diff --git a/configs/common/packages.yaml b/configs/common/packages.yaml
index ffff67872..47a19d437 100644
--- a/configs/common/packages.yaml
+++ b/configs/common/packages.yaml
@@ -223,7 +223,7 @@ packages:
       - ~netcdf
     hdf5:
       require:
-      - '@1.14.5'
+      - '@2.1.0'
       - +hl
       - +fortran
       - +mpi
@@ -301,9 +301,13 @@ packages:
     nemsiogfs:
       require:
       - '@2.5.4'
+    # Note: per spack, the first is "preferred", so if you
+    # need 1.9.0.1, you need to explicitly request it in your spec.
     nccmp:
       require:
-      - '@1.9.0.1'
+      - any_of:
+        - '@1.11.0.0'
+        - '@1.9.0.1'
     ncio:
       require:
       - '@1.1.2'
diff --git a/configs/sites/tier1/discover/README.md b/configs/sites/tier1/discover/README.md
new file mode 100644
index 000000000..f823e3279
--- /dev/null
+++ b/configs/sites/tier1/discover/README.md
@@ -0,0 +1,432 @@
+Discover (Tier 1 / JCSDA)
+
+---
+
+## Table of Contents
+
+- [Overview](#overview)
+- [Clone spack-stack](#clone-spack-stack)
+- [Setup spack-stack](#setup-spack-stack)
+- [Using batch\_install.sh script](#using-batch_installsh-script)
+  - [Help and dry-run](#help-and-dry-run)
+  - [Roles and modes](#roles-and-modes)
+  - [The -H flag](#the--h-flag)
+  - [The -e flag](#the--e-flag)
+  - [The -s flag](#the--s-flag)
+  - [The -a flag](#the--a-flag)
+  - [The -p, -q, and --constraint flags](#the--p--q-and---constraint-flags)
+  - [Typical workflow](#typical-workflow)
+  - [Environment names](#environment-names)
+  - [Loading the stack](#loading-the-stack)
+- [Adding or Updating a Single Package](#adding-or-updating-a-single-package)
+  - [Scenario A: Add an additional version](#scenario-a-add-an-additional-version)
+  - [Scenario B: Replace an existing version](#scenario-b-replace-an-existing-version)
+  - [Pushing to the build cache after manual changes](#pushing-to-the-build-cache-after-manual-changes)
+- [Updating a Package Build Recipe](#updating-a-package-build-recipe)
+- [Additional Options Reference](#additional-options-reference)
+- [Debugging Package Builds](#debugging-package-builds)
+
+---
+
+## Overview
+
+This configuration provides the Spack Stack setup for the Tier 1 JCSDA installation on the NASA Discover supercomputer. It is maintained under the JCSDA `/discover/swdev/` space.
+
+The site builds the `unified-dev` environment template with the following compilers:
+
+- `gcc@=14.2.0`
+- `oneapi@=2024.2.0`
+- `oneapi@=2025.3.0`
+
+Module files are managed with `lmod`. Shared caches are located under `/discover/swdev/jcsda/spack-stack/`.
+
+> **Note:** This site (`discover`) is distinct from the GMAO Tier 2 site (`discover-gmao`). The two sites use different cache locations, compiler sets, and environment templates. If you are doing GMAO-specific work, see `configs/sites/tier2/discover-gmao/README.md`.
+
+---
+
+## Clone spack-stack
+
+Use the appropriate branch or tag:
+
+### Fixed Tag - JCSDA
+
+```bash
+git clone --recurse-submodules https://github.com/JCSDA/spack-stack.git -b x.y.z spack-stack-x.y.z
+```
+
+### Development - JCSDA
+
+```bash
+git clone --recurse-submodules https://github.com/JCSDA/spack-stack.git -b develop spack-stack-dev
+```
+
+### Development - SI Team
+
+```bash
+git clone --recurse-submodules https://github.com/GMAO-SI-Team/spack-stack.git -b develop spack-stack-siteam
+```
+
+---
+
+## Setup spack-stack
+
+Activate the base spack-stack environment from the root of the repository:
+
+```bash
+cd spack-stack-dev
+. ./setup.sh
+```
+
+> **Important:** You must run `. ./setup.sh` before running interactive Spack commands. The `batch_install.sh` script sources `setup.sh` internally, so this step is not required before calling it.
