fix: prevent category Cancel overflow and add Tab/Enter to create options

- TreeMetadataForm: add min-w-0 + shrink-0 to keep Cancel button in-panel
- NodeFormDecision: Tab or Enter on the last non-empty option input adds a
  new option and auto-focuses it; empty last input lets Tab pass through normally

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/components/tree-editor/NodeFormDecision.tsx

@@ -1,3 +1,4 @@
+import { useRef, useEffect } from 'react'
 import { Play } from 'lucide-react'
 import { DynamicArrayField } from './DynamicArrayField'
 import { useTreeEditorStore } from '@/store/treeEditorStore'
@@ -18,6 +19,9 @@ const indexToLetter = (index: number): string => {
 export function NodeFormDecision({ node, onUpdate }: NodeFormDecisionProps) {
   const { validationErrors } = useTreeEditorStore()
   const isRootNode = node.id === 'root'
+  // Track input elements by index so we can focus the newly added one
+  const inputRefs = useRef<Map<number, HTMLInputElement>>(new Map())
+  const shouldFocusLast = useRef(false)
 
   const questionError = validationErrors.find(
     e => e.nodeId === node.id && e.field === 'question'
@@ -27,6 +31,15 @@ export function NodeFormDecision({ node, onUpdate }: NodeFormDecisionProps) {
     e => e.nodeId === node.id && e.field === 'options'
   )
 
+  // After options array grows (due to keyboard-triggered add), focus the last input
+  useEffect(() => {
+    if (shouldFocusLast.current) {
+      shouldFocusLast.current = false
+      const lastIndex = (node.options?.length ?? 1) - 1
+      inputRefs.current.get(lastIndex)?.focus()
+    }
+  }, [node.options?.length])
+
   const handleAddOption = () => {
     const newOption: TreeOption = {
       id: crypto.randomUUID(),
@@ -38,6 +51,12 @@ export function NodeFormDecision({ node, onUpdate }: NodeFormDecisionProps) {
     })
   }
 
+  // Add a new option and focus it (used by keyboard shortcut)
+  const handleAddOptionAndFocus = () => {
+    shouldFocusLast.current = true
+    handleAddOption()
+  }
+
   const handleRemoveOption = (index: number) => {
     const newOptions = [...(node.options || [])]
     newOptions.splice(index, 1)
@@ -147,6 +166,7 @@ export function NodeFormDecision({ node, onUpdate }: NodeFormDecisionProps) {
                 e => e.nodeId === node.id && e.field === `options[${index}].label`
               )
               const letter = indexToLetter(index)
+              const isLastOption = index === (node.options?.length ?? 1) - 1
 
               return (
                 <div className="flex items-center gap-2">
@@ -158,12 +178,22 @@ export function NodeFormDecision({ node, onUpdate }: NodeFormDecisionProps) {
                   </span>
                   <div className="flex-1">
                     <input
+                      ref={(el) => {
+                        if (el) inputRefs.current.set(index, el)
+                        else inputRefs.current.delete(index)
+                      }}
                       type="text"
                       value={option.label}
                       onChange={(e) => handleUpdateOption(index, { label: e.target.value })}
                       placeholder={isRootNode
                         ? `Branch ${letter}: e.g., "Network Issues"...`
                         : `Option ${letter} label`}
+                      onKeyDown={(e) => {
+                        if ((e.key === 'Tab' || e.key === 'Enter') && isLastOption && option.label.trim()) {
+                          e.preventDefault()
+                          handleAddOptionAndFocus()
+                        }
+                      }}
                       className={cn(
                         'block w-full rounded-md border px-3 py-2 text-sm',
                         'bg-background text-foreground placeholder:text-muted-foreground',

frontend/src/components/tree-editor/TreeMetadataForm.tsx

@@ -132,19 +132,20 @@ export function TreeMetadataForm() {
               onChange={(e) => setCategory(e.target.value)}
               placeholder="Enter new category"
               className={cn(
-                'block flex-1 rounded-md border border-border px-3 py-2 text-sm',
+                'block min-w-0 flex-1 rounded-md border border-border px-3 py-2 text-sm',
                 'bg-card text-foreground placeholder:text-muted-foreground',
                 'focus:border-primary focus:outline-none focus:ring-1 focus:ring-primary/20'
               )}
               autoFocus
             />
             <button
+              type="button"
               onClick={() => {
                 setCustomCategory(false)
                 setCategory('')
                 setCategoryId(null)
               }}
-              className="rounded-md border border-border px-3 py-2 text-sm text-muted-foreground hover:bg-accent hover:text-foreground"
+              className="shrink-0 rounded-md border border-border px-2.5 py-2 text-xs text-muted-foreground hover:bg-accent hover:text-foreground"
             >
               Cancel
             </button>