feat: add document file upload support for spec creation and project expansion

Add support for uploading Markdown, Text, Word (.docx), CSV, Excel (.xlsx),
PDF, and PowerPoint (.pptx) files in addition to existing JPEG/PNG image
uploads in the spec creation and project expansion chat interfaces.

Backend changes:
- New server/utils/document_extraction.py: in-memory text extraction for all
  document formats using python-docx, openpyxl, PyPDF2, python-pptx (no disk
  persistence)
- Rename ImageAttachment to FileAttachment across schemas, routers, and
  chat session services
- Add build_attachment_content_blocks() helper in chat_constants.py to route
  images as image content blocks and documents as extracted text blocks
- Separate size limits: 5MB for images, 20MB for documents
- Handle extraction errors (corrupt files, encrypted PDFs) gracefully

Frontend changes:
- Widen accepted MIME types and file extensions in both chat components
- Add resolveMimeType() fallback for browsers that don't set MIME on .md files
- Document attachments display with FileText icon instead of image thumbnail
- ChatMessage renders documents as compact pills with filename and size
- Update help text from "attach images" to "attach files"

Dependencies added: python-docx, openpyxl, PyPDF2, python-pptx

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

requirements-prod.txt

@@ -12,3 +12,7 @@ aiofiles>=24.0.0
 apscheduler>=3.10.0,<4.0.0
 pywinpty>=2.0.0; sys_platform == "win32"
 pyyaml>=6.0.0
+python-docx>=1.1.0
+openpyxl>=3.1.0
+PyPDF2>=3.0.0
+python-pptx>=1.0.0

requirements.txt

@@ -10,6 +10,10 @@ aiofiles>=24.0.0
 apscheduler>=3.10.0,<4.0.0
 pywinpty>=2.0.0; sys_platform == "win32"
 pyyaml>=6.0.0
+python-docx>=1.1.0
+openpyxl>=3.1.0
+PyPDF2>=3.0.0
+python-pptx>=1.0.0
 
 # Dev dependencies
 ruff>=0.8.0

server/routers/expand_project.py

@@ -13,7 +13,7 @@ from typing import Optional
 from fastapi import APIRouter, HTTPException, WebSocket, WebSocketDisconnect
 from pydantic import BaseModel, ValidationError
 
-from ..schemas import ImageAttachment
+from ..schemas import FileAttachment
 from ..services.expand_chat_session import (
     ExpandChatSession,
     create_expand_session,
@@ -181,12 +181,12 @@ async def expand_project_websocket(websocket: WebSocket, project_name: str):
                     user_content = message.get("content", "").strip()
 
                     # Parse attachments if present
-                    attachments: list[ImageAttachment] = []
+                    attachments: list[FileAttachment] = []
                     raw_attachments = message.get("attachments", [])
                     if raw_attachments:
                         try:
                             for raw_att in raw_attachments:
-                                attachments.append(ImageAttachment(**raw_att))
+                                attachments.append(FileAttachment(**raw_att))
                         except (ValidationError, Exception) as e:
                             logger.warning(f"Invalid attachment data: {e}")
                             await websocket.send_json({

server/routers/spec_creation.py

@@ -12,7 +12,7 @@ from typing import Optional
 from fastapi import APIRouter, HTTPException, WebSocket, WebSocketDisconnect
 from pydantic import BaseModel, ValidationError
 
-from ..schemas import ImageAttachment
+from ..schemas import FileAttachment
 from ..services.spec_chat_session import (
     SpecChatSession,
     create_session,
@@ -242,12 +242,12 @@ async def spec_chat_websocket(websocket: WebSocket, project_name: str):
                     user_content = message.get("content", "").strip()
 
                     # Parse attachments if present
-                    attachments: list[ImageAttachment] = []
+                    attachments: list[FileAttachment] = []
                     raw_attachments = message.get("attachments", [])
                     if raw_attachments:
                         try:
                             for raw_att in raw_attachments:
-                                attachments.append(ImageAttachment(**raw_att))
+                                attachments.append(FileAttachment(**raw_att))
                         except (ValidationError, Exception) as e:
                             logger.warning(f"Invalid attachment data: {e}")
                             await websocket.send_json({

server/schemas.py

@@ -11,7 +11,7 @@ from datetime import datetime
 from pathlib import Path
 from typing import Literal
 
-from pydantic import BaseModel, Field, field_validator
+from pydantic import BaseModel, Field, field_validator, model_validator
 
 # Import model constants from registry (single source of truth)
 _root = Path(__file__).parent.parent
@@ -331,36 +331,61 @@ class WSAgentUpdateMessage(BaseModel):
 
 
 # ============================================================================
-# Spec Chat Schemas
+# Chat Attachment Schemas
 # ============================================================================
 
-# Maximum image file size: 5 MB
-MAX_IMAGE_SIZE = 5 * 1024 * 1024
+# Size limits
+MAX_IMAGE_SIZE = 5 * 1024 * 1024      # 5 MB for images
+MAX_DOCUMENT_SIZE = 20 * 1024 * 1024   # 20 MB for documents
+
+_IMAGE_MIME_TYPES = {'image/jpeg', 'image/png'}
 
 
-class ImageAttachment(BaseModel):
-    """Image attachment from client for spec creation chat."""
+class FileAttachment(BaseModel):
+    """File attachment from client for spec creation / expand project chat."""
     filename: str = Field(..., min_length=1, max_length=255)
-    mimeType: Literal['image/jpeg', 'image/png']
+    mimeType: Literal[
+        'image/jpeg', 'image/png',
+        'text/plain', 'text/markdown', 'text/csv',
+        'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
+        'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
+        'application/pdf',
+        'application/vnd.openxmlformats-officedocument.presentationml.presentation',
+    ]
     base64Data: str
 