+
+---
+
+## Using batch_install.sh script
+
+The `batch_install.sh` script automates environment creation, cache population, and the Spack installation pipeline. It is the recommended way to build or install the full stack on Discover.
+
+### Help and dry-run
+
+```bash
+./util/gmao/batch_install.sh -h
+```
+
+Before running a full build, use the `-n` (dry-run) flag to preview exactly what the script would execute without making any changes:
+
+```bash
+./util/gmao/batch_install.sh -r dev -m build -H discover -s -n
+```
+
+---
+
+### Roles and modes
+
+The script requires two key flags on every invocation:
+
+- **`-r ROLE`** — either `dev` or `ops`
+- **`-m MODE`** — either `build` or `install`
+
+| Role + Mode | What it does |
+|---|---|
+| `-r dev -m build` | For SI Team developers with write access to the shared mirrors. Builds packages from source and writes results to the **default shared build cache**. |
+| `-r dev -m install` | Installs packages from the shared build cache (no compilation) and generates module files. |
+| `-r ops -m build` | For operational partners **without** write access to the shared mirrors. Builds packages and writes to a **custom build cache** specified with `-c BUILDCACHE_DIR`. Allows partners to maintain their own binary cache independently. |
+| `-r ops -m install` | Installs packages from the shared build cache and generates module files. |
+
+The `-m install` step is **required** to generate usable `lmod` module files. A `-m build` run alone does not produce modules.
+
+---
+
+### The -H flag
+
+Always pass `-H discover` explicitly on Discover:
+
+```bash
+./util/gmao/batch_install.sh -r dev -m build -H discover -s
+```
+
+Without `-H`, the script autodetects the hostname by stripping digits and the domain suffix from `$HOSTNAME`. On a node like `discover23`, this produces `discover` correctly — but if you are logged into a node whose name does not strip cleanly (or if you are on a `discover-gmao`-type node), explicit `-H` avoids any ambiguity.
+
+---
+
+### The -e flag
+
+The `-e` flag tells the script to continue even if the environment directories already exist. Without it, the script exits with an error if any target environment directory is present.
+
+- On the **very first run**, you do not need `-e` (the directories do not exist yet).
+- On **every subsequent run** (rebuilds, retries, installs), you must pass `-e`.
+
+---
+
+### The -s flag
+
+The `-s` flag submits the `spack install` step to the SLURM scheduler via `salloc` rather than running it directly in your current shell. This is strongly recommended for full stack builds on Discover:
+
+- Allocates a single node with 120 tasks
+- Targets Milan nodes (`--constraint=mil`) by default
+- Walltime: 8 hours
+- Output is redirected to `spack.<hostname>.<env_name>.log` in the current directory
+
+If the default account (`s1873`) is active, the job defaults to `--partition=preops --qos=benchmark`. Use `-p`, `-q`, and `--constraint` to override these. See `-a`, `-p`, `-q`, and `--constraint` below.
+
+---
+
+### The -a flag
+
+Override the SLURM account (default: `s1873`):
+
+```bash
+./util/gmao/batch_install.sh -r dev -m build -H discover -s -a <YOUR_ACCOUNT>
+```
+
+When the account is `s1873`, the job defaults to `--partition=preops --qos=benchmark`. For any other account, no partition or QOS flags are set by default. Use `-p` and `-q` to override.
+
+---
+
+### The -p, -q, and --constraint flags
+
+Override the SLURM partition, QOS, and node constraint independently. These options only apply to NCCS hosts (`discover`, `discover-gmao`).
