Build Chat Interface.user.prompt

# Build Streamlit Chat Interface

**Agent:** Streamlit UI Development Agent  
**Category:** UI Development  
**Complexity:** Intermediate  
**Duration:** 1-2 hours

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## Purpose

Build a production-quality Streamlit chat interface with session state management, message history display, and integration points for Claude API calls.

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## Instructions for Agent

Create a complete Streamlit chat interface with the following features:

### Requirements

1. **Chat Display**
   - Display message history using `st.chat_message`
   - Show user and assistant messages with proper formatting
   - Support markdown rendering in messages
   - Display timestamps

2. **User Input**
   - Use `st.chat_input` for message entry
   - Handle empty input gracefully
   - Show placeholder text
   - Clear input after submission

3. **Session State Management**
   - Initialize `messages` list in session state
   - Persist conversation across reruns
   - Support conversation clearing
   - Track conversation metadata

4. **Integration Points**
   - Provide clear integration point for Claude Integration Agent
   - Pass messages to backend processing
   - Display streaming responses
   - Handle loading states

5. **UI Polish**
   - Add chat header with title
   - Include "Clear Chat" button
   - Show token usage (if available)
   - Responsive layout

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## Expected Output