refactor: extract nested handlers to fix function depth violations (S2004)

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

src/design-system/composites/BarChart/BarChart.tsx

@@ -83,6 +83,20 @@ export function BarChart({
     setTooltip({ x: mx, y: my, label: catLabel, values })
   }
 
+  function showBarTooltip(e: React.MouseEvent<SVGRectElement>, cat: string) {
+    const rect = e.currentTarget.closest('svg')!.getBoundingClientRect()
+    handleMouseEnter(
+      cat,
+      e.clientX - rect.left,
+      e.clientY - rect.top,
+      series.map((ss, ssi) => ({
+        series: ss.label,
+        value: ss.data.find((d) => d.x === cat)?.y ?? 0,
+        color: ss.color ?? CHART_COLORS[ssi % CHART_COLORS.length],
+      })),
+    )
+  }
+
   return (
     <div className={`${styles.wrapper} ${className ?? ''}`}>
       {yLabel && <div className={styles.yLabel}>{yLabel}</div>}
@@ -138,19 +152,7 @@ export function BarChart({
                       height={barH}
                       fill={color}
                       className={styles.bar}
-                      onMouseEnter={(e) => {
+                      onMouseEnter={(e) => showBarTooltip(e, cat)}
-                        const rect = e.currentTarget.closest('svg')!.getBoundingClientRect()
-                        handleMouseEnter(
-                          cat,
-                          e.clientX - rect.left,
-                          e.clientY - rect.top,
-                          series.map((ss, ssi) => ({
-                            series: ss.label,
-                            value: ss.data.find((d) => d.x === cat)?.y ?? 0,
-                            color: ss.color ?? CHART_COLORS[ssi % CHART_COLORS.length],
-                          })),
-                        )
-                      }}
                     />
                   )
                 })}
@@ -184,19 +186,7 @@ export function BarChart({
                     height={barH}
                     fill={color}
                     className={styles.bar}
-                    onMouseEnter={(e) => {
+                    onMouseEnter={(e) => showBarTooltip(e, cat)}
-                      const svgEl = e.currentTarget.closest('svg')!.getBoundingClientRect()
-                      handleMouseEnter(
-                        cat,
-                        e.clientX - svgEl.left,
-                        e.clientY - svgEl.top,
-                        series.map((ss, ssi) => ({
-                          series: ss.label,
-                          value: ss.data.find((d) => d.x === cat)?.y ?? 0,
-                          color: ss.color ?? CHART_COLORS[ssi % CHART_COLORS.length],
-                        })),
-                      )
-                    }}
                   />
                 )
               })}

src/design-system/composites/CommandPalette/CommandPalette.tsx

@@ -186,6 +186,11 @@ export function CommandPalette({ open, onClose, onSelect, data, onOpen, onQueryC
     setScopeFilters((prev) => prev.filter((_, i) => i !== idx))
   }
 
+  function toggleExpanded(e: React.MouseEvent, id: string) {
+    e.stopPropagation()
+    setExpandedId((prev) => (prev === id ? null : id))
+  }
+
   if (!open) return null
 
   return createPortal(
@@ -328,10 +333,7 @@ export function CommandPalette({ open, onClose, onSelect, data, onOpen, onQueryC
                         {result.expandedContent && (
                           <button
                             className={styles.expandBtn}
-                            onClick={(e) => {
+                            onClick={(e) => toggleExpanded(e, result.id)}
-                              e.stopPropagation()
-                              setExpandedId((prev) => (prev === result.id ? null : result.id))
-                            }}
                             aria-expanded={isExpanded}
                             aria-label="Toggle detail"
                           >

src/design-system/composites/Toast/Toast.tsx

@@ -57,6 +57,10 @@ export function ToastProvider({ children }: { children: ReactNode }) {
   const [toasts, setToasts] = useState<ToastItem[]>([])
   const timersRef = useRef<Map<string, ReturnType<typeof setTimeout>>>(new Map())
 
+  const removeToast = useCallback((id: string) => {
+    setToasts((prev) => prev.filter((t) => t.id !== id))
+  }, [])
+
   const dismiss = useCallback((id: string) => {
     // Clear auto-dismiss timer if running
     const timer = timersRef.current.get(id)
@@ -71,10 +75,8 @@ export function ToastProvider({ children }: { children: ReactNode }) {
     )
 
