Cheaper, clearer dropzones: memoize, hatch refused, label slots as words

DropZones re-ran the accept predicates and a DOM walk on every overlay
render (pointermove-driven). Matching now runs once per drag via
matchZones(); scroll/resize ticks only re-measure the cached rects (new
test pins the predicate count across ticks).

Refused slots get a diagonal hatch on top of the red tint so the state is
not color-only, slot tags show handles as words (`3d-accessories` ->
"3d accessories", raw key kept in title), and the ghost pop honours
prefers-reduced-motion.

The mock section template now marks its sidebar slot like a real
template, so slot tests use the fixture instead of hand-injected DOM
(the old palette test asserting "no tagged slots" now expects both
sections' slots).

🤖 Generated with Codebuff
Co-Authored-By: Codebuff <noreply@codebuff.com>

mock/fixtures.ts

@@ -191,9 +191,11 @@ export function render(g: Graph, id: string): string {
   const attrs = `data-cms="${n.id}" data-cms-type="${n.dataType}"`
   switch (n.dataType) {
     case 'section':
+      // The schema declares a `sidebar` connection, so the template marks the zone
+      // (empty when nothing is slotted) the way a real template would.
       return `<section class="sec sec--${esc(n.data.tone ?? 'light')}${n.data.padded ? ' sec--padded' : ''}" ${attrs} data-cms-container="true">${
         n.data.title ? `<p class="sec__title">${esc(n.data.title)}</p>` : ''
-      }\n${kids()}\n</section>`
+      }\n${kids()}\n<div data-cms-slot="sidebar" data-cms-slot-parent="${n.id}"></div>\n</section>`
     case 'heading': {
       const l = n.data.level ?? 2
       return `<h${l} ${attrs} data-cms-field="text" data-cms-editor="text">${esc(n.data.text)}</h${l}>`

src/controller.ts

@@ -268,8 +268,7 @@ export class Controller {
     })
   }
 
-  /** Live slot rects for the drag engine (measured per move like blocks). */
-  private slotRects(): DndSlot[] {
+  /** Live slot rects for the drag engine (measured per move like blocks). */    private slotRects(): DndSlot[] {
       return this.slots.flatMap((s) => {
         if (!s.el.isConnected) return []
         const r = s.el.getBoundingClientRect()
@@ -277,6 +276,11 @@ export class Controller {
       })
     }
 
+    /** Tagged slot zones from the last scan. Elements stay live; measure their rects per use. */
+    slotZones(): Array<{ handle: string; parentId: string; el: HTMLElement }> {
+      return this.slots.filter((s) => s.el.isConnected).map(({ handle, parentId, el }) => ({ handle, parentId, el }))
+    }
+
   block(id: string | null | undefined): Block | undefined {
     return id ? this.store.get().blocks.find((b) => b.id === id) : undefined
   }

src/ui/Overlay.tsx

@@ -1,4 +1,4 @@
-import { createElement, useEffect, useRef, useState } from 'react'
+import { createElement, useEffect, useMemo, useRef, useState } from 'react'
 import type { Block, Controller } from '../controller'
 import { AttrEditor } from '../editors/AttrEditor'
 import { InsertPicker } from '../editors/builtin'
@@ -223,16 +223,23 @@ function DropGhost() {
 // --- dropzone highlights: while dragging, outline every zone the dragged item can land in --------
 // Palette blueprints, searched nodes and moving blocks share one engine (`accepts` /
 // `acceptsInSlot` in the controller); the highlights use the same predicates so what
-// glows is exactly where a drop commits. Refused slots stay visible but dimmed,
-// so it is clear they exist and just do not take this item.
+// glows is exactly where a drop commits. Refused slots stay visible but dimmed
+// (hatched, so the state is not color-only), so it is clear they exist and
+// just do not take this item.
+//
+// Matching runs once per drag: the page cannot restructure mid-drag, so renders
+// triggered by scroll/resize ticks only re-measure the cached rects.
 
