feat(admin): multi-image carousel with add/remove in product editor

Rewrite ImageUploadSlot to read the full images array via
useField({ path: 'images', hasRows: true }), resolve each row's
media id via /api/media/<id>, and render prev/next arrows on hover,
dot navigation, and a remove button. Uploading appends a new row via
dispatchFields ADD_ROW.

Dots are 14px black squares with a 1px yellow border and a 6px yellow
inner square when active.

Frontend already supports multi-image carousel (main.js) via
data-images JSON on product cards — no frontend changes needed.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

nextjs/src/components/admin/ImageUploadSlot.tsx

@@ -1,7 +1,7 @@
 'use client'
 
 import { useField, useForm } from '@payloadcms/ui'
-import { useEffect, useRef, useState } from 'react'
+import { useCallback, useEffect, useMemo, useRef, useState } from 'react'
 
 type MediaDoc = { id: number | string; url?: string | null; alt?: string | null }
 
@@ -19,43 +19,88 @@ function extractMediaId(value: unknown): string | number | null {
 }
 
 export function ImageUploadSlot({ displayName }: Props) {
-  const { value: mediaValue, setValue: setMedia } = useField<unknown>({ path: 'images.0.image' })
-  const { dispatchFields } = useForm()
+  const { rows } = useField<unknown>({ path: 'images', hasRows: true })
+  const { dispatchFields, getDataByPath } = useForm()
   const fileInput = useRef<HTMLInputElement | null>(null)
   const [uploading, setUploading] = useState(false)
   const [error, setError] = useState<string | null>(null)
-  const [resolved, setResolved] = useState<MediaDoc | null>(null)
+  const [cache, setCache] = useState<Record<string, MediaDoc>>({})
+  const [index, setIndex] = useState(0)
 
-  const mediaId = extractMediaId(mediaValue)
+  const rowCount = rows?.length ?? 0
+
+  const mediaIds = useMemo<Array<string | number | null>>(() => {
+    const ids: Array<string | number | null> = []
+    for (let i = 0; i < rowCount; i++) {
+      const raw = getDataByPath(`images.${i}.image`)
+      ids.push(extractMediaId(raw))
+    }
+    return ids
+  }, [rowCount, getDataByPath])
 
   useEffect(() => {
     let cancelled = false
-    if (mediaId == null) {
-      setResolved(null)
-      return
-    }
-    if (resolved && resolved.id === mediaId) return
-    if (mediaValue && typeof mediaValue === 'object' && 'url' in (mediaValue as object)) {
-      setResolved(mediaValue as MediaDoc)
-      return
-    }
+    const toFetch = mediaIds.filter((id): id is string | number => id != null && !cache[String(id)])
+    if (!toFetch.length) return
     ;(async () => {
+      const entries = await Promise.all(
+        toFetch.map(async (id) => {
           try {
-        const res = await fetch(`/api/media/${mediaId}`, { credentials: 'include' })
-        if (!res.ok) return
+            const res = await fetch(`/api/media/${id}`, { credentials: 'include' })
+            if (!res.ok) return null
             const doc = await res.json()
-        if (!cancelled) setResolved({ id: doc.id, url: doc.url, alt: doc.alt })
+            return [String(id), { id: doc.id, url: doc.url, alt: doc.alt }] as const
           } catch {
-        /* ignore */
+            return null
           }
+        }),
+      )
+      if (cancelled) return
+      const next: Record<string, MediaDoc> = {}
+      for (const e of entries) if (e) next[e[0]] = e[1]
+      if (Object.keys(next).length) setCache((prev) => ({ ...prev, ...next }))
     })()
     return () => {
       cancelled = true
     }
-  }, [mediaId, mediaValue, resolved])
+  }, [mediaIds, cache])
+
+  useEffect(() => {
+    if (index >= rowCount && rowCount > 0) setIndex(rowCount - 1)
+    if (rowCount === 0 && index !== 0) setIndex(0)
+  }, [rowCount, index])
+
+  const resolved: MediaDoc[] = mediaIds.map((id) => (id != null ? cache[String(id)] : undefined)).filter(Boolean) as MediaDoc[]
+  const current = resolved[index]
+  const alt = current?.alt ?? displayName ?? 'Produit'
 
   const onPick = () => fileInput.current?.click()
 