     // Remove after animation completes
-    setTimeout(() => {
+    setTimeout(() => removeToast(id), EXIT_ANIMATION_MS)
-      setToasts((prev) => prev.filter((t) => t.id !== id))
+  }, [removeToast])
-    }, EXIT_ANIMATION_MS)
-  }, [])
 
   const toast = useCallback(
     (options: ToastOptions): string => {

src/design-system/composites/TreeView/TreeView.tsx

@@ -31,6 +31,52 @@ function flattenVisibleNodes(
   return result
 }
 
+// ── Keyboard nav helpers ─────────────────────────────────────────────────────
+
+function handleArrowDown(visibleNodes: FlatNode[], currentIndex: number, focusNode: (id: string) => void) {
+  const next = visibleNodes[currentIndex + 1]
+  if (next) focusNode(next.node.id)
+}
+
+function handleArrowUp(visibleNodes: FlatNode[], currentIndex: number, focusNode: (id: string) => void) {
+  const prev = visibleNodes[currentIndex - 1]
+  if (prev) focusNode(prev.node.id)
+}
+
+function handleArrowRight(
+  current: FlatNode | undefined,
+  currentIndex: number,
+  expandedSet: Set<string>,
+  visibleNodes: FlatNode[],
+  handleToggle: (id: string) => void,
+  focusNode: (id: string) => void,
+) {
+  if (!current) return
+  const hasChildren = current.node.children && current.node.children.length > 0
+  if (!hasChildren) return
+  if (!expandedSet.has(current.node.id)) {
+    handleToggle(current.node.id)
+  } else {
+    const next = visibleNodes[currentIndex + 1]
+    if (next) focusNode(next.node.id)
+  }
+}
+
+function handleArrowLeft(
+  current: FlatNode | undefined,
+  expandedSet: Set<string>,
+  handleToggle: (id: string) => void,
+  focusNode: (id: string) => void,
+) {
+  if (!current) return
+  const hasChildren = current.node.children && current.node.children.length > 0
+  if (hasChildren && expandedSet.has(current.node.id)) {
+    handleToggle(current.node.id)
+  } else if (current.parentId !== null) {
+    focusNode(current.parentId)
+  }
+}
+
 interface TreeViewProps {
   nodes: TreeNode[]
   onSelect?: (id: string) => void
@@ -105,68 +151,13 @@ export function TreeView({
       const current = visibleNodes[currentIndex]
 
       switch (e.key) {
-        case 'ArrowDown': {
+        case 'ArrowDown': { e.preventDefault(); handleArrowDown(visibleNodes, currentIndex, focusNode); break }
-          e.preventDefault()
+        case 'ArrowUp': { e.preventDefault(); handleArrowUp(visibleNodes, currentIndex, focusNode); break }
-          const next = visibleNodes[currentIndex + 1]
+        case 'ArrowRight': { e.preventDefault(); handleArrowRight(current, currentIndex, expandedSet, visibleNodes, handleToggle, focusNode); break }
-          if (next) focusNode(next.node.id)
+        case 'ArrowLeft': { e.preventDefault(); handleArrowLeft(current, expandedSet, handleToggle, focusNode); break }
-          break
+        case 'Enter': { e.preventDefault(); if (current) onSelect?.(current.node.id); break }
-        }
+        case 'Home': { e.preventDefault(); if (visibleNodes.length > 0) focusNode(visibleNodes[0].node.id); break }
-        case 'ArrowUp': {
+        case 'End': { e.preventDefault(); if (visibleNodes.length > 0) focusNode(visibleNodes[visibleNodes.length - 1].node.id); break }
-          e.preventDefault()
-          const prev = visibleNodes[currentIndex - 1]
-          if (prev) focusNode(prev.node.id)
-          break
-        }
-        case 'ArrowRight': {
-          e.preventDefault()
-          if (!current) break
-          const hasChildren = current.node.children && current.node.children.length > 0
-          if (hasChildren) {
-            if (!expandedSet.has(current.node.id)) {
-              // Expand it
-              handleToggle(current.node.id)
-            } else {
-              // Move to first child (it will be the next visible node)
-              const next = visibleNodes[currentIndex + 1]
-              if (next) focusNode(next.node.id)
-            }
-          }
-          break
-        }
-        case 'ArrowLeft': {
-          e.preventDefault()
-          if (!current) break
-          const hasChildren = current.node.children && current.node.children.length > 0
-          if (hasChildren && expandedSet.has(current.node.id)) {
-            // Collapse
-            handleToggle(current.node.id)
-          } else if (current.parentId !== null) {
-            // Move to parent
-            focusNode(current.parentId)
-          }
-          break
-        }
-        case 'Enter': {
-          e.preventDefault()
-          if (current) {
-            onSelect?.(current.node.id)
-          }
-          break
-        }
-        case 'Home': {
-          e.preventDefault()
-          if (visibleNodes.length > 0) {
-            focusNode(visibleNodes[0].node.id)
-          }
-          break
-        }
-        case 'End': {
-          e.preventDefault()
-          if (visibleNodes.length > 0) {
-            focusNode(visibleNodes[visibleNodes.length - 1].node.id)
-          }
-          break
-        }
       }
     },
     // eslint-disable-next-line react-hooks/exhaustive-deps

src/design-system/layout/Sidebar/SidebarTree.tsx

@@ -124,6 +124,52 @@ function filterNodes(
   return { filtered: walk(nodes), matchedParentIds }
 }
 