     @field_validator('base64Data')
     @classmethod
-    def validate_base64_and_size(cls, v: str) -> str:
-        """Validate that base64 data is valid and within size limit."""
+    def validate_base64(cls, v: str) -> str:
+        """Validate that base64 data is decodable."""
         try:
-            decoded = base64.b64decode(v)
-            if len(decoded) > MAX_IMAGE_SIZE:
-                raise ValueError(
-                    f'Image size ({len(decoded) / (1024 * 1024):.1f} MB) exceeds '
-                    f'maximum of {MAX_IMAGE_SIZE // (1024 * 1024)} MB'
-                )
+            base64.b64decode(v)
             return v
         except Exception as e:
-            if 'Image size' in str(e):
-                raise
             raise ValueError(f'Invalid base64 data: {e}')
 
+    @model_validator(mode='after')
+    def validate_size(self) -> 'FileAttachment':
+        """Validate file size based on MIME type."""
+        try:
+            decoded = base64.b64decode(self.base64Data)
+        except Exception:
+            return self  # Already caught by field validator
+
+        if self.mimeType in _IMAGE_MIME_TYPES:
+            max_size = MAX_IMAGE_SIZE
+            label = "Image"
+        else:
+            max_size = MAX_DOCUMENT_SIZE
+            label = "Document"
+
+        if len(decoded) > max_size:
+            raise ValueError(
+                f'{label} size ({len(decoded) / (1024 * 1024):.1f} MB) exceeds '
+                f'maximum of {max_size // (1024 * 1024)} MB'
+            )
+        return self
+
 
 # ============================================================================
 # Filesystem Schemas

server/services/chat_constants.py

@@ -35,6 +35,13 @@ if _root_str not in sys.path:
 from env_constants import API_ENV_VARS  # noqa: E402, F401
 from rate_limit_utils import is_rate_limit_error, parse_retry_after  # noqa: E402, F401
 
+from ..schemas import FileAttachment
+from ..utils.document_extraction import (
+    extract_text_from_document,
+    is_document,
+    is_image,
+)
+
 logger = logging.getLogger(__name__)
 
 
@@ -88,6 +95,35 @@ async def safe_receive_response(client: Any, log: logging.Logger) -> AsyncGenera
             raise
 
 
+def build_attachment_content_blocks(attachments: list[FileAttachment]) -> list[dict]:
+    """Convert FileAttachment objects to Claude API content blocks.
+
+    Images become image content blocks (passed directly to Claude's vision).
+    Documents are extracted to text and become text content blocks.
+
+    Raises:
+        DocumentExtractionError: If a document cannot be read.
+    """
+    blocks: list[dict] = []
+    for att in attachments:
+        if is_image(att.mimeType):
+            blocks.append({
+                "type": "image",
+                "source": {
+                    "type": "base64",
+                    "media_type": att.mimeType,
+                    "data": att.base64Data,
+                }
+            })
+        elif is_document(att.mimeType):
+            text = extract_text_from_document(att.base64Data, att.mimeType, att.filename)
+            blocks.append({
+                "type": "text",
+                "text": f"[Content of uploaded file: {att.filename}]\n\n{text}",
+            })
+    return blocks
+
+
 async def make_multimodal_message(content_blocks: list[dict]) -> AsyncGenerator[dict, None]:
     """Yield a single multimodal user message in Claude Agent SDK format.
 

server/services/expand_chat_session.py

@@ -21,9 +21,11 @@ from typing import Any, AsyncGenerator, Optional
 from claude_agent_sdk import ClaudeAgentOptions, ClaudeSDKClient
 from dotenv import load_dotenv
 
-from ..schemas import ImageAttachment
+from ..schemas import FileAttachment
+from ..utils.document_extraction import DocumentExtractionError
 from .chat_constants import (
     ROOT_DIR,
+    build_attachment_content_blocks,
     check_rate_limit_error,
     make_multimodal_message,
     safe_receive_response,
@@ -226,7 +228,7 @@ class ExpandChatSession:
     async def send_message(
         self,
         user_message: str,
-        attachments: list[ImageAttachment] | None = None
+        attachments: list[FileAttachment] | None = None
     ) -> AsyncGenerator[dict, None]:
         """
         Send user message and stream Claude's response.
@@ -273,7 +275,7 @@ class ExpandChatSession:
     async def _query_claude(
         self,
         message: str,
-        attachments: list[ImageAttachment] | None = None
+        attachments: list[FileAttachment] | None = None
     ) -> AsyncGenerator[dict, None]:
         """
         Internal method to query Claude and stream responses.
@@ -289,17 +291,16 @@ class ExpandChatSession:
             content_blocks: list[dict[str, Any]] = []
             if message:
                 content_blocks.append({"type": "text", "text": message})
-            for att in attachments:
-                content_blocks.append({
-                    "type": "image",
-                    "source": {
-                        "type": "base64",
-                        "media_type": att.mimeType,
-                        "data": att.base64Data,
-                    }
-                })
+
+            # Add attachment blocks (images as image blocks, documents as extracted text)
+            try:
+                content_blocks.extend(build_attachment_content_blocks(attachments))
+            except DocumentExtractionError as e:
+                yield {"type": "error", "content": str(e)}
+                return
+
             await self.client.query(make_multimodal_message(content_blocks))
-            logger.info(f"Sent multimodal message with {len(attachments)} image(s)")
+            logger.info(f"Sent multimodal message with {len(attachments)} attachment(s)")
         else:
             await self.client.query(message)
 

server/services/spec_chat_session.py

@@ -18,9 +18,11 @@ from typing import Any, AsyncGenerator, Optional
 from claude_agent_sdk import ClaudeAgentOptions, ClaudeSDKClient
 from dotenv import load_dotenv
 
