feat: no error display on sync integration and no test connectivity

[Davsooonowy]

Note

Left for further consideration.

Problem

Two gaps in the Integrations page UX:

1. When a sync fails (e.g. a typo in base_url), the user receives no feedback — the button returns to its default state silently and the error is lost
2. There was no way to verify a source's connectivity before saving configuration, meaning users only discovered misconfiguration after attempting a full sync

Solution

• Sync error notification
  When a sync is triggered, the button shows a spinner while the Celery task runs. The frontend polls /api/tasks/<task_id> every 2s until the task completes. On failure, a destructive Alert appears above the sources table with the error message returned by the task.

• Test Connection
  A "Test Connection" button is added to the Add/Edit source modal. It instantiates the plugin with the current config and attempts to fetch data without persisting anything.
  The result is shown inline — green on success, red with the error message on failure. Works for product sources, document sources, and e-commerce integrations.

Backend changes

• TaskStatusView — GET /api/tasks/<task_id> returns Celery task state and error string on failure
• TestProductSourceConnectionView, TestDocumentSourceConnectionView, TestECommerceConnectionView — POST /api/data_sets//{source_type}/test validates connectivity without
  side effects

Demo

Sync error alert

Screen.Recording.2026-04-03.at.14.45.04.mov

Test Connection

Screen.Recording.2026-04-03.at.14.46.36.mov

[Davsooonowy]

Note on the polling approach

The current implementation polls GET /api/tasks/<task_id> every 2s to detect sync failures. There's an open PR - #51 that saves synchronization status
directly to the database and builds a full sync history UI with error details surfaced there.

Once #51 lands, the polling approach here could be replaced with a simpler solution: read sync status from the DB (via a dedicated endpoint or WebSocket
push) rather than querying Celery's AsyncResult. This would also make the error state persistent - right now the alert disappears on page refresh.

Worth keeping in mind as a follow-up or coordinating with #51 before merging.

Priority is not high but it might be discussed :)
@rafalcymerys @mateus-po

[Davsooonowy]

close it for now - left for further consideration