diff --git a/.github/AGENT_GUIDE.md b/.github/AGENT_GUIDE.md
index 79ce4de965..a1041058f4 100644
--- a/.github/AGENT_GUIDE.md
+++ b/.github/AGENT_GUIDE.md
@@ -208,7 +208,7 @@ Key constraints:
 - **Spin-up restart**: cold-start `init.nc` has zero hydrometeors. Ensemble generation runs 24h unperturbed first, then perturbs from the restart.
 - **PyCECT minimum members**: ensemble size must be >= number of output variables (~48). Default: 200.
 - **Time slice**: `run-perturb-mpas` invokes `trim_history.py` with `--tslice (Time.size - 1)`, producing files with exactly **one** time dimension (`Time=1`). PyCECT (`pyCECT.py` and `pyEnsSumMPAS.py`) is then called with `--tslice 0` — the only valid index in a single-slice file. There is no `ECT_TSLICE` knob in `ci-config.env`; changing the effective slice would require editing `run-perturb-mpas` (not config). Slice 0 in a cold-start (untrimmed) run is the unintegrated initial state, which is why we trim before validation.
-- ECT parameters and paths in `.github/ci-config.env` (`ECT_*`, `ECT_EXCLUDED_VARS`, `PYCECT_TAG`); the ECT release tag itself is derived at runtime from `Registry.xml` via the `mpas-version` composite action.
+- Per-case ECT parameters (archive, durations, perturbation, summary/restart names, excluded variables) are in `.github/ect-cases.yml`; PyCECT tag/commit stay in `.github/ci-config.env` (`PYCECT_*`); the ECT release tag itself is derived at runtime from `Registry.xml`.
 
 ## Shell Scripting Notes
 
@@ -233,3 +233,11 @@ Workflows accept `mpas-repository` and `mpas-ref` inputs for testing upstream MP
 
 - **NVHPC+OpenMPI**: model exits 134 (SIGABRT) on GA runners with 4 ranks. MPICH works. Caller workflows and reusable CPU/GPU jobs mark this combination `continue-on-error` until resolved.
 - **NVHPC/Intel MPI F08 bindings**: broken with hpcdev MPI libraries. Both use `MPAS_MPI_F08=0` workaround.
+
+### ECT cases (`.github/ect-cases.yml`)
+
+One table lists the ECT cases: `default` (used when a workflow's `ect-case` input is empty), `defaults` (shared values) and `cases`
+(per-case fields such as `summary-file`, `restart-file`, `resolution`, durations, perturbation; quote durations and magnitudes, YAML reads
+unquoted `1_00:00:00` as a number). Each workflow resolves its case once in its config job (`resolve-ect-case` action) and passes the
+values on as inputs. Run a case by typing its name into the `ect-case` input of `ect-test.yml` (or `ect-ensemble-gen.yml` to build its
+reference). A new case needs its own summary and restart assets in the ECT release. Results record the case in an `ect-case` column.
diff --git a/.github/actions/resolve-ect-case/action.yml b/.github/actions/resolve-ect-case/action.yml
new file mode 100644
index 0000000000..3c3f1fd14f
--- /dev/null
+++ b/.github/actions/resolve-ect-case/action.yml
@@ -0,0 +1,54 @@
+name: 'Resolve ECT case'
+description: >
+  Resolve one ECT case from .github/ect-cases.yml (defaults merged with the case) into explicit outputs. Run it in a workflow's
+  config job (the repository must be checked out) and pass the outputs on as inputs; nothing is read from the environment.
+
+inputs:
+  ect-case:
+    description: 'ECT case name (a key under `cases` in .github/ect-cases.yml). Empty = the table default.'
+    required: false
+    default: ''
+
+outputs:
+  case:
+    description: 'Resolved case name'
+    value: ${{ steps.resolve.outputs.case }}
+  resolution:
+    description: 'Test archive name (<resolution>.tar.gz, RELEASE_TESTDATA_<RES> in ci-config.env)'
+    value: ${{ steps.resolve.outputs.resolution }}
+  summary-file:
+    description: 'Ensemble summary release asset name'
+    value: ${{ steps.resolve.outputs.summary-file }}
+  restart-file:
+    description: 'Spin-up restart release asset name (stored gzipped)'
+    value: ${{ steps.resolve.outputs.restart-file }}
+  spinup-duration:
+    description: 'Spin-up duration (config_run_duration format)'
+    value: ${{ steps.resolve.outputs.spinup-duration }}
+  run-duration:
+    description: 'Duration of each ensemble/test member (config_run_duration format)'
+    value: ${{ steps.resolve.outputs.run-duration }}
+  ensemble-size:
+    description: 'Reference ensemble size'
+    value: ${{ steps.resolve.outputs.ensemble-size }}
+  perturb-variable:
+    description: 'Perturbed initial-condition variable'
+    value: ${{ steps.resolve.outputs.perturb-variable }}
+  perturb-magnitude:
+    description: 'Perturbation magnitude'
+    value: ${{ steps.resolve.outputs.perturb-magnitude }}
+  excluded-vars:
+    description: 'Path (relative to the repo root) of the excluded-variables file'
+    value: ${{ steps.resolve.outputs.excluded-vars }}
+
+runs:
+  using: 'composite'
+  steps:
+    - name: Resolve ECT case
+      id: resolve
+      shell: bash
+      env:
+        ECT_CASE_INPUT: ${{ inputs.ect-case }}
+      run: |
+        python3 -c "import yaml" 2>/dev/null || python3 -m pip install --quiet pyyaml
+        python3 "${GITHUB_WORKSPACE}/.github/scripts/resolve-ect-case.py" --case "${ECT_CASE_INPUT}" | tee -a "${GITHUB_OUTPUT}"
diff --git a/.github/actions/run-perturb-mpas/action.yml b/.github/actions/run-perturb-mpas/action.yml
index df5952a1f0..1e5bdfed7a 100644
--- a/.github/actions/run-perturb-mpas/action.yml
+++ b/.github/actions/run-perturb-mpas/action.yml
@@ -33,6 +33,12 @@ inputs:
     description: 'MPI implementation (openmpi, mpich)'
     required: false
     default: 'openmpi'
+  excluded-vars:
+    description: 'Path (relative to the repo root) of the file listing history variables to drop before PyCECT (from resolve-ect-case)'
+    required: true
+  perturb-magnitude:
+    description: 'Magnitude of the initial-condition perturbation (from resolve-ect-case)'
+    required: true
   gpu-aware-mpi:
     description: >
       Use GPU-aware MPI halo exchanges (config_gpu_aware_mpi = .true. in each member's namelist plus the MPI
@@ -124,8 +130,14 @@ runs:
         fi
 
