Summary

Add driver support for the $minMaxScaler window operator. $minMaxScaler linearly rescales numeric values within a window to a target range using an observed minimum and maximum, and is valid only as an output expression inside $setWindowFields. The common normalization use case in $rankFusion / $scoreFusion is already covered by those stages' built-in normalization parameter (e.g. "normalization: minMaxScaler"); this ticket is for the standalone operator, which is the implementation building block behind that shorthand and is intended for power users building custom normalization workflows.

Motivation

Who is the affected end user?

Application developers building custom score normalization or general numeric rescaling inside $setWindowFields. Most users normalizing scores for fusion stages will rely on $rankFusion / $scoreFusion's
built-in normalization parameter and never reach for the standalone operator.

How does this affect the end user?

Annoyed — must inject $minMaxScaler via raw BSON when building custom $setWindowFields output expressions.

How likely is it that this problem or use case will occur?

Edge case. The standalone operator is the implementation building block behind the $scoreFusion shorthand "normalization: minMaxScaler"; the majority of users will use the shorthand and not need the operator
directly.

If the problem does occur, what are the consequences and how severe are they?

Friction and inconsistency; no severe runtime consequence.

Is this issue urgent?

Not urgent.

Is this ticket required by a downstream team?

Not directly required by Atlas / Shell / Compass.

Is this ticket only for tests?

No — functional builder API work.

Acceptance Criteria

Support for a $minMaxScaler window operator builder exists in each driver's $setWindowFields output builder surface.