+
+```bash
+# Use a different partition
+./util/gmao/batch_install.sh -r dev -m build -H discover -s -p compute
+
+# Use a different QOS
+./util/gmao/batch_install.sh -r dev -m build -H discover -s -q high
+
+# Override the node constraint (default: mil for Milan nodes)
+./util/gmao/batch_install.sh -r dev -m build -H discover -s --constraint=cas
+
+# Override all three
+./util/gmao/batch_install.sh -r dev -m build -H discover -s -p compute -q normal --constraint=sky
+```
+
+`-p` and `-q` also accept long-option forms (`--partition=`, `--qos=`). `--constraint` has no short form because `-c` and `-C` are already in use.
+
+---
+
+### Typical workflow
+
+The normal progression from a fresh clone to a fully installed, module-ready stack is three steps:
+
+#### Step 1 — First run: build and populate caches
+
+On the very first run, use `-u` to populate the bootstrap, source, and cargo mirrors. This requires `-r dev -m build`.
+
+```bash
+./util/gmao/batch_install.sh -r dev -m build -H discover -s -u
+```
+
+- `-u`: Builds and populates the bootstrap mirror, source cache, and cargo mirror under `/discover/swdev/jcsda/spack-stack/`. Only needed once (or when the caches need to be refreshed).
+- `-s`: Submits the install step to SLURM.
+- No `-e` needed since the environment directories do not exist yet.
+
+#### Step 2 — Rebuild or retry runs
+
+After the first run, the environment directories exist and the caches are populated. Drop `-u` and add `-e`:
+
+```bash
+./util/gmao/batch_install.sh -r dev -m build -H discover -s -e
+```
+
+Use this if a build failed and you need to retry, or if you are iterating on the build configuration. The `-e` flag is required because the environment directories were created in Step 1.
+
+#### Step 3 — Install from cache and generate modules
+
+Once the build cache is ready, run in install mode to install from the cache and generate `lmod` module files:
+
+```bash
+./util/gmao/batch_install.sh -r dev -m install -H discover -s -e
+```
+
+This step is **required** to produce usable modules. The `-m build` steps above do not generate module files.
+
+---
+
+### Environment names
+
+The script creates one environment per compiler under `envs/` (relative to the repository root, unless overridden with `-d`):
+
+| Mode | Environment names created |
+|---|---|
+| `build` | `ue-gcc-14.2.0-build`, `ue-oneapi-2024.2.0-build`, `ue-oneapi-2025.3.0-build` |
+| `install` | `ue-gcc-14.2.0`, `ue-oneapi-2024.2.0`, `ue-oneapi-2025.3.0` |
+
+The `ue-` prefix comes from the `unified-dev` template used by this site.
+
+---
+
+### Loading the stack
+
+After the `install` step completes, point your shell to the generated module files:
+
+```bash
+module use -a /path/to/spack-stack/envs/ue-gcc-14.2.0/install/modulefiles/Core
+module load stack-gcc stack-openmpi
+```
+
+Replace `ue-gcc-14.2.0` with the appropriate environment name for your compiler of choice.
+
+---
+
+## Adding or Updating a Single Package
+
+If the full stack is already installed and you need to add or change a single package — for example, someone needs `nco@5.3.8` but `nco@5.3.9` was built — it is easier to work inside the environment directly rather than re-running the full `batch_install.sh` pipeline.
+
+First, activate spack-stack (required for interactive Spack commands) and activate the relevant environment:
+
+```bash
+. ./setup.sh
+cd envs/ue-gcc-14.2.0
+spack env activate -p .