         EXCLUDE_FILE=""
-        if [ -n "${ECT_EXCLUDED_VARS}" ]; then
-          EXCLUDE_FILE="${GITHUB_WORKSPACE}/${ECT_EXCLUDED_VARS}"
+        EXCLUDED_VARS="${{ inputs.excluded-vars }}"
+        PERTURB_MAGNITUDE="${{ inputs.perturb-magnitude }}"
+        if [ -z "${PERTURB_MAGNITUDE}" ]; then
+          echo "::error::perturb-magnitude is required (resolve it with the resolve-ect-case action)"
+          exit 1
+        fi
+        if [ -n "${EXCLUDED_VARS}" ]; then
+          EXCLUDE_FILE="${GITHUB_WORKSPACE}/${EXCLUDED_VARS}"
         fi
 
         mkdir -p "${OUTDIR}"
@@ -173,7 +185,7 @@ runs:
 
           echo "[$(date +%H:%M:%S)] Perturbing theta (seed=${MEMBER})..."
           python3 ${GITHUB_WORKSPACE}/.github/actions/run-perturb-mpas/perturb_theta.py \
-            "${PERTURB_FILE}" --seed ${MEMBER} --magnitude ${ECT_PERTURB_MAGNITUDE}
+            "${PERTURB_FILE}" --seed ${MEMBER} --magnitude ${PERTURB_MAGNITUDE}
 
           if [ "${VERBOSE}" = "true" ]; then
             echo "  Restart MD5: $(md5sum "${PERTURB_FILE}" | cut -d' ' -f1)"
diff --git a/.github/actions/run-perturb-mpas/trim_history.py b/.github/actions/run-perturb-mpas/trim_history.py
index 706b4268ef..81b3c21825 100644
--- a/.github/actions/run-perturb-mpas/trim_history.py
+++ b/.github/actions/run-perturb-mpas/trim_history.py
@@ -9,7 +9,7 @@
 areaTriangle) to compute global means. These static variables are
 preserved even though they lack a Time dimension.
 
-The ECT exclusion list path is configured via ECT_EXCLUDED_VARS in ci-config.env
+The ECT exclusion list path comes from the ECT case (excluded-vars in .github/ect-cases.yml)
 and passed via --exclude-file.
 
 Usage:
diff --git a/.github/actions/validate-ect/action.yml b/.github/actions/validate-ect/action.yml
index 62da7d62cd..dc7591df15 100644
--- a/.github/actions/validate-ect/action.yml
+++ b/.github/actions/validate-ect/action.yml
@@ -15,6 +15,13 @@ inputs:
   ect-tag:
     description: 'ECT data release tag (from the mpas-version action, e.g. ect-v8.4)'
     required: true
+  summary-file:
+    description: 'Ensemble summary release asset name for the ECT case (from resolve-ect-case)'
+    required: true
+  ect-case:
+    description: "Resolved ECT case name (from resolve-ect-case). Recorded as the 'ect-case' column of the result."
+    required: false
+    default: ''
   dimensions:
     description: 'Multi-line key=value pairs describing this test combination (written into result file)'
     required: false
@@ -44,7 +51,11 @@ runs:
 