-function DropZones() {
-  const ctrl = useCtrl()
-  const drag = useEditorState((s) => s.drag)!
-  const blocks = useEditorState((s) => s.blocks)
-  useEditorState((s) => s.tick) // re-measure on scroll/resize/mutation
-  useEditorState((s) => s.schemasVersion)
-  if (!drag) return null
+export interface ZoneDefs {
+  containers: Block[]
+  slots: { key: string; parentId: string; handle: string; el: HTMLElement; refused: boolean }[]
+}
+
+export function matchZones(
+  ctrl: Controller,
+  blocks: Block[],
+  drag: { source: string; id: string | null; type?: string; blueprint?: string },
+): ZoneDefs {
   const type = drag.type
   // A moving block can never land inside itself: mirror the engine, which
   // excludes the dragged block and its descendants from every hit test.
@@ -255,31 +262,47 @@ function DropZones() {
   const containers = blocks.filter(
     (b) => b.container && b.el.isConnected && !excluded.has(b.id) && (!type || ctrl.accepts(b.id, type) || ctrl.handleForDrop(b.id, type) !== undefined),
   )
-  // NB: doc.querySelectorAll does not pierce the editor's shadow root, so
-  // editor UI is never included (same as SlotAdds below).
-  const slots = [...ctrl.doc.querySelectorAll<HTMLElement>('[data-cms-slot]')].flatMap((el, i) => {
-    const handle = el.getAttribute('data-cms-slot')
-    if (!handle || !el.isConnected) return []
-    const parentId = el.getAttribute('data-cms-slot-parent') ?? el.closest('[data-cms]')?.getAttribute('data-cms') ?? ''
-    if (!parentId) return []
-    if (drag.source === 'block' && parentId === drag.id) return [] // engine never targets the dragged block's own zones
-    const r = el.getBoundingClientRect()
+  // Slot zones come from the controller's last scan (no second DOM walk; the
+  // query never pierces the editor's shadow root, so editor UI is excluded).
   // Blueprints cannot land in slots (the outline refuses them too); a type
   // fits when the slot's own `to` list takes it.
-    const refused = !type || !ctrl.acceptsInSlot(parentId, handle, type)
-    return [{ key: `${parentId}:${handle}:${i}`, parentId, handle, rect: r, refused }]
+  const slots = ctrl.slotZones().flatMap((s, i) => {
+    if (drag.source === 'block' && s.parentId === drag.id) return [] // engine never targets the dragged block's own zones
+    const refused = !type || !ctrl.acceptsInSlot(s.parentId, s.handle, type)
+    return [{ key: `${s.parentId}:${s.handle}:${i}`, parentId: s.parentId, handle: s.handle, el: s.el, refused }]
   })
+  return { containers, slots }
+}
+
+/** Slot handles are template keys (`3d-accessories`); show them as words. */
+export function slotLabel(handle: string): string {
+  return handle.replace(/[-_]+/g, ' ').replace(/\s+/g, ' ').trim()
+}
+
+function DropZones() {
+  const ctrl = useCtrl()
+  const drag = useEditorState((s) => s.drag)!
+  const blocks = useEditorState((s) => s.blocks)
+  useEditorState((s) => s.tick) // re-measure on scroll/resize/mutation
+  const schemasVersion = useEditorState((s) => s.schemasVersion)
+  // The drag object is rebuilt every pointermove; key on what matching reads.
+  const spec = drag ? `${drag.source}:${drag.id ?? ''}:${drag.type ?? ''}:${drag.blueprint ?? ''}` : ''
+  const zones = useMemo(() => (drag ? matchZones(ctrl, blocks, drag) : null), [ctrl, blocks, schemasVersion, spec])
+  if (!drag || !zones) return null
   return (
     <>
-      {containers.map((b) => {
+      {zones.containers.map((b) => {
         const r = b.el.getBoundingClientRect()
         return <div key={b.id} className="cms-dropzone" data-dropzone={b.id} style={{ left: r.left, top: r.top, width: r.width, height: r.height }} />
       })}
-      {slots.map((z) => (
-        <div key={z.key} className={`cms-dropzone cms-dropzone--slot${z.refused ? ' is-refused' : ''}`} data-dropzone={`slot:${z.parentId}:${z.handle}`} style={{ left: z.rect.left, top: z.rect.top, width: z.rect.width, height: z.rect.height }}>
-          <span className="cms-dropzone__tag">{z.handle}</span>
+      {zones.slots.map((z) => {
+        const r = z.el.getBoundingClientRect()
+        return (
+          <div key={z.key} className={`cms-dropzone cms-dropzone--slot${z.refused ? ' is-refused' : ''}`} data-dropzone={`slot:${z.parentId}:${z.handle}`} title={z.handle} style={{ left: r.left, top: r.top, width: r.width, height: r.height }}>
+            <span className="cms-dropzone__tag">{slotLabel(z.handle)}</span>
           </div>
-      ))}
+        )
+      })}
     </>
   )
 }

