chore: import upstream snapshot with attribution

showcase/integrations/langgraph-python/qa/gen-ui-tool-based.md

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+# QA: Tool-Based Generative UI — LangGraph (Python)
+
+The demo registers two `useComponent` renderers (`render_bar_chart`,
+`render_pie_chart`) on a centered `<CopilotChat>`. The agent emits
+chart-shaped tool calls and the frontend materializes them as Recharts
+SVG inside the assistant message bubble.
+
+## Prerequisites
+
+- Demo is deployed and accessible at `/demos/gen-ui-tool-based`
+- Agent backend is healthy (`/api/health`)
+
+## Test Steps
+
+### 1. Initial render
+
+- [ ] Navigate to `/demos/gen-ui-tool-based`
+- [ ] Verify the chat composer mounts (`textarea` with placeholder
+      matching `/message/i`)
+- [ ] Verify all three suggestion pills are visible
+      (`data-testid="copilot-suggestion"`):
+  - "Sales bar chart"
+  - "Traffic pie chart"
+  - "Market share"
+
+### 2. Bar chart flow
+
+- [ ] Click the "Sales bar chart" suggestion (or type "Show me a bar
+      chart of monthly expenses")
+- [ ] Verify the assistant message bubble
+      (`[data-testid="copilot-assistant-message"]`) renders, and its inner
+      Recharts SVG is visible
+
+### 3. Pie chart flow
+
+- [ ] Click the "Traffic pie chart" or "Market share" suggestion
+- [ ] Verify the assistant message bubble renders an SVG (the donut
+      pie) inside
+
+### 4. Free-form chat
+
+- [ ] Type "Hello" and press Enter
+- [ ] Verify the assistant streams back a text response in a fresh
+      `[data-testid="copilot-assistant-message"]` bubble
+
+### 5. Hygiene
+
+- [ ] No console errors during normal usage
+- [ ] No layout breakage with a very long input
+
+## Expected Results
+
+- Chat composer mounts within ~3 seconds
+- Suggestion pills render alongside an empty chat
+- Tool-driven chart bubbles materialize within ~30 seconds for short
+  prompts; the SVG renders progressively as Recharts mounts