fix: exemplar draw keeps other classes' full-set preview (REQ-182 amended)

- AutoAnnotateModal: render merges last full-set detections for
  non-exemplared classes with conditioned results for exemplared ones
  (selected-not-exemplared filter); drawing an example no longer clears
  the other classes' detections
- Run Preview now always refreshes full-set first (exemplars: []) then
  re-runs exemplared classes
- docs: REQ-182 amended (merge semantics), design/ui-spec/tasks synced

frontend/src/components/AutoAnnotateModal.jsx

@@ -20,7 +20,6 @@ export default function AutoAnnotateModal({
   const [minBoxFrac, setMinBoxFrac] = useState(0.0)
   const [classParams, setClassParams] = useState({})
 
-  
   // Class selection state
   const [selectedClasses, setSelectedClasses] = useState(() => {
     if (engine === 'base_model') {
@@ -85,20 +84,25 @@ export default function AutoAnnotateModal({
   })
 
   const activePool = activeClassName ? pools[activeClassName] || [] : []
-  // While any selected class has examples, only those classes contribute.
   const exemplaredClasses = selectedClasses.filter(name => pools[name]?.length)
+  // merged: exemplared classes show conditioned results (replacing their full-set
+  // boxes); everyone else keeps the last full-set run (amended REQ-182)
+  const nameById = Object.fromEntries(project.classes.map(c => [c.class_id, c.name]))
+  const exemplaredSet = new Set(exemplaredClasses)
+  const selectedSet = new Set(selectedClasses)
   const renderShapes = exemplaredClasses.length > 0
-    ? exemplaredClasses.flatMap(name => shapesByClass[name] || [])
+    ? [
+        ...previewShapes.filter(s => {
+          const n = nameById[s.class_id]
+          return selectedSet.has(n) && !exemplaredSet.has(n)
+        }),
+        ...exemplaredClasses.flatMap(name => shapesByClass[name] || []),
+      ]
     : previewShapes
 
   const handlePreview = () => {
-    if (exemplaredClasses.length > 0) {
-      run(exemplaredClasses)
-      return
-    }
     const frame = currentFrame
     if (!frame) return
-
     let isMounted = true
     setIsLoadingPreview(true)
     setPreviewError('')
@@ -111,8 +115,8 @@ export default function AutoAnnotateModal({
       target_class_names: selectedClasses,
       class_params: buildClassParams(classParams),
       custom_model_path: customModelStagedPath,
-      exemplars: engine === 'sam3' ? activePool : [],
-      exemplar_class_name: engine === 'sam3' ? activeClassName : null
+      exemplars: [],
+      exemplar_class_name: null
     }).then(res => {
       if (isMounted && res.shapes) {
         setPreviewShapes(res.shapes)
@@ -123,7 +127,9 @@ export default function AutoAnnotateModal({
       setPreviewError(err.message || 'Preview failed')
       setPreviewShapes([])
     }).finally(() => {
-      setIsLoadingPreview(false)
+      if (!isMounted) return
+      if (exemplaredClasses.length > 0) run(exemplaredClasses)  // manages busy itself
+      else setIsLoadingPreview(false)
     })
   }
 
@@ -212,11 +218,9 @@ export default function AutoAnnotateModal({
         border: '1px solid rgba(168, 85, 247, 0.4)', background: '#18181b',
         overflowY: 'auto', borderRadius: 8
       }}>
-        
         {/* Left Side: Preview */}
         <div style={{ flex: '1 1 450px', display: 'flex', flexDirection: 'column', minWidth: 280 }}>
           <h3 style={{ margin: '0 0 8px 0', color: '#e4e4e7', fontSize: '1rem' }}>Preview</h3>
-          
           <div style={{ position: 'relative', width: '100%', background: '#000', borderRadius: 6, overflow: 'hidden', display: 'flex', justifyContent: 'center', alignItems: 'center' }}>
             {currentFrame ? (
               /* This wrapper must hug the image and nothing else: both overlays
@@ -294,7 +298,6 @@ export default function AutoAnnotateModal({
               </>
             )}
           </div>
-          
           <div style={{ marginTop: 10 }}>
             <div className="row" style={{ justifyContent: 'space-between', marginBottom: 4 }}>
               <span className="hint" style={{ fontSize: '0.8rem' }}>Preview Frame ({frameIndex + 1} / {frames.length}):</span>
@@ -380,7 +383,6 @@ export default function AutoAnnotateModal({
             promptError={promptError}
             savedPrompt={activeClass ? classPrompts[activeClass.class_id] : ''}
           />
-
           <div className="row" style={{ justifyContent: 'flex-end', gap: 10, marginTop: 16, paddingTop: 10, borderTop: '1px solid rgba(255,255,255,0.08)' }}>
             <button className="btn btn-ghost" onClick={onClose} disabled={isSubmitting}>Cancel</button>
             <button
@@ -392,9 +394,7 @@ export default function AutoAnnotateModal({
             </button>
           </div>
         </div>
-
       </div>
     </div>
   )
 }
-