         # ECT release tag is passed in, not stored in ci-config.env.
         # See .github/actions/mpas-version.
-        echo "summary-file=${ECT_SUMMARY_FILE}" >> $GITHUB_OUTPUT
+        if [ -z "${{ inputs.summary-file }}" ]; then
+          echo "::error::summary-file is required (resolve it with the resolve-ect-case action)"
+          exit 1
+        fi
+        echo "summary-file=${{ inputs.summary-file }}" >> $GITHUB_OUTPUT
         echo "pycect-tag=${PYCECT_TAG}" >> $GITHUB_OUTPUT
         echo "pycect-commit=${PYCECT_COMMIT}" >> $GITHUB_OUTPUT
         echo "release-tag=${{ inputs.ect-tag }}" >> $GITHUB_OUTPUT
@@ -207,4 +218,7 @@ runs:
           if [ -n "${DIMS}" ]; then
             echo "${DIMS}"
           fi
+          if [ -n "${{ inputs.ect-case }}" ]; then
+            echo "ect-case=${{ inputs.ect-case }}"
+          fi
         } > ect-result.txt
diff --git a/.github/ci-config.env b/.github/ci-config.env
index e54eab1b90..ba8e26d9da 100644
--- a/.github/ci-config.env
+++ b/.github/ci-config.env
@@ -102,17 +102,11 @@ RELEASE_TESTDATA_120KM=testdata-120km-v2
 
 
 # ── ECT configuration ────────────────────────────
-# Parameters for the Ensemble Consistency Test (PyCECT).
-# These are CI-specific settings not carried in the model namelist.
+# Per-case ECT settings (test archive, physics namelist overrides, run lengths, perturbation, summary/restart asset names,
+# excluded variables) live in ONE table, .github/ect-cases.yml, resolved by the .github/actions/resolve-ect-case action.
+# Only tool-level settings stay here.
 # Reference: Price-Broncucia et al. (2025), doi:10.5194/gmd-18-2349-2025
 
-ECT_RESOLUTION=120km
-ECT_ENSEMBLE_SIZE=200
-ECT_PERTURB_MAGNITUDE=1e-14
-ECT_PERTURB_VARIABLE=theta
-ECT_SUMMARY_FILE=mpas_ect_summary_120km.nc
-ECT_RESTART_FILE=120km-spinup-restart.nc
-ECT_EXCLUDED_VARS=.github/data/ect_excluded_vars.txt
 PYCECT_TAG=3.3.1
 PYCECT_COMMIT=b3c36a9d72ee211f396d1bc7078f6d5466916b0a
 