+```
+
+### Scenario A: Add an additional version
+
+If you want both `nco@5.3.9` and `nco@5.3.8` to coexist as separate modules:
+
+1. Edit `spack.yaml` in the environment directory and add the additional spec:
+
+   ```yaml
+   specs:
+   - nco@5.3.9
+   - nco@5.3.8   # add this line
+   ```
+
+2. Re-concretize the environment:
+
+   ```bash
+   spack concretize 2>&1 | tee log.concretize
+   ```
+
+3. Install only the new package:
+
+   ```bash
+   spack install nco@5.3.8 2>&1 | tee log.install.nco
+   ```
+
+4. Refresh module files:
+
+   ```bash
+   spack module lmod refresh -y --delete-tree
+   spack stack setup-meta-modules
+   ```
+
+5. Deactivate when done:
+
+   ```bash
+   spack env deactivate
+   ```
+
+### Scenario B: Replace an existing version
+
+If you want to replace `nco@5.3.9` with `nco@5.3.8` (removing the old version):
+
+1. Edit `spack.yaml` to change the spec:
+
+   ```yaml
+   specs:
+   - nco@5.3.8   # was nco@5.3.9
+   ```
+
+2. Re-concretize:
+
+   ```bash
+   spack concretize 2>&1 | tee log.concretize
+   ```
+
+3. Install the new version:
+
+   ```bash
+   spack install nco@5.3.8 2>&1 | tee log.install.nco
+   ```
+
+4. Uninstall the old version:
+
+   ```bash
+   spack uninstall nco@5.3.9
+   ```
+
+5. Refresh module files:
+
+   ```bash
+   spack module lmod refresh -y --delete-tree
+   spack stack setup-meta-modules
+   ```
+
+6. Deactivate when done:
+
+   ```bash
+   spack env deactivate
+   ```
+
+### Pushing to the build cache after manual changes
+
+If you want the manually installed package to be available in the shared build cache for others to install from, push it after installation:
+
+```bash
+spack buildcache push -u local-binary
+spack buildcache update-index local-binary
+```
+
+> **Warning:** This writes to the default shared build cache at `/discover/swdev/jcsda/spack-stack/build-cache`. Only do this if you have write access and intend to publish the change.
+
+---
+
+## Updating a Package Build Recipe
+
+If a package needs a new version or checksum update (e.g., a new upstream release of `nco` or `cdo`), you can update the recipe and install the new version by hand without running the full pipeline.
+
+1. Update the Spack package recipe (e.g., in `var/spack/repos/` or the upstream Spack packages repo) to add the new version and checksum.
+
+2. Activate spack-stack (required for interactive Spack commands):
+
+   ```bash
+   . ./setup.sh
+   ```
+
+3. Activate the relevant environment:
+
+   ```bash
+   cd envs/ue-gcc-14.2.0
+   spack env activate -p .
+   ```
+
+4. If the version spec in `spack.yaml` needs to change, edit it now.
+
+5. Re-concretize:
+
+   ```bash
+   spack concretize 2>&1 | tee log.concretize
+   ```
+
+6. Install the updated package (Spack will only build what has changed):
+
+   ```bash
+   spack install <package>@<new_version> 2>&1 | tee log.install.<package>
+   ```
+
+7. Refresh module files:
+
+   ```bash
+   spack module lmod refresh -y --delete-tree
+   spack stack setup-meta-modules
+   ```
+
+8. Deactivate:
+
+   ```bash
+   spack env deactivate
+   ```
+
+---
+
+## Additional Options Reference
+
+The following flags are less commonly used. The descriptions below reflect our best current understanding; confirm with the SI Team if you need to use them.
