index.bob: separate title logic from per-controller screens

- Per-controller screens always use their own PV prefix as title
- index.bob title uses EpicsGUIOptions.title if set, otherwise falls
  back to the first root controller's PV prefix or 'FastCS Devices'
- Setting title='' suppresses the title widget entirely (via pvi's
  new without_title() path when Device.label is empty)
- Document the ~30-character truncation limit in EpicsGUIOptions.title

Author: ggayDiamond

pyproject.toml

@@ -34,8 +34,8 @@ requires-python = ">=3.11"
 
 [project.optional-dependencies]
 demo = ["tickit~=0.4.3"]
-epicsca = ["pvi==0.14.0b1", "softioc>=4.5.0"]
-epicspva = ["p4p", "pvi==0.14.0b1"]
+epicsca = ["pvi==0.14.0b3", "softioc>=4.5.0"]
+epicspva = ["p4p", "pvi==0.14.0b3"]
 epics = ["fastcs[epicsca]", "fastcs[epicspva]"]
 tango = ["pytango"]
 graphql = ["strawberry-graphql", "uvicorn[standard]>=0.12.0"]

src/fastcs/transports/epics/emission.py

@@ -121,9 +121,7 @@ def emit_gui_files(
         controller_path = (output_dir / ui_filename).resolve()
 
         device = gui_builder(api).build_device(
-            options.title
-            if options.title is not None
-            else (api.path[0] if api.path else "FastCS Devices")
+            api.path[0] if api.path else "FastCS Devices"
         )
         formatter.format(device, controller_path)
 
@@ -138,15 +136,13 @@ def emit_gui_files(
         )
 
     index_path = (output_dir / f"{INDEX_STEM}{ext}").resolve()
-    index_title = (
-        options.title
-        if options.title is not None
-        else (
-            controller_apis[0].path[0]
-            if controller_apis and controller_apis[0].path
-            else "FastCS Devices"
-        )
-    )
+    if options.title is not None:
+        # Explicit title: use as-is (empty string suppresses the title widget)
+        index_title = options.title
+    elif controller_apis and controller_apis[0].path:
+        index_title = controller_apis[0].path[0]
+    else:
+        index_title = "FastCS Devices"
     formatter.format(Device(label=index_title, children=refs), index_path)
 
 

src/fastcs/transports/epics/options.py

@@ -29,7 +29,14 @@ class EpicsGUIOptions:
     output_dir: Path = Path(".")
     file_format: EpicsGUIFormat = EpicsGUIFormat.bob
     title: str | None = None
-    """Screen title. Defaults to the controller id when not provided."""
+    """Index screen title.
+
+    ``None`` (default): use the root controller PV prefix, or ``"FastCS Devices"``
+    if no root controller is present.  Set to ``""`` to suppress the title widget
+    entirely.
+
+    Note: titles longer than about 30 characters may be truncated in the
+    generated ``.bob`` screen."""
 
 
 @dataclass