-from ..schemas import ImageAttachment
+from ..schemas import FileAttachment
+from ..utils.document_extraction import DocumentExtractionError
 from .chat_constants import (
     ROOT_DIR,
+    build_attachment_content_blocks,
     check_rate_limit_error,
     make_multimodal_message,
     safe_receive_response,
@@ -201,7 +203,7 @@ class SpecChatSession:
     async def send_message(
         self,
         user_message: str,
-        attachments: list[ImageAttachment] | None = None
+        attachments: list[FileAttachment] | None = None
     ) -> AsyncGenerator[dict, None]:
         """
         Send user message and stream Claude's response.
@@ -247,7 +249,7 @@ class SpecChatSession:
     async def _query_claude(
         self,
         message: str,
-        attachments: list[ImageAttachment] | None = None
+        attachments: list[FileAttachment] | None = None
     ) -> AsyncGenerator[dict, None]:
         """
         Internal method to query Claude and stream responses.
@@ -273,21 +275,17 @@ class SpecChatSession:
             if message:
                 content_blocks.append({"type": "text", "text": message})
 
-            # Add image blocks
-            for att in attachments:
-                content_blocks.append({
-                    "type": "image",
-                    "source": {
-                        "type": "base64",
-                        "media_type": att.mimeType,
-                        "data": att.base64Data,
-                    }
-                })
+            # Add attachment blocks (images as image blocks, documents as extracted text)
+            try:
+                content_blocks.extend(build_attachment_content_blocks(attachments))
+            except DocumentExtractionError as e:
+                yield {"type": "error", "content": str(e)}
+                return
 
             # Send multimodal content to Claude using async generator format
             # The SDK's query() accepts AsyncIterable[dict] for custom message formats
             await self.client.query(make_multimodal_message(content_blocks))
-            logger.info(f"Sent multimodal message with {len(attachments)} image(s)")
+            logger.info(f"Sent multimodal message with {len(attachments)} attachment(s)")
         else:
             # Text-only message: use string format
             await self.client.query(message)

