feat: zoom-bucket text sharpness + remove fontSize toolbar controls

Add TextSharpnessManager for crisp text rendering at all zoom levels:
- Discrete zoom buckets (0.5–3x) avoid texture churn on small zoom changes
- Initial bucket applied to all items on setup and newly created items
  via SceneManager.onItemCreated callback (fixes blurry-on-load)
- Visibility check uses getItemWorldBounds for correct grouped item coords
- TextSprite/StickySprite gain setZoomBucket() for resolution control

Remove fontSize +/- controls from contextual toolbar — font size is now
controlled purely through direct manipulation (resize → bake).

frontend/src/canvas/SceneManager.ts

@@ -161,6 +161,7 @@ export class SceneManager {
 
   private _onChange: (() => void) | null = null;
   private _onItemDimensionsChanged: ((itemId: string) => void) | null = null;
+  private _onItemCreated: ((item: SceneItem) => void) | null = null;
   private _zCounter: number = 0;
 
   constructor(viewport: Viewport, textures: TextureManager, springs: SpringManager) {
@@ -190,6 +191,10 @@ export class SceneManager {
     this._onItemDimensionsChanged = fn;
   }
 
+  set onItemCreated(fn: ((item: SceneItem) => void) | null) {
+    this._onItemCreated = fn;
+  }
+
   get onChange(): (() => void) | null {
     return this._onChange;
   }
@@ -387,6 +392,7 @@ export class SceneManager {
     }
 
     // No entrance animation — items must be visible and draggable immediately.
+    this._onItemCreated?.(item);
   }
 
   // -- Item Update ---------------------------------------------------------

frontend/src/canvas/sprites/StickySprite.ts

@@ -49,6 +49,7 @@ export class StickySprite extends Container {
 
   // Background redraw cache: skip Graphics.clear()+redraw when shape is unchanged
   private _bgCacheKey = '';
+  private _zoomBucket = 1;
 
   /** After layout, the computed card height. Parent should sync to data.h. */
   get computedHeight(): number {
@@ -60,6 +61,16 @@ export class StickySprite extends Container {
     this._text.visible = visible;
   }
 
+  /**
+   * Update text rasterization resolution for zoom-bucket crisp rendering.
+   * Only re-rasterizes when the bucket actually changes.
+   */
+  setZoomBucket(bucket: number): void {
+    if (bucket === this._zoomBucket) return;
+    this._zoomBucket = bucket;
+    this._text.resolution = bucket;
+  }
+
   constructor(data: StickyObject) {
     super();
 

frontend/src/canvas/sprites/TextSprite.ts

@@ -23,6 +23,7 @@ export class TextSprite extends Container {
   private _lastFontSize = 24;
   private _lastFontFamily = 'sans-serif';
   private _lastFill = '#ffffff';
+  private _zoomBucket = 1;
 
   /** Measured width after last text change. */
   get measuredWidth(): number {
@@ -39,6 +40,16 @@ export class TextSprite extends Container {
     this._text.visible = visible;
   }
 
+  /**
+   * Update text rasterization resolution for zoom-bucket crisp rendering.
+   * Only re-rasterizes when the bucket actually changes.
+   */
+  setZoomBucket(bucket: number): void {
+    if (bucket === this._zoomBucket) return;
+    this._zoomBucket = bucket;
+    this._text.resolution = bucket;
+  }
+
   constructor(data: TextObject) {
     super();
 

