diff --git a/packages/create-python-app-core/src/create_python_app_core/__init__.py b/packages/create-python-app-core/src/create_python_app_core/__init__.py
index 44b63d0..5e21b16 100644
--- a/packages/create-python-app-core/src/create_python_app_core/__init__.py
+++ b/packages/create-python-app-core/src/create_python_app_core/__init__.py
@@ -25,7 +25,12 @@
     read_cache_meta,
     write_cache_meta,
 )
-from create_python_app_core.paths import default_cache_dir, resolve_source
+from create_python_app_core.loaders import load_layer, merge_layers
+from create_python_app_core.paths import (
+    default_cache_dir,
+    get_template_dir_path,
+    resolve_source,
+)
 
 __all__ = [
     "__version__",
@@ -42,6 +47,9 @@
     "CacheMeta",
     "read_cache_meta",
     "write_cache_meta",
+    "merge_layers",
+    "load_layer",
+    "get_template_dir_path",
     "CPA_USER_AGENT",
     "check_for_latest_version",
     "check_python_version",
diff --git a/packages/create-python-app-core/src/create_python_app_core/loaders.py b/packages/create-python-app-core/src/create_python_app_core/loaders.py
new file mode 100644
index 0000000..d4e0783
--- /dev/null
+++ b/packages/create-python-app-core/src/create_python_app_core/loaders.py
@@ -0,0 +1,51 @@
+"""Template/extension file loaders and merge model."""
+
+from __future__ import annotations
+
+import shutil
+from pathlib import Path
+
+from create_python_app_core.errors import ManifestLoadError
+from create_python_app_core.paths import ResolvedSource, get_template_dir_path
+
+
+def copy_tree(src: Path, dest: Path, *, overwrite: bool = True) -> list[Path]:
+    """Copy files from src into dest. Returns list of written paths."""
+    written: list[Path] = []
+    if not src.is_dir():
+        raise ManifestLoadError(f"template directory not found: {src}")
+    dest.mkdir(parents=True, exist_ok=True)
+    for path in src.rglob("*"):
+        if path.is_dir():
+            continue
+        rel = path.relative_to(src)
+        target = dest / rel
+        if target.exists() and not overwrite:
+            continue
+        target.parent.mkdir(parents=True, exist_ok=True)
+        shutil.copy2(path, target)
+        written.append(target)
+    return written
+
+
+def load_layer(
+    source: ResolvedSource,
+    root: Path,
+    dest: Path,
+    *,
+    overwrite: bool = True,
+) -> list[Path]:
+    """Load one template/extension layer into dest."""
+    template_root = get_template_dir_path(source, root)
+    return copy_tree(template_root, dest, overwrite=overwrite)
+
+
+def merge_layers(
+    layers: list[tuple[ResolvedSource, Path]],
+    dest: Path,
+) -> list[Path]:
+    """Apply layers in order: template → addons → extend (later wins)."""
+    written: list[Path] = []
+    for source, root in layers:
+        written.extend(load_layer(source, root, dest, overwrite=True))
+    return written
diff --git a/packages/create-python-app-core/tests/test_loaders.py b/packages/create-python-app-core/tests/test_loaders.py
new file mode 100644
index 0000000..38299e5
--- /dev/null
+++ b/packages/create-python-app-core/tests/test_loaders.py
@@ -0,0 +1,24 @@
+from pathlib import Path
+
+from create_python_app_core.loaders import merge_layers
+from create_python_app_core.paths import ResolvedSource
+
+
+def _layer(tmp: Path, name: str, files: dict[str, str]) -> tuple[ResolvedSource, Path]:
+    root = tmp / name
+    tpl = root / "template"
+    for rel, content in files.items():
+        path = tpl / rel
+        path.parent.mkdir(parents=True, exist_ok=True)
+        path.write_text(content)
+    src = ResolvedSource(kind="file", url=f"file://{root}", local_path=root)
+    return src, root
+
+
+def test_merge_later_wins(tmp_path: Path) -> None:
+    a = _layer(tmp_path, "a", {"README.md": "a", "keep.txt": "keep"})
+    b = _layer(tmp_path, "b", {"README.md": "b"})
+    dest = tmp_path / "out"
+    merge_layers([a, b], dest)
+    assert (dest / "README.md").read_text() == "b"
+    assert (dest / "keep.txt").read_text() == "keep"