server/utils/document_extraction.py

@@ -0,0 +1,221 @@
+"""
+Document Extraction Utility
+============================
+
+Extracts text content from various document formats in memory (no disk I/O).
+Supports: TXT, MD, CSV, DOCX, XLSX, PDF, PPTX.
+"""
+
+import base64
+import csv
+import io
+import logging
+
+logger = logging.getLogger(__name__)
+
+# Maximum characters of extracted text to send to Claude
+MAX_EXTRACTED_CHARS = 200_000
+
+# Maximum rows per sheet for Excel files
+MAX_EXCEL_ROWS_PER_SHEET = 10_000
+MAX_EXCEL_SHEETS = 50
+
+# MIME type classification
+DOCUMENT_MIME_TYPES: dict[str, str] = {
+    "text/plain": ".txt",
+    "text/markdown": ".md",
+    "text/csv": ".csv",
+    "application/vnd.openxmlformats-officedocument.wordprocessingml.document": ".docx",
+    "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet": ".xlsx",
+    "application/pdf": ".pdf",
+    "application/vnd.openxmlformats-officedocument.presentationml.presentation": ".pptx",
+}
+
+IMAGE_MIME_TYPES = {"image/jpeg", "image/png"}
+
+ALL_ALLOWED_MIME_TYPES = IMAGE_MIME_TYPES | set(DOCUMENT_MIME_TYPES.keys())
+
+
+def is_image(mime_type: str) -> bool:
+    """Check if the MIME type is a supported image format."""
+    return mime_type in IMAGE_MIME_TYPES
+
+
+def is_document(mime_type: str) -> bool:
+    """Check if the MIME type is a supported document format."""
+    return mime_type in DOCUMENT_MIME_TYPES
+
+
+class DocumentExtractionError(Exception):
+    """Raised when text extraction from a document fails."""
+
+    def __init__(self, filename: str, reason: str):
+        self.filename = filename
+        self.reason = reason
+        super().__init__(f"Failed to read {filename}: {reason}")
+
+
+def _truncate(text: str) -> str:
+    """Truncate text if it exceeds the maximum character limit."""
+    if len(text) > MAX_EXTRACTED_CHARS:
+        omitted = len(text) - MAX_EXTRACTED_CHARS
+        return text[:MAX_EXTRACTED_CHARS] + f"\n\n[... truncated, {omitted:,} characters omitted]"
+    return text
+
+
+def _extract_plain_text(data: bytes) -> str:
+    """Extract text from plain text or markdown files."""
+    try:
+        return data.decode("utf-8")
+    except UnicodeDecodeError:
+        return data.decode("latin-1")
+
+
+def _extract_csv(data: bytes) -> str:
+    """Extract text from CSV files, formatted as a readable table."""
+    try:
+        text = data.decode("utf-8")
+    except UnicodeDecodeError:
+        text = data.decode("latin-1")
+
+    reader = csv.reader(io.StringIO(text))
+    lines = []
+    for i, row in enumerate(reader):
+        lines.append(f"Row {i + 1}: {', '.join(row)}")
+    return "\n".join(lines)
+
+
+def _extract_docx(data: bytes) -> str:
+    """Extract text from Word documents."""
+    from docx import Document
+
+    doc = Document(io.BytesIO(data))
+    paragraphs = [p.text for p in doc.paragraphs if p.text.strip()]
+    return "\n\n".join(paragraphs)
+
+
+def _extract_xlsx(data: bytes) -> str:
+    """Extract text from Excel spreadsheets."""
+    from openpyxl import load_workbook
+
+    wb = load_workbook(io.BytesIO(data), read_only=True, data_only=True)
+    sections = []
+
+    for sheet_idx, sheet_name in enumerate(wb.sheetnames):
+        if sheet_idx >= MAX_EXCEL_SHEETS:
+            sections.append(f"\n[... {len(wb.sheetnames) - MAX_EXCEL_SHEETS} more sheets omitted]")
+            break
+
+        ws = wb[sheet_name]
+        rows_text = [f"=== Sheet: {sheet_name} ==="]
+        row_count = 0
+
+        for row in ws.iter_rows(values_only=True):
+            if row_count >= MAX_EXCEL_ROWS_PER_SHEET:
+                rows_text.append(f"[... more rows omitted, limit {MAX_EXCEL_ROWS_PER_SHEET:,} rows/sheet]")
+                break
+            cells = [str(cell) if cell is not None else "" for cell in row]
+            rows_text.append("\t".join(cells))
+            row_count += 1
+
+        sections.append("\n".join(rows_text))
+
+    wb.close()
+    return "\n\n".join(sections)
+
+
+def _extract_pdf(data: bytes, filename: str) -> str:
+    """Extract text from PDF files."""
+    from PyPDF2 import PdfReader
+    from PyPDF2.errors import PdfReadError
+
+    try:
+        reader = PdfReader(io.BytesIO(data))
+    except PdfReadError as e:
+        if "encrypt" in str(e).lower() or "password" in str(e).lower():
+            raise DocumentExtractionError(filename, "PDF is password-protected")
+        raise
+
+    if reader.is_encrypted:
+        raise DocumentExtractionError(filename, "PDF is password-protected")
+
+    pages = []
+    for i, page in enumerate(reader.pages):
+        text = page.extract_text()
+        if text and text.strip():
+            pages.append(f"--- Page {i + 1} ---\n{text}")
+
+    return "\n\n".join(pages)
+
+
+def _extract_pptx(data: bytes) -> str:
+    """Extract text from PowerPoint presentations."""
+    from pptx import Presentation
+
+    prs = Presentation(io.BytesIO(data))
+    slides_text = []
+
+    for i, slide in enumerate(prs.slides):
+        texts = []
+        for shape in slide.shapes:
+            if shape.has_text_frame:
+                for paragraph in shape.text_frame.paragraphs:
+                    text = paragraph.text.strip()
+                    if text:
+                        texts.append(text)
+        if texts:
+            slides_text.append(f"--- Slide {i + 1} ---\n" + "\n".join(texts))
+
+    return "\n\n".join(slides_text)
+
+
+def extract_text_from_document(base64_data: str, mime_type: str, filename: str) -> str:
+    """
+    Extract text content from a document file.
+
+    Args:
+        base64_data: Base64-encoded file content
+        mime_type: MIME type of the document
+        filename: Original filename (for error messages)
+
+    Returns:
+        Extracted text content, truncated if necessary
+
+    Raises:
+        DocumentExtractionError: If extraction fails
+    """
+    if mime_type not in DOCUMENT_MIME_TYPES:
+        raise DocumentExtractionError(filename, f"unsupported document type: {mime_type}")
+
+    try:
+        data = base64.b64decode(base64_data)
+    except Exception as e:
+        raise DocumentExtractionError(filename, f"invalid base64 data: {e}")
+
+    try:
+        if mime_type in ("text/plain", "text/markdown"):
+            text = _extract_plain_text(data)
+        elif mime_type == "text/csv":
+            text = _extract_csv(data)
+        elif mime_type == "application/vnd.openxmlformats-officedocument.wordprocessingml.document":
+            text = _extract_docx(data)
+        elif mime_type == "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet":
+            text = _extract_xlsx(data)
+        elif mime_type == "application/pdf":
+            text = _extract_pdf(data, filename)
+        elif mime_type == "application/vnd.openxmlformats-officedocument.presentationml.presentation":
+            text = _extract_pptx(data)
+        else:
+            raise DocumentExtractionError(filename, f"unsupported document type: {mime_type}")
+    except DocumentExtractionError:
+        raise
+    except Exception as e:
+        logger.warning(f"Document extraction failed for {filename}: {e}")
+        raise DocumentExtractionError(
+            filename, "file appears to be corrupt or in an unexpected format"
+        )
+
+    if not text or not text.strip():
+        return f"[File {filename} is empty or contains no extractable text]"
+
+    return _truncate(text)

ui/src/components/ChatMessage.tsx

@@ -6,10 +6,11 @@
  */
 
 import { memo } from 'react'
-import { Bot, User, Info } from 'lucide-react'
+import { Bot, User, Info, FileText } from 'lucide-react'
 import ReactMarkdown, { type Components } from 'react-markdown'
 import remarkGfm from 'remark-gfm'
 import type { ChatMessage as ChatMessageType } from '../lib/types'
+import { isImageAttachment } from '../lib/types'
 import { Card } from '@/components/ui/card'
 
 interface ChatMessageProps {
@@ -104,21 +105,35 @@ export const ChatMessage = memo(function ChatMessage({ message }: ChatMessagePro
               </div>
             )}
 