src/ui/styles.css

@@ -218,7 +218,7 @@ input.cms-map__key { padding-top: 6px; }
 /* dropzone highlights: while dragging, every zone the dragged item can land in */
 .cms-dropzone { position: fixed; pointer-events: none; z-index: 1; border: 1.5px dashed rgba(94,224,160,.7); border-radius: 6px; background: rgba(94,224,160,.05); }
 .cms-dropzone--slot { border-color: rgba(106,167,255,.75); background: rgba(106,167,255,.07); }
-.cms-dropzone--slot.is-refused { border-color: rgba(163,58,74,.55); background: rgba(163,58,74,.04); }
+.cms-dropzone--slot.is-refused { border-color: rgba(163,58,74,.55); background-color: rgba(163,58,74,.06); background-image: repeating-linear-gradient(45deg, rgba(163,58,74,.16) 0 6px, transparent 6px 12px); }
 .cms-dropzone__tag { position: absolute; top: -9px; left: 8px; padding: 0 6px; font-size: 10px; font-weight: 600; letter-spacing: .04em; text-transform: uppercase; white-space: nowrap; background: #1c2b25; color: #8fe3b8; border: 1px solid rgba(94,224,160,.7); border-radius: 999px; }
 .cms-dropzone--slot .cms-dropzone__tag { background: #232c4a; color: #aebdff; border-color: rgba(106,167,255,.75); }
 .cms-dropzone--slot.is-refused .cms-dropzone__tag { background: #33222a; color: #e89aa6; border-color: rgba(163,58,74,.55); }
@@ -311,7 +311,7 @@ input.cms-map__key { padding-top: 6px; }
 .cms-snap { position: fixed; pointer-events: none; background: rgba(94,224,160,.28); border-radius: 2px; }
 .cms-snap.is-active { background: transparent; }
 .cms-dropline { transition: left .09s ease-out, top .09s ease-out, width .09s ease-out, height .09s ease-out; }
-@media (prefers-reduced-motion: reduce) { .cms-dropline { transition: none; } }
+@media (prefers-reduced-motion: reduce) { .cms-dropline { transition: none; } .cms-ghost { animation: none; } }
 
 /* titles + groups */
 .cms-frame__tag i { font-style: normal; opacity: .7; font-weight: 400; }

test/onpage.test.tsx

@@ -3,6 +3,7 @@ import { act } from 'react'
 import { byId, click, setup } from './harness'
 import type { Harness } from './harness'
 import { Icon, TypeIcon, registerTypeIcon } from '../src/ui/Icon'
+import { slotLabel } from '../src/ui/Overlay'
 import { createRoot } from 'react-dom/client'
 
