## ADDED Requirements

### Requirement: Drag-and-drop email upload

The chat message area SHALL accept files dragged from the desktop or file explorer. When a supported file is dropped, the client SHALL read the file content and send it to the extraction endpoint.

#### Scenario: Drag HTML file onto chat

- **WHEN** the user drags an .html file over the message area
- **THEN** a visual drop indicator appears (e.g., highlighted border, overlay text "Drop email here")

#### Scenario: Drop HTML file triggers extraction

- **WHEN** the user drops an .html file onto the message area
- **THEN** the client reads the HTML content, sends it to `POST /api/chat/extract`, and streams the extraction response in the chat

#### Scenario: Unsupported file type rejected

- **WHEN** the user drops a non-.html file (e.g., .pdf, .docx)
- **THEN** the client shows a brief error message indicating only .html files are supported

### Requirement: File picker upload button

The chat input area SHALL include an upload button (e.g., attachment icon) that opens a file picker dialog for selecting .html email files.

#### Scenario: Upload via file picker

- **WHEN** the user clicks the upload button and selects an .html file
- **THEN** the client reads the HTML content and sends it to the extraction endpoint, same as drag-and-drop

### Requirement: Upload disabled during streaming

The upload zone and file picker SHALL be disabled while a response is streaming.

#### Scenario: Drop during streaming

- **WHEN** the user attempts to drop a file while the assistant is streaming
- **THEN** the drop is ignored and no extraction request is sent