added basic connection between the files, fixed small issues. some parts were achieved using ai.

route_planning.py

@@ -5,10 +5,16 @@ haTerm - v0.1
 haTerm is a Terminal Based hafas client, using the ivb endpoint.
 Prompt_toolkit (https://github.com/prompt-toolkit/python-prompt-toolkit) will be used to render a terminal user interface (TUI).
 The application will provide routing information and station departures/arrivals.
-"""
-#routenplanung mit promt tool kit
 
-import prompt_toolkit as pk
+Route planning UI.
+
+Wrapped in a function so it can be launched from `main.py` with a shared
+`HafasClient` instance from `backend.py`.
+
+Note: This module is a minimal TUI stub. Many features are not implemented
+yet (station lookup, route rendering). Add TODOs where appropriate.
+"""
+
 import time
 from prompt_toolkit import Application
 from prompt_toolkit.buffer import Buffer
@@ -17,25 +23,39 @@ from prompt_toolkit.layout.controls import BufferControl
 from prompt_toolkit.layout.layout import Layout
 from prompt_toolkit.key_binding import KeyBindings
 
-kb = KeyBindings()
-startBuffer = Buffer()
-endBuffer = Buffer()
+import backend
 
 
-root_container = HSplit(children=[
-    HSplit(children=[
-        Window(content=BufferControl(buffer=startBuffer, focusable=True)),
-        Window(width=1, char='-', style="fg:#2A71D5"),
+def run_route_planning(hafas: backend.HafasClient | None = None):
+    """Run the route planning TUI.
 
-        Window(content=BufferControl(buffer=endBuffer, focusable=True))
-    ]),
-    Window(height=1, char=' ', style="bg:#2A71D5 fg:black"),
-    #Window(content=BufferControl(buffer=userBuffer),height=4),
-])
+    Parameters:
+    - hafas: optional shared HafasClient instance. If omitted, a new one is
+      created. Prefer passing the shared client from `main.py`.
+    """
+    if hafas is None:
+        hafas = backend.HafasClient()
 
-layout = Layout(root_container)
+    # TODO: integrate actual station search + routing using `hafas`.
+    kb = KeyBindings()
+    startBuffer = Buffer()
+    endBuffer = Buffer()
 
-app = Application(layout=layout, key_bindings=kb, full_screen=True)
+    root_container = HSplit(children=[
+        HSplit(children=[
+            Window(content=BufferControl(buffer=startBuffer, focusable=True)),
+            Window(width=1, char='-', style="fg:#2A71D5"),
+            Window(content=BufferControl(buffer=endBuffer, focusable=True))
+        ]),
+        Window(height=1, char=' ', style="bg:#2A71D5 fg:black"),
+    ])
 
-app.run()
+    layout = Layout(root_container)
+    app = Application(layout=layout, key_bindings=kb, full_screen=True)
+
+    try:
+        app.run()
+    except KeyboardInterrupt:
+        # graceful exit on Ctrl-C
+        return