 let h: Harness
@@ -204,8 +205,7 @@ describe('block palette and drag & drop', () => {
     h = await setup()
     await h.settle()
     place('s1', 0, 0, 600, 300)
-    // The section schema declares a `sidebar` slot taking text/button/footer; the template marks it.
-    byId('s1').insertAdjacentHTML('beforeend', '<div data-cms-slot="sidebar" data-cms-slot-parent="s1"></div>')
+    // The section schema declares a `sidebar` slot taking text/button/footer; the fixture template marks it.
     const zone = byId('s1').querySelector<HTMLElement>('[data-cms-slot]')!
     zone.getBoundingClientRect = () => ({ x: 10, y: 190, left: 10, top: 190, right: 590, bottom: 250, width: 580, height: 60, toJSON() {} }) as DOMRect
     h.editor.ctrl.scan()
@@ -223,7 +223,6 @@ describe('block palette and drag & drop', () => {
     h = await setup()
     await h.settle()
     place('s1', 0, 0, 600, 300)
-    byId('s1').insertAdjacentHTML('beforeend', '<div data-cms-slot="sidebar" data-cms-slot-parent="s1"></div>')
     const zone = byId('s1').querySelector<HTMLElement>('[data-cms-slot]')!
     zone.getBoundingClientRect = () => ({ x: 10, y: 190, left: 10, top: 190, right: 590, bottom: 250, width: 580, height: 60, toJSON() {} }) as DOMRect
     h.editor.ctrl.scan()
@@ -267,7 +266,7 @@ describe('insertion slots (virtual "+" elements)', () => {
     h = await setup()
     await h.settle()
     await select('s1')
-    expect(qa('.cms-slot').map((s) => s.getAttribute('aria-label'))).toEqual(['Add block at position 1', 'Add block at position 2', 'Add block at position 3', 'Add block at position 4'])
+    expect(qa('.cms-slot').map((s) => s.getAttribute('aria-label'))).toEqual(['Add block at position 1', 'Add block at position 2', 'Add block at position 3', 'Add block at position 4', 'Add to sidebar'])
     await act(async () => void qa('.cms-slot')[1].click())
     await h.settle()
     expect([...h.shadow.querySelectorAll('.cms-dialog h4')].map((x) => x.textContent)).toEqual(['Content', 'Layout', 'Blueprints']) // grouped by x-graph.group
@@ -419,7 +418,9 @@ describe('dropzone highlights', () => {
     expect(ids).toContain('s2')
     expect(ids).toContain('l1') // layout takes text too
     expect(ids).not.toContain('t1') // leaves are never dropzones
-    expect(slots().length).toBe(0) // the fixture page has no tagged slots
+    const s = slots()
+    expect(s.map((el) => el.getAttribute('data-dropzone'))).toEqual(['slot:s1:sidebar', 'slot:s2:sidebar']) // both sections mark their sidebar slot
+    expect(s.every((el) => !el.className.includes('is-refused'))).toBe(true) // sidebar takes text
     await stop()
     expect(qa('.cms-dropzone').length).toBe(0)
   })
@@ -438,13 +439,12 @@ describe('dropzone highlights', () => {
   it('a blueprint drag lights up containers and marks every slot refused', async () => {
     h = await setup()
     await h.settle()
-    byId('s1').insertAdjacentHTML('beforeend', '<div data-cms-slot="sidebar" data-cms-slot-parent="s1"></div>')
     h.editor.ctrl.scan()
     h.editor.ctrl.beginPaletteDrag({ blueprint: 'hero', label: 'Hero' })
     await h.settle()
     expect(zones()).toContain('s1') // typeless: every container fits
     const s = slots()
-    expect(s.map((el) => el.getAttribute('data-dropzone'))).toEqual(['slot:s1:sidebar'])
+    expect(s.map((el) => el.getAttribute('data-dropzone'))).toEqual(['slot:s1:sidebar', 'slot:s2:sidebar'])
     expect(s[0].className).toContain('is-refused') // blueprints cannot land in slots
     expect(s[0].querySelector('.cms-dropzone__tag')!.textContent).toBe('sidebar')
     await stop()
@@ -453,17 +453,16 @@ describe('dropzone highlights', () => {
   it('a node drag accepts a fitting slot and refuses one that does not take the type', async () => {
     h = await setup()
     await h.settle()
-    byId('s1').insertAdjacentHTML('beforeend', '<div data-cms-slot="sidebar" data-cms-slot-parent="s1"></div>')
     h.editor.ctrl.scan()
     h.editor.ctrl.beginExistingDrag({ id: 'orphan1', type: 'text', label: 'sparrows' })
     await h.settle()
-    expect(slots().length).toBe(1)
-    expect(slots()[0].className).not.toContain('is-refused') // sidebar takes text
+    expect(slots()).toHaveLength(2)
+    expect(slots().every((el) => !el.className.includes('is-refused'))).toBe(true) // sidebar takes text
     await stop()
     h.editor.ctrl.beginExistingDrag({ id: 'orphan1', type: 'heading', label: 'headline' })
     await h.settle()
-    expect(slots().length).toBe(1)
-    expect(slots()[0].className).toContain('is-refused') // sidebar takes text/button/footer
+    expect(slots()).toHaveLength(2)
+    expect(slots().every((el) => el.className.includes('is-refused'))).toBe(true) // sidebar takes text/button/footer
     expect(zones()).toContain('s1') // ... while the section itself still takes it
     await stop()
   })
@@ -479,4 +478,38 @@ describe('dropzone highlights', () => {
     expect(ids).not.toContain('h1') // leaves are never dropzones
     await stop()
   })
+
+  it('zones match once per drag: scroll ticks re-measure but do not re-match', async () => {
+    h = await setup()
+    await h.settle()
+    const ctrl = h.editor.ctrl
+    let n = 0
+    const orig = ctrl.accepts
+    ctrl.accepts = (...args: [string, string]) => {
+      n++
+      return orig.call(ctrl, ...args)
+    }
+    try {
+      ctrl.beginPaletteDrag({ type: 'text', label: 'Text' })
+      await h.settle()
+      expect(n).toBeGreaterThan(0) // matching ran: every container checked
+      expect(qa('.cms-dropzone').length).toBeGreaterThan(0)
+      ctrl.store.set({ tick: ctrl.store.get().tick + 1 }) // scroll/resize/mutation tick
+      await h.settle()
+      expect(qa('.cms-dropzone').length).toBeGreaterThan(0) // still drawn, rects re-measured ...
+      const after = n
+      ctrl.store.set({ tick: ctrl.store.get().tick + 1 })
+      await h.settle()
+      expect(n).toBe(after) // ... without re-running the accept predicates
+      await stop()
+    } finally {
+      ctrl.accepts = orig
+    }
+  })
+
+  it('slot tags show handles as words', () => {
+    expect(slotLabel('sidebar')).toBe('sidebar')
+    expect(slotLabel('3d-accessories')).toBe('3d accessories')
+    expect(slotLabel('hero_slot')).toBe('hero slot')
+  })
 })