Add think block support for AI assistant messages

[lyzno1]

Summary

• Added collapsible think block support for AI assistant messages
• Supports both <think> and <details> tags for compatibility
• Integrated seamlessly with existing StreamdownMarkdown component

Implementation Details

Components Created

• ThinkBlockHeader: Displays thinking status with animated loading indicator, supports expand/collapse functionality
• ThinkBlockContent: Renders think block content using Streamdown with smooth transitions

Core Features

• Automatic detection of <think> and <details> tags at the beginning of messages
• Real-time streaming support with "thinking" status animation
• Auto-expands when thinking starts for better user experience
• Smooth animations for expand/collapse transitions
• Full internationalization support (en, zh, ja, fr, es, vi)

Technical Approach

The implementation extends the existing StreamdownMarkdown component to:

1. Extract think block content from the message
2. Render think blocks separately with appropriate styling
3. Maintain streaming capabilities for both think and main content
4. Handle incomplete/unclosed tags during streaming

Test Plan

• Tested with <think> tags
• Tested with <details> tags
• Verified streaming behavior
• Tested expand/collapse functionality
• Verified all language translations display correctly

🤖 Generated with Claude Code

[lyzno1]

@Eric-Guo cc : )

[Copilot]

Pull Request Overview

Adds collapsible think block support for AI assistant messages to enhance user experience by providing visibility into AI reasoning processes. The implementation supports both <think> and <details> tags for compatibility and integrates seamlessly with the existing streaming markdown component.

• Added ThinkBlockHeader and ThinkBlockContent components for rendering collapsible think blocks
• Extended StreamdownMarkdown component to extract and handle think block content
• Added internationalization support for think block status text across 6 languages

Reviewed Changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
i18n/lang/common.*.ts	Added translations for thinking states (thinking, stopped, completed)
app/components/chat/think-block/think-block-header.tsx	Header component with status display and toggle functionality
app/components/chat/think-block/think-block-content.tsx	Content component for rendering think block markdown
app/components/chat/think-block/index.tsx	Barrel export for think block components
app/components/chat/answer/index.tsx	Updated to pass streaming status to StreamdownMarkdown
app/components/base/streamdown-markdown.tsx	Enhanced to detect and render think blocks with streaming support

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[Eric-Guo]

UI is good, I only suggest like 7d177ce, using upstream changed Streamdown component, so every chat can using only one Streamdown component to save some memory, also such Streamdown will running much effective.