-            {/* Display image attachments */}
+            {/* Display file attachments */}
             {attachments && attachments.length > 0 && (
               <div className={`flex flex-wrap gap-2 ${content ? 'mt-3' : ''}`}>
                 {attachments.map((attachment) => (
                   <div key={attachment.id} className="border border-border rounded p-1 bg-card">
-                    <img
-                      src={attachment.previewUrl}
-                      alt={attachment.filename}
-                      className="max-w-48 max-h-48 object-contain cursor-pointer hover:opacity-90 transition-opacity rounded"
-                      onClick={() => window.open(attachment.previewUrl, '_blank')}
-                      title={`${attachment.filename} (click to enlarge)`}
-                    />
-                    <span className="text-xs text-muted-foreground block mt-1 text-center">
-                      {attachment.filename}
-                    </span>
+                    {isImageAttachment(attachment) ? (
+                      <>
+                        <img
+                          src={attachment.previewUrl}
+                          alt={attachment.filename}
+                          className="max-w-48 max-h-48 object-contain cursor-pointer hover:opacity-90 transition-opacity rounded"
+                          onClick={() => window.open(attachment.previewUrl, '_blank')}
+                          title={`${attachment.filename} (click to enlarge)`}
+                        />
+                        <span className="text-xs text-muted-foreground block mt-1 text-center">
+                          {attachment.filename}
+                        </span>
+                      </>
+                    ) : (
+                      <div className="flex items-center gap-2 px-2 py-1">
+                        <FileText size={16} className="text-muted-foreground flex-shrink-0" />
+                        <span className="text-xs text-muted-foreground">
+                          {attachment.filename}
+                        </span>
+                        <span className="text-xs text-muted-foreground/60">
+                          ({(attachment.size / 1024).toFixed(0)} KB)
+                        </span>
+                      </div>
+                    )}
                   </div>
                 ))}
               </div>

ui/src/components/ExpandProjectChat.tsx

@@ -6,20 +6,22 @@
  */
 
 import { useCallback, useEffect, useRef, useState } from 'react'
-import { Send, X, CheckCircle2, AlertCircle, Wifi, WifiOff, RotateCcw, Paperclip, Plus } from 'lucide-react'
+import { Send, X, CheckCircle2, AlertCircle, Wifi, WifiOff, RotateCcw, Paperclip, Plus, FileText } from 'lucide-react'
 import { useExpandChat } from '../hooks/useExpandChat'
 import { ChatMessage } from './ChatMessage'
 import { TypingIndicator } from './TypingIndicator'
-import type { ImageAttachment } from '../lib/types'
+import type { FileAttachment } from '../lib/types'
+import { ALL_ALLOWED_MIME_TYPES, IMAGE_MIME_TYPES, isImageAttachment, resolveMimeType } from '../lib/types'
 import { isSubmitEnter } from '../lib/keyboard'
 import { Button } from '@/components/ui/button'
 import { Input } from '@/components/ui/input'
 import { Card, CardContent } from '@/components/ui/card'
 import { Alert, AlertDescription } from '@/components/ui/alert'
 
-// Image upload validation constants
-const MAX_FILE_SIZE = 5 * 1024 * 1024 // 5 MB
-const ALLOWED_TYPES = ['image/jpeg', 'image/png']
+// File upload validation constants
+const MAX_IMAGE_SIZE = 5 * 1024 * 1024 // 5 MB for images
+const MAX_DOCUMENT_SIZE = 20 * 1024 * 1024 // 20 MB for documents
+const ALLOWED_EXTENSIONS = ['md', 'txt', 'csv', 'docx', 'xlsx', 'pdf', 'pptx', 'jpg', 'jpeg', 'png']
 
 interface ExpandProjectChatProps {
   projectName: string
@@ -34,7 +36,7 @@ export function ExpandProjectChat({
 }: ExpandProjectChatProps) {
   const [input, setInput] = useState('')
   const [error, setError] = useState<string | null>(null)
-  const [pendingAttachments, setPendingAttachments] = useState<ImageAttachment[]>([])
+  const [pendingAttachments, setPendingAttachments] = useState<FileAttachment[]>([])
   const messagesEndRef = useRef<HTMLDivElement>(null)
   const inputRef = useRef<HTMLInputElement>(null)
   const fileInputRef = useRef<HTMLInputElement>(null)
@@ -95,20 +97,33 @@ export function ExpandProjectChat({
     }
   }
 
-  // File handling for image attachments
+  // File handling for attachments (images and documents)
   const handleFileSelect = useCallback((files: FileList | null) => {
     if (!files) return
 
     Array.from(files).forEach((file) => {
-      // Validate file type
-      if (!ALLOWED_TYPES.includes(file.type)) {
-        setError(`Invalid file type: ${file.name}. Only JPEG and PNG are supported.`)
-        return
+      // Resolve MIME type (browsers may not set it for .md files)
+      let mimeType = file.type
+      if (!mimeType || !ALL_ALLOWED_MIME_TYPES.includes(mimeType)) {
+        mimeType = resolveMimeType(file.name)
       }
 
