Complete writing style transformation implementation

[frankbria]

Problem

Different writing styles are mentioned in the user manual (Professional, Conversational, Academic, Creative, Technical) but not fully implemented.

Current Behavior

• Writing styles may be listed in UI
• Unclear if style transformation actually works
• Style differences may not be significant
• May only work in draft generation, not style conversion

Expected Behavior

• Users can select any writing style
• AI transforms existing text to match selected style
• Style transformation preserves meaning and facts
• Clear differences between styles
• Users can compare styles before committing

Implementation Guidance

1. Create style transformation prompts for each style type
2. Test that each style produces distinctly different output
3. Add style selector to chapter editor
4. Implement "Transform to [Style]" action
5. Show preview before applying transformation
6. Allow reverting to previous version

Files Likely Involved

• backend/app/services/ai_service.py - Add style transformation
• backend/app/prompts/style_templates.py - Create style prompts (if doesn't exist)
• frontend/src/components/chapters/StyleSelector.tsx - Style UI
• backend/app/api/routes/style.py - Create endpoint

Acceptance Criteria

• All 5 writing styles implemented
• Each style produces clearly different output
• Users can transform existing text to any style
• Preview shows before/after comparison
• Users can revert to previous style
• Style transformation preserves facts and meaning
• Integration tests verify distinct style outputs
• E2E test covers style transformation flow

Blocked by

• Issue Implement robust error handling and fallback for AI service failures #41 (Implement robust error handling for AI service failures)
• Issue Implement AI draft generation from chapter questions and answers #55 (Implement AI draft generation)

[traycerai]

Plan

Observations

The codebase has a partial implementation of writing styles in the draft generation feature, but lacks the complete style transformation system described in the user manual. Currently:

• DraftGenerator.tsx defines 6 styles (conversational, formal, narrative, educational, inspirational, technical) but the user manual mentions 5 different styles (Professional, Conversational, Academic, Creative, Technical)
• The ai_service.py accepts a writing_style parameter but doesn't have style-specific prompts or transformation logic
• There's no dedicated style transformation endpoint - only draft generation from Q&A
• No preview/comparison UI, version history for content, or revert functionality exists
• The E2E test file 06-draft-writing-styles.spec.ts validates style differences but the backend doesn't enforce distinct outputs

Approach

The implementation will follow a layered approach: (1) standardize the 5 writing styles across frontend and backend, (2) create style-specific prompt templates in the AI service, (3) add a new style transformation endpoint separate from draft generation, (4) build a StyleSelector component with preview functionality, (5) implement content version history for revert capability, and (6) update tests to verify distinct style outputs. This approach ensures backward compatibility with existing draft generation while adding the new transformation feature.

Implementation Steps

1. Backend: Standardize Writing Styles and Create Style Prompts

File: file:backend/app/services/style_templates.py (create new)

Create a new module to define the 5 writing styles with their characteristics and transformation prompts:

• Define an enum WritingStyle with values: PROFESSIONAL, CONVERSATIONAL, ACADEMIC, CREATIVE, TECHNICAL
• Create a dictionary STYLE_CHARACTERISTICS mapping each style to:
  • Description of the style
  • Tone indicators (formal/informal, technical/accessible, etc.)
  • Vocabulary preferences
  • Sentence structure guidelines
  • Example phrases
• Create a function get_style_transformation_prompt(content: str, target_style: WritingStyle, source_style: Optional[WritingStyle]) -> str that builds a detailed prompt for transforming existing text
• Create a function get_style_generation_prompt(style: WritingStyle) -> str that returns style-specific instructions for draft generation
• Include validation to ensure the transformation preserves facts, meaning, and key information

File: file:backend/app/services/ai_service.py

Enhance the AI service with style transformation capabilities:

• Import the new style_templates module
• Add method async def transform_text_style(content: str, target_style: str, source_style: Optional[str] = None) -> Dict[str, Any] that:
  • Validates the content is not empty
  • Converts style strings to WritingStyle enum
  • Builds transformation prompt using get_style_transformation_prompt
  • Calls OpenAI API with temperature=0.7 for creativity while maintaining accuracy
  • Returns transformed content with metadata (original_length, transformed_length, style_applied, transformation_notes)
• Update _build_draft_generation_prompt method to use get_style_generation_prompt when a writing style is specified
• Add validation to ensure transformed content maintains similar length (±30%) and preserves key facts

2. Backend: Add Content Version History

File: file:backend/app/models/book.py

Add content version tracking to the chapter schema:

• Create a new model ContentVersion with fields:
  • version_id: str (UUID)
  • content: str
  • word_count: int
  • created_at: datetime
  • created_by: str (user_id)
  • change_type: str (manual_edit, style_transformation, ai_draft)
  • metadata: Dict (style_applied, transformation_source, etc.)
• Add content_history: List[ContentVersion] field to chapter structure (optional, defaults to empty list)
• Set a maximum history limit (e.g., last 10 versions) to prevent database bloat

File: file:backend/app/api/endpoints/books.py

Update content management endpoints:

• Modify update_chapter_content endpoint to:
  • Before updating, save current content to content_history array
  • Trim history to last 10 versions if it exceeds limit
  • Include change_type in the request body (default: "manual_edit")
• Add new endpoint GET /{book_id}/chapters/{chapter_id}/content/history to retrieve version history
• Add new endpoint POST /{book_id}/chapters/{chapter_id}/content/revert to revert to a specific version by version_id

3. Backend: Create Style Transformation Endpoint

File: file:backend/app/api/endpoints/books.py

Add a new endpoint for style transformation:

POST /{book_id}/chapters/{chapter_id}/transform-style

Request body:

• target_style: str (required: professional, conversational, academic, creative, technical)
• source_style: Optional[str] (auto-detect if not provided)
• preview_only: bool (default: false - if true, don't save to chapter)

Implementation:

• Verify book ownership and chapter existence
• Get current chapter content
• Validate content is not empty (minimum 50 characters)
• Call ai_service.transform_text_style() with the content and target style
• If preview_only=false, save transformed content with version history
• Return both original and transformed content for comparison
• Include metadata: word_count_change, estimated_reading_time_change, style_indicators_found

4. Frontend: Create StyleSelector Component

File: file:frontend/src/components/chapters/StyleSelector.tsx (create new)

Build a reusable style selector component:

• Create a dropdown/select component with the 5 writing styles
• Display style descriptions on hover/focus
• Include a "Transform" button that triggers the transformation
• Show loading state during transformation
• Props: currentStyle, onStyleSelect, disabled, className