+
+| Flag | Description |
+|---|---|
+| `-c BUILDCACHE_DIR` | Use a custom build cache directory. Required with `-r ops -m build` for operational partners who do not have write access to the shared mirrors. |
+| `-d ENV_DIRS` | Override the default environment directory (default: `envs/` in the repo root). |
+| `-C COMPILERS` | Comma-separated list of compilers to build (e.g., `gcc@=14.2.0,oneapi@=2025.3.0`). Overrides the site defaults. |
+| `-p` / `--partition` | Override the SLURM partition. Defaults to `preops` when account is `s1873`, otherwise unset. NCCS hosts only. |
+| `-q` / `--qos` | Override the SLURM QOS. Defaults to `benchmark` when account is `s1873`, otherwise unset. NCCS hosts only. |
+| `--constraint` | Override the SLURM node constraint. Defaults to `mil` (Milan nodes). No short form. NCCS hosts only. |
+| `-t` | Run tests for specific third-party dependencies after installation. The list of packages to test is hardcoded in `batch_install.sh`. |
+| `-u` | Populate bootstrap, source, and cargo mirrors. Requires `-r dev -m build`. Only needed on first run or when refreshing caches. |
+
+---
+
+## Debugging Package Builds
+
+If a specific package fails to build, drop into Spack's build environment to debug it manually:
+
+```bash
+spack clean <package>
+spack stage <package>
+cd $(spack location -s <package>)
+spack build-env <package> -- bash --norc --noprofile
+```
+
+This drops you into a clean bash shell with the exact environment variables, compiler wrappers, and dependencies loaded that Spack uses during the build.
diff --git a/configs/sites/tier2/discover-gmao/README.md b/configs/sites/tier2/discover-gmao/README.md
new file mode 100644
index 000000000..ed8b466be
--- /dev/null
+++ b/configs/sites/tier2/discover-gmao/README.md
@@ -0,0 +1,430 @@
+Discover GMAO
+
+---
+
+## Table of Contents
+
+- [Overview](#overview)
+- [Clone spack-stack](#clone-spack-stack)
+- [Setup spack-stack](#setup-spack-stack)
+- [Using batch\_install.sh script](#using-batch_installsh-script)
+  - [Help and dry-run](#help-and-dry-run)
+  - [Roles and modes](#roles-and-modes)
+  - [The -H flag](#the--h-flag)
+  - [The -e flag](#the--e-flag)
+  - [The -s flag](#the--s-flag)
+  - [The -a flag](#the--a-flag)
+  - [The -p, -q, and --constraint flags](#the--p--q-and---constraint-flags)
+  - [Typical workflow](#typical-workflow)
+  - [Environment names](#environment-names)
+  - [Loading the stack](#loading-the-stack)
+- [Adding or Updating a Single Package](#adding-or-updating-a-single-package)
+  - [Scenario A: Add an additional version](#scenario-a-add-an-additional-version)
+  - [Scenario B: Replace an existing version](#scenario-b-replace-an-existing-version)
+  - [Pushing to the build cache after manual changes](#pushing-to-the-build-cache-after-manual-changes)
+- [Updating a Package Build Recipe](#updating-a-package-build-recipe)
+- [Additional Options Reference](#additional-options-reference)
+- [Debugging Package Builds](#debugging-package-builds)
+
+---
+
+## Overview
+
+This configuration provides the Spack Stack setup for GMAO users on the NASA Discover supercomputer. It is a Tier 2 site (`discover-gmao`) maintained by the GMAO SI Team.
+
+The site builds the `geos-dev` environment template with the following compilers:
+
+- `gcc@=15.2.0`
+- `oneapi@=2024.2.0`
+- `oneapi@=2025.3.0`
+
+Module files are managed with `lmod`. Shared caches are located under `/discover/nobackup/projects/gmao/SIteam/spack-stack/`.
+
+---
+
+## Clone spack-stack
+
+Use the appropriate branch or tag:
+
+### Fixed Tag - JCSDA
+
+```bash
+git clone --recurse-submodules https://github.com/JCSDA/spack-stack.git -b x.y.z spack-stack-x.y.z
+```
+
+### Development - JCSDA
+
+```bash
+git clone --recurse-submodules https://github.com/JCSDA/spack-stack.git -b develop spack-stack-dev
+```
+
+### Development - SI Team
+
+```bash
+git clone --recurse-submodules https://github.com/GMAO-SI-Team/spack-stack.git -b develop spack-stack-siteam
+```
+
+---
+
+## Setup spack-stack
+
+Activate the base spack-stack environment from the root of the repository:
+
+```bash
+cd spack-stack-siteam
+. ./setup.sh
+```
+
+> **Important:** You must run `. ./setup.sh` before running interactive Spack commands. The `batch_install.sh` script sources `setup.sh` internally, so this step is not required before calling it.