-      // Validate file size
-      if (file.size > MAX_FILE_SIZE) {
-        setError(`File too large: ${file.name}. Maximum size is 5 MB.`)
+      // Validate file type
+      if (!ALL_ALLOWED_MIME_TYPES.includes(mimeType)) {
+        const ext = file.name.split('.').pop()?.toLowerCase()
+        if (!ext || !ALLOWED_EXTENSIONS.includes(ext)) {
+          setError(`Unsupported file type: ${file.name}. Supported: images (JPEG, PNG) and documents (MD, TXT, CSV, DOCX, XLSX, PDF, PPTX).`)
+          return
+        }
+        mimeType = resolveMimeType(file.name)
+      }
+
+      // Validate size based on type
+      const isImage = (IMAGE_MIME_TYPES as readonly string[]).includes(mimeType)
+      const maxSize = isImage ? MAX_IMAGE_SIZE : MAX_DOCUMENT_SIZE
+      const maxLabel = isImage ? '5 MB' : '20 MB'
+      if (file.size > maxSize) {
+        setError(`File too large: ${file.name}. Maximum size is ${maxLabel}.`)
         return
       }
 
@@ -118,12 +133,12 @@ export function ExpandProjectChat({
         const dataUrl = e.target?.result as string
         const base64Data = dataUrl.split(',')[1]
 
-        const attachment: ImageAttachment = {
+        const attachment: FileAttachment = {
           id: `${Date.now()}-${Math.random().toString(36).substring(2, 9)}`,
           filename: file.name,
-          mimeType: file.type as 'image/jpeg' | 'image/png',
+          mimeType: mimeType as FileAttachment['mimeType'],
           base64Data,
-          previewUrl: dataUrl,
+          previewUrl: isImage ? dataUrl : '',
           size: file.size,
         }
 
@@ -291,11 +306,17 @@ export function ExpandProjectChat({
                   key={attachment.id}
                   className="relative group border-2 border-border p-1 bg-card rounded shadow-sm"
                 >
-                  <img
-                    src={attachment.previewUrl}
-                    alt={attachment.filename}
-                    className="w-16 h-16 object-cover rounded"
-                  />
+                  {isImageAttachment(attachment) ? (
+                    <img
+                      src={attachment.previewUrl}
+                      alt={attachment.filename}
+                      className="w-16 h-16 object-cover rounded"
+                    />
+                  ) : (
+                    <div className="w-16 h-16 flex items-center justify-center bg-muted rounded">
+                      <FileText size={24} className="text-muted-foreground" />
+                    </div>
+                  )}
                   <button
                     onClick={() => handleRemoveAttachment(attachment.id)}
                     className="absolute -top-2 -right-2 bg-destructive text-destructive-foreground rounded-full p-0.5 border-2 border-border hover:scale-110 transition-transform"
@@ -318,7 +339,7 @@ export function ExpandProjectChat({
             <input
               ref={fileInputRef}
               type="file"
-              accept="image/jpeg,image/png"
+              accept="image/jpeg,image/png,.md,.txt,.csv,.docx,.xlsx,.pdf,.pptx"
               multiple
               onChange={(e) => handleFileSelect(e.target.files)}
               className="hidden"
@@ -330,7 +351,7 @@ export function ExpandProjectChat({
               disabled={connectionStatus !== 'connected'}
               variant="ghost"
               size="icon"
-              title="Attach image (JPEG, PNG - max 5MB)"
+              title="Attach files (images: JPEG/PNG up to 5MB, documents: MD, TXT, CSV, DOCX, XLSX, PDF, PPTX up to 20MB)"
             >
               <Paperclip size={18} />
             </Button>
@@ -364,7 +385,7 @@ export function ExpandProjectChat({
 
           {/* Help text */}
           <p className="text-xs text-muted-foreground mt-2">
-            Press Enter to send. Drag & drop or click <Paperclip size={12} className="inline" /> to attach images.
+            Press Enter to send. Drag & drop or click <Paperclip size={12} className="inline" /> to attach files.
           </p>
         </div>
       )}

ui/src/components/SpecCreationChat.tsx

@@ -11,16 +11,18 @@ import { useSpecChat } from '../hooks/useSpecChat'
 import { ChatMessage } from './ChatMessage'
 import { QuestionOptions } from './QuestionOptions'
 import { TypingIndicator } from './TypingIndicator'
-import type { ImageAttachment } from '../lib/types'
+import type { FileAttachment } from '../lib/types'
+import { ALL_ALLOWED_MIME_TYPES, IMAGE_MIME_TYPES, isImageAttachment, resolveMimeType } from '../lib/types'
 import { isSubmitEnter } from '../lib/keyboard'
 import { Button } from '@/components/ui/button'
 import { Textarea } from '@/components/ui/textarea'
 import { Card, CardContent } from '@/components/ui/card'
 import { Alert, AlertDescription } from '@/components/ui/alert'
 
-// Image upload validation constants
-const MAX_FILE_SIZE = 5 * 1024 * 1024 // 5 MB
-const ALLOWED_TYPES = ['image/jpeg', 'image/png']
+// File upload validation constants
+const MAX_IMAGE_SIZE = 5 * 1024 * 1024 // 5 MB for images
+const MAX_DOCUMENT_SIZE = 20 * 1024 * 1024 // 20 MB for documents
+const ALLOWED_EXTENSIONS = ['md', 'txt', 'csv', 'docx', 'xlsx', 'pdf', 'pptx', 'jpg', 'jpeg', 'png']
 