File: file:frontend/src/components/chapters/StyleTransformPreview.tsx (create new)

Create a preview dialog component:

• Display side-by-side comparison of original and transformed text
• Show metadata: word count change, style indicators, reading time
• Include "Apply Transformation" and "Cancel" buttons
• Highlight key differences (optional: use a diff library like react-diff-viewer)
• Show warning if content length changed significantly (>30%)

5. Frontend: Integrate Style Transformation into Chapter Editor

File: file:frontend/src/components/chapters/EditorToolbar.tsx

Add style transformation UI to the editor toolbar:

• Import StyleSelector component
• Add a new toolbar section for "Writing Style"
• Place StyleSelector next to the existing "Generate AI Draft" button
• Detect current style from content (or default to "conversational")
• On style selection, open StyleTransformPreview dialog

File: file:frontend/src/components/chapters/ChapterEditor.tsx

Integrate style transformation functionality:

• Add state for currentStyle, isTransforming, transformPreview
• Create handler handleStyleTransform(targetStyle: string) that:
  • Calls bookClient.transformChapterStyle() with preview_only=true
  • Opens preview dialog with results
• Create handler handleApplyTransformation(transformedContent: string) that:
  • Calls bookClient.transformChapterStyle() with preview_only=false
  • Updates editor content
  • Shows success toast
• Add version history UI (dropdown or modal) to view and revert to previous versions

6. Frontend: Add API Client Methods

File: file:frontend/src/lib/api/bookClient.ts

Add new methods for style transformation:

• transformChapterStyle(bookId: string, chapterId: string, targetStyle: string, previewOnly: boolean) - calls the transform-style endpoint
• getChapterContentHistory(bookId: string, chapterId: string) - retrieves version history
• revertChapterContent(bookId: string, chapterId: string, versionId: string) - reverts to a specific version

7. Update DraftGenerator to Use Standardized Styles

File: file:frontend/src/components/chapters/DraftGenerator.tsx

Align with the 5 standardized styles:

• Update WRITING_STYLES constant to match: professional, conversational, academic, creative, technical
• Remove: formal, narrative, educational, inspirational
• Update style descriptions to match the backend definitions
• Ensure the writing_style parameter sent to the API matches the backend enum values

8. Testing: Update E2E Tests

File: file:frontend/tests/e2e/deployment/06-draft-writing-styles.spec.ts

Update the E2E test to validate style transformation:

• Update WRITING_STYLES array to the 5 standardized styles
• Add new test case: "Transform existing text to different styles"
  • Create a chapter with sample content
  • Transform to each of the 5 styles
  • Verify each transformation produces distinct output
  • Verify tone indicators are present
  • Verify facts are preserved
• Add test case: "Preview and revert style transformation"
  • Transform content with preview
  • Verify preview shows both versions
  • Apply transformation
  • Revert to previous version
  • Verify content matches original

9. Testing: Add Integration Tests

File: file:backend/tests/test_services/test_style_transformation.py (create new)

Create comprehensive backend tests:

• Test transform_text_style() for each of the 5 styles
• Verify distinct outputs for same input across different styles
• Test fact preservation (e.g., numbers, names, dates remain unchanged)
• Test error handling (empty content, invalid style, API failures)
• Test that transformations maintain similar length (±30%)

File: file:backend/tests/test_api/test_style_transformation_endpoint.py (create new)

Test the API endpoint:

• Test successful transformation with preview
• Test successful transformation with save
• Test version history creation
• Test revert functionality
• Test authorization (only book owner can transform)
• Test validation errors (empty content, invalid style)

10. Documentation Updates

File: file:AUTO_AUTHOR_USER_MANUAL.md

Update the user manual to reflect the actual implementation:

• Update the "AI Draft Generation" section (lines 146-163) to list the correct 5 styles: Professional, Conversational, Academic, Creative, Technical
• Add a new section "Transform Writing Style" explaining:
  • How to select existing text and transform it
  • How to preview before applying
  • How to revert to previous versions
  • Best practices for style transformation

Architecture Diagram

sequenceDiagram
    participant User
    participant ChapterEditor
    participant StyleSelector
    participant PreviewDialog
    participant BookClient
    participant API
    participant AIService
    participant Database

    User->>ChapterEditor: Selects text & clicks "Transform Style"
    ChapterEditor->>StyleSelector: Opens style selector
    User->>StyleSelector: Selects target style (e.g., "Academic")
    StyleSelector->>BookClient: transformChapterStyle(preview=true)
    BookClient->>API: POST /transform-style
    API->>Database: Get current chapter content
    Database-->>API: Return content
    API->>AIService: transform_text_style(content, "academic")
    AIService->>AIService: Build transformation prompt
    AIService->>OpenAI: Request transformation
    OpenAI-->>AIService: Return transformed text
    AIService-->>API: Return transformed content + metadata
    API-->>BookClient: Return preview data
    BookClient-->>PreviewDialog: Display comparison
    PreviewDialog->>User: Show original vs transformed
    User->>PreviewDialog: Clicks "Apply Transformation"
    PreviewDialog->>BookClient: transformChapterStyle(preview=false)
    BookClient->>API: POST /transform-style
    API->>Database: Save current to content_history
    API->>Database: Update chapter content
    Database-->>API: Confirm save
    API-->>BookClient: Success response
    BookClient-->>ChapterEditor: Update editor content
    ChapterEditor->>User: Show success message

Loading

Key Implementation Details

Component	Files Modified/Created	Key Changes
Style Templates	backend/app/services/style_templates.py (new)	Define 5 styles with prompts and characteristics
AI Service	backend/app/services/ai_service.py	Add transform_text_style() method
Content Versioning	backend/app/models/book.py	Add ContentVersion model and content_history field
API Endpoints	backend/app/api/endpoints/books.py	Add transform-style, history, revert endpoints
Style Selector	frontend/src/components/chapters/StyleSelector.tsx (new)	Dropdown with 5 styles
Preview Dialog	frontend/src/components/chapters/StyleTransformPreview.tsx (new)	Side-by-side comparison UI
Editor Integration	frontend/src/components/chapters/ChapterEditor.tsx	Add style transformation handlers
API Client	frontend/src/lib/api/bookClient.ts	Add transformation methods
Draft Generator	frontend/src/components/chapters/DraftGenerator.tsx	Update to 5 standardized styles
E2E Tests	frontend/tests/e2e/deployment/06-draft-writing-styles.spec.ts	Add transformation test cases

