Fix headless deployment: set matplotlib Agg backend and simplify Docker deps

Dockerfile

@@ -10,17 +10,17 @@ WORKDIR /app
 ENV PYTHONPATH="/app"
 ENV PYTHONDONTWRITEBYTECODE=1
 ENV PYTHONUNBUFFERED=1
+ENV MPLCONFIGDIR=/tmp/matplotlib
+ENV QT_QPA_PLATFORM=offscreen
 
-# Install system dependencies
+# Install minimal system dependencies for headless OpenCV
 RUN apt-get update && apt-get install -y \
     libglib2.0-0 \
     libsm6 \
     libxext6 \
-    libxrender-dev \
+    libxrender1 \
     libgomp1 \
-    libgtk-3-0 \
-    libgl1-mesa-dri \
-    libglu1-mesa \
+    libglib2.0-0 \
     curl \
     && rm -rf /var/lib/apt/lists/*
 
@@ -39,7 +39,7 @@ COPY knowledge_base/ ./knowledge_base/
 COPY test_leaf_sample.jpg .
 
 # Create necessary directories
-RUN mkdir -p outputs temp
+RUN mkdir -p outputs temp /tmp/matplotlib
 
 # Expose the port FastAPI runs on
 EXPOSE 7860

app.py

@@ -20,7 +20,12 @@ import uuid
 import tempfile
 import asyncio
 from pathlib import Path
+
+# Set matplotlib backend before importing pyplot (fixes headless environment)
+import matplotlib
+matplotlib.use('Agg')
 import matplotlib.pyplot as plt
+
 import cv2
 import base64
 from datetime import datetime