+  const appendRow = useCallback(
+    (mediaId: number | string) => {
+      dispatchFields({
+        type: 'ADD_ROW',
+        path: 'images',
+        rowIndex: rowCount,
+        subFieldState: {
+          image: { initialValue: mediaId, valid: true, value: mediaId },
+        },
+      })
+    },
+    [dispatchFields, rowCount],
+  )
+
+  const removeRow = useCallback(
+    (rowIndex: number) => {
+      dispatchFields({
+        type: 'REMOVE_ROW',
+        path: 'images',
+        rowIndex,
+      })
+    },
+    [dispatchFields],
+  )
+
   const onFile = async (e: React.ChangeEvent<HTMLInputElement>) => {
     const file = e.target.files?.[0]
     e.target.value = ''
@@ -69,19 +114,9 @@ export function ImageUploadSlot({ displayName }: Props) {
       const res = await fetch('/api/media', { method: 'POST', body: fd, credentials: 'include' })
       if (!res.ok) throw new Error(`upload ${res.status}`)
       const { doc } = await res.json()
-      if (mediaId == null) {
-        dispatchFields({
-          type: 'ADD_ROW',
-          path: 'images',
-          rowIndex: 0,
-          subFieldState: {
-            image: { initialValue: doc.id, valid: true, value: doc.id },
-          },
-        })
-      } else {
-        setMedia(doc.id)
-      }
-      setResolved({ id: doc.id, url: doc.url, alt: doc.alt })
+      appendRow(doc.id)
+      setCache((prev) => ({ ...prev, [String(doc.id)]: { id: doc.id, url: doc.url, alt: doc.alt } }))
+      setIndex(rowCount)
     } catch (err) {
       setError(err instanceof Error ? err.message : 'upload failed')
     } finally {
@@ -89,22 +124,93 @@ export function ImageUploadSlot({ displayName }: Props) {
     }
   }
 
-  const url = resolved?.url ?? ''
-  const alt = resolved?.alt ?? displayName ?? 'Produit'
+  const prev = (e: React.MouseEvent) => {
+    e.stopPropagation()
+    if (resolved.length < 2) return
+    setIndex((i) => (i - 1 + resolved.length) % resolved.length)
+  }
+  const next = (e: React.MouseEvent) => {
+    e.stopPropagation()
+    if (resolved.length < 2) return
+    setIndex((i) => (i + 1) % resolved.length)
+  }
+  const goTo = (e: React.MouseEvent, i: number) => {
+    e.stopPropagation()
+    setIndex(i)
+  }
+  const removeCurrent = (e: React.MouseEvent) => {
+    e.stopPropagation()
+    if (rowCount === 0) return
+    removeRow(index)
+  }
 
   return (
-    <div className="rebours-admin-panel__img-slot" onClick={onPick} role="button" tabIndex={0}>
-      {url ? (
-        <img src={url} alt={alt} />
+    <div className="rebours-admin-panel__img-slot-wrap">
+      <div
+        className="rebours-admin-panel__img-slot"
+        onClick={onPick}
+        role="button"
+        tabIndex={0}
+      >
+        {current?.url ? (
+          <img src={current.url} alt={alt} />
         ) : (
           <div className="rebours-admin-panel__img-placeholder">
             Cliquez pour<br />uploader une image
           </div>
         )}
+
+        {resolved.length > 1 && (
+          <>
+            <button
+              type="button"
+              className="rebours-admin-panel__img-arrow rebours-admin-panel__img-arrow--prev"
+              onClick={prev}
+              aria-label="Image précédente"
+            >
+              ←
+            </button>
+            <button
+              type="button"
+              className="rebours-admin-panel__img-arrow rebours-admin-panel__img-arrow--next"
+              onClick={next}
+              aria-label="Image suivante"
+            >
+              →
+            </button>
+          </>
+        )}
+
         <div className="rebours-admin-panel__img-overlay">
-        {error ? `Erreur: ${error}` : 'Cliquez pour changer l\u2019image'}
+          {error ? `Erreur: ${error}` : 'Cliquez pour uploader une nouvelle image'}
         </div>
+
         {uploading && <div className="rebours-admin-panel__img-uploading">Upload…</div>}
+      </div>
+
+      <div className="rebours-admin-panel__img-dots">
+        {resolved.map((_, i) => (
+          <button
+            key={i}
+            type="button"
+            className={`rebours-admin-panel__img-dot${i === index ? ' is-active' : ''}`}
+            onClick={(e) => goTo(e, i)}
+            aria-label={`Image ${i + 1}`}
+          />
+        ))}
+        {resolved.length > 0 && (
+          <button
+            type="button"
+            className="rebours-admin-panel__img-remove"
+            onClick={removeCurrent}
+            aria-label="Supprimer cette image"
+            title="Supprimer cette image"
+          >
+            ✕
+          </button>
+        )}
+      </div>
+
       <input
         ref={fileInput}
         type="file"

