Aux source display names bypass SourceMetadata titles

[SimonHeybrock]

Context

SourceMetadata (introduced Jan 2026, 9fb104e6) added human-readable titles for source names, used in source selectors, plot toolbars, and status widgets via Instrument.get_source_title(). However, AuxSourcesBase (introduced Oct 2025, 75ccc48c) predates this and uses a separate mechanism — pydantic Field metadata — that never got connected to the source title system.

Problem

When the dashboard renders auxiliary source configuration (e.g., LOKI's incident/transmission monitors), users see raw stream names like monitor1 instead of titles like "Incident Monitor". Two independent gaps cause this:

Gap A — Widget labels ignore field_info.title: ParamWidget._create_widget_for_field() always uses snake_to_camel(field_name) for the widget label (e.g., incident_monitor → "IncidentMonitor"). It never checks field_info.title. This is inconsistent with ModelWidget, PlotConfigModal, WorkflowStatusWidget, and PlotWidgets, which all respect field_info.title.

Gap B — Dropdown options show raw stream names: For Literal['monitor1'] fields, ParamWidget builds options as {str(val): val} → {'monitor1': 'monitor1'}. There is no mechanism to look up the human-readable title from SourceMetadata. The ConfigurationAdapter.get_source_title() method exists but is only called by the source selector (MultiChoice for detectors), not by the aux sources widget.

It should be noted that for the source names (as opposed to axus source names) the UI does indeed correctly display the titles.

Affected instruments

All instruments with aux sources are affected:

• LOKI: incident_monitor (monitor1), transmission_monitor (monitor2) — titles defined in SourceMetadata but not displayed
• DREAM: cave_monitor (monitor_cave)
• Bifrost: detector_rotation, sample_rotation
• DetectorROIAuxSources: ROI stream (different pattern — uses render() for job-specific names)

Design tension

The aux source fields serve a dual purpose:

• Routing: Field values are stream names used by the backend for message routing (via AuxSourcesBase.render())
• Display: Field names and values appear in the configuration UI

SourceMetadata was designed for the source selector (detector/monitor MultiChoice) where internal names map to display titles. The aux sources widget is a generic pydantic model renderer (ParamWidget) with no access to Instrument configuration.

Possible approaches

These are starting points for discussion, not prescriptions:

• Minimal fix: Make ParamWidget respect field_info.title (fixes Gap A only). Add title= to aux source Field definitions. This doesn't fix the dropdown option labels (Gap B).
• Pass source metadata to ParamWidget: Thread Instrument or a title-lookup callable through ConfigurationAdapter → ConfigurationWidget → ParamWidget so Literal option labels can use SourceMetadata titles. This is more invasive but addresses both gaps.
• Use Field json_schema_extra or similar: Encode display titles in the aux source model itself, removing the need to look up SourceMetadata at render time. But this duplicates title information.