diff --git a/.github/ect-cases.yml b/.github/ect-cases.yml
new file mode 100644
index 0000000000..f38737434e
--- /dev/null
+++ b/.github/ect-cases.yml
@@ -0,0 +1,35 @@
+# ECT cases: one table, read by .github/actions/resolve-ect-case.
+#
+# A case = one ECT configuration (test archive, run lengths, perturbation, and the names of its
+# ensemble-summary and spin-up-restart release assets). Fields not set on a case come from `defaults`. Nothing here overrides
+# ci-config.env: containers, compilers, MPI flags, PyCECT version and test-data release tags stay in ci-config.env.
+# Workflows take an `ect-case` input (empty = `default`), resolve it once in their config job, and pass the resolved values on
+# as explicit inputs/outputs.
+#
+# Fields
+#   description         free text
+#   resolution          test-archive name; must have RELEASE_TESTDATA_<RES> in ci-config.env (the archive is <resolution>.tar.gz)
+#   summary-file        ensemble summary asset in the ECT release (ect-v{MAJOR.MINOR}); give each case its own name
+#   restart-file        spin-up restart asset in the ECT release (stored gzipped as <restart-file>.gz)
+#   spinup-duration     (QUOTE durations and magnitudes) unperturbed spin-up before the ensemble is perturbed (config_run_duration format)
+#   run-duration        length of each (perturbed) member
+#   ensemble-size       reference ensemble size (must be >= number of analysed variables; ~48 minimum)
+#   perturb-variable    initial-condition variable perturbed (O(1e-14), needs double precision)
+#   perturb-magnitude
+#   excluded-vars       file listing history variables dropped before PyCECT
+default: mesoscale_reference
+
+defaults:
+  resolution: 120km
+  spinup-duration: "1_00:00:00"       # quote durations: unquoted 1_00:00:00 would be read as a base-60 number
+  run-duration: "0_02:36:00"
+  ensemble-size: 200
+  perturb-variable: theta
+  perturb-magnitude: "1e-14"
+  excluded-vars: .github/data/ect_excluded_vars.txt
+
+cases:
+  mesoscale_reference:
+    description: 120km global mesh, mesoscale_reference physics suite as shipped in the archive's namelist
+    summary-file: mpas_ect_summary_120km.nc
+    restart-file: 120km-spinup-restart.nc
diff --git a/.github/scripts/resolve-ect-case.py b/.github/scripts/resolve-ect-case.py
new file mode 100755
index 0000000000..654d2d2146
--- /dev/null
+++ b/.github/scripts/resolve-ect-case.py
@@ -0,0 +1,41 @@
+#!/usr/bin/env python3
+"""Resolve one ECT case from .github/ect-cases.yml: defaults merged with the case, printed as key=value lines.
+
+usage: resolve-ect-case.py [--case NAME] [--table PATH]      (empty/omitted case = the table's `default`)
+Output keys: case, resolution, summary-file, restart-file, spinup-duration, run-duration,
+ensemble-size, perturb-variable, perturb-magnitude, excluded-vars.
+"""
+import argparse, sys
+from pathlib import Path
+try:
+    import yaml
+except ImportError:
+    sys.exit("::error::PyYAML is required (pip install pyyaml)")
+ap = argparse.ArgumentParser()
+ap.add_argument('--case', default='')
+ap.add_argument('--table', default=str(Path(__file__).resolve().parent.parent / 'ect-cases.yml'))
+a = ap.parse_args()
+t = yaml.safe_load(open(a.table))
+cases = t.get('cases') or {}
+name = a.case.strip() or t['default']
+if name not in cases:
+    sys.exit(f"::error::Unknown ECT case '{name}' in {a.table}. Available: {', '.join(cases)}")
+r = dict(t.get('defaults') or {}); r.update(cases[name] or {})
+required = ['resolution', 'summary-file', 'restart-file', 'spinup-duration', 'run-duration', 'perturb-variable',
+            'perturb-magnitude', 'excluded-vars']
+missing = [k for k in required if r.get(k) in (None, '')]
+if missing:
+    sys.exit(f"::error::ECT case '{name}' is missing required field(s): {', '.join(missing)}")
+for k in ['resolution', 'summary-file', 'restart-file', 'spinup-duration', 'run-duration', 'perturb-variable',
+          'perturb-magnitude', 'excluded-vars']:
+    if k in r and not isinstance(r[k], str):
+        sys.exit(f"::error::ECT case '{name}': field {k} must be a quoted string in {a.table} (got {type(r[k]).__name__} {r[k]!r}; "
+                 "YAML turns unquoted durations like 1_00:00:00 into numbers)")
+out = {'case': name}
+for k in ['resolution', 'summary-file', 'restart-file', 'spinup-duration', 'run-duration', 'ensemble-size', 'perturb-variable',
+          'perturb-magnitude', 'excluded-vars']:
+    out[k] = str(r.get(k, '')).strip()
+for k, v in out.items():
+    if '\n' in v:
+        sys.exit(f"::error::ECT case field {k} must be a single line")
+    print(f"{k}={v}")
diff --git a/.github/workflows/_test-compiler.yml b/.github/workflows/_test-compiler.yml
index c6bc1bd700..a4f387e76e 100644
--- a/.github/workflows/_test-compiler.yml
+++ b/.github/workflows/_test-compiler.yml
@@ -13,6 +13,11 @@ permissions:
 on:
   workflow_call:
     inputs:
+      ect-case:
+        description: 'ECT case (a key under `cases` in .github/ect-cases.yml). Empty = the table default (mesoscale_reference).'
+        required: false
+        type: string
+        default: ''
       compiler:
         description: 'Compiler family (gcc, nvhpc, oneapi)'
         required: true
@@ -39,6 +44,13 @@ jobs:
     outputs:
       image: ${{ steps.container.outputs.image }}
       ect-tag: ${{ steps.version.outputs.ect-tag }}
+      ect-resolution: ${{ steps.ectcase.outputs.resolution }}
+      ect-summary-file: ${{ steps.ectcase.outputs.summary-file }}
+      ect-restart-file: ${{ steps.ectcase.outputs.restart-file }}
+      ect-run-duration: ${{ steps.ectcase.outputs.run-duration }}
+      ect-excluded-vars: ${{ steps.ectcase.outputs.excluded-vars }}
+      ect-perturb-magnitude: ${{ steps.ectcase.outputs.perturb-magnitude }}
+      ect-case: ${{ steps.ectcase.outputs.case }}
     steps:
       - uses: actions/checkout@93cb6efe18208431cddfb8368fd83d5badbf9bfd # v5
         with:
@@ -54,6 +66,10 @@ jobs:
           mpi: ${{ inputs.mpi }}
       - uses: ./.github/actions/mpas-version
         id: version
+      - uses: ./.github/actions/resolve-ect-case
+        id: ectcase
+        with:
+          ect-case: ${{ inputs.ect-case }}
 
   build:
     needs: config
@@ -127,7 +143,7 @@ jobs:
         if: steps.download.outcome == 'success'
         uses: ./.github/actions/download-testdata
         with:
-          resolution: 120km
+          resolution: ${{ needs.config.outputs.ect-resolution }}
           dest-dir: base-case
 
