Is it possible that Hibernate Search doesn't have a built-in bridge to pad numbers??

Padding is not built-in. The documentation and in test code contain a PaddedIntegerBridge which you could use for build your own field bridge. This relates to HSEARCH-17

--Hardy

Seems like buying a car and then realizing you have to build the steering wheel... The Hibernate Search teem did such a great job on the product and didn't add the very basic but critical component of searching on numbers? Not a big deal.. and don't want to complain about what seems like an excellent product at an even better price :).

I think it was never done as the format to be used depends a lot on use cases, like having negative numbers or not, float precision and effectively know the min/max boundaries; it's really recommended that users make their own conscious decision about it rather than let the framework pick an implementation flavor.

Of course if you can come up with some general purpose utility which you think would always be useful, that would definitely be considered to be included.
Please remember padding then needs to be applied also at query time, so it must satisfy both sorting and query requirements, and possibly also two-way bridge to enable projections or use on primary keys.