Acceptance Criteria Mapping

• ✅ All 5 writing styles implemented: Style templates define Professional, Conversational, Academic, Creative, Technical
• ✅ Each style produces clearly different output: AI prompts enforce distinct tone, vocabulary, and structure per style
• ✅ Users can transform existing text: New transform-style endpoint and UI in chapter editor
• ✅ Preview shows before/after comparison: StyleTransformPreview component displays side-by-side view
• ✅ Users can revert to previous style: Content version history with revert endpoint
• ✅ Style transformation preserves facts: AI prompts explicitly instruct to maintain factual accuracy
• ✅ Integration tests verify distinct outputs: New test file validates each style produces unique results
• ✅ E2E test covers transformation flow: Updated E2E test includes transformation and revert scenarios

Import In IDE

🤖 Prompt for AI Agents

## Observations

The codebase has a partial implementation of writing styles in the draft generation feature, but lacks the complete style transformation system described in the user manual. Currently:

- **DraftGenerator.tsx** defines 6 styles (conversational, formal, narrative, educational, inspirational, technical) but the user manual mentions 5 different styles (Professional, Conversational, Academic, Creative, Technical)
- The **ai_service.py** accepts a `writing_style` parameter but doesn't have style-specific prompts or transformation logic
- There's no dedicated style transformation endpoint - only draft generation from Q&A
- No preview/comparison UI, version history for content, or revert functionality exists
- The E2E test file `06-draft-writing-styles.spec.ts` validates style differences but the backend doesn't enforce distinct outputs

## Approach

The implementation will follow a layered approach: (1) standardize the 5 writing styles across frontend and backend, (2) create style-specific prompt templates in the AI service, (3) add a new style transformation endpoint separate from draft generation, (4) build a StyleSelector component with preview functionality, (5) implement content version history for revert capability, and (6) update tests to verify distinct style outputs. This approach ensures backward compatibility with existing draft generation while adding the new transformation feature.

## Implementation Steps

### 1. Backend: Standardize Writing Styles and Create Style Prompts

**File:** `file:backend/app/services/style_templates.py` (create new)

Create a new module to define the 5 writing styles with their characteristics and transformation prompts:

- Define an enum `WritingStyle` with values: PROFESSIONAL, CONVERSATIONAL, ACADEMIC, CREATIVE, TECHNICAL
- Create a dictionary `STYLE_CHARACTERISTICS` mapping each style to:
  - Description of the style
  - Tone indicators (formal/informal, technical/accessible, etc.)
  - Vocabulary preferences
  - Sentence structure guidelines
  - Example phrases
- Create a function `get_style_transformation_prompt(content: str, target_style: WritingStyle, source_style: Optional[WritingStyle]) -> str` that builds a detailed prompt for transforming existing text
- Create a function `get_style_generation_prompt(style: WritingStyle) -> str` that returns style-specific instructions for draft generation
- Include validation to ensure the transformation preserves facts, meaning, and key information

**File:** `file:backend/app/services/ai_service.py`

Enhance the AI service with style transformation capabilities:

- Import the new `style_templates` module
- Add method `async def transform_text_style(content: str, target_style: str, source_style: Optional[str] = None) -> Dict[str, Any]` that:
  - Validates the content is not empty
  - Converts style strings to `WritingStyle` enum
  - Builds transformation prompt using `get_style_transformation_prompt`
  - Calls OpenAI API with temperature=0.7 for creativity while maintaining accuracy
  - Returns transformed content with metadata (original_length, transformed_length, style_applied, transformation_notes)
- Update `_build_draft_generation_prompt` method to use `get_style_generation_prompt` when a writing style is specified
- Add validation to ensure transformed content maintains similar length (±30%) and preserves key facts

### 2. Backend: Add Content Version History

**File:** `file:backend/app/models/book.py`

Add content version tracking to the chapter schema:

- Create a new model `ContentVersion` with fields:
  - `version_id: str` (UUID)
  - `content: str`
  - `word_count: int`
  - `created_at: datetime`
  - `created_by: str` (user_id)
  - `change_type: str` (manual_edit, style_transformation, ai_draft)
  - `metadata: Dict` (style_applied, transformation_source, etc.)
- Add `content_history: List[ContentVersion]` field to chapter structure (optional, defaults to empty list)
- Set a maximum history limit (e.g., last 10 versions) to prevent database bloat

**File:** `file:backend/app/api/endpoints/books.py`

Update content management endpoints:

- Modify `update_chapter_content` endpoint to:
  - Before updating, save current content to `content_history` array
  - Trim history to last 10 versions if it exceeds limit
  - Include `change_type` in the request body (default: "manual_edit")
- Add new endpoint `GET /{book_id}/chapters/{chapter_id}/content/history` to retrieve version history
- Add new endpoint `POST /{book_id}/chapters/{chapter_id}/content/revert` to revert to a specific version by `version_id`

### 3. Backend: Create Style Transformation Endpoint

**File:** `file:backend/app/api/endpoints/books.py`

Add a new endpoint for style transformation:

```
POST /{book_id}/chapters/{chapter_id}/transform-style
```

Request body:
- `target_style: str` (required: professional, conversational, academic, creative, technical)
- `source_style: Optional[str]` (auto-detect if not provided)
- `preview_only: bool` (default: false - if true, don't save to chapter)

Implementation:
- Verify book ownership and chapter existence
- Get current chapter content
- Validate content is not empty (minimum 50 characters)
- Call `ai_service.transform_text_style()` with the content and target style
- If `preview_only=false`, save transformed content with version history
- Return both original and transformed content for comparison
- Include metadata: word_count_change, estimated_reading_time_change, style_indicators_found

### 4. Frontend: Create StyleSelector Component

**File:** `file:frontend/src/components/chapters/StyleSelector.tsx` (create new)

Build a reusable style selector component:

- Create a dropdown/select component with the 5 writing styles
- Display style descriptions on hover/focus
- Include a "Transform" button that triggers the transformation
- Show loading state during transformation
- Props: `currentStyle`, `onStyleSelect`, `disabled`, `className`

**File:** `file:frontend/src/components/chapters/StyleTransformPreview.tsx` (create new)

Create a preview dialog component:

- Display side-by-side comparison of original and transformed text
- Show metadata: word count change, style indicators, reading time
- Include "Apply Transformation" and "Cancel" buttons
- Highlight key differences (optional: use a diff library like `react-diff-viewer`)
- Show warning if content length changed significantly (>30%)

### 5. Frontend: Integrate Style Transformation into Chapter Editor

**File:** `file:frontend/src/components/chapters/EditorToolbar.tsx`

Add style transformation UI to the editor toolbar:

- Import `StyleSelector` component
- Add a new toolbar section for "Writing Style"
- Place `StyleSelector` next to the existing "Generate AI Draft" button
- Detect current style from content (or default to "conversational")
- On style selection, open `StyleTransformPreview` dialog

**File:** `file:frontend/src/components/chapters/ChapterEditor.tsx`

Integrate style transformation functionality:

- Add state for `currentStyle`, `isTransforming`, `transformPreview`
- Create handler `handleStyleTransform(targetStyle: string)` that:
  - Calls `bookClient.transformChapterStyle()` with `preview_only=true`
  - Opens preview dialog with results
- Create handler `handleApplyTransformation(transformedContent: string)` that:
  - Calls `bookClient.transformChapterStyle()` with `preview_only=false`
  - Updates editor content
  - Shows success toast
- Add version history UI (dropdown or modal) to view and revert to previous versions

### 6. Frontend: Add API Client Methods

**File:** `file:frontend/src/lib/api/bookClient.ts`

Add new methods for style transformation:

- `transformChapterStyle(bookId: string, chapterId: string, targetStyle: string, previewOnly: boolean)` - calls the transform-style endpoint
- `getChapterContentHistory(bookId: string, chapterId: string)` - retrieves version history
- `revertChapterContent(bookId: string, chapterId: string, versionId: string)` - reverts to a specific version

### 7. Update DraftGenerator to Use Standardized Styles

**File:** `file:frontend/src/components/chapters/DraftGenerator.tsx`

Align with the 5 standardized styles:

- Update `WRITING_STYLES` constant to match: professional, conversational, academic, creative, technical
- Remove: formal, narrative, educational, inspirational
- Update style descriptions to match the backend definitions
- Ensure the `writing_style` parameter sent to the API matches the backend enum values

### 8. Testing: Update E2E Tests

**File:** `file:frontend/tests/e2e/deployment/06-draft-writing-styles.spec.ts`

Update the E2E test to validate style transformation:

- Update `WRITING_STYLES` array to the 5 standardized styles
- Add new test case: "Transform existing text to different styles"
  - Create a chapter with sample content
  - Transform to each of the 5 styles
  - Verify each transformation produces distinct output
  - Verify tone indicators are present
  - Verify facts are preserved
- Add test case: "Preview and revert style transformation"
  - Transform content with preview
  - Verify preview shows both versions
  - Apply transformation
  - Revert to previous version
  - Verify content matches original

### 9. Testing: Add Integration Tests

**File:** `file:backend/tests/test_services/test_style_transformation.py` (create new)

Create comprehensive backend tests:

- Test `transform_text_style()` for each of the 5 styles
- Verify distinct outputs for same input across different styles
- Test fact preservation (e.g., numbers, names, dates remain unchanged)
- Test error handling (empty content, invalid style, API failures)
- Test that transformations maintain similar length (±30%)

**File:** `file:backend/tests/test_api/test_style_transformation_endpoint.py` (create new)

Test the API endpoint:

- Test successful transformation with preview
- Test successful transformation with save
- Test version history creation
- Test revert functionality
- Test authorization (only book owner can transform)
- Test validation errors (empty content, invalid style)

### 10. Documentation Updates

**File:** `file:AUTO_AUTHOR_USER_MANUAL.md`

Update the user manual to reflect the actual implementation:

- Update the "AI Draft Generation" section (lines 146-163) to list the correct 5 styles: Professional, Conversational, Academic, Creative, Technical
- Add a new section "Transform Writing Style" explaining:
  - How to select existing text and transform it
  - How to preview before applying
  - How to revert to previous versions
  - Best practices for style transformation

## Architecture Diagram

```mermaid
sequenceDiagram
    participant User
    participant ChapterEditor
    participant StyleSelector
    participant PreviewDialog
    participant BookClient
    participant API
    participant AIService
    participant Database

    User->>ChapterEditor: Selects text & clicks "Transform Style"
    ChapterEditor->>StyleSelector: Opens style selector
    User->>StyleSelector: Selects target style (e.g., "Academic")
    StyleSelector->>BookClient: transformChapterStyle(preview=true)
    BookClient->>API: POST /transform-style
    API->>Database: Get current chapter content
    Database-->>API: Return content
    API->>AIService: transform_text_style(content, "academic")
    AIService->>AIService: Build transformation prompt
    AIService->>OpenAI: Request transformation
    OpenAI-->>AIService: Return transformed text
    AIService-->>API: Return transformed content + metadata
    API-->>BookClient: Return preview data
    BookClient-->>PreviewDialog: Display comparison
    PreviewDialog->>User: Show original vs transformed
    User->>PreviewDialog: Clicks "Apply Transformation"
    PreviewDialog->>BookClient: transformChapterStyle(preview=false)
    BookClient->>API: POST /transform-style
    API->>Database: Save current to content_history
    API->>Database: Update chapter content
    Database-->>API: Confirm save
    API-->>BookClient: Success response
    BookClient-->>ChapterEditor: Update editor content
    ChapterEditor->>User: Show success message
```

## Key Implementation Details

| Component | Files Modified/Created | Key Changes |
|-----------|----------------------|-------------|
| Style Templates | `backend/app/services/style_templates.py` (new) | Define 5 styles with prompts and characteristics |
| AI Service | `backend/app/services/ai_service.py` | Add `transform_text_style()` method |
| Content Versioning | `backend/app/models/book.py` | Add `ContentVersion` model and `content_history` field |
| API Endpoints | `backend/app/api/endpoints/books.py` | Add transform-style, history, revert endpoints |
| Style Selector | `frontend/src/components/chapters/StyleSelector.tsx` (new) | Dropdown with 5 styles |
| Preview Dialog | `frontend/src/components/chapters/StyleTransformPreview.tsx` (new) | Side-by-side comparison UI |
| Editor Integration | `frontend/src/components/chapters/ChapterEditor.tsx` | Add style transformation handlers |
| API Client | `frontend/src/lib/api/bookClient.ts` | Add transformation methods |
| Draft Generator | `frontend/src/components/chapters/DraftGenerator.tsx` | Update to 5 standardized styles |
| E2E Tests | `frontend/tests/e2e/deployment/06-draft-writing-styles.spec.ts` | Add transformation test cases |

## Acceptance Criteria Mapping

- ✅ **All 5 writing styles implemented**: Style templates define Professional, Conversational, Academic, Creative, Technical
- ✅ **Each style produces clearly different output**: AI prompts enforce distinct tone, vocabulary, and structure per style
- ✅ **Users can transform existing text**: New transform-style endpoint and UI in chapter editor
- ✅ **Preview shows before/after comparison**: `StyleTransformPreview` component displays side-by-side view
- ✅ **Users can revert to previous style**: Content version history with revert endpoint
- ✅ **Style transformation preserves facts**: AI prompts explicitly instruct to maintain factual accuracy
- ✅ **Integration tests verify distinct outputs**: New test file validates each style produces unique results
- ✅ **E2E test covers transformation flow**: Updated E2E test includes transformation and revert scenarios

---

Execution Information

Branch: main
Commit: 6841238

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🔗 Similar Issues

Related Issues

• Implement AI draft generation from chapter questions and answers #55
• Implement content enhancement features for existing chapter text #57

👤 Suggested Assignees

• frankbria

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[traycerai]

I have updated the Implementation Plan to reflect the recent changes in the ticket.