+
+---
+
+## Using batch_install.sh script
+
+The `batch_install.sh` script automates environment creation, cache population, and the Spack installation pipeline. It is the recommended way to build or install the full stack on Discover.
+
+### Help and dry-run
+
+```bash
+./util/gmao/batch_install.sh -h
+```
+
+Before running a full build, use the `-n` (dry-run) flag to preview exactly what the script would execute without making any changes:
+
+```bash
+./util/gmao/batch_install.sh -r dev -m build -H discover-gmao -s -n
+```
+
+---
+
+### Roles and modes
+
+The script requires two key flags on every invocation:
+
+- **`-r ROLE`** — either `dev` or `ops`
+- **`-m MODE`** — either `build` or `install`
+
+| Role + Mode | What it does |
+|---|---|
+| `-r dev -m build` | For SI Team developers with write access to the shared mirrors. Builds packages from source and writes results to the **default shared build cache**. |
+| `-r dev -m install` | Installs packages from the shared build cache (no compilation) and generates module files. |
+| `-r ops -m build` | For operational partners **without** write access to the shared mirrors. Builds packages and writes to a **custom build cache** specified with `-c BUILDCACHE_DIR`. Allows partners to maintain their own binary cache independently. |
+| `-r ops -m install` | Installs packages from the shared build cache and generates module files. |
+
+The `-m install` step is **required** to generate usable `lmod` module files. A `-m build` run alone does not produce modules.
+
+---
+
+### The -H flag
+
+Always pass `-H discover-gmao` explicitly on Discover:
+
+```bash
+./util/gmao/batch_install.sh -r dev -m build -H discover-gmao -s
+```
+
+Without `-H`, the script autodetects the hostname by stripping digits and the domain suffix from `$HOSTNAME`. On a node like `discover23`, this produces `discover` (without the `-gmao` suffix), which is a different site configuration. Providing `-H discover-gmao` forces the correct site.
+
+---
+
+### The -e flag
+
+The `-e` flag tells the script to continue even if the environment directories already exist. Without it, the script exits with an error if any target environment directory is present.
+
+- On the **very first run**, you do not need `-e` (the directories do not exist yet).
+- On **every subsequent run** (rebuilds, retries, installs), you must pass `-e`.
+
+---
+
+### The -s flag
+
+The `-s` flag submits the `spack install` step to the SLURM scheduler via `salloc` rather than running it directly in your current shell. This is strongly recommended for full stack builds on Discover:
+
+- Allocates a single node with 120 tasks
+- Targets Milan nodes (`--constraint=mil`)
+- Walltime: 8 hours
+- Output is redirected to `spack.<hostname>.<env_name>.log` in the current directory
+
+If the default account (`s1873`) is active, the job defaults to `--partition=preops --qos=benchmark`. Use `-p`, `-q`, and `--constraint` to override these. See `-a`, `-p`, `-q`, and `--constraint` below.
+
+---
+
+### The -a flag
+
+Override the SLURM account (default: `s1873`):
+
+```bash
+./util/gmao/batch_install.sh -r dev -m build -H discover-gmao -s -a <YOUR_ACCOUNT>
+```
+
+When the account is `s1873`, the job defaults to `--partition=preops --qos=benchmark`. For any other account, no partition or QOS flags are set by default. Use `-p` and `-q` to override.
