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.

internal/store/vote.go

@@ -3,38 +3,62 @@ package store
 import (
 	"context"
 	"database/sql"
+	"errors"
 	"fmt"
 
+	"github.com/jackc/pgx/v5/pgconn"
+
 	"plumber/internal/store/sqlc"
 )
 
-// Vote toggles or sets a user's vote on a question (value must be 1 or -1).
-func Vote(ctx context.Context, db *sql.DB, userID, questionID string, value int) error {
-	if value != 1 && value != -1 {
+// ErrDuplicateUsername is returned when inserting a username that already exists.
+var ErrDuplicateUsername = errors.New("username taken")
+
+// ErrHiddenOrMissing is returned when voting on a hidden or unknown question.
+var ErrHiddenOrMissing = errors.New("question not votable")
+
+// SetVote sets the user's vote to value (1, -1, or 0 to clear) on a visible question.
+func SetVote(ctx context.Context, db *sql.DB, userID, questionID string, value int) error {
+	if value != 1 && value != -1 && value != 0 {
 		return fmt.Errorf("invalid vote")
 	}
-	tx, err := db.BeginTx(ctx, nil)
-	if err != nil {
-		return err
-	}
-	defer tx.Rollback()
-
-	q := sqlc.New(tx)
-	current, err := q.GetVote(ctx, sqlc.GetVoteParams{UserID: userID, QuestionID: questionID})
-	if err != nil && err != sql.ErrNoRows {
-		return err
-	}
-	if err == nil && int(current) == value {
-		err = q.DeleteVote(ctx, sqlc.DeleteVoteParams{UserID: userID, QuestionID: questionID})
-	} else {
-		err = q.UpsertVote(ctx, sqlc.UpsertVoteParams{
+	q := sqlc.New(db)
+	if value == 0 {
+		visible, err := q.QuestionIsVisible(ctx, questionID)
+		if err != nil {
+			return err
+		}
+		if !visible {
+			return ErrHiddenOrMissing
+		}
+		return q.DeleteVote(ctx, sqlc.DeleteVoteParams{
 			UserID:     userID,
 			QuestionID: questionID,
-			Value:      int32(value),
 		})
 	}
+	n, err := q.UpsertVoteOnVisible(ctx, sqlc.UpsertVoteOnVisibleParams{
+		UserID:     userID,
+		QuestionID: questionID,
+		Value:      int32(value),
+	})
 	if err != nil {
-		return err
+		return mapUniqueViolation(err)
 	}
-	return tx.Commit()
+	if n == 0 {
+		return ErrHiddenOrMissing
+	}
+	return nil
+}
+
+// Vote is kept as an alias for SetVote for callers that still use the old name.
+func Vote(ctx context.Context, db *sql.DB, userID, questionID string, value int) error {
+	return SetVote(ctx, db, userID, questionID, value)
+}
+
+func mapUniqueViolation(err error) error {
+	var pgErr *pgconn.PgError
+	if errors.As(err, &pgErr) && pgErr.Code == "23505" {
+		return ErrDuplicateUsername
+	}
+	return err
 }