 // Sample prompt for quick testing
 const SAMPLE_PROMPT = `Let's call it Simple Todo. This is a really simple web app that I can use to track my to-do items using a Kanban board. I should be able to add to-dos and then drag and drop them through the Kanban board. The different columns in the Kanban board are:
@@ -64,7 +66,7 @@ export function SpecCreationChat({
   const [input, setInput] = useState('')
   const [error, setError] = useState<string | null>(null)
   const [yoloEnabled, setYoloEnabled] = useState(false)
-  const [pendingAttachments, setPendingAttachments] = useState<ImageAttachment[]>([])
+  const [pendingAttachments, setPendingAttachments] = useState<FileAttachment[]>([])
   const messagesEndRef = useRef<HTMLDivElement>(null)
   const inputRef = useRef<HTMLTextAreaElement>(null)
   const fileInputRef = useRef<HTMLInputElement>(null)
@@ -138,20 +140,33 @@ export function SpecCreationChat({
     sendAnswer(answers)
   }
 
-  // File handling for image attachments
+  // File handling for attachments (images and documents)
   const handleFileSelect = useCallback((files: FileList | null) => {
     if (!files) return
 
     Array.from(files).forEach((file) => {
-      // Validate file type
-      if (!ALLOWED_TYPES.includes(file.type)) {
-        setError(`Invalid file type: ${file.name}. Only JPEG and PNG are supported.`)
-        return
+      // Resolve MIME type (browsers may not set it for .md files)
+      let mimeType = file.type
+      if (!mimeType || !ALL_ALLOWED_MIME_TYPES.includes(mimeType)) {
+        mimeType = resolveMimeType(file.name)
       }
 
-      // Validate file size
-      if (file.size > MAX_FILE_SIZE) {
-        setError(`File too large: ${file.name}. Maximum size is 5 MB.`)
+      // Validate file type
+      if (!ALL_ALLOWED_MIME_TYPES.includes(mimeType)) {
+        const ext = file.name.split('.').pop()?.toLowerCase()
+        if (!ext || !ALLOWED_EXTENSIONS.includes(ext)) {
+          setError(`Unsupported file type: ${file.name}. Supported: images (JPEG, PNG) and documents (MD, TXT, CSV, DOCX, XLSX, PDF, PPTX).`)
+          return
+        }
+        mimeType = resolveMimeType(file.name)
+      }
+
+      // Validate size based on type
+      const isImage = (IMAGE_MIME_TYPES as readonly string[]).includes(mimeType)
+      const maxSize = isImage ? MAX_IMAGE_SIZE : MAX_DOCUMENT_SIZE
+      const maxLabel = isImage ? '5 MB' : '20 MB'
+      if (file.size > maxSize) {
+        setError(`File too large: ${file.name}. Maximum size is ${maxLabel}.`)
         return
       }
 
@@ -159,15 +174,14 @@ export function SpecCreationChat({
       const reader = new FileReader()
       reader.onload = (e) => {
         const dataUrl = e.target?.result as string
-        // dataUrl is "data:image/png;base64,XXXXXX"
         const base64Data = dataUrl.split(',')[1]
 
-        const attachment: ImageAttachment = {
+        const attachment: FileAttachment = {
           id: `${Date.now()}-${Math.random().toString(36).substring(2, 9)}`,
           filename: file.name,
-          mimeType: file.type as 'image/jpeg' | 'image/png',
+          mimeType: mimeType as FileAttachment['mimeType'],
           base64Data,
-          previewUrl: dataUrl,
+          previewUrl: isImage ? dataUrl : '',
           size: file.size,
         }
 
@@ -364,11 +378,17 @@ export function SpecCreationChat({
                   key={attachment.id}
                   className="relative group border-2 border-border p-1 bg-card rounded shadow-sm"
                 >
-                  <img
-                    src={attachment.previewUrl}
-                    alt={attachment.filename}
-                    className="w-16 h-16 object-cover rounded"
-                  />
+                  {isImageAttachment(attachment) ? (
+                    <img
+                      src={attachment.previewUrl}
+                      alt={attachment.filename}
+                      className="w-16 h-16 object-cover rounded"
+                    />
+                  ) : (
+                    <div className="w-16 h-16 flex items-center justify-center bg-muted rounded">
+                      <FileText size={24} className="text-muted-foreground" />
+                    </div>
+                  )}
                   <button
                     onClick={() => handleRemoveAttachment(attachment.id)}
                     className="absolute -top-2 -right-2 bg-destructive text-destructive-foreground rounded-full p-0.5 border-2 border-border hover:scale-110 transition-transform"
@@ -391,7 +411,7 @@ export function SpecCreationChat({
             <input
               ref={fileInputRef}
               type="file"
-              accept="image/jpeg,image/png"
+              accept="image/jpeg,image/png,.md,.txt,.csv,.docx,.xlsx,.pdf,.pptx"
               multiple
               onChange={(e) => handleFileSelect(e.target.files)}
               className="hidden"
@@ -403,7 +423,7 @@ export function SpecCreationChat({
               disabled={connectionStatus !== 'connected'}
               variant="ghost"
               size="icon"
-              title="Attach image (JPEG, PNG - max 5MB)"
+              title="Attach files (images: JPEG/PNG up to 5MB, documents: MD, TXT, CSV, DOCX, XLSX, PDF, PPTX up to 20MB)"
             >
               <Paperclip size={18} />
             </Button>
@@ -444,7 +464,7 @@ export function SpecCreationChat({
 
