How to prevent panel from expanding back after hitting minSize when container grows?

[callmeYe]

Summary

I'm not reporting a bug — I'm looking for guidance on how to achieve
a specific resize behavior when the container size changes dynamically.

Use Case

I have a chat-like layout with two panels stacked vertically:

• Panel A (input box): has minSize and maxSize constraints,
  and can be manually resized by the user via a resize handle
• Panel B (conversation area): no size constraints

<PanelGroup direction="vertical">
  <Panel>
    Panel B (conversation area)
  </Panel>
  <PanelResizeHandle />
  <Panel minSize={100} maxSize={200}>
    Panel A (input box)
  </Panel>
</PanelGroup>

Current Behavior

When the container shrinks:

1. Panel A and Panel B shrink proportionally ✅
2. Once Panel A hits minSize, only Panel B continues to shrink ✅

When the container grows back:
3. Panel A and Panel B both grow proportionally ❌

Expected Behavior

When the container grows back after Panel A has hit minSize:
3. Panel A should stay at minSize and remain unchanged
4. Only Panel B should grow to fill the extra space ✅

In other words, once Panel A has been "pinned" to its minSize due to
container shrinking, it should not automatically expand when the
container grows back — only Panel B should absorb the new space.

Real-World Scenario

This happens in practice when using browser DevTools:

1. Open DevTools docked to the bottom → container height shrinks
2. Panel A (input box) hits minSize and stops shrinking
3. Panel B (conversation area) continues to shrink ✅
4. Close DevTools → container height grows back
5. Both panels grow proportionally, causing Panel A (input box)
   to become disproportionately large again ❌

The user had previously manually resized Panel A to a comfortable
height. After the DevTools open/close cycle, Panel A is no longer
at the user's preferred size, which is a poor UX.

What I've Tried / What I'm Looking For

Is there a recommended way to achieve this behavior?

For example:

• Listening to a "panel hit minSize" event and locking Panel A's size?
• Using onLayout to detect and manually correct the layout after
  the container grows?
• Setting imperative panel ref to programmatically fix Panel A's
  size once it hits minSize?

Any guidance or workaround would be greatly appreciated!

[callmeYe]

DingTalk.Recording.Screen_2026-02-27.162001.mp4

[callmeYe]

sorry i just found #675

[bvaughn]

Maybe there's an element of this (the part that overlaps with #675) that this library will support, but I think a general "auto-shrink but don't auto-grow" UX is not one I'm going to try to support, at least for the time being.

Going to close this issue and we can continue the discussion over on #675.

Really promising work over on #677 so I think the issue you're asking about might be at least partially supported soon.