New Plan

Observations

The codebase has a partial implementation of writing styles in the draft generation feature, but lacks the complete style transformation system described in the user manual. Currently:

• DraftGenerator.tsx defines 6 styles (conversational, formal, narrative, educational, inspirational, technical) but the user manual mentions 5 different styles (Professional, Conversational, Academic, Creative, Technical)
• The ai_service.py accepts a writing_style parameter but doesn't have style-specific prompts or transformation logic
• There's no dedicated style transformation endpoint - only draft generation from Q&A
• No preview/comparison UI, version history for content, or revert functionality exists
• The E2E test file 06-draft-writing-styles.spec.ts validates style differences but the backend doesn't enforce distinct outputs

Approach

The implementation will follow a layered approach: (1) standardize the 5 writing styles across frontend and backend, (2) create style-specific prompt templates in the AI service, (3) add a new style transformation endpoint separate from draft generation, (4) build a StyleSelector component with preview functionality, (5) implement content version history for revert capability, and (6) update tests to verify distinct style outputs. This approach ensures backward compatibility with existing draft generation while adding the new transformation feature.

Implementation Steps

1. Backend: Standardize Writing Styles and Create Style Prompts

File: file:backend/app/services/style_templates.py (create new)

Create a new module to define the 5 writing styles with their characteristics and transformation prompts:

• Define an enum WritingStyle with values: PROFESSIONAL, CONVERSATIONAL, ACADEMIC, CREATIVE, TECHNICAL
• Create a dictionary STYLE_CHARACTERISTICS mapping each style to:
  • Description of the style
  • Tone indicators (formal/informal, technical/accessible, etc.)
  • Vocabulary preferences
  • Sentence structure guidelines
  • Example phrases
• Create a function get_style_transformation_prompt(content: str, target_style: WritingStyle, source_style: Optional[WritingStyle]) -> str that builds a detailed prompt for transforming existing text
• Create a function get_style_generation_prompt(style: WritingStyle) -> str that returns style-specific instructions for draft generation
• Include validation to ensure the transformation preserves facts, meaning, and key information

File: file:backend/app/services/ai_service.py

Enhance the AI service with style transformation capabilities:

• Import the new style_templates module
• Add method async def transform_text_style(content: str, target_style: str, source_style: Optional[str] = None) -> Dict[str, Any] that:
  • Validates the content is not empty
  • Converts style strings to WritingStyle enum
  • Builds transformation prompt using get_style_transformation_prompt
  • Calls OpenAI API with temperature=0.7 for creativity while maintaining accuracy
  • Returns transformed content with metadata (original_length, transformed_length, style_applied, transformation_notes)
• Update _build_draft_generation_prompt method to use get_style_generation_prompt when a writing style is specified
• Add validation to ensure transformed content maintains similar length (±30%) and preserves key facts

2. Backend: Add Content Version History

File: file:backend/app/models/book.py

Add content version tracking to the chapter schema:

• Create a new model ContentVersion with fields:
  • version_id: str (UUID)
  • content: str
  • word_count: int
  • created_at: datetime
  • created_by: str (user_id)
  • change_type: str (manual_edit, style_transformation, ai_draft)
  • metadata: Dict (style_applied, transformation_source, etc.)
• Add content_history: List[ContentVersion] field to chapter structure (optional, defaults to empty list)
• Set a maximum history limit (e.g., last 10 versions) to prevent database bloat

File: file:backend/app/api/endpoints/books.py

Update content management endpoints:

• Modify update_chapter_content endpoint to:
  • Before updating, save current content to content_history array
  • Trim history to last 10 versions if it exceeds limit
  • Include change_type in the request body (default: "manual_edit")
• Add new endpoint GET /{book_id}/chapters/{chapter_id}/content/history to retrieve version history
• Add new endpoint POST /{book_id}/chapters/{chapter_id}/content/revert to revert to a specific version by version_id

3. Backend: Create Style Transformation Endpoint

File: file:backend/app/api/endpoints/books.py

Add a new endpoint for style transformation:

POST /{book_id}/chapters/{chapter_id}/transform-style

Request body:

• target_style: str (required: professional, conversational, academic, creative, technical)
• source_style: Optional[str] (auto-detect if not provided)
• preview_only: bool (default: false - if true, don't save to chapter)

Implementation:

• Verify book ownership and chapter existence
• Get current chapter content
• Validate content is not empty (minimum 50 characters)
• Call ai_service.transform_text_style() with the content and target style
• If preview_only=false, save transformed content with version history
• Return both original and transformed content for comparison
• Include metadata: word_count_change, estimated_reading_time_change, style_indicators_found

4. Frontend: Create StyleSelector Component

File: file:frontend/src/components/chapters/StyleSelector.tsx (create new)

Build a reusable style selector component:

• Create a dropdown/select component with the 5 writing styles
• Display style descriptions on hover/focus
• Include a "Transform" button that triggers the transformation
• Show loading state during transformation
• Props: currentStyle, onStyleSelect, disabled, className

File: file:frontend/src/components/chapters/StyleTransformPreview.tsx (create new)

Create a preview dialog component:

• Display side-by-side comparison of original and transformed text
• Show metadata: word count change, style indicators, reading time
• Include "Apply Transformation" and "Cancel" buttons
• Highlight key differences (optional: use a diff library like react-diff-viewer)
• Show warning if content length changed significantly (>30%)

5. Frontend: Integrate Style Transformation into Chapter Editor

File: file:frontend/src/components/chapters/EditorToolbar.tsx

Add style transformation UI to the editor toolbar:

• Import StyleSelector component
• Add a new toolbar section for "Writing Style"
• Place StyleSelector next to the existing "Generate AI Draft" button
• Detect current style from content (or default to "conversational")
• On style selection, open StyleTransformPreview dialog

File: file:frontend/src/components/chapters/ChapterEditor.tsx

Integrate style transformation functionality:

• Add state for currentStyle, isTransforming, transformPreview
• Create handler handleStyleTransform(targetStyle: string) that:
  • Calls bookClient.transformChapterStyle() with preview_only=true
  • Opens preview dialog with results
• Create handler handleApplyTransformation(transformedContent: string) that:
  • Calls bookClient.transformChapterStyle() with preview_only=false
  • Updates editor content
  • Shows success toast
• Add version history UI (dropdown or modal) to view and revert to previous versions

6. Frontend: Add API Client Methods

File: file:frontend/src/lib/api/bookClient.ts

Add new methods for style transformation:

• transformChapterStyle(bookId: string, chapterId: string, targetStyle: string, previewOnly: boolean) - calls the transform-style endpoint
• getChapterContentHistory(bookId: string, chapterId: string) - retrieves version history
• revertChapterContent(bookId: string, chapterId: string, versionId: string) - reverts to a specific version

7. Update DraftGenerator to Use Standardized Styles

File: file:frontend/src/components/chapters/DraftGenerator.tsx

Align with the 5 standardized styles:

• Update WRITING_STYLES constant to match: professional, conversational, academic, creative, technical
• Remove: formal, narrative, educational, inspirational
• Update style descriptions to match the backend definitions
• Ensure the writing_style parameter sent to the API matches the backend enum values

8. Testing: Update E2E Tests

File: file:frontend/tests/e2e/deployment/06-draft-writing-styles.spec.ts

Update the E2E test to validate style transformation:

• Update WRITING_STYLES array to the 5 standardized styles
• Add new test case: "Transform existing text to different styles"
  • Create a chapter with sample content
  • Transform to each of the 5 styles
  • Verify each transformation produces distinct output
  • Verify tone indicators are present
  • Verify facts are preserved
• Add test case: "Preview and revert style transformation"
  • Transform content with preview
  • Verify preview shows both versions
  • Apply transformation
  • Revert to previous version
  • Verify content matches original

9. Testing: Add Integration Tests

File: file:backend/tests/test_services/test_style_transformation.py (create new)

Create comprehensive backend tests:

• Test transform_text_style() for each of the 5 styles
• Verify distinct outputs for same input across different styles
• Test fact preservation (e.g., numbers, names, dates remain unchanged)
• Test error handling (empty content, invalid style, API failures)
• Test that transformations maintain similar length (±30%)

File: file:backend/tests/test_api/test_style_transformation_endpoint.py (create new)

Test the API endpoint:

• Test successful transformation with preview
• Test successful transformation with save
• Test version history creation
• Test revert functionality
• Test authorization (only book owner can transform)
• Test validation errors (empty content, invalid style)

10. Documentation Updates

File: file:AUTO_AUTHOR_USER_MANUAL.md

Update the user manual to reflect the actual implementation:

• Update the "AI Draft Generation" section (lines 146-163) to list the correct 5 styles: Professional, Conversational, Academic, Creative, Technical
• Add a new section "Transform Writing Style" explaining:
  • How to select existing text and transform it
  • How to preview before applying
  • How to revert to previous versions
  • Best practices for style transformation

Architecture Diagram

sequenceDiagram
    participant User
    participant ChapterEditor
    participant StyleSelector
    participant PreviewDialog
    participant BookClient
    participant API
    participant AIService
    participant Database

    User->>ChapterEditor: Selects text & clicks "Transform Style"
    ChapterEditor->>StyleSelector: Opens style selector
    User->>StyleSelector: Selects target style (e.g., "Academic")
    StyleSelector->>BookClient: transformChapterStyle(preview=true)
    BookClient->>API: POST /transform-style
    API->>Database: Get current chapter content
    Database-->>API: Return content
    API->>AIService: transform_text_style(content, "academic")
    AIService->>AIService: Build transformation prompt
    AIService->>OpenAI: Request transformation
    OpenAI-->>AIService: Return transformed text
    AIService-->>API: Return transformed content + metadata
    API-->>BookClient: Return preview data
    BookClient-->>PreviewDialog: Display comparison
    PreviewDialog->>User: Show original vs transformed
    User->>PreviewDialog: Clicks "Apply Transformation"
    PreviewDialog->>BookClient: transformChapterStyle(preview=false)
    BookClient->>API: POST /transform-style
    API->>Database: Save current to content_history
    API->>Database: Update chapter content
    Database-->>API: Confirm save
    API-->>BookClient: Success response
    BookClient-->>ChapterEditor: Update editor content
    ChapterEditor->>User: Show success message

Loading

Key Implementation Details

Component	Files Modified/Created	Key Changes
Style Templates	backend/app/services/style_templates.py (new)	Define 5 styles with prompts and characteristics
AI Service	backend/app/services/ai_service.py	Add transform_text_style() method
Content Versioning	backend/app/models/book.py	Add ContentVersion model and content_history field
API Endpoints	backend/app/api/endpoints/books.py	Add transform-style, history, revert endpoints
Style Selector	frontend/src/components/chapters/StyleSelector.tsx (new)	Dropdown with 5 styles
Preview Dialog	frontend/src/components/chapters/StyleTransformPreview.tsx (new)	Side-by-side comparison UI
Editor Integration	frontend/src/components/chapters/ChapterEditor.tsx	Add style transformation handlers
API Client	frontend/src/lib/api/bookClient.ts	Add transformation methods
Draft Generator	frontend/src/components/chapters/DraftGenerator.tsx	Update to 5 standardized styles
E2E Tests	frontend/tests/e2e/deployment/06-draft-writing-styles.spec.ts	Add transformation test cases

Acceptance Criteria Mapping

• ✅ All 5 writing styles implemented: Style templates define Professional, Conversational, Academic, Creative, Technical
• ✅ Each style produces clearly different output: AI prompts enforce distinct tone, vocabulary, and structure per style
• ✅ Users can transform existing text: New transform-style endpoint and UI in chapter editor
• ✅ Preview shows before/after comparison: StyleTransformPreview component displays side-by-side view
• ✅ Users can revert to previous style: Content version history with revert endpoint
• ✅ Style transformation preserves facts: AI prompts explicitly instruct to maintain factual accuracy
• ✅ Integration tests verify distinct outputs: New test file validates each style produces unique results
• ✅ E2E test covers transformation flow: Updated E2E test includes transformation and revert scenarios

