diff --git a/README.md b/README.md
index 230b0c5..4f44168 100644
--- a/README.md
+++ b/README.md
@@ -24,6 +24,7 @@ source .venv/bin/activate         # Windows: .venv\Scripts\activate
 uv pip install .                  # install ICRS and dependencies
 uv run icrs                       # launches the GUI
 ```
+The launcher copies Tcl/Tk resources into the virtualenv on first run, so no manual environment tweaks are needed.
 To include the optional ttkbootstrap theme pack:
 ```bash
 uv pip install '.[ui]'
diff --git a/app/launcher.py b/app/launcher.py
new file mode 100644
index 0000000..80c61d4
--- /dev/null
+++ b/app/launcher.py
@@ -0,0 +1,50 @@
+"""Launcher ensuring Tcl/Tk resources are available before starting ICRS."""
+
+from __future__ import annotations
+
+import os
+import shutil
+import subprocess
+import sys
+from pathlib import Path
+
+
+def _copy_tcl_runtime(venv_root: Path) -> tuple[Path, Path] | None:
+    """Copy Tcl/Tk directories from the base interpreter into the venv if needed."""
+
+    base_prefix = Path(getattr(sys, "base_prefix", sys.prefix))
+    base_tcl_dir = base_prefix / "tcl"
+    if not base_tcl_dir.exists():
+        return None
+
+    tcl_src = base_tcl_dir / "tcl8.6"
+    tk_src = base_tcl_dir / "tk8.6"
+    if not tcl_src.exists() or not tk_src.exists():
+        return None
+
+    target_root = venv_root / "tcl"
+    tcl_dest = target_root / "tcl8.6"
+    tk_dest = target_root / "tk8.6"
+
+    if not tcl_dest.exists():
+        shutil.copytree(tcl_src, tcl_dest, dirs_exist_ok=True)
+    if not tk_dest.exists():
+        shutil.copytree(tk_src, tk_dest, dirs_exist_ok=True)
+
+    return tcl_dest, tk_dest
+
+
+def main() -> int:
+    venv_root = Path(sys.prefix)
+    tcl_paths = _copy_tcl_runtime(venv_root)
+
+    env = os.environ.copy()
+    if tcl_paths:
+        env.setdefault("TCL_LIBRARY", str(tcl_paths[0]))
+        env.setdefault("TK_LIBRARY", str(tcl_paths[1]))
+
+    return subprocess.call([sys.executable, "main.py"], env=env)
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())
diff --git a/pyproject.toml b/pyproject.toml
index eec0cc1..7981976 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -14,7 +14,7 @@ dependencies = [
 ui = ["ttkbootstrap>=1.10.0"]
 
 [project.scripts]
-icrs = "app.app:start_app"
+icrs = "app.launcher:main"
 
 [tool.uv]
 package = true