+
+---
+
+### The -p, -q, and --constraint flags
+
+Override the SLURM partition, QOS, and node constraint independently:
+
+```bash
+# Use a different partition
+./util/gmao/batch_install.sh -r dev -m build -H discover-gmao -s -p compute
+
+# Use a different QOS
+./util/gmao/batch_install.sh -r dev -m build -H discover-gmao -s -q high
+
+# Override the node constraint (default: mil for Milan nodes)
+./util/gmao/batch_install.sh -r dev -m build -H discover-gmao -s --constraint=cas
+
+# Override all three
+./util/gmao/batch_install.sh -r dev -m build -H discover-gmao -s -p compute -q normal --constraint=sky
+```
+
+`-p` and `-q` also accept long-option forms (`--partition=`, `--qos=`). `--constraint` has no short form because `-c` and `-C` are already in use.
+
+These flags override the site defaults regardless of the account. Useful when working under a non-`s1873` account that still has access to specific partitions, QOS levels, or node types.
+
+---
+
+### Typical workflow
+
+The normal progression from a fresh clone to a fully installed, module-ready stack is three steps:
+
+#### Step 1 — First run: build and populate caches
+
+On the very first run, use `-u` to populate the bootstrap, source, and cargo mirrors. This requires `-r dev -m build`.
+
+```bash
+./util/gmao/batch_install.sh -r dev -m build -H discover-gmao -s -u
+```
+
+- `-u`: Builds and populates the bootstrap mirror, source cache, and cargo mirror under `/discover/nobackup/projects/gmao/SIteam/spack-stack/`. Only needed once (or when the caches need to be refreshed).
+- `-s`: Submits the install step to SLURM.
+- No `-e` needed since the environment directories do not exist yet.
+
+#### Step 2 — Rebuild or retry runs
+
+After the first run, the environment directories exist and the caches are populated. Drop `-u` and add `-e`:
+
+```bash
+./util/gmao/batch_install.sh -r dev -m build -H discover-gmao -s -e
+```
+
+Use this if a build failed and you need to retry, or if you are iterating on the build configuration. The `-e` flag is required because the environment directories were created in Step 1.
+
+#### Step 3 — Install from cache and generate modules
+
+Once the build cache is ready, run in install mode to install from the cache and generate `lmod` module files:
+
+```bash
+./util/gmao/batch_install.sh -r dev -m install -H discover-gmao -s -e
+```
+
+This step is **required** to produce usable modules. The `-m build` steps above do not generate module files.
+
+---
+
+### Environment names
+
+The script creates one environment per compiler under `envs/` (relative to the repository root, unless overridden with `-d`):
+
+| Mode | Environment names created |
+|---|---|
+| `build` | `ge-gcc-15.2.0-build`, `ge-oneapi-2024.2.0-build`, `ge-oneapi-2025.3.0-build` |
+| `install` | `ge-gcc-15.2.0`, `ge-oneapi-2024.2.0`, `ge-oneapi-2025.3.0` |
+
+---
+
+### Loading the stack
+
+After the `install` step completes, point your shell to the generated module files:
+
+```bash
+module use -a /path/to/spack-stack-siteam/envs/ge-gcc-15.2.0/install/modulefiles/Core
+module load stack-gcc stack-openmpi geos-gcm-env
+```
+
+Replace `ge-gcc-15.2.0` with the appropriate environment name for your compiler of choice.
+
+---
+
+## Adding or Updating a Single Package
+
+If the full stack is already installed and you need to add or change a single package — for example, someone needs `nco@5.3.8` but `nco@5.3.9` was built — it is easier to work inside the environment directly rather than re-running the full `batch_install.sh` pipeline.
+
+First, activate spack-stack (required for interactive Spack commands) and activate the relevant environment:
+
+```bash
+. ./setup.sh
+cd envs/ge-gcc-15.2.0
+spack env activate -p .