Import In IDE

🤖 Prompt for AI Agents

## Observations

The codebase has a partial implementation of writing styles in the draft generation feature, but lacks the complete style transformation system described in the user manual. Currently:

- **DraftGenerator.tsx** defines 6 styles (conversational, formal, narrative, educational, inspirational, technical) but the user manual mentions 5 different styles (Professional, Conversational, Academic, Creative, Technical)
- The **ai_service.py** accepts a `writing_style` parameter but doesn't have style-specific prompts or transformation logic
- There's no dedicated style transformation endpoint - only draft generation from Q&A
- No preview/comparison UI, version history for content, or revert functionality exists
- The E2E test file `06-draft-writing-styles.spec.ts` validates style differences but the backend doesn't enforce distinct outputs

## Approach

The implementation will follow a layered approach: (1) standardize the 5 writing styles across frontend and backend, (2) create style-specific prompt templates in the AI service, (3) add a new style transformation endpoint separate from draft generation, (4) build a StyleSelector component with preview functionality, (5) implement content version history for revert capability, and (6) update tests to verify distinct style outputs. This approach ensures backward compatibility with existing draft generation while adding the new transformation feature.

## Implementation Steps

### 1. Backend: Standardize Writing Styles and Create Style Prompts

**File:** `file:backend/app/services/style_templates.py` (create new)

Create a new module to define the 5 writing styles with their characteristics and transformation prompts:

- Define an enum `WritingStyle` with values: PROFESSIONAL, CONVERSATIONAL, ACADEMIC, CREATIVE, TECHNICAL
- Create a dictionary `STYLE_CHARACTERISTICS` mapping each style to:
  - Description of the style
  - Tone indicators (formal/informal, technical/accessible, etc.)
  - Vocabulary preferences
  - Sentence structure guidelines
  - Example phrases
- Create a function `get_style_transformation_prompt(content: str, target_style: WritingStyle, source_style: Optional[WritingStyle]) -> str` that builds a detailed prompt for transforming existing text
- Create a function `get_style_generation_prompt(style: WritingStyle) -> str` that returns style-specific instructions for draft generation
- Include validation to ensure the transformation preserves facts, meaning, and key information

**File:** `file:backend/app/services/ai_service.py`

Enhance the AI service with style transformation capabilities:

- Import the new `style_templates` module
- Add method `async def transform_text_style(content: str, target_style: str, source_style: Optional[str] = None) -> Dict[str, Any]` that:
  - Validates the content is not empty
  - Converts style strings to `WritingStyle` enum
  - Builds transformation prompt using `get_style_transformation_prompt`
  - Calls OpenAI API with temperature=0.7 for creativity while maintaining accuracy
  - Returns transformed content with metadata (original_length, transformed_length, style_applied, transformation_notes)
- Update `_build_draft_generation_prompt` method to use `get_style_generation_prompt` when a writing style is specified
- Add validation to ensure transformed content maintains similar length (±30%) and preserves key facts

### 2. Backend: Add Content Version History

**File:** `file:backend/app/models/book.py`

Add content version tracking to the chapter schema:

- Create a new model `ContentVersion` with fields:
  - `version_id: str` (UUID)
  - `content: str`
  - `word_count: int`
  - `created_at: datetime`
  - `created_by: str` (user_id)
  - `change_type: str` (manual_edit, style_transformation, ai_draft)
  - `metadata: Dict` (style_applied, transformation_source, etc.)
- Add `content_history: List[ContentVersion]` field to chapter structure (optional, defaults to empty list)
- Set a maximum history limit (e.g., last 10 versions) to prevent database bloat

**File:** `file:backend/app/api/endpoints/books.py`

Update content management endpoints:

- Modify `update_chapter_content` endpoint to:
  - Before updating, save current content to `content_history` array
  - Trim history to last 10 versions if it exceeds limit
  - Include `change_type` in the request body (default: "manual_edit")
- Add new endpoint `GET /{book_id}/chapters/{chapter_id}/content/history` to retrieve version history
- Add new endpoint `POST /{book_id}/chapters/{chapter_id}/content/revert` to revert to a specific version by `version_id`

### 3. Backend: Create Style Transformation Endpoint

**File:** `file:backend/app/api/endpoints/books.py`

Add a new endpoint for style transformation:

```
POST /{book_id}/chapters/{chapter_id}/transform-style
```

Request body:
- `target_style: str` (required: professional, conversational, academic, creative, technical)
- `source_style: Optional[str]` (auto-detect if not provided)
- `preview_only: bool` (default: false - if true, don't save to chapter)

Implementation:
- Verify book ownership and chapter existence
- Get current chapter content
- Validate content is not empty (minimum 50 characters)
- Call `ai_service.transform_text_style()` with the content and target style
- If `preview_only=false`, save transformed content with version history
- Return both original and transformed content for comparison
- Include metadata: word_count_change, estimated_reading_time_change, style_indicators_found

### 4. Frontend: Create StyleSelector Component

**File:** `file:frontend/src/components/chapters/StyleSelector.tsx` (create new)

Build a reusable style selector component:

- Create a dropdown/select component with the 5 writing styles
- Display style descriptions on hover/focus
- Include a "Transform" button that triggers the transformation
- Show loading state during transformation
- Props: `currentStyle`, `onStyleSelect`, `disabled`, `className`

**File:** `file:frontend/src/components/chapters/StyleTransformPreview.tsx` (create new)

Create a preview dialog component:

- Display side-by-side comparison of original and transformed text
- Show metadata: word count change, style indicators, reading time
- Include "Apply Transformation" and "Cancel" buttons
- Highlight key differences (optional: use a diff library like `react-diff-viewer`)
- Show warning if content length changed significantly (>30%)

### 5. Frontend: Integrate Style Transformation into Chapter Editor

**File:** `file:frontend/src/components/chapters/EditorToolbar.tsx`

Add style transformation UI to the editor toolbar:

- Import `StyleSelector` component
- Add a new toolbar section for "Writing Style"
- Place `StyleSelector` next to the existing "Generate AI Draft" button
- Detect current style from content (or default to "conversational")
- On style selection, open `StyleTransformPreview` dialog

**File:** `file:frontend/src/components/chapters/ChapterEditor.tsx`

Integrate style transformation functionality:

- Add state for `currentStyle`, `isTransforming`, `transformPreview`
- Create handler `handleStyleTransform(targetStyle: string)` that:
  - Calls `bookClient.transformChapterStyle()` with `preview_only=true`
  - Opens preview dialog with results
- Create handler `handleApplyTransformation(transformedContent: string)` that:
  - Calls `bookClient.transformChapterStyle()` with `preview_only=false`
  - Updates editor content
  - Shows success toast
- Add version history UI (dropdown or modal) to view and revert to previous versions

### 6. Frontend: Add API Client Methods

**File:** `file:frontend/src/lib/api/bookClient.ts`

Add new methods for style transformation:

- `transformChapterStyle(bookId: string, chapterId: string, targetStyle: string, previewOnly: boolean)` - calls the transform-style endpoint
- `getChapterContentHistory(bookId: string, chapterId: string)` - retrieves version history
- `revertChapterContent(bookId: string, chapterId: string, versionId: string)` - reverts to a specific version

### 7. Update DraftGenerator to Use Standardized Styles

**File:** `file:frontend/src/components/chapters/DraftGenerator.tsx`

Align with the 5 standardized styles:

- Update `WRITING_STYLES` constant to match: professional, conversational, academic, creative, technical
- Remove: formal, narrative, educational, inspirational
- Update style descriptions to match the backend definitions
- Ensure the `writing_style` parameter sent to the API matches the backend enum values

### 8. Testing: Update E2E Tests

**File:** `file:frontend/tests/e2e/deployment/06-draft-writing-styles.spec.ts`

Update the E2E test to validate style transformation:

- Update `WRITING_STYLES` array to the 5 standardized styles
- Add new test case: "Transform existing text to different styles"
  - Create a chapter with sample content
  - Transform to each of the 5 styles
  - Verify each transformation produces distinct output
  - Verify tone indicators are present
  - Verify facts are preserved
- Add test case: "Preview and revert style transformation"
  - Transform content with preview
  - Verify preview shows both versions
  - Apply transformation
  - Revert to previous version
  - Verify content matches original

### 9. Testing: Add Integration Tests

**File:** `file:backend/tests/test_services/test_style_transformation.py` (create new)

Create comprehensive backend tests:

- Test `transform_text_style()` for each of the 5 styles
- Verify distinct outputs for same input across different styles
- Test fact preservation (e.g., numbers, names, dates remain unchanged)
- Test error handling (empty content, invalid style, API failures)
- Test that transformations maintain similar length (±30%)

**File:** `file:backend/tests/test_api/test_style_transformation_endpoint.py` (create new)

Test the API endpoint:

- Test successful transformation with preview
- Test successful transformation with save
- Test version history creation
- Test revert functionality
- Test authorization (only book owner can transform)
- Test validation errors (empty content, invalid style)

### 10. Documentation Updates

**File:** `file:AUTO_AUTHOR_USER_MANUAL.md`

Update the user manual to reflect the actual implementation:

- Update the "AI Draft Generation" section (lines 146-163) to list the correct 5 styles: Professional, Conversational, Academic, Creative, Technical
- Add a new section "Transform Writing Style" explaining:
  - How to select existing text and transform it
  - How to preview before applying
  - How to revert to previous versions
  - Best practices for style transformation

## Architecture Diagram

```mermaid
sequenceDiagram
    participant User
    participant ChapterEditor
    participant StyleSelector
    participant PreviewDialog
    participant BookClient
    participant API
    participant AIService
    participant Database

    User->>ChapterEditor: Selects text & clicks "Transform Style"
    ChapterEditor->>StyleSelector: Opens style selector
    User->>StyleSelector: Selects target style (e.g., "Academic")
    StyleSelector->>BookClient: transformChapterStyle(preview=true)
    BookClient->>API: POST /transform-style
    API->>Database: Get current chapter content
    Database-->>API: Return content
    API->>AIService: transform_text_style(content, "academic")
    AIService->>AIService: Build transformation prompt
    AIService->>OpenAI: Request transformation
    OpenAI-->>AIService: Return transformed text
    AIService-->>API: Return transformed content + metadata
    API-->>BookClient: Return preview data
    BookClient-->>PreviewDialog: Display comparison
    PreviewDialog->>User: Show original vs transformed
    User->>PreviewDialog: Clicks "Apply Transformation"
    PreviewDialog->>BookClient: transformChapterStyle(preview=false)
    BookClient->>API: POST /transform-style
    API->>Database: Save current to content_history
    API->>Database: Update chapter content
    Database-->>API: Confirm save
    API-->>BookClient: Success response
    BookClient-->>ChapterEditor: Update editor content
    ChapterEditor->>User: Show success message
```

## Key Implementation Details

| Component | Files Modified/Created | Key Changes |
|-----------|----------------------|-------------|
| Style Templates | `backend/app/services/style_templates.py` (new) | Define 5 styles with prompts and characteristics |
| AI Service | `backend/app/services/ai_service.py` | Add `transform_text_style()` method |
| Content Versioning | `backend/app/models/book.py` | Add `ContentVersion` model and `content_history` field |
| API Endpoints | `backend/app/api/endpoints/books.py` | Add transform-style, history, revert endpoints |
| Style Selector | `frontend/src/components/chapters/StyleSelector.tsx` (new) | Dropdown with 5 styles |
| Preview Dialog | `frontend/src/components/chapters/StyleTransformPreview.tsx` (new) | Side-by-side comparison UI |
| Editor Integration | `frontend/src/components/chapters/ChapterEditor.tsx` | Add style transformation handlers |
| API Client | `frontend/src/lib/api/bookClient.ts` | Add transformation methods |
| Draft Generator | `frontend/src/components/chapters/DraftGenerator.tsx` | Update to 5 standardized styles |
| E2E Tests | `frontend/tests/e2e/deployment/06-draft-writing-styles.spec.ts` | Add transformation test cases |

## Acceptance Criteria Mapping

- ✅ **All 5 writing styles implemented**: Style templates define Professional, Conversational, Academic, Creative, Technical
- ✅ **Each style produces clearly different output**: AI prompts enforce distinct tone, vocabulary, and structure per style
- ✅ **Users can transform existing text**: New transform-style endpoint and UI in chapter editor
- ✅ **Preview shows before/after comparison**: `StyleTransformPreview` component displays side-by-side view
- ✅ **Users can revert to previous style**: Content version history with revert endpoint
- ✅ **Style transformation preserves facts**: AI prompts explicitly instruct to maintain factual accuracy
- ✅ **Integration tests verify distinct outputs**: New test file validates each style produces unique results
- ✅ **E2E test covers transformation flow**: Updated E2E test includes transformation and revert scenarios

---

Execution Information

Branch: main
Commit: 6841238