diff --git a/aggregate.py b/aggregate.py
index 8157880..4da1133 100644
--- a/aggregate.py
+++ b/aggregate.py
@@ -17,6 +17,7 @@ import glob
 from pathlib import Path, PureWindowsPath
 import summarize
 import project_manager
+from file_cache import ASTParser
 
 def find_next_increment(output_dir: Path, namespace: str) -> int:
     pattern = re.compile(rf"^{re.escape(namespace)}_(\d+)\.md$")
@@ -255,7 +256,17 @@ def build_tier3_context(file_items: list[dict], screenshot_base_dir: Path, scree
                 sections.append("### `" + (entry or path_str) + "`\n\n" + 
                                 f"```{path.suffix.lstrip('.') if path and path.suffix else 'text'}\n{item.get('content', '')}\n```")
             else:
-                sections.append(summarize.summarise_file(path, item.get("content", "")))
+                content = item.get("content", "")
+                if path and path.suffix == ".py" and not item.get("error"):
+                    try:
+                        parser = ASTParser("python")
+                        skeleton = parser.get_skeleton(content)
+                        sections.append(f"### `{entry or path_str}` (AST Skeleton)\n\n```python\n{skeleton}\n```")
+                    except Exception as e:
+                        # Fallback to summary if AST parsing fails
+                        sections.append(summarize.summarise_file(path, content))
+                else:
+                    sections.append(summarize.summarise_file(path, content))
                 
         parts.append("## Files (Tier 3 - Focused)\n\n" + "\n\n---\n\n".join(sections))
 
diff --git a/mcp_client.py b/mcp_client.py
index 7d31019..2ca791f 100644
--- a/mcp_client.py
+++ b/mcp_client.py
@@ -300,7 +300,7 @@ def get_definition(path: str, name: str) -> str:
 
     try:
         import ast
-        code = p.read_text(encoding="utf-8")
+        code = p.read_text(encoding="utf-8").lstrip(chr(0xFEFF))
         lines = code.splitlines()
         tree = ast.parse(code)
         
diff --git a/tests/test_tiered_context.py b/tests/test_tiered_context.py
index 6ad8712..c673095 100644
--- a/tests/test_tiered_context.py
+++ b/tests/test_tiered_context.py
@@ -24,13 +24,45 @@ def test_build_tier2_context_exists():
     result = build_tier2_context(file_items, Path("."), [], history)
     assert "Other content" in result
 
+def test_build_tier3_context_ast_skeleton(monkeypatch):
+    from unittest.mock import MagicMock
+    import aggregate
+    import file_cache
+    
+    # Mock ASTParser
+    mock_parser_instance = MagicMock()
+    mock_parser_instance.get_skeleton.return_value = "def other():\n    ..."
+    mock_parser_class = MagicMock(return_value=mock_parser_instance)
+    
+    # Mock file_cache.ASTParser in aggregate module
+    monkeypatch.setattr("aggregate.ASTParser", mock_parser_class)
+    
+    file_items = [
+        {"path": Path("other.py"), "entry": "other.py", "content": "def other():\n    pass", "error": False}
+    ]
+    history = []
+    
+    # New behavior check: it should use ASTParser for .py files not in focus
+    result = build_tier3_context(file_items, Path("."), [], history, focus_files=[])
+    
+    assert "def other():" in result
+    assert "..." in result
+    assert "Python" not in result # summarize.py output should not be there if AST skeleton is used
+    mock_parser_class.assert_called_once_with("python")
+    mock_parser_instance.get_skeleton.assert_called_once_with("def other():\n    pass")
+
 def test_build_tier3_context_exists():
     file_items = [
-        {"path": Path("focus.py"), "entry": "focus.py", "content": "Focus content", "error": False},
-        {"path": Path("other.py"), "entry": "other.py", "content": "Other content", "error": False}
+        {"path": Path("focus.py"), "entry": "focus.py", "content": "def focus():\n    pass", "error": False},
+        {"path": Path("other.py"), "entry": "other.py", "content": "def other():\n    pass", "error": False}
     ]
     history = ["User: hello"]
     result = build_tier3_context(file_items, Path("."), [], history, focus_files=["focus.py"])
     
-    assert "Focus content" in result
-    assert "Other content" not in result
+    assert "def focus():" in result
+    assert "pass" in result
+    # other.py should have skeletonized content, not full "pass" (if get_skeleton works)
+    # However, for a simple "pass", the skeleton might be the same or similar.
+    # Let's check for the header
+    assert "other.py" in result
+    assert "AST Skeleton" in result