feat: Add task dependencies and spawn sub-task functionality

- Add edge dragging to create dependencies in graph view
- Add spawn sub-task action available in graph view and kanban board
- Implement ancestor context selection when spawning tasks
- Add dependency validation (circular, self, duplicate prevention)
- Include ancestor context in spawned task descriptions

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

apps/ui/src/components/views/board-view/shared/ancestor-context-section.tsx

@@ -0,0 +1,201 @@
+import { useState } from 'react';
+import { Checkbox } from '@/components/ui/checkbox';
+import { Label } from '@/components/ui/label';
+import { Button } from '@/components/ui/button';
+import { ChevronDown, ChevronRight, Users } from 'lucide-react';
+import { cn } from '@/lib/utils';
+import { AncestorContext } from '@/components/views/graph-view/utils';
+import { Collapsible, CollapsibleContent, CollapsibleTrigger } from '@/components/ui/collapsible';
+
+interface ParentFeatureContext {
+  id: string;
+  title?: string;
+  description: string;
+  spec?: string;
+  summary?: string;
+}
+
+interface AncestorContextSectionProps {
+  parentFeature: ParentFeatureContext;
+  ancestors: AncestorContext[];
+  selectedAncestorIds: Set<string>;
+  onSelectionChange: (ids: Set<string>) => void;
+}
+
+export function AncestorContextSection({
+  parentFeature,
+  ancestors,
+  selectedAncestorIds,
+  onSelectionChange,
+}: AncestorContextSectionProps) {
+  const [expandedIds, setExpandedIds] = useState<Set<string>>(new Set());
+
+  const toggleExpanded = (id: string) => {
+    const newExpanded = new Set(expandedIds);
+    if (newExpanded.has(id)) {
+      newExpanded.delete(id);
+    } else {
+      newExpanded.add(id);
+    }
+    setExpandedIds(newExpanded);
+  };
+
+  const toggleSelected = (id: string) => {
+    const newSelected = new Set(selectedAncestorIds);
+    if (newSelected.has(id)) {
+      newSelected.delete(id);
+    } else {
+      newSelected.add(id);
+    }
+    onSelectionChange(newSelected);
+  };
+
+  const selectAll = () => {
+    const allIds = new Set([parentFeature.id, ...ancestors.map((a) => a.id)]);
+    onSelectionChange(allIds);
+  };
+
+  const selectNone = () => {
+    onSelectionChange(new Set());
+  };
+
+  // Combine parent and ancestors into a single list
+  const allAncestorItems: Array<
+    (AncestorContext | ParentFeatureContext) & { isParent: boolean; depth: number }
+  > = [
+    { ...parentFeature, depth: -1, isParent: true },
+    ...ancestors.map((a) => ({ ...a, isParent: false })),
+  ];
+
+  const totalCount = allAncestorItems.length;
+
+  return (
+    <div className="space-y-3">
+      <div className="flex items-center justify-between">
+        <div className="flex items-center gap-2">
+          <Users className="w-4 h-4 text-muted-foreground" />
+          <Label className="text-sm font-medium">Ancestor Context</Label>
+          <span className="text-xs text-muted-foreground">
+            ({selectedAncestorIds.size}/{totalCount} selected)
+          </span>
+        </div>
+        <div className="flex items-center gap-1">
+          <Button
+            type="button"
+            variant="ghost"
+            size="sm"
+            onClick={selectAll}
+            className="h-6 px-2 text-xs"
+          >
+            All
+          </Button>
+          <Button
+            type="button"
+            variant="ghost"
+            size="sm"
+            onClick={selectNone}
+            className="h-6 px-2 text-xs"
+          >
+            None
+          </Button>
+        </div>
+      </div>
+
+      <p className="text-xs text-muted-foreground">
+        Select ancestors to include their context in the new task&apos;s prompt.
+      </p>
+
+      <div className="space-y-1 max-h-[200px] overflow-y-auto border rounded-lg p-2 bg-muted/20">
+        {allAncestorItems.map((item) => {
+          const isSelected = selectedAncestorIds.has(item.id);
+          const isExpanded = expandedIds.has(item.id);
+          const hasContent =
+            item.description ||
+            ('spec' in item && item.spec) ||
+            ('summary' in item && item.summary);
+          const displayTitle =
+            item.title ||
+            item.description.slice(0, 50) + (item.description.length > 50 ? '...' : '');
+
+          return (
+            <Collapsible key={item.id} open={isExpanded}>
+              <div
+                className={cn(
+                  'flex items-start gap-2 p-2 rounded-md transition-colors',
+                  isSelected ? 'bg-primary/10' : 'hover:bg-muted/50'
+                )}
+                style={{ marginLeft: item.isParent ? 0 : `${item.depth * 12}px` }}
+              >
+                <Checkbox
+                  id={`ancestor-${item.id}`}
+                  checked={isSelected}
+                  onCheckedChange={() => toggleSelected(item.id)}
+                  className="mt-0.5"
+                />
+                <div className="flex-1 min-w-0">
+                  <div className="flex items-center gap-1">
+                    {hasContent && (
+                      <CollapsibleTrigger asChild>
+                        <Button
+                          type="button"
+                          variant="ghost"
+                          size="sm"
+                          className="h-5 w-5 p-0"
+                          onClick={() => toggleExpanded(item.id)}
+                        >
+                          {isExpanded ? (
+                            <ChevronDown className="w-3 h-3" />
+                          ) : (
+                            <ChevronRight className="w-3 h-3" />
+                          )}
+                        </Button>
+                      </CollapsibleTrigger>
+                    )}
+                    <label
+                      htmlFor={`ancestor-${item.id}`}
+                      className="text-sm font-medium cursor-pointer truncate flex-1"
+                    >
+                      {displayTitle}
+                      {item.isParent && (
+                        <span className="ml-2 text-xs text-primary font-normal">(Parent)</span>
+                      )}
+                    </label>
+                  </div>
+
+                  <CollapsibleContent>
+                    <div className="mt-2 space-y-2 text-xs text-muted-foreground pl-5">
+                      {item.description && (
+                        <div>
+                          <span className="font-medium text-foreground">Description:</span>
+                          <p className="mt-0.5 line-clamp-3">{item.description}</p>
+                        </div>
+                      )}
+                      {'spec' in item && item.spec && (
+                        <div>
+                          <span className="font-medium text-foreground">Specification:</span>
+                          <p className="mt-0.5 line-clamp-3">{item.spec}</p>
+                        </div>
+                      )}
+                      {'summary' in item && item.summary && (
+                        <div>
+                          <span className="font-medium text-foreground">Summary:</span>
+                          <p className="mt-0.5 line-clamp-3">{item.summary}</p>
+                        </div>
+                      )}
+                    </div>
+                  </CollapsibleContent>
+                </div>
+              </div>
+            </Collapsible>
+          );
+        })}
+
+        {ancestors.length === 0 && (
+          <p className="text-xs text-muted-foreground text-center py-2">
+            Parent task has no additional ancestors
+          </p>
+        )}
+      </div>
+    </div>
+  );
+}

apps/ui/src/components/views/board-view/shared/index.ts

@@ -6,3 +6,4 @@ export * from './testing-tab-content';
 export * from './priority-selector';
 export * from './branch-selector';
 export * from './planning-mode-selector';
+export * from './ancestor-context-section';