CCPP Framework Meeting Minutes 2026 06 04

Agenda

• GitHub issues/PRs
• New items
• Updates
• Other business
• notes

---

Attendees: Michael Kavulich, Jesse Nusbaumer, Dustin Swales, RhaeSung Kim, Courtney Peverley, Dom Heinzeller, Cheryl Craig

GitHub issues, PRs, discussions

PRs

• https://github.com/climbfuji/ccpp-scm/pull/4

Issues

• Update on capgen-ng Issue#759
  • Rethinking horizontal dimensions Issue#760

Drafts/On Hold

• New test to demonstrate GNU failure #689 - worth adding as additional test in capgen-ng?
  • Associated issue: Unallocated fields passed into Group Caps #690 will be closed by #759
• DRAFT FOR DOM: Feature/capgen_for_fuji #718 now CLOSED
• DRAFT Update to capgen-ng "sneak preview"

Capgen project board

New items for discussion

• CAM-SIMA compatibility layer in capgen-ng

Updates from last time

Previous notes

Other business

Meeting notes

capgen-ng progress

• Dom updated issue #759
  • New test for auto-clone constituents
  • Flag to enable auto-clone constituents (in metadata) for use by CAM-SIMA
  • NEPTUNE complete
  • CAM-SIMA python unit tests pass; kessler test passes with GNU
    • Had some tricky constituent mods
    • Added capgen compatibility layer to handle things CAM-SIMA does that framework tests didn’t do
  • CCPP-SCM all suites compile and all manual tests runs
    • Dustin made update to get single precision builds to work
• CAM-SIMA compatibility layer
  • Goal is to slowly phase out the compatibility layer
  • CAM-SIMA talks to top-level python interfaces in capgen, also gets back internal objects from capgen and uses parse tools, etc
    • Problematic to use non-”public” interfaces
    • SIMA would ultimately only like to interact with public interfaces
      • Can pull the fortran writer over into SIMA
    • Fortran writer lives in CAM-SIMA code base (but CCPP caps are still in fortran)
    • Changes to CAM-SIMA physics: renaming “finalize” to “final”; constituents can’t be intent(out) -> change to intent(inout)
      • Longer term differences: horizontal_loop_extent => horizontal_dimension; no auto-clone constituents (defined only in metadata)
• Long-term language interoperability?
  • We’d need a new interface to a new language; Dom recommends crossing the bridge when we get there
• Command-line interface vs python interface
  • capgen-ng has command-line, would we rather have python interface long-term?
  • Command line lends itself to cmake build system (used by non-SIMA models)
  • After Dom looked at CIME stuff, would like to build python interface as well (with feature parity - in/out should be equivalent)
    • Dom thinks it’d be pretty quick to create the python interfaces
• ccpp-physics meeting recap
  • Discussion was about physics cleanup; using suite / interstitial variables
  • In original capgen, if variable is not provided by the host model, it is handled by the caps (possibly promoted); new capgen has simplified version - everything lives in ccpp suite data module, defined at suite level
    • Everything is now allocated once
    • Potential problem with physics scheme itself wanting to allocate something? TBD.
• Dom open to new name suggestions for this new version of caggen