History mode: BPMN diagram shows no historic activity information (executed activities invisible)

[javahippie]

Summary

In the process instance view with history mode enabled, the BPMN diagram shows no instance-specific information: which activities were executed cannot be seen. For finished instances there is no activity highlighting at all.

Root cause (src/pages/Processes.jsx, ProcessDiagram)

is_instance_view = params.selection_id !== undefined && !history_mode

With history mode active the viewer falls back to mode="definition" and renders definition-wide statistics tokens. The only activity-instance data source in the API layer is the runtime endpoint /process-instance/{id}/activity-instances (src/api/resources/process_instance.js), which is deliberately skipped in history mode and returns nothing for finished instances. GET /history/activity-instance is not used anywhere in the codebase.

Expected (C7 Cockpit parity)

The history view badges each activity with the count of historic activity instances (executed/canceled markers included), sourced from GET /history/activity-instance?processInstanceId={id}.

Suggested implementation

• New history resource function (e.g. get_activity_instances_by_process_instance) + signal.
• Extend BPMNViewer (src/components/BPMNViewer.jsx) with a third token mode besides definition/instance — e.g. history — that renders per-activity counts from historic activity instances; completed vs. canceled state is available on each entry (canceled, endTime).
• In ProcessDiagram, use that mode when selection_id && history_mode.

Related: the historic task list gap in the same view is filed separately.