chore: mark US-020 as complete and update progress log

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

prd.json

@@ -354,7 +354,7 @@
         "Verify in browser using dev-browser skill"
       ],
       "priority": 20,
-      "passes": false,
+      "passes": true,
       "notes": ""
     },
     {

progress.txt

@@ -20,6 +20,8 @@
 - React Flow editor is in `src/app/editor/[projectId]/` with page.tsx (server) and FlowchartEditor.tsx (client)
 - React Flow requires 'use client' and importing 'reactflow/dist/style.css'
 - Use toReactFlowNodes/toReactFlowEdges helpers to convert app types to React Flow types
+- Custom node components go in `src/components/editor/nodes/` with NodeProps<T> typing and useReactFlow() for updates
+- Register custom node types in nodeTypes object (memoized with useMemo) and pass to ReactFlow component
 
 ---
 
@@ -305,3 +307,18 @@
   - FlowchartEditor now uses flex-col layout to stack toolbar above canvas
   - Placeholder handlers with TODO comments help track future implementation work
 ---
+
+## 2026-01-21 - US-020
+- What was implemented: Custom DialogueNode component for displaying/editing character dialogue
+- Files changed:
+  - src/components/editor/nodes/DialogueNode.tsx - new custom node component with editable speaker and text fields
+  - src/app/editor/[projectId]/FlowchartEditor.tsx - registered DialogueNode as custom node type
+- **Learnings for future iterations:**
+  - Custom React Flow nodes use NodeProps<T> for typing, where T is the data shape
+  - Use useReactFlow() hook to get setNodes for updating node data from within the node component
+  - Handle components need Position enum (Position.Top, Position.Bottom) for positioning
+  - Custom handles can be styled with className and TailwindCSS, use ! prefix to override defaults (e.g., !h-3, !w-3)
+  - Node types must be registered in a nodeTypes object and passed to ReactFlow component
+  - Memoize nodeTypes with useMemo to prevent unnecessary re-renders
+  - Custom node components go in src/components/editor/nodes/ directory
+---