frontend/src/canvas/textSharpness.ts

@@ -0,0 +1,129 @@
+/**
+ * textSharpness — zoom-bucket-aware text rendering.
+ *
+ * Tracks the viewport zoom level and groups it into discrete buckets.
+ * When the bucket changes, visible text/sticky sprites are re-rasterized
+ * at the new resolution for crisp rendering. Small zoom movements within
+ * the same bucket are ignored to avoid unnecessary texture churn.
+ *
+ * This does NOT mutate scene data (fontSize stays stable).
+ * It only changes the render resolution of text textures.
+ */
+
+import type { Viewport } from 'pixi-viewport';
+import type { SceneManager, SceneItem } from './SceneManager';
+import { getItemWorldBounds } from './SceneManager';
+import { TextSprite } from './sprites/TextSprite';
+import { StickySprite } from './sprites/StickySprite';
+
+/**
+ * Map continuous zoom to discrete bucket.
+ * Fewer buckets = fewer re-rasterizations = better perf.
+ */
+export function getTextZoomBucket(scale: number): number {
+  if (scale < 0.4) return 0.5;
+  if (scale < 0.75) return 0.75;
+  if (scale < 1.25) return 1;
+  if (scale < 1.75) return 1.5;
+  if (scale < 2.5) return 2;
+  return 3;
+}
+
+export class TextSharpnessManager {
+  private _viewport: Viewport;
+  private _scene: SceneManager;
+  private _currentBucket = 1;
+
+  constructor(viewport: Viewport, scene: SceneManager) {
+    this._viewport = viewport;
+    this._scene = scene;
+    this._currentBucket = getTextZoomBucket(viewport.scale.x);
+    // Apply initial bucket to all existing text/sticky items
+    this._refreshAll();
+  }
+
+  /**
+   * Call on viewport zoom/move. Returns true if bucket changed.
+   */
+  check(): boolean {
+    const bucket = getTextZoomBucket(this._viewport.scale.x);
+    if (bucket === this._currentBucket) return false;
+    this._currentBucket = bucket;
+    this._refreshVisible();
+    return true;
+  }
+
+  /**
+   * Apply current zoom bucket to a single item.
+   * Call this when a new text/sticky sprite is created.
+   */
+  applyToItem(item: SceneItem): void {
+    if (item.displayObject instanceof TextSprite) {
+      item.displayObject.setZoomBucket(this._currentBucket);
+    } else if (item.displayObject instanceof StickySprite) {
+      item.displayObject.setZoomBucket(this._currentBucket);
+    }
+  }
+
+  /** Refresh all text/sticky items (used on initial setup). */
+  private _refreshAll(): void {
+    const bucket = this._currentBucket;
+    for (const item of this._scene.getAllItems()) {
+      if (item.type !== 'text' && item.type !== 'sticky') continue;
+      if (item.displayObject instanceof TextSprite) {
+        item.displayObject.setZoomBucket(bucket);
+      } else if (item.displayObject instanceof StickySprite) {
+        item.displayObject.setZoomBucket(bucket);
+      }
+    }
+  }
+
+  /** Refresh visible text/sticky items at current bucket (on zoom change). */
+  private _refreshVisible(): void {
+    const bucket = this._currentBucket;
+    const items = this._scene.getAllItems();
+    const vb = this._getViewportWorldBounds();
+
+    for (const item of items) {
+      if (item.type !== 'text' && item.type !== 'sticky') continue;
+      // Skip off-screen items
+      if (vb && !this._intersects(item, vb)) continue;
+
+      if (item.displayObject instanceof TextSprite) {
+        item.displayObject.setZoomBucket(bucket);
+      } else if (item.displayObject instanceof StickySprite) {
+        item.displayObject.setZoomBucket(bucket);
+      }
+    }
+  }
+
+  /** Get viewport bounds in world coordinates. */
+  private _getViewportWorldBounds(): { x: number; y: number; w: number; h: number } | null {
+    const vp = this._viewport;
+    if (!vp.screenWidth || !vp.screenHeight) return null;
+    const tl = vp.toWorld(0, 0);
+    const br = vp.toWorld(vp.screenWidth, vp.screenHeight);
+    return { x: tl.x, y: tl.y, w: br.x - tl.x, h: br.y - tl.y };
+  }
+
+  /** Check if item intersects viewport bounds (with margin). Uses world bounds for group children. */
+  private _intersects(item: SceneItem, vb: { x: number; y: number; w: number; h: number }): boolean {
+    const margin = 200; // world-space margin to include near-screen items
+    const { x: ix, y: iy, w: iw, h: ih } = getItemWorldBounds(item);
+    return (
+      ix + iw >= vb.x - margin &&
+      iy + ih >= vb.y - margin &&
+      ix <= vb.x + vb.w + margin &&
+      iy <= vb.y + vb.h + margin
+    );
+  }
+
+  /** Current bucket value (for initial setup of new items). */
+  get currentBucket(): number {
+    return this._currentBucket;
+  }
+
+  destroy(): void {
+    // nothing to clean up currently
+  }
+}

frontend/src/components/TextFormatToolbar.tsx

@@ -4,14 +4,12 @@ interface TextFormatToolbarProps {
   kind: 'text' | 'sticky';
   x: number;
   y: number;
-  fontSize: number;
   fontFamily: string;
   /** Text color (both text and sticky). */
   fill: string;
   /** Note background color (sticky only). */
   noteFill?: string;
   position?: 'above' | 'below';
-  onFontSizeChange: (size: number) => void;
   onFontFamilyChange: (family: string) => void;
   onFillChange: (color: string) => void;
   /** Called when sticky note background color changes. */
@@ -35,7 +33,7 @@ const PRESET_COLORS = [
 ];
 
