Added files for the GCHP GitHub repo suggested by Claude Code

[yantosca]

Name and Institution (Required)

Name: Bob Yantosca
Institution: Harvard + GCST

Describe the update

This PR adds repository-level files for the GCHP superproject, first suggested by Claude Code, and brings them up to date with the 14.8.0 release. The branch is rebased onto dev/no-diff-to-benchmark.

This PR is part of a set with geoschem/geos-chem#3350, geoschem/HEMCO#364, and geoschem/GCClassic#110, which add the same kinds of files to those repositories.

New files

File	Description
.gitattributes	Normalizes line endings to LF (* text=auto eol=lf), except *.bat, which keeps CRLF for cmd.exe; marks images, PDFs, and NetCDF (*.nc, *.nc4) as binary
.github/dependabot.yml	Tells GitHub to check if any GitHub actions (e.g. checkout) need updating. If so, a PR containing proposed fixes will be opened for GCST review.
CITATION.cff	How to cite GCHP (version 14.8.0, released 2026-09-15)
CLAUDE.md	Guidance for Claude Code: the 11 submodules and which owns what, the files this repo actually owns, root symlinks, build switches and their traps, run-directory workflow, CI coverage, MAPL3 status, docs build, contribution and release workflow
GOVERNANCE.md	Summary of the GEOS-Chem governance structure (GCSC, Working Groups, GCST), taken from existing documentation, and how a change becomes a release
SECURITY.md	Security policy covering GCHP and its submodules: private reporting through GitHub advisories; the primary threat class is arbitrary code execution when reading a data/config file

Modified files

File	Description
.github/PULL_REQUEST_TEMPLATE.md	Added an "AI disclosure" section
.release/changeVersionNumbers.sh	Now updates version and date-released in CITATION.cff, and exits with an error if those edits did not land. It no longer edits the geos-chem submodule's CHANGELOG.md or KPP/fullchem/CHANGELOG_fullchem.md; the geos-chem repo's own .release/changeVersionNumbers.sh (added in geoschem/geos-chem#3350) updates those
docs/make.bat	Stored with LF in the repository under the *.bat rule; still checked out with CRLF, so the file on disk is unchanged
CHANGELOG.md	Updated accordingly. Also corrected the HEMCO submodule changelog path at the top of the file (src/GCHP_GridComp/GEOSChem_GridComp/HEMCO/HEMCO)

Notes for reviewers

• CLAUDE.md documents that -DAPM=y is only partly wired in GCHP. geos-chem's CMake compiles apm_driv_mod.F90 and links the APM library, but GEOSChemBuildProperties in src/GCHP_GridComp/GEOSChem_GridComp/CMakeLists.txt never adds the APM compile definition, so the #if ... APM blocks in geos-chem stay compiled out. This PR only documents that; fixing it, or blocking APM in GCHP, would be a separate change. This is OK as there is no need for APM in GCHP right now.
• GOVERNANCE.md and CLAUDE.md say that zero-diff updates target dev/no-diff-to-benchmark, updates that change output target dev/X.Y.Z, and main receives only released versions.
• CLAUDE.md warns that there is no CI that compiles GCHP, and that a PR into any dev/* branch triggers the cloud benchmarking workflow.

Expected changes

This is a zero-diff update. No CMake, Fortran, or run-directory files are changed, and the submodule pointers are not changed. docs/make.bat changes only in how it is stored in the repository; it is still checked out with CRLF, so the file on disk is the same.

Related GitHub issues

• Added files for the GEOS-Chem "science codebase" GitHub repo suggested by Claude Code geos-chem#3350
• Added files for the GCClassic GitHub repository suggested by Claude Code GCClassic#110
• Added files for the HEMCO repository suggested by Claude Code HEMCO#364
• Added .gitattributes, CLAUDE.md, SECURITY.md, and .pylintrc (suggested by Claude Code) gcpy#435

AI disclosure

Claude Code (Claude Opus 5.5) was used to draft CLAUDE.md, CITATION.cff, GOVERNANCE.md, SECURITY.md, and .gitattributes, to update .release/changeVersionNumbers.sh, and to check these files against the code after the 14.8.0 release. All changes were reviewed by the author.

🤖 Generated with Claude Code

[yantosca]

All GEOS-Chem Classic execution tests passed.

==============================================================================
GEOS-Chem Classic: Execution Test Results

CodeDir   : 21eb4b2 HEMCO update: Merge PR #364 (Add files sugg. by Claude)
GEOS-Chem : ec4787028 Merge PR #3403 (Carbon HEMCO switches)
HEMCO     : 8c87680 Merge PR #364 (Add files suggested by Claude Code)
Cloud-J   : 16d18b0 Merge PR #34 (Fixed issues in format statements for verbose output)
HETP      : df2f942 Merge PR #4 (Multiphase aerosol chemistry, cf Travis et al 2025)

Using 24 OpenMP threads
Number of execution tests: 38

Submitted as SLURM job: 51160734
==============================================================================

Summary of test results:
------------------------------------------------------------------------------
Execution tests passed:   38
Execution tests failed:   0

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%  All execution tests passed!  %%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

GEOS-Chem Classic tests with differences w/r/t gcc.3.c00f393:

• Parallel error (known issue)
  • gc_4x5_merra2_fullchem_APM

All GCHP execution tests passed.

==============================================================================
GCHP: Execution Test Results

CodeDir       : 1893b9e HEMCO update: Merge PR #364 (Add files sugg. by Claude)
MAPL          : e87909dbc Merge PR #45 (ExtData2G, importing GC-Classic output data)
GMAO_Shared   : 4ddb3ec Merge pull request #2 from geoschem/feature/mapl-upgrade
ESMA_cmake    : 01bbf2f Merge pull request #9 from geoschem/feature/turn_off_f2py_builds_in_gchp
FMS           : 259759d1 Merge pull request #3 from geoschem/feature/update_gmao_libs
FVdycoreCubed : 9d86304 Merge PR #13 (Add option to get upwards mass flux as real4, not just real8)
geos-chem     : 4e085a04d Merge branch dev/no-diff-to-benchmark into feature/claude-code
HEMCO         : 8c87680 Merge PR #364 (Add files suggested by Claude Code)
Cloud-J       : 16d18b0 Merge PR #34 (Fixed issues in format statements for verbose output)
HETP          : df2f942 Merge PR #4 (Multiphase aerosol chemistry, cf Travis et al 2025)
GFE           : bac529f Merge pull request #40 from Goddard-Fortran-Ecosystem/feature/mathomp4/update-gftl-1.15.2

Number of execution tests: 12

Submitted as SLURM job: 51161073
==============================================================================

Summary of test results:
------------------------------------------------------------------------------
Execution tests passed:   12
Execution tests failed:   0

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%  All execution tests passed!  %%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

All GCHP tests were zero-diff w/r/t gchp.3.a2e9d65.