       - name: Restore cached restart
@@ -136,7 +152,7 @@ jobs:
         uses: actions/cache/restore@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5
         with:
           path: spinup-restart.nc
-          key: ect-spinup-restart-${{ needs.config.outputs.ect-tag }}-${{ hashFiles('.github/ci-config.env') }}
+          key: ect-spinup-restart-${{ needs.config.outputs.ect-tag }}-${{ hashFiles('.github/ci-config.env') }}-${{ needs.config.outputs.ect-case }}
 
       - name: Download spin-up restart
         if: steps.download.outcome == 'success'
@@ -144,7 +160,7 @@ jobs:
         shell: bash
         run: |
           source .github/ci-config.env
-          RESTART="${ECT_RESTART_FILE}"
+          RESTART="${{ needs.config.outputs.ect-restart-file }}"
           RELEASE_TAG="${{ needs.config.outputs.ect-tag }}"
 
           if [ -f "spinup-restart.nc" ]; then
@@ -174,13 +190,15 @@ jobs:
         if: steps.download.outcome == 'success'
         uses: ./.github/actions/run-perturb-mpas
         with:
+          excluded-vars: ${{ needs.config.outputs.ect-excluded-vars }}
+          perturb-magnitude: ${{ needs.config.outputs.ect-perturb-magnitude }}
           base-dir: base-case
           executable: ./atmosphere_model
           member-start: '${{ matrix.member }}'
           member-end: '${{ matrix.member }}'
           num-ranks: '4'
           mpi-impl: ${{ inputs.mpi }}
-          run-duration: '0_02:36:00'
+          run-duration: ${{ needs.config.outputs.ect-run-duration }}
           run-timeout: '45'
           restart-file: ${{ steps.restart.outputs.available == 'true' && steps.restart.outputs.file || '' }}
 
@@ -224,6 +242,8 @@ jobs:
           history-dir: ect-test-files
           label: ${{ inputs.compiler }}/${{ inputs.mpi }}/smiol
           ect-tag: ${{ needs.config.outputs.ect-tag }}
+          summary-file: ${{ needs.config.outputs.ect-summary-file }}
+          ect-case: ${{ needs.config.outputs.ect-case }}
           dimensions: |
             compiler=${{ inputs.compiler }}
             mpi=${{ inputs.mpi }}
diff --git a/.github/workflows/_test-gpu.yml b/.github/workflows/_test-gpu.yml
index 4c44ffa426..c1eaefadbf 100644
--- a/.github/workflows/_test-gpu.yml
+++ b/.github/workflows/_test-gpu.yml
@@ -13,6 +13,11 @@ name: _test-gpu
 on:
   workflow_call:
     inputs:
+      ect-case:
+        description: 'ECT case (a key under `cases` in .github/ect-cases.yml). Empty = the table default (mesoscale_reference).'
+        required: false
+        type: string
+        default: ''
       mpi:
         description: 'MPI implementation (mpich, openmpi)'
         required: true
@@ -43,6 +48,13 @@ jobs:
       image: ${{ steps.container.outputs.image }}
       image-gpu: ${{ steps.gpu-container.outputs.image }}
       ect-tag: ${{ steps.version.outputs.ect-tag }}
+      ect-resolution: ${{ steps.ectcase.outputs.resolution }}
+      ect-summary-file: ${{ steps.ectcase.outputs.summary-file }}
+      ect-restart-file: ${{ steps.ectcase.outputs.restart-file }}
+      ect-run-duration: ${{ steps.ectcase.outputs.run-duration }}
+      ect-excluded-vars: ${{ steps.ectcase.outputs.excluded-vars }}
+      ect-perturb-magnitude: ${{ steps.ectcase.outputs.perturb-magnitude }}
+      ect-case: ${{ steps.ectcase.outputs.case }}
     steps:
       - uses: actions/checkout@v5
         with:
@@ -63,6 +75,10 @@ jobs:
           gpu: cuda
       - uses: ./.github/actions/mpas-version
         id: version
+      - uses: ./.github/actions/resolve-ect-case
+        id: ectcase
+        with:
+          ect-case: ${{ inputs.ect-case }}
 
   build:
     needs: config
@@ -148,7 +164,7 @@ jobs:
         if: steps.download.outcome == 'success'
         uses: ./.github/actions/download-testdata
         with:
-          resolution: 120km
+          resolution: ${{ needs.config.outputs.ect-resolution }}
           dest-dir: base-case
 
       - name: Restore cached restart
@@ -157,7 +173,7 @@ jobs:
         uses: actions/cache/restore@v5
         with:
           path: spinup-restart.nc
-          key: ect-spinup-restart-${{ needs.config.outputs.ect-tag }}-${{ hashFiles('.github/ci-config.env') }}
+          key: ect-spinup-restart-${{ needs.config.outputs.ect-tag }}-${{ hashFiles('.github/ci-config.env') }}-${{ needs.config.outputs.ect-case }}
 
