Adjust resize logic for hidden view

Issue with some iPhones blurring the canvas after switching to code view and back. (Since recent changes to resizing to address canvas buttons.)

Part of #705

AI use: Interactive session with Opus 4.8 to investigate and apply small code changes. Review and manual testing.

Author: tracygardner

main/view.js

@@ -25,7 +25,12 @@ let pendingScrollBlockId = null;
 export function onResize(mode) {
   // First handle canvas and engine
   resizeCanvas();
-  if (flock.engine) flock.engine.resize();
+  // Don't resize the engine against a hidden canvas (0 width in code view);
+  // it would collapse the render buffer. Visibility paths re-resize.
+  const renderCanvas = document.getElementById('renderCanvas');
+  if (flock.engine && renderCanvas && renderCanvas.clientWidth > 0) {
+    flock.engine.resize();
+  }
   // Notify listeners that layout needs updating for the new canvas size.
   window.dispatchEvent(new Event('flock:canvas-resize'));
 
@@ -68,6 +73,9 @@ function resizeCanvas() {
   if (!canvasArea || !canvas) return;
 
   const areaRect = canvasArea.getBoundingClientRect();
+  // Hidden or collapsed (e.g. display:none in narrow-screen code view). Skip so
+  // the buffer isn't shrunk to near-minimum; visibility paths re-resize.
+  if (areaRect.width <= 0 || areaRect.height <= 0) return;
   let areaWidth = Math.max(1, Math.round(areaRect.width));
   let areaHeight = Math.max(1, Math.round(areaRect.height));
 
@@ -669,7 +677,11 @@ const scrollEditingBlockIntoView = () => {
 let _lastViewportHeight = null;
 
 const adjustViewport = () => {
-  const viewportHeight = window.visualViewport?.height || window.innerHeight;
+  // Under pinch/auto zoom visualViewport.height shrinks though the layout
+  // viewport hasn't; multiply by scale so --app-height doesn't collapse. At
+  // scale 1 this is identical to the raw height.
+  const vv = window.visualViewport;
+  const viewportHeight = vv ? vv.height * vv.scale : window.innerHeight;
   const vh = viewportHeight * 0.01;
   document.documentElement.style.setProperty('--vh', `${vh}px`);
   document.documentElement.style.setProperty('--app-height', `${viewportHeight}px`);