nextjs/src/components/admin/panel.css

@@ -112,6 +112,118 @@
   letter-spacing: 0.1em;
 }
 
+.rebours-admin-panel__img-slot-wrap {
+  position: relative;
+  width: 100%;
+  height: 100%;
+  display: flex;
+  flex-direction: column;
+}
+
+.rebours-admin-panel__img-slot-wrap .rebours-admin-panel__img-slot {
+  flex: 1;
+  min-height: 0;
+}
+
+.rebours-admin-panel__img-arrow {
+  position: absolute;
+  top: 50%;
+  transform: translateY(-50%);
+  width: 2.4rem;
+  height: 2.4rem;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  background: rgba(0, 0, 0, 0.55);
+  color: #fff;
+  border: 1px solid rgba(255, 255, 255, 0.25);
+  font-family: var(--font-mono);
+  font-size: 1rem;
+  cursor: pointer;
+  opacity: 0;
+  transition: opacity 0.15s, background 0.15s;
+  z-index: 2;
+}
+
+.rebours-admin-panel__img-slot:hover .rebours-admin-panel__img-arrow {
+  opacity: 1;
+}
+
+.rebours-admin-panel__img-arrow:hover {
+  background: rgba(232, 168, 0, 0.85);
+  color: #111;
+}
+
+.rebours-admin-panel__img-arrow--prev {
+  left: 0.75rem;
+}
+
+.rebours-admin-panel__img-arrow--next {
+  right: 0.75rem;
+}
+
+.rebours-admin-panel__img-dots {
+  position: absolute;
+  bottom: 0.75rem;
+  left: 0;
+  right: 0;
+  display: flex;
+  justify-content: center;
+  align-items: center;
+  gap: 0.45rem;
+  z-index: 3;
+  pointer-events: none;
+}
+
+.rebours-admin-panel__img-dots > * {
+  pointer-events: auto;
+}
+
+.rebours-admin-panel__img-dot {
+  width: 14px;
+  height: 14px;
+  background: #111;
+  border: 1px solid #e8a800;
+  padding: 0;
+  cursor: pointer;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  transition: background 0.15s;
+}
+
+.rebours-admin-panel__img-dot::before {
+  content: '';
+  width: 6px;
+  height: 6px;
+  background: transparent;
+  transition: background 0.15s;
+}
+
+.rebours-admin-panel__img-dot.is-active::before {
+  background: #e8a800;
+}
+
+.rebours-admin-panel__img-remove {
+  margin-left: 0.75rem;
+  width: 1.6rem;
+  height: 1.6rem;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  background: rgba(0, 0, 0, 0.55);
+  color: #fff;
+  border: 1px solid rgba(255, 255, 255, 0.25);
+  font-family: var(--font-mono);
+  font-size: 0.75rem;
+  cursor: pointer;
+  transition: background 0.15s;
+}
+
+.rebours-admin-panel__img-remove:hover {
+  background: #c0392b;
+}
+
 /* Right: info */
 .rebours-admin-panel__info-col {
   padding: 2.5rem var(--pad);