       - name: Download spin-up restart
         if: steps.download.outcome == 'success'
@@ -165,7 +181,7 @@ jobs:
         shell: bash
         run: |
           source .github/ci-config.env
-          RESTART="${ECT_RESTART_FILE}"
+          RESTART="${{ needs.config.outputs.ect-restart-file }}"
           RELEASE_TAG="${{ needs.config.outputs.ect-tag }}"
 
           if [ -f "spinup-restart.nc" ]; then
@@ -195,13 +211,15 @@ jobs:
         if: steps.download.outcome == 'success'
         uses: ./.github/actions/run-perturb-mpas
         with:
+          excluded-vars: ${{ needs.config.outputs.ect-excluded-vars }}
+          perturb-magnitude: ${{ needs.config.outputs.ect-perturb-magnitude }}
           base-dir: base-case
           executable: ./atmosphere_model
           member-start: '${{ matrix.member }}'
           member-end: '${{ matrix.member }}'
           num-ranks: '4'
           mpi-impl: ${{ inputs.mpi }}
-          run-duration: '0_02:36:00'
+          run-duration: ${{ needs.config.outputs.ect-run-duration }}
           run-timeout: '45'
           restart-file: ${{ steps.restart.outputs.available == 'true' && steps.restart.outputs.file || '' }}
           gpu-aware-mpi: ${{ inputs.gpu-aware-mpi }}
@@ -245,6 +263,8 @@ jobs:
           history-dir: ect-test-files
           label: nvhpc/${{ inputs.mpi }}/cuda/smiol
           ect-tag: ${{ needs.config.outputs.ect-tag }}
+          summary-file: ${{ needs.config.outputs.ect-summary-file }}
+          ect-case: ${{ needs.config.outputs.ect-case }}
           dimensions: |
             compiler=nvhpc
             mpi=${{ inputs.mpi }}
diff --git a/.github/workflows/ect-ensemble-gen.yml b/.github/workflows/ect-ensemble-gen.yml
index 8a1dd1f9fd..0d40647380 100644
--- a/.github/workflows/ect-ensemble-gen.yml
+++ b/.github/workflows/ect-ensemble-gen.yml
@@ -12,6 +12,11 @@ name: ECT Ensemble Generation
 on:
   workflow_dispatch:
     inputs:
+      ect-case:
+        description: 'ECT case (a key under `cases` in .github/ect-cases.yml). Empty = the table default (mesoscale_reference).'
+        required: false
+        type: string
+        default: ''
       mpas-repository:
         description: 'MPAS source repo (e.g. MPAS-Dev/MPAS-Model). Leave empty to use this repo.'
         required: false
@@ -21,10 +26,10 @@ on:
         required: false
         default: ''
       ensemble-size:
-        description: 'Number of ensemble members to generate'
-        type: number
+        description: "Number of ensemble members to generate. Empty = the case's ensemble-size from .github/ect-cases.yml."
+        type: string
         required: false
-        default: 200
+        default: ''
       members-per-job:
         description: 'Number of ensemble members to run per job (batch size)'
         type: number
@@ -58,11 +63,25 @@ jobs:
       batches: ${{ steps.compute.outputs.batches }}
       ensemble-size: ${{ steps.compute.outputs.ensemble-size }}
       container-image: ${{ steps.container.outputs.image }}
+      ect-case: ${{ steps.ectcase.outputs.case }}
+      ect-resolution: ${{ steps.ectcase.outputs.resolution }}
+      ect-summary-file: ${{ steps.ectcase.outputs.summary-file }}
+      ect-restart-file: ${{ steps.ectcase.outputs.restart-file }}
+      ect-spinup-duration: ${{ steps.ectcase.outputs.spinup-duration }}
+      ect-run-duration: ${{ steps.ectcase.outputs.run-duration }}
+      ect-perturb-variable: ${{ steps.ectcase.outputs.perturb-variable }}
+      ect-perturb-magnitude: ${{ steps.ectcase.outputs.perturb-magnitude }}
+      ect-excluded-vars: ${{ steps.ectcase.outputs.excluded-vars }}
     steps:
       - uses: actions/checkout@v5
         with:
           sparse-checkout: .github
 
+      - uses: ./.github/actions/resolve-ect-case
+        id: ectcase
+        with:
+          ect-case: ${{ inputs.ect-case }}
+
       - uses: ./.github/actions/resolve-container
         id: container
         with:
@@ -72,7 +91,7 @@ jobs:
       - name: Compute batch ranges
         id: compute
         run: |
-          ESIZE=${{ inputs.ensemble-size || 200 }}
+          ESIZE=${{ inputs.ensemble-size || steps.ectcase.outputs.ensemble-size }}
           BATCH=${{ inputs.members-per-job || 10 }}
           echo "ensemble-size=${ESIZE}" >> $GITHUB_OUTPUT
 
@@ -172,7 +191,7 @@ jobs:
         uses: actions/cache/restore@v5
         with:
           path: spinup-restart.nc
-          key: ect-spinup-restart-${{ needs.build.outputs.ect-tag }}-${{ hashFiles('.github/ci-config.env') }}
+          key: ect-spinup-restart-${{ needs.build.outputs.ect-tag }}-${{ hashFiles('.github/ci-config.env') }}-${{ needs.prepare.outputs.ect-case }}
 
