Slider widget does not trigger updates unless explicitly reloaded each time

[HariharanBalakrishnan22]

Describe the bug
The slider() component does not trigger updates or re-render downstream logic when the slider is moved. The UI only updates if the page is manually refreshed or the script is re-executed.

To Reproduce
Steps to reproduce the behavior:

1. Go to 'threshold = slider("Threshold", min_val=0, max_val=100)'
2. Do not use threshold.value anywhere else
3. Move the slider
4. Observe that the UI does not react or re-render any component

Expected behavior
I expected moving the slider to automatically trigger updates in dependent components or show some indication of interactivity.

Screenshots
If applicable, add screenshots to help explain your problem.

Environment:

• OS: macOS Ventura
• Browser: chrome
• Version: Cloud app

Additional context
After experimenting, I found that the slider only works when threshold.value is explicitly referenced in logic (e.g., filtering a dataframe). This makes sense based on the DAG model, but it might be confusing for new users. It would help to:
-Include better documentation around reactive input usage
-Offer a visual debugger or “reactive graph” view to show what's connected

[grajat90]

#699 Does not solve this issue. From initial analysis, it looks like a problem in the workflow engine. It somehow does not properly create atoms out of sliders, checkbox, etc.
In runner.py line 137-147:

            # determine affected components and force recomputation
            changed_component_ids = set(new_widget_states.keys())
            changed_atoms = {
                self._service.get_workflow().get_component_producer(cid)
                for cid in changed_component_ids
                if self._service.get_workflow().get_component_producer(cid)
            }

            affected = self._service.get_affected_components(changed_atoms)
            self._service.force_recompute(affected)

• Changed atoms is returned blank or without the complete list of affected atoms
• As a result, affected components returned is blank {} and force_recompute triggers recompute of no components

[shivam-singhal]

Working on fixing this ASAP

[grajat90]

I can confirm this does not fix the issue. widget updates still don't trigger properly. From what I see, the problem with the runner appears fixed now and frontend seems to be getting the proper recomputed data, but the frontend doesn't update it properly thereafter.

[shivam-singhal]

@HariharanBalakrishnan22 @grajat90 wait what's the issue then? re-renders should only happen if the value of the slider is used somewhere. otherwise, re-rendering based on an update to the slider would not be useful.

[grajat90]

Hey, yes I am using the latest code from main and not the pypi version. Let me attach a small clip to show what's happening:

preswald_issue.mp4

What to notice:

• On selecting a new value from the slider, it doesn't change data for all dependent components
• It was able to change data for the text immediately after it, but that's it
• On refreshing the page, components are shown properly with new updated value from slider
• Need to refresh the page every time for the effect to take place
• Yes, I can confirm I am using the correct new main branch for this with the updated code that re runs the entire script when no affected components are found
• I checked in debugging mode and prior to this PR that got merged, the runner would give the same un-updated components to the frontend in the websocket. However, after this update, I can confirm that the websocket is now receiving the updated components data. The issue now lies in the frontend where reactivity is not properly being handled. I have a working PR for this that I'll soon tag that fixes this

[grajat90]

@shivam-singhal Raised PR #711