           {/* Help text */}
           <p className="text-xs text-muted-foreground mt-2">
-            Press Enter to send, Shift+Enter for new line. Drag & drop or click <Paperclip size={12} className="inline" /> to attach images (JPEG/PNG, max 5MB).
+            Press Enter to send, Shift+Enter for new line. Drag & drop or click <Paperclip size={12} className="inline" /> to attach files.
           </p>
         </div>
       )}

ui/src/hooks/useExpandChat.ts

@@ -3,7 +3,7 @@
  */
 
 import { useState, useCallback, useRef, useEffect } from 'react'
-import type { ChatMessage, ImageAttachment, ExpandChatServerMessage } from '../lib/types'
+import type { ChatMessage, FileAttachment, ExpandChatServerMessage } from '../lib/types'
 
 type ConnectionStatus = 'disconnected' | 'connecting' | 'connected' | 'error'
 
@@ -27,7 +27,7 @@ interface UseExpandChatReturn {
   featuresCreated: number
   recentFeatures: CreatedFeature[]
   start: () => void
-  sendMessage: (content: string, attachments?: ImageAttachment[]) => void
+  sendMessage: (content: string, attachments?: FileAttachment[]) => void
   disconnect: () => void
 }
 
@@ -278,7 +278,7 @@ export function useExpandChat({
     setTimeout(checkAndSend, 100)
   }, [connect, onError])
 
-  const sendMessage = useCallback((content: string, attachments?: ImageAttachment[]) => {
+  const sendMessage = useCallback((content: string, attachments?: FileAttachment[]) => {
     if (!wsRef.current || wsRef.current.readyState !== WebSocket.OPEN) {
       onError?.('Not connected')
       return

ui/src/hooks/useSpecChat.ts

@@ -3,7 +3,7 @@
  */
 
 import { useState, useCallback, useRef, useEffect } from 'react'
-import type { ChatMessage, ImageAttachment, SpecChatServerMessage, SpecQuestion } from '../lib/types'
+import type { ChatMessage, FileAttachment, SpecChatServerMessage, SpecQuestion } from '../lib/types'
 import { getSpecStatus } from '../lib/api'
 
 type ConnectionStatus = 'disconnected' | 'connecting' | 'connected' | 'error'
@@ -22,7 +22,7 @@ interface UseSpecChatReturn {
   currentQuestions: SpecQuestion[] | null
   currentToolId: string | null
   start: () => void
-  sendMessage: (content: string, attachments?: ImageAttachment[]) => void
+  sendMessage: (content: string, attachments?: FileAttachment[]) => void
   sendAnswer: (answers: Record<string, string | string[]>) => void
   disconnect: () => void
 }
@@ -367,7 +367,7 @@ export function useSpecChat({
     setTimeout(checkAndSend, 100)
   }, [connect])
 
-  const sendMessage = useCallback((content: string, attachments?: ImageAttachment[]) => {
+  const sendMessage = useCallback((content: string, attachments?: FileAttachment[]) => {
     if (!wsRef.current || wsRef.current.readyState !== WebSocket.OPEN) {
       onError?.('Not connected')
       return

ui/src/lib/types.ts

@@ -417,22 +417,67 @@ export type SpecChatServerMessage =
   | SpecChatPongMessage
   | SpecChatResponseDoneMessage
 
-// Image attachment for chat messages
-export interface ImageAttachment {
+// File attachment for chat messages (images and documents)
+export interface FileAttachment {
   id: string
   filename: string
-  mimeType: 'image/jpeg' | 'image/png'
+  mimeType:
+    | 'image/jpeg'
+    | 'image/png'
+    | 'text/plain'
+    | 'text/markdown'
+    | 'text/csv'
+    | 'application/vnd.openxmlformats-officedocument.wordprocessingml.document'
+    | 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet'
+    | 'application/pdf'
+    | 'application/vnd.openxmlformats-officedocument.presentationml.presentation'
   base64Data: string    // Raw base64 (without data: prefix)
-  previewUrl: string    // data: URL for display
+  previewUrl: string    // data: URL for images, empty string for documents
   size: number          // File size in bytes
 }
 
+/** @deprecated Use FileAttachment instead */
+export type ImageAttachment = FileAttachment
+
+export const IMAGE_MIME_TYPES = ['image/jpeg', 'image/png'] as const
+export const DOCUMENT_MIME_TYPES = [
+  'text/plain',
+  'text/markdown',
+  'text/csv',
+  'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
+  'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
+  'application/pdf',
+  'application/vnd.openxmlformats-officedocument.presentationml.presentation',
+] as const
+export const ALL_ALLOWED_MIME_TYPES: string[] = [...IMAGE_MIME_TYPES, ...DOCUMENT_MIME_TYPES]
+
+export function isImageAttachment(att: FileAttachment): boolean {
+  return (IMAGE_MIME_TYPES as readonly string[]).includes(att.mimeType)
+}
+
+export function resolveMimeType(filename: string): string {
+  const ext = filename.split('.').pop()?.toLowerCase()
+  const map: Record<string, string> = {
+    md: 'text/markdown',
+    txt: 'text/plain',
+    csv: 'text/csv',
+    docx: 'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
+    xlsx: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
+    pdf: 'application/pdf',
+    pptx: 'application/vnd.openxmlformats-officedocument.presentationml.presentation',
+    jpg: 'image/jpeg',
+    jpeg: 'image/jpeg',
+    png: 'image/png',
+  }
+  return map[ext || ''] || 'application/octet-stream'
+}
+
 // UI chat message for display
 export interface ChatMessage {
   id: string
   role: 'user' | 'assistant' | 'system'
   content: string
-  attachments?: ImageAttachment[]
+  attachments?: FileAttachment[]
   timestamp: Date
   questions?: SpecQuestion[]
   isStreaming?: boolean