       - name: Download executable
         if: steps.cache.outputs.cache-hit != 'true'
@@ -189,21 +208,21 @@ jobs:
         uses: ./.github/actions/run-mpas
         with:
           executable: ./atmosphere_model
-          resolution: 120km
+          resolution: ${{ needs.prepare.outputs.ect-resolution }}
           num-procs: '4'
           mpi-impl: ${{ inputs.mpi-impl || 'mpich' }}
-          run-duration: '1_00:00:00'
-          restart-interval: '1_00:00:00'
+          run-duration: ${{ needs.prepare.outputs.ect-spinup-duration }}
+          restart-interval: ${{ needs.prepare.outputs.ect-spinup-duration }}
           run-timeout: '350'
           strict-exit-check: 'false'
 
       - name: Verify restart file
         if: steps.cache.outputs.cache-hit != 'true'
         run: |
-          RESTART=$(ls run-120km/restart.*.nc 2>/dev/null | head -1)
+          RESTART=$(ls run-${{ needs.prepare.outputs.ect-resolution }}/restart.*.nc 2>/dev/null | head -1)
           if [ -z "${RESTART}" ]; then
             echo "::error::Spin-up did not produce a restart file"
-            ls -la run-120km/*.nc 2>/dev/null || true
+            ls -la run-${{ needs.prepare.outputs.ect-resolution }}/*.nc 2>/dev/null || true
             exit 1
           fi
           echo "Spin-up restart: ${RESTART} ($(du -h ${RESTART} | cut -f1))"
@@ -214,7 +233,7 @@ jobs:
         uses: actions/cache/save@v5
         with:
           path: spinup-restart.nc
-          key: ect-spinup-restart-${{ needs.build.outputs.ect-tag }}-${{ hashFiles('.github/ci-config.env') }}
+          key: ect-spinup-restart-${{ needs.build.outputs.ect-tag }}-${{ hashFiles('.github/ci-config.env') }}-${{ needs.prepare.outputs.ect-case }}
 
       - name: Upload restart artifact
         uses: actions/upload-artifact@v6
@@ -252,7 +271,7 @@ jobs:
       - name: Download test case
         uses: ./.github/actions/download-testdata
         with:
-          resolution: 120km
+          resolution: ${{ needs.prepare.outputs.ect-resolution }}
           dest-dir: base-case
 
       - name: Download spin-up restart
@@ -263,13 +282,15 @@ jobs:
       - name: Run ensemble members ${{ matrix.batch.start }}-${{ matrix.batch.end }}
         uses: ./.github/actions/run-perturb-mpas
         with:
+          excluded-vars: ${{ needs.prepare.outputs.ect-excluded-vars }}
+          perturb-magnitude: ${{ needs.prepare.outputs.ect-perturb-magnitude }}
           base-dir: base-case
           executable: ./atmosphere_model
           member-start: ${{ matrix.batch.start }}
           member-end: ${{ matrix.batch.end }}
           num-ranks: ${{ inputs.num-ranks || 4 }}
           mpi-impl: ${{ inputs.mpi-impl || 'mpich' }}
-          run-duration: '0_02:36:00'
+          run-duration: ${{ needs.prepare.outputs.ect-run-duration }}
           run-timeout: '45'
           restart-file: spinup-restart.nc
 
@@ -320,9 +341,12 @@ jobs:
       - name: Collect metadata
         id: meta
         run: |
-          source .github/ci-config.env
+          ECT_SUMMARY_FILE="${{ needs.prepare.outputs.ect-summary-file }}"
+          ECT_RESOLUTION="${{ needs.prepare.outputs.ect-resolution }}"
+          ECT_PERTURB_MAGNITUDE="${{ needs.prepare.outputs.ect-perturb-magnitude }}"
+          ECT_PERTURB_VARIABLE="${{ needs.prepare.outputs.ect-perturb-variable }}"
+          RUN_DURATION="${{ needs.prepare.outputs.ect-run-duration }}"
           ECT_SUMMARY_PREFIX="${ECT_SUMMARY_FILE%.nc}"
-          RUN_DURATION=0_02:36:00
           VERSION="${{ needs.build.outputs.mpas-version }}"
           DATE=$(date -u +%Y-%m-%d)
           SUMMARY_NAME="${ECT_SUMMARY_PREFIX}_v${VERSION}_${DATE//-/}.nc"
@@ -470,7 +494,7 @@ jobs:
   # Auto-creates the release (tagged by version series) if it doesn't exist.
   #===========================================================================
   publish-restart:
-    needs: [build, spinup]
+    needs: [prepare, build, spinup]
     name: Publish Restart
     runs-on: ubuntu-latest
     permissions:
@@ -504,7 +528,7 @@ jobs:
               --notes "ECT ensemble summary and spin-up restart shared by all MPAS v${SERIES}.x releases. Generated from v${VERSION}. Updated automatically by the ect-ensemble-gen workflow."
           fi
 