 export default function TextFormatToolbar(props: TextFormatToolbarProps) {
-  const { kind, x, y, fontSize, fontFamily, fill, noteFill, position = 'above', onFontSizeChange, onFontFamilyChange, onFillChange, onNoteFillChange } = props;
+  const { kind, x, y, fontFamily, fill, noteFill, position = 'above', onFontFamilyChange, onFillChange, onNoteFillChange } = props;
   const [showFontMenu, setShowFontMenu] = useState(false);
   const [showColorPicker, setShowColorPicker] = useState(false);
   const [showNoteFillPicker, setShowNoteFillPicker] = useState(false);
@@ -97,30 +95,6 @@ export default function TextFormatToolbar(props: TextFormatToolbarProps) {
       }}
       onPointerDown={(e) => e.stopPropagation()}
     >
-      {/* Font size: decrease / value / increase */}
-      <button
-        style={{ ...btnStyle, width: '26px', padding: 0 }}
-        onClick={() => onFontSizeChange(Math.max(8, fontSize - 2))}
-        title="Decrease font size"
-        {...hoverHandlers}
-      >
-        <svg width="12" height="12" viewBox="0 0 12 12" fill="none" stroke="currentColor" strokeWidth="1.5"><line x1="2" y1="6" x2="10" y2="6" /></svg>
-      </button>
-      <span style={{ color: '#ccc', fontSize: '11px', minWidth: '24px', textAlign: 'center', userSelect: 'none' }}>
-        {fontSize}
-      </span>
-      <button
-        style={{ ...btnStyle, width: '26px', padding: 0 }}
-        onClick={() => onFontSizeChange(Math.min(200, fontSize + 2))}
-        title="Increase font size"
-        {...hoverHandlers}
-      >
-        <svg width="12" height="12" viewBox="0 0 12 12" fill="none" stroke="currentColor" strokeWidth="1.5"><line x1="2" y1="6" x2="10" y2="6" /><line x1="6" y1="2" x2="6" y2="10" /></svg>
-      </button>
-
-      {/* Divider */}
-      <div style={{ width: '1px', height: '18px', background: '#333', margin: '0 2px', flexShrink: 0 }} />
-
       {/* Font family dropdown */}
       <div style={{ position: 'relative' }}>
         <button

frontend/src/hooks/useCanvasSetup.ts

@@ -14,6 +14,7 @@ import { AnnotationStore } from '../stores/annotationStore';
 import { PinOverlay } from '../canvas/PinOverlay';
 import { CropOverlay } from '../canvas/CropOverlay';
 import { TextSprite } from '../canvas/sprites/TextSprite';
+import { TextSharpnessManager } from '../canvas/textSharpness';
 // PresenceOverlay removed — remote selection highlighting was too heavy for minimal benefit
 import { connectSocket, disconnectSocket } from '../socket';
 import api from '../api';
@@ -70,6 +71,7 @@ export function useCanvasSetup(deps: CanvasSetupDeps) {
   const dropCleanupRef = useRef<(() => void) | null>(null);
   const pasteCleanupRef = useRef<(() => void) | null>(null);
   const laserCleanupRef = useRef<(() => void) | null>(null);
+  const sharpnessCleanupRef = useRef<(() => void) | null>(null);
   const annotationStoreRef = useRef<AnnotationStore | null>(null);
   if (!annotationStoreRef.current) annotationStoreRef.current = new AnnotationStore();
   const pinOverlayRef = useRef<PinOverlay | null>(null);
@@ -161,6 +163,17 @@ export function useCanvasSetup(deps: CanvasSetupDeps) {
       // Create UndoManager
       undoRef.current = new UndoManager(scene);
 
