Fix broken system prompt causing thinking blocks in generated code

- Simplify system prompt to prevent AI model confusion
- Remove complex numbered rules that were causing thinking blocks to appear in code
- Add explicit instruction to only generate code, no explanations
- Keep essential requirements for answer variable and filename syntax

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

src.py

@@ -285,22 +285,17 @@ df["Timestamp"] = pd.to_datetime(df["Timestamp"])
 # If returning text/numbers, store the result directly in 'answer'
 ```"""
 
-        system_prompt = """You are a helpful assistant that generates Python code for data analysis.
-        
-        Rules:
-        1. Always save your final result in a variable called 'answer'
-        2. If creating a plot, save it with plt.savefig() and store the filename in 'answer'
-        3. If returning text/numbers, store the result directly in 'answer'
-        4. Use descriptive variable names and add comments
-        5. Handle potential errors gracefully
-        6. For plots, use unique filenames: f"plot_name_{{uuid.uuid4().hex[:8]}}.png" (note proper bracket syntax)
-        7. Make plots professional with proper titles, labels, and styling
-        8. Use plt.tight_layout() before saving plots
-        9. For line plots, use linewidth=2.5 and markersize=8 for better visibility
-        10. Add proper axis labels with units (e.g., 'PM2.5 (µg/m³)')
-        11. For high-resolution plots, use bbox_inches='tight', dpi=400 in plt.savefig()
-        12. IMPORTANT: Use double curly braces {{}} in f-strings within the template to avoid syntax errors
-        """
+        system_prompt = """Generate Python code to answer the user's question about air quality data.
+
+IMPORTANT: Only generate Python code - no explanations, no thinking, just clean code.
+
+Requirements:
+- Save final result in variable called 'answer'
+- For plots: save with unique filename using uuid and store filename in 'answer'
+- For text answers: store text directly in 'answer'
+- Use proper syntax: f"filename_{{uuid.uuid4().hex[:8]}}.png"
+- Add plt.tight_layout() before saving plots
+"""
 
         query = f"""{system_prompt}