fix: chat accepts posts

internal/repository/post_repo.go

@@ -160,6 +160,46 @@ func (r *PostRepo) FindByID(ctx context.Context, id string) (*model.Post, error)
 	return p, nil
 }
 
+// FindByIDs loads many posts at once, keyed by id. Missing and soft-deleted
+// ids are simply absent from the map.
+//
+// Exists so a page of chat messages sharing N posts costs one query instead of
+// N — the same reason ImagesFor is batched.
+func (r *PostRepo) FindByIDs(ctx context.Context, ids []string) (map[string]*model.Post, error) {
+	out := make(map[string]*model.Post, len(ids))
+	if len(ids) == 0 {
+		return out, nil
+	}
+	q := `SELECT ` + postSelectColumns + postSelectFrom + `WHERE p.id = ANY($1) AND p.deleted_at IS NULL`
+	rows, err := r.pg.Pool.Query(ctx, q, ids)
+	if err != nil {
+		return nil, fmt.Errorf("find posts: %w", err)
+	}
+	defer rows.Close()
+
+	found := make([]string, 0, len(ids))
+	for rows.Next() {
+		p := &model.Post{}
+		if err := scanPost(rows, p); err != nil {
+			return nil, fmt.Errorf("scan post: %w", err)
+		}
+		out[p.ID] = p
+		found = append(found, p.ID)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, fmt.Errorf("find posts: %w", err)
+	}
+
+	imgs, err := r.ImagesFor(ctx, found)
+	if err != nil {
+		return nil, err
+	}
+	for id, p := range out {
+		p.Images = imgs[id]
+	}
+	return out, nil
+}
+
 // ListByHandle returns the profile feed for a user. Unknown handle →
 // empty page (matches pre-existing behaviour).
 func (r *PostRepo) ListByHandle(ctx context.Context, handle string, limit, offset int) ([]model.Post, int, error) {