqlc.arg(search) || '%'
+)
+AND (
+  sqlc.arg(cursor_created) = ''
+  OR created_at < sqlc.arg(cursor_created)
+  OR (created_at = sqlc.arg(cursor_created) AND id < sqlc.arg(cursor_id))
+)
+ORDER BY created_at DESC, id DESC
 LIMIT sqlc.arg(row_limit);
 
 -- name: CountAdmins :one

db/queries/votes.sql

@@ -3,12 +3,22 @@ SELECT value
 FROM votes
 WHERE user_id = $1 AND question_id = $2;
 
+-- name: QuestionIsVisible :one
+SELECT EXISTS(
+  SELECT 1 FROM questions WHERE id = $1 AND hidden = 0
+)::bool;
+
 -- name: DeleteVote :exec
 DELETE FROM votes
 WHERE user_id = $1 AND question_id = $2;
 
--- name: UpsertVote :exec
+-- name: UpsertVoteOnVisible :execrows
 INSERT INTO votes (user_id, question_id, value)
-VALUES ($1, $2, $3)
+SELECT $1, $2, $3
+FROM questions q
+WHERE q.id = $2 AND q.hidden = 0
 ON CONFLICT (user_id, question_id) DO UPDATE
-SET value = excluded.value;
+SET value = excluded.value
+WHERE EXISTS (
+  SELECT 1 FROM questions q2 WHERE q2.id = excluded.question_id AND q2.hidden = 0
+);