refactor(prompt): Consolidate system prompts with Jinja inheritance (#9797)

Co-authored-by: openhands <openhands@all-hands.dev>

tests/unit/test_prompt_manager.py

@@ -307,6 +307,87 @@ def test_prompt_manager_custom_system_prompt_filename_not_found(prompt_dir):
     """Test that PromptManager raises an error if custom system prompt file is not found."""
     with pytest.raises(
         FileNotFoundError,
-        match=r'System prompt file "non_existent\.j2" not found at .*/non_existent\.j2\. Please ensure the file exists in the prompt directory:',
+        match=r'Prompt file .*/non_existent\.j2 not found',
     ):
         PromptManager(prompt_dir=prompt_dir, system_prompt_filename='non_existent.j2')
+
+
+def test_jinja2_template_inheritance(prompt_dir):
+    """Test that PromptManager._load_template works with Jinja2 template inclusion.
+
+    This test demonstrates that we can use {% include %} to import a base system_prompt.j2
+    into other templates without defining any blocks in the base template, and that
+    PromptManager._load_template can load these templates correctly.
+    """
+    # Create base system prompt template (no blocks defined here)
+    with open(os.path.join(prompt_dir, 'system_prompt.j2'), 'w') as f:
+        f.write("""You are OpenHands agent, a helpful AI assistant that can interact with a computer to solve tasks.
+
+<ROLE>
+Your primary role is to assist users by executing commands, modifying code, and solving technical problems effectively.
+</ROLE>
+""")
+
+    # Create interactive system prompt that imports the base template and adds content
+    with open(os.path.join(prompt_dir, 'system_prompt_interactive.j2'), 'w') as f:
+        f.write("""{% include "system_prompt.j2" %}
+
+<INTERACTION_RULES>
+1. Always respond in a friendly, helpful manner
+2. Ask clarifying questions when needed
+3. Provide step-by-step explanations
+</INTERACTION_RULES>
+""")
+
+    # Create long horizon system prompt that imports the base template and adds content
+    with open(os.path.join(prompt_dir, 'system_prompt_long_horizon.j2'), 'w') as f:
+        f.write("""{% include "system_prompt.j2" %}
+
+<TASK_MANAGEMENT>
+1. Break down complex tasks into smaller steps
+2. Track progress through a TODO list
+3. Focus on one task at a time
+</TASK_MANAGEMENT>
+""")
+
+    # Test PromptManager._load_template with base system prompt
+    base_manager = PromptManager(prompt_dir=prompt_dir)
+    base_template = base_manager._load_template('system_prompt.j2')
+    base_msg = base_template.render().strip()
+    assert 'You are OpenHands agent' in base_msg
+    assert '<ROLE>' in base_msg
+    assert '<INTERACTION_RULES>' not in base_msg
+    assert '<TASK_MANAGEMENT>' not in base_msg
+
+    # Test PromptManager._load_template with interactive system prompt
+    interactive_manager = PromptManager(
+        prompt_dir=prompt_dir, system_prompt_filename='system_prompt_interactive.j2'
+    )
+    interactive_template = interactive_manager._load_template(
+        'system_prompt_interactive.j2'
+    )
+    interactive_msg = interactive_template.render().strip()
+    assert 'You are OpenHands agent' in interactive_msg
+    assert '<ROLE>' in interactive_msg
+    assert '<INTERACTION_RULES>' in interactive_msg
+    assert 'Ask clarifying questions when needed' in interactive_msg
+    assert '<TASK_MANAGEMENT>' not in interactive_msg
+
+    # Test PromptManager._load_template with long horizon system prompt
+    long_horizon_manager = PromptManager(
+        prompt_dir=prompt_dir, system_prompt_filename='system_prompt_long_horizon.j2'
+    )
+    long_horizon_template = long_horizon_manager._load_template(
+        'system_prompt_long_horizon.j2'
+    )
+    long_horizon_msg = long_horizon_template.render().strip()
+    assert 'You are OpenHands agent' in long_horizon_msg
+    assert '<ROLE>' in long_horizon_msg
+    assert '<INTERACTION_RULES>' not in long_horizon_msg
+    assert '<TASK_MANAGEMENT>' in long_horizon_msg
+    assert 'Track progress through a TODO list' in long_horizon_msg
+
+    # Clean up
+    os.remove(os.path.join(prompt_dir, 'system_prompt.j2'))
+    os.remove(os.path.join(prompt_dir, 'system_prompt_interactive.j2'))
+    os.remove(os.path.join(prompt_dir, 'system_prompt_long_horizon.j2'))