Date: March 16, 2026 Analysis Method: MCP GraphRAG tools (find_env_dependencies, get_code_context, trace_data_flow, search_documentation) + codebase grep Scope: All CI platform configs, CI case YAMLs, CTest infrastructure, and downstream config.stage_ic.j2 templates

ICSDIR_ROOT is an environment variable exported by all 6 CI platform config scripts under dev/ci/platforms/. It provides the root path to pre-staged initial condition data used by CI test experiments. Analysis reveals that ICSDIR_ROOT is redundant with BASE_IC (defined per-platform in dev/workflow/hosts/<platform>.yaml), and the config.stage_ic.j2 template already has a built-in fallback that constructs ICSDIR from BASE_IC when the user-provided value is blank.

Verdict: Safe to remove from platform configs and most CI case YAMLs, with documented exceptions for 3 non-standard cases and a required CTest infrastructure update.

Both dev/parm/config/gfs/config.stage_ic.j2 and dev/parm/config/gefs/config.stage_ic.j2 contain:

export ICSDIR="{{ ICSDIR }}" # User provided ICSDIR; blank if not provided

# ...

# Set ICSDIR (if not defined)
if [[ -z "${ICSDIR}" ]] ; then
  dir_name="${CASE}${ensic:-}${ocnic:-}"
  ic_ver="${ic_versions[${dir_name}]}"
  export ICSDIR="${BASE_IC}/${dir_name}/${ic_ver}"
fi

When ICSDIR is blank (i.e., --icsdir not provided or empty), the template constructs the path automatically using:

• BASE_IC — platform-specific root from dev/workflow/hosts/<platform>.yaml
• Resolution — e.g., C96C48, C48mx500
• IC version — from versions/ic.ver

Note: Hercules and Orion have divergent paths (/work/ vs /work2/, glopara vs role-global). This should be verified to determine which is the current authoritative path before removing ICSDIR_ROOT.

All CI case YAMLs use Jinja templating to resolve the path:

icsdir: {{ 'ICSDIR_ROOT' | getenv }}/C96C48/20250808

All files under dev/ci/cases/pr/ and dev/ci/cases/weekly/ whose resolution+date matches ic.ver:

• pr/C96C48_hybatmDA.yaml, pr/C96_atm3DVar.yaml, pr/C96_atm3DVar_extended.yaml
• pr/C96C48_hybatmsnowDA.yaml, pr/C96C48_hybatmsoilDA.yaml, pr/C96C48_ufsgsi_hybatmDA.yaml
• pr/C96C48_ufs_hybatmDA.yaml, pr/C96C48mx500_S2SW_cyc_gfs.yaml
• pr/C48mx500_3DVarAOWCDA.yaml, pr/C48mx500_hybAOWCDA.yaml
• pr/C48_gsienkf_atmDA.yaml, pr/C48_ufsenkf_atmDA.yaml
• pr/C96_gcafs_cycled.yaml, pr/C96_gcafs_cycled_noDA.yaml
• pr/C96mx100_S2S.yaml
• weekly/C384C192_hybatmda.yaml, weekly/C384_atm3DVar.yaml

These use IC versions or paths that differ from ic.ver defaults and cannot rely on the fallback:

These 8 files could either keep explicit icsdir values (hardcoded paths instead of ICSDIR_ROOT + getenv) or have their IC versions added to versions/ic.ver.

Files under dev/ci/cases/gfsv17/ and pr/C48_S2SWA_gefs_RT.yaml already use platform-specific hardcoded paths and are unaffected by ICSDIR_ROOT removal.

CI platform config (exports ICSDIR_ROOT)
  → sourced by ci_utils.sh / driver_weekly.sh / launch_gitlab_runner.sh
    → YAML cases resolve {{ 'ICSDIR_ROOT' | getenv }} → icsdir value
      → create_experiment.py --yaml <case.yaml>
        → setup_expt.py maps icsdir → ICSDIR in experiment config
          → config.stage_ic.j2 (fallback: BASE_IC + resolution + ic.ver)
            → parm/stage/*.yaml.j2 templates use {{ ICSDIR }} for staging files

dev/ctests/CMakeLists.txt treats ICSDIR_ROOT as required:

set_from_env_or_default(ICSDIR_ROOT ICSDIR_ROOT "")
if (NOT DEFINED ICSDIR_ROOT)
  message(WARNING "ICSDIR_ROOT must be set. CTests will not be created.")
  return()
endif()

This would need to either:

• Remove the ICSDIR_ROOT requirement (since config.stage_ic.j2 handles the fallback)
• Or replace it with BASE_IC awareness

Also dev/ctests/scripts/setup.sh.in passes ICSDIR_ROOT to create_experiment.py directly:

ICSDIR_ROOT="${ICSDIR_ROOT}" \
./create_experiment.py --yaml "${YAML_FILE}" --overwrite

dev/ci/scripts/unittests/test_create_experiment.py explicitly sets ICSDIR_ROOT:

env['ICSDIR_ROOT'] = ICSDIR_FAKE

This would need updating to either remove the env var or set ICSDIR directly.

The MCP find_env_dependencies tool confirmed:

• ICSDIR_ROOT: 0 scripts found in the Neo4j graph — it exists only in CI infrastructure, not the operational workflow
• ICSDIR: 0 direct script dependencies, but GGSR weighted analysis revealed 15 config.stage_ic nodes with SETS_ENV relationships across experiment directories (C48_ATM, C96C48_hybatmDA, etc.)

This confirms ICSDIR is a config-level variable resolved at experiment creation time, not a runtime variable sourced by operational scripts.

1. Remove export ICSDIR_ROOT=... from all 6 platform configs
2. Remove icsdir: lines from the 19 standard PR/weekly YAML case files
3. Convert 8 non-standard cases to use hardcoded paths or update versions/ic.ver
4. Verify Hercules/Orion paths — determine if /work/ or /work2/ is current
5. Update CTest CMakeLists.txt — remove ICSDIR_ROOT requirement
6. Update unit test — remove ICSDIR_ROOT from env setup
7. Update versions/ic.ver — add C96mx025 entry if GCAFS/SFS cases should use the fallback