---
id: TASK-004
title: Editor rebuilds full visual model twice per keystroke (O(document))
status: "\U0001F7E6 Backlog"
assignee: []
created_date: '2026-06-28 18:38'
labels:
  - perf
dependencies: []
priority: low
ordinal: 4000
---

## Description

<!-- SECTION:DESCRIPTION:BEGIN -->
Every InsertRune→followCursor→buildVisual rescans+rewraps all lines; MoveUp/MoveDown call buildVisual then followCursor calls it again (2 full scans/vertical keystroke). Fine for notes, costly for long docs in the writing canvas. Fix: thread one []vrow through move→followCursorWith(rows); longer term cache the visual model, invalidate on edit/resize.
<!-- SECTION:DESCRIPTION:END -->

## Acceptance Criteria
<!-- AC:BEGIN -->
- [ ] #1 at most one buildVisual per keystroke
<!-- AC:END -->