docs: RFC - Number Field Stepping

rfcs/2025-number-field-stepping.md

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+
+- Start Date: 2025-04-09
+- RFC PR:
+- Authors: @AndrewLeedham
+
+# Number Field Stepping
+
+## Summary
+
+The step option for number fields limits decimal places of the saved value, that is to say you cannot increment/decrement by a different precision that the value is stored.
+
+## Motivation
+
+Certain values (especially in science based domains) may want to be displayed with say 4 decimal places, but incrementing/decrementing by 0.0001 is too fine-grained, something like 0.1 or even 1 often makes more sense.
+
+## Detailed Design
+
+Introducing a new prop say `interval` which controls how the field is incremented/decremented across all mediums (buttons, arrow keys, mouse wheel etc.) would allow the value to be optionally specified separately from `step`. This prop should only influence incrementing and decrementing it should not round/clamp the value to the same number of decimal places as `step` does, but `step` should retain this behaviour.
+
+## Documentation
+
+Since the proposed `interval` prop does not change existing behaviour, a simple addition to the documentation should suffice.
+
+## Drawbacks
+
+- Explaining the difference between `step` and `interval` may be tricky.
+- This strays from built-in behaviour of number inputs which only provide the `step` option.
+
+## Backwards Compatibility Analysis
+
+No change.
+
+## Alternatives
+
+The only feasible alternative would be to rewrite the `<NumberField>` logic from scratch, or use a different library.
+
+## Open Questions
+
+Does having 2 options similarly named `step` and `interval` make sense or should it be `step` or `clamp` and `interval`?
+
+## Help Needed
+
+If we are happy with the approach, I am happy to give an implementation a go.
+
+## Frequently Asked Questions
+
+<!--
+    This section is optional but suggested.
+
+    Try to anticipate points of clarification that might be needed by
+    the people reviewing this RFC. Include those questions and answers
+    in this section.
+-->
+
+## Related Discussions
+
+- https://github.com/adobe/react-spectrum/issues/7288
+- https://github.com/adobe/react-spectrum/issues/6359
+- https://github.com/adobe/react-spectrum/issues/7867