Release 4.2.2

What's Changed Here

• Cherry-picked the hybrid compilation fix (missing include) by @YoshuaNava #2483

What's Changed in 4.2.1

GTSAM 4.2.1 is a patch release on top of 4.2 focused on maintenance fixes, improved Python packaging, and release workflow updates.

Highlights

• Fixed several ISAM2 issues and added a regression test to ensure marginal-factor updates do not grow the graph unexpectedly.
• Improved Pose2 Python support by adding Jacobians for component extraction.
• Updated package metadata so downstream users correctly pick up required dependencies.
• Backported Python wheel release automation to the 4.2 maintenance line, including:
  • production wheel workflow
  • Python 3.11 through 3.14 build coverage
  • separate macOS arm64 and x86_64 wheel jobs
  • NumPy pinned to <2.0.0 for compatibility with the vendored pybind11 stack
• Improved compatibility with modern Boost and current CMake behavior in the release build pipeline.
• Fixed a missing include in testLinearEquality so the full check target passes cleanly on current toolchains.

Notable Changes Since 4.2

Core library and tests:

• ISAM2 bugfixes
• regression test for marginal-factor graph growth
• Pose2 component Jacobians exposed in Python
• Pose2 accessor behavior restored to the 4.2 API shape

Packaging and release engineering:

• version bump to 4.2.1
• updated package.xml dependency metadata
• backported Python wheel build scripts and release workflow
• Boost detection adjusted for newer environments while keeping Boost.Filesystem linked
• wheel bootstrap updated to build the required Boost components
• NumPy compatibility capped below 2.0.0

Compatibility Notes

• Python wheels are intended for Python 3.11 to 3.14.
• macOS wheels are now produced per architecture rather than labeled as universal2.
• NumPy is constrained to <2.0.0 in this release line.

Full Changelog: 4.2.1...4.2.2