-          RESTART_NAME="${ECT_RESTART_FILE}"
+          RESTART_NAME="${{ needs.prepare.outputs.ect-restart-file }}"
           mv spinup-restart.nc "${RESTART_NAME}"
 
           echo "Compressing ${RESTART_NAME} ($(du -h "${RESTART_NAME}" | cut -f1))..."
@@ -522,7 +546,7 @@ jobs:
   # Auto-creates the release (tagged by version series) if it doesn't exist.
   #===========================================================================
   publish-summary:
-    needs: [build, generate-summary]
+    needs: [prepare, build, generate-summary]
     if: needs.generate-summary.result == 'success'
     name: Publish Summary
     runs-on: ubuntu-latest
diff --git a/.github/workflows/ect-test.yml b/.github/workflows/ect-test.yml
index 7dfbf69baf..0f941fe83b 100644
--- a/.github/workflows/ect-test.yml
+++ b/.github/workflows/ect-test.yml
@@ -15,6 +15,11 @@ on:
     branches: [master]
   workflow_dispatch:
     inputs:
+      ect-case:
+        description: 'ECT case (a key under `cases` in .github/ect-cases.yml). Empty = the table default (mesoscale_reference).'
+        required: false
+        type: string
+        default: ''
       mpas-repository:
         description: 'MPAS source repo (e.g. MPAS-Dev/MPAS-Model). Leave empty to use this repo.'
         required: false
@@ -34,6 +39,13 @@ jobs:
     outputs:
       image: ${{ steps.container.outputs.image }}
       ect-tag: ${{ steps.version.outputs.ect-tag }}
+      ect-resolution: ${{ steps.ectcase.outputs.resolution }}
+      ect-summary-file: ${{ steps.ectcase.outputs.summary-file }}
+      ect-restart-file: ${{ steps.ectcase.outputs.restart-file }}
+      ect-run-duration: ${{ steps.ectcase.outputs.run-duration }}
+      ect-excluded-vars: ${{ steps.ectcase.outputs.excluded-vars }}
+      ect-perturb-magnitude: ${{ steps.ectcase.outputs.perturb-magnitude }}
+      ect-case: ${{ steps.ectcase.outputs.case }}
     steps:
       - uses: actions/checkout@v5
         with:
@@ -48,6 +60,10 @@ jobs:
           mpi: openmpi
       - uses: ./.github/actions/mpas-version
         id: version
+      - uses: ./.github/actions/resolve-ect-case
+        id: ectcase
+        with:
+          ect-case: ${{ inputs.ect-case }}
 
   #===========================================================================
   # BUILD
@@ -116,7 +132,7 @@ jobs:
       - name: Download test case
         uses: ./.github/actions/download-testdata
         with:
-          resolution: 120km
+          resolution: ${{ needs.config.outputs.ect-resolution }}
           dest-dir: base-case
 
       - name: Restore cached restart
@@ -124,14 +140,14 @@ jobs:
         uses: actions/cache/restore@v5
         with:
           path: spinup-restart.nc
-          key: ect-spinup-restart-${{ needs.config.outputs.ect-tag }}-${{ hashFiles('.github/ci-config.env') }}
+          key: ect-spinup-restart-${{ needs.config.outputs.ect-tag }}-${{ hashFiles('.github/ci-config.env') }}-${{ needs.config.outputs.ect-case }}
 
       - name: Download spin-up restart
         id: restart
         shell: bash
         run: |
           source .github/ci-config.env
-          RESTART="${ECT_RESTART_FILE}"
+          RESTART="${{ needs.config.outputs.ect-restart-file }}"
           RELEASE_TAG="${{ needs.config.outputs.ect-tag }}"
 
           if [ -f "spinup-restart.nc" ]; then
@@ -159,11 +175,13 @@ jobs:
       - name: Run perturbed MPAS-A
         uses: ./.github/actions/run-perturb-mpas
         with:
+          excluded-vars: ${{ needs.config.outputs.ect-excluded-vars }}
+          perturb-magnitude: ${{ needs.config.outputs.ect-perturb-magnitude }}
           base-dir: base-case
           executable: ./atmosphere_model
           member-start: ${{ matrix.member }}
           member-end: ${{ matrix.member }}
-          run-duration: '0_02:36:00'
+          run-duration: ${{ needs.config.outputs.ect-run-duration }}
           run-timeout: '45'
           restart-file: ${{ steps.restart.outputs.available == 'true' && steps.restart.outputs.file || '' }}
 
@@ -214,6 +232,8 @@ jobs:
           history-dir: ect-test-files
           label: gcc/openmpi/ect-standalone
           ect-tag: ${{ needs.config.outputs.ect-tag }}
+          summary-file: ${{ needs.config.outputs.ect-summary-file }}
+          ect-case: ${{ needs.config.outputs.ect-case }}
 
   #===========================================================================
   # CLEANUP