+      // Zoom-bucket text sharpness — re-rasterize visible text when zoom crosses bucket boundary
+      const sharpness = new TextSharpnessManager(viewport, scene);
+      const onZoomBucketCheck = () => { sharpness.check(); };
+      viewport.on('zoomed', onZoomBucketCheck);
+      scene.onItemCreated = (item) => { sharpness.applyToItem(item); };
+      sharpnessCleanupRef.current = () => {
+        viewport.off('zoomed', onZoomBucketCheck);
+        scene.onItemCreated = null;
+        sharpness.destroy();
+      };
+
       // Create InboxZone and add to viewport
       const inboxZone = new InboxZone(scene.textures, scene.springs);
       viewport.addChild(inboxZone);
@@ -475,6 +488,8 @@ export function useCanvasSetup(deps: CanvasSetupDeps) {
         pinOverlayRef.current = null;
       }
       annotationStoreRef.current?.clear();
+      sharpnessCleanupRef.current?.();
+      sharpnessCleanupRef.current = null;
       disconnectSocket();
     };
   }, [boardData, resolvedBoardId, user, isPublicView, onCanvasChange, showToast, canvasRef, selectionRef, undoRef, syncRef, inboxZoneRef, uploadManager, setOnlineUsers, setSelectedLayerIds]);

frontend/src/pages/Editor.tsx

@@ -122,8 +122,8 @@ export default function Editor({ isPublicView }: EditorProps) {
   const [selectedLayerIds, setSelectedLayerIds] = useState<string[]>([]);
   const [selToolbar, setSelToolbar] = useState<{ x: number; y: number; count: number } | null>(null);
   const [textToolbar, setTextToolbar] = useState<
-    | { kind: 'text'; x: number; y: number; fontSize: number; fontFamily: string; fill: string; items: SceneItem[] }
+    | { kind: 'text'; x: number; y: number; fontFamily: string; fill: string; items: SceneItem[] }
-    | { kind: 'sticky'; x: number; y: number; fontSize: number; fontFamily: string; textColor: string; fill: string; items: SceneItem[] }
+    | { kind: 'sticky'; x: number; y: number; fontFamily: string; textColor: string; fill: string; items: SceneItem[] }
     | null
   >(null);
   const [videoCtrl, setVideoCtrl] = useState<{ videoSprite: VideoSprite; screenRect: { x: number; y: number; w: number; h: number } } | null>(null);
@@ -619,14 +619,14 @@ export default function Editor({ isPublicView }: EditorProps) {
         const td = textItems[0].data as TextObject;
         setTextToolbar({
           kind: 'text', x: posX, y: posY,
-          fontSize: td.fontSize, fontFamily: td.fontFamily, fill: td.fill,
+          fontFamily: td.fontFamily, fill: td.fill,
           items: textItems,
         });
       } else {
         const sd = stickyItems[0].data as StickyObject;
         setTextToolbar({
           kind: 'sticky', x: posX, y: posY,
-          fontSize: sd.fontSize || 14, fontFamily: sd.fontFamily || 'Inter, system-ui, sans-serif',
+          fontFamily: sd.fontFamily || 'Inter, system-ui, sans-serif',
           textColor: sd.textColor || '#1a1a1a', fill: sd.fill || '#ffd43b',
           items: stickyItems,
         });
@@ -912,36 +912,10 @@ export default function Editor({ isPublicView }: EditorProps) {
             kind={textToolbar.kind}
             x={textToolbar.x}
             y={textToolbar.y}
-            fontSize={textToolbar.fontSize}
             fontFamily={textToolbar.fontFamily}
             fill={textToolbar.kind === 'sticky' ? textToolbar.textColor : textToolbar.fill}
             noteFill={textToolbar.kind === 'sticky' ? textToolbar.fill : undefined}
             position={textToolbar.items.length >= 2 ? 'below' : 'above'}
-            onFontSizeChange={(size) => {
-              const scene = canvasRef.current?.getScene();
-              for (const item of textToolbar.items) {
-                if (textToolbar.kind === 'text') {
-                  const d = item.data as TextObject;
-                  d.fontSize = size;
-                  if (item.displayObject instanceof TextSprite) {
-                    item.displayObject.updateFromData(d);
-                    d.w = item.displayObject.measuredWidth;
-                    d.h = item.displayObject.measuredHeight;
-                  }
-                } else {
-                  const d = item.data as StickyObject;
-                  d.fontSize = size;
-                  if (item.displayObject instanceof StickySprite) {
-                    item.displayObject.updateFromData(d);
-                    d.h = item.displayObject.computedHeight;
-                  }
-                }
-                if (scene) scene.updateSpatialEntry(item);
-              }
-              selectionRef.current?.transformBox.update(textToolbar.items);
-              onCanvasChange(textToolbar.items.map(i => i.id));
-              updateOverlays();
-            }}
             onFontFamilyChange={(family) => {
               const scene = canvasRef.current?.getScene();
               for (const item of textToolbar.items) {