chore: import upstream snapshot with attribution

showcase/integrations/langgraph-python/qa/gen-ui-agent.md

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+# QA: Agentic Generative UI — LangGraph (Python)
+
+## Prerequisites
+
+- Demo is deployed and accessible
+- Agent backend is healthy (check /api/health)
+
+## Test Steps
+
+### 1. Basic Functionality
+
+- [ ] Navigate to the gen-ui-agent demo page
+- [ ] Verify the chat interface loads in a centered full-height layout
+- [ ] Verify the chat input placeholder "Type a message" is visible
+- [ ] Send a basic message
+- [ ] Verify the agent responds
+
+### 2. Feature-Specific Checks
+
+#### Suggestions
+
+- [ ] Verify "Simple plan" suggestion button is visible (plan to go to Mars in 5 steps)
+- [ ] Verify "Complex plan" suggestion button is visible (plan to make pizza in 10 steps)
+
+#### Task Progress Tracker (useAgent with state streaming)
+
+- [ ] Click "Simple plan" suggestion or type "Build a plan to go to Mars in 5 steps"
+- [ ] Verify the TaskProgress component renders (`data-testid="task-progress"`)
+- [ ] Verify the progress bar appears with a gradient fill
+- [ ] Verify step items appear with descriptions (`data-testid="task-step-text"`)
+- [ ] Verify the "N/N Complete" counter updates as steps complete
+- [ ] Verify completed steps show:
+  - Green background gradient
+  - Check icon
+  - Green text color
+- [ ] Verify the current pending step shows:
+  - Blue/purple background gradient
+  - Spinner icon with "Processing..." text
+  - Pulsing animation
+- [ ] Verify future pending steps show:
+  - Gray background
+  - Clock icon
+  - Muted text color
+
+#### Complex Plan
+
+- [ ] Type "Plan to make pizza in 10 steps"
+- [ ] Verify 10 steps appear in the progress tracker
+- [ ] Verify progress bar width increases as steps complete
+
+### 3. Error Handling
+
+- [ ] Send an empty message (should be handled gracefully)
+- [ ] Verify no console errors during normal usage
+
+## Expected Results
+
+- Chat loads within 3 seconds
+- Agent responds within 10 seconds
+- Task progress tracker shows live step completion
+- Progress bar animates smoothly
+- No UI errors or broken layouts