+// ── Keyboard nav helpers ─────────────────────────────────────────────────────
+
+function handleArrowDown(visibleNodes: FlatNode[], currentIndex: number, focusNode: (id: string) => void) {
+  const next = visibleNodes[currentIndex + 1]
+  if (next) focusNode(next.node.id)
+}
+
+function handleArrowUp(visibleNodes: FlatNode[], currentIndex: number, focusNode: (id: string) => void) {
+  const prev = visibleNodes[currentIndex - 1]
+  if (prev) focusNode(prev.node.id)
+}
+
+function handleArrowRight(
+  current: FlatNode | undefined,
+  currentIndex: number,
+  expandedSet: Set<string>,
+  visibleNodes: FlatNode[],
+  handleToggle: (id: string) => void,
+  focusNode: (id: string) => void,
+) {
+  if (!current) return
+  const hasChildren = current.node.children && current.node.children.length > 0
+  if (!hasChildren) return
+  if (!expandedSet.has(current.node.id)) {
+    handleToggle(current.node.id)
+  } else {
+    const next = visibleNodes[currentIndex + 1]
+    if (next) focusNode(next.node.id)
+  }
+}
+
+function handleArrowLeft(
+  current: FlatNode | undefined,
+  expandedSet: Set<string>,
+  handleToggle: (id: string) => void,
+  focusNode: (id: string) => void,
+) {
+  if (!current) return
+  const hasChildren = current.node.children && current.node.children.length > 0
+  if (hasChildren && expandedSet.has(current.node.id)) {
+    handleToggle(current.node.id)
+  } else if (current.parentId !== null) {
+    focusNode(current.parentId)
+  }
+}
+
 // ── SidebarTree ──────────────────────────────────────────────────────────────
 
 export function SidebarTree({
@@ -222,64 +268,13 @@ export function SidebarTree({
       const current = visibleNodes[currentIndex]
 
       switch (e.key) {
-        case 'ArrowDown': {
+        case 'ArrowDown': { e.preventDefault(); handleArrowDown(visibleNodes, currentIndex, focusNode); break }
-          e.preventDefault()
+        case 'ArrowUp': { e.preventDefault(); handleArrowUp(visibleNodes, currentIndex, focusNode); break }
-          const next = visibleNodes[currentIndex + 1]
+        case 'ArrowRight': { e.preventDefault(); handleArrowRight(current, currentIndex, expandedSet, visibleNodes, handleToggle, focusNode); break }
-          if (next) focusNode(next.node.id)
+        case 'ArrowLeft': { e.preventDefault(); handleArrowLeft(current, expandedSet, handleToggle, focusNode); break }
-          break
+        case 'Enter': { e.preventDefault(); if (current?.node.path) navigate(current.node.path); break }
-        }
+        case 'Home': { e.preventDefault(); if (visibleNodes.length > 0) focusNode(visibleNodes[0].node.id); break }
-        case 'ArrowUp': {
+        case 'End': { e.preventDefault(); if (visibleNodes.length > 0) focusNode(visibleNodes[visibleNodes.length - 1].node.id); break }
-          e.preventDefault()
-          const prev = visibleNodes[currentIndex - 1]
-          if (prev) focusNode(prev.node.id)
-          break
-        }
-        case 'ArrowRight': {
-          e.preventDefault()
-          if (!current) break
-          const hasChildren = current.node.children && current.node.children.length > 0
-          if (hasChildren) {
-            if (!expandedSet.has(current.node.id)) {
-              handleToggle(current.node.id)
-            } else {
-              const next = visibleNodes[currentIndex + 1]
-              if (next) focusNode(next.node.id)
-            }
-          }
-          break
-        }
-        case 'ArrowLeft': {
-          e.preventDefault()
-          if (!current) break
-          const hasChildren = current.node.children && current.node.children.length > 0
-          if (hasChildren && expandedSet.has(current.node.id)) {
-            handleToggle(current.node.id)
-          } else if (current.parentId !== null) {
-            focusNode(current.parentId)
-          }
-          break
-        }
-        case 'Enter': {
-          e.preventDefault()
-          if (current?.node.path) {
-            navigate(current.node.path)
-          }
-          break
-        }
-        case 'Home': {
-          e.preventDefault()
-          if (visibleNodes.length > 0) {
-            focusNode(visibleNodes[0].node.id)
-          }
-          break
-        }
-        case 'End': {
-          e.preventDefault()
-          if (visibleNodes.length > 0) {
-            focusNode(visibleNodes[visibleNodes.length - 1].node.id)
-          }
-          break
-        }
       }
     },
     // eslint-disable-next-line react-hooks/exhaustive-deps