+```
+
+### Scenario A: Add an additional version
+
+If you want both `nco@5.3.9` and `nco@5.3.8` to coexist as separate modules:
+
+1. Edit `spack.yaml` in the environment directory and add the additional spec:
+
+   ```yaml
+   specs:
+   - nco@5.3.9
+   - nco@5.3.8   # add this line
+   ```
+
+2. Re-concretize the environment:
+
+   ```bash
+   spack concretize 2>&1 | tee log.concretize
+   ```
+
+3. Install only the new package:
+
+   ```bash
+   spack install nco@5.3.8 2>&1 | tee log.install.nco
+   ```
+
+4. Refresh module files:
+
+   ```bash
+   spack module lmod refresh -y --delete-tree
+   spack stack setup-meta-modules
+   ```
+
+5. Deactivate when done:
+
+   ```bash
+   spack env deactivate
+   ```
+
+### Scenario B: Replace an existing version
+
+If you want to replace `nco@5.3.9` with `nco@5.3.8` (removing the old version):
+
+1. Edit `spack.yaml` to change the spec:
+
+   ```yaml
+   specs:
+   - nco@5.3.8   # was nco@5.3.9
+   ```
+
+2. Re-concretize:
+
+   ```bash
+   spack concretize 2>&1 | tee log.concretize
+   ```
+
+3. Install the new version:
+
+   ```bash
+   spack install nco@5.3.8 2>&1 | tee log.install.nco
+   ```
+
+4. Uninstall the old version:
+
+   ```bash
+   spack uninstall nco@5.3.9
+   ```
+
+5. Refresh module files:
+
+   ```bash
+   spack module lmod refresh -y --delete-tree
+   spack stack setup-meta-modules
+   ```
+
+6. Deactivate when done:
+
+   ```bash
+   spack env deactivate
+   ```
+
+### Pushing to the build cache after manual changes
+
+If you want the manually installed package to be available in the shared build cache for others to install from, push it after installation:
+
+```bash
+spack buildcache push -u local-binary
+spack buildcache update-index local-binary
+```
+
+> **Warning:** This writes to the default shared build cache at `/discover/nobackup/projects/gmao/SIteam/spack-stack/build-cache`. Only do this if you have write access and intend to publish the change.
+
+---
+
+## Updating a Package Build Recipe
+
+If a package needs a new version or checksum update (e.g., a new upstream release of `nco` or `cdo`), you can update the recipe and install the new version by hand without running the full pipeline.
+
+1. Update the Spack package recipe (e.g., in `var/spack/repos/` or the upstream Spack packages repo) to add the new version and checksum.
+
+2. Activate spack-stack (required for interactive Spack commands):
+
+   ```bash
+   . ./setup.sh
+   ```
+
+3. Activate the relevant environment:
+
+   ```bash
+   cd envs/ge-gcc-15.2.0
+   spack env activate -p .
+   ```
+
+4. If the version spec in `spack.yaml` needs to change, edit it now.
+
+5. Re-concretize:
+
+   ```bash
+   spack concretize 2>&1 | tee log.concretize
+   ```
+
+6. Install the updated package (Spack will only build what has changed):
+
+   ```bash
+   spack install <package>@<new_version> 2>&1 | tee log.install.<package>
+   ```
+
+7. Refresh module files:
+
+   ```bash
+   spack module lmod refresh -y --delete-tree
+   spack stack setup-meta-modules
+   ```
+
+8. Deactivate:
+
+   ```bash
+   spack env deactivate
+   ```
+
+---
+
+## Additional Options Reference
+
+The following flags are less commonly used. The descriptions below reflect our best current understanding; confirm with the SI Team if you need to use them.
+
+| Flag | Description |
+|---|---|
+| `-c BUILDCACHE_DIR` | Use a custom build cache directory. Required with `-r ops -m build` for operational partners who do not have write access to the shared mirrors. |
+| `-d ENV_DIRS` | Override the default environment directory (default: `envs/` in the repo root). |
+| `-C COMPILERS` | Comma-separated list of compilers to build (e.g., `gcc@=15.2.0,oneapi@=2025.3.0`). Overrides the site defaults. |
+| `-p` / `--partition` | Override the SLURM partition. Defaults to `preops` when account is `s1873`, otherwise unset. |
+| `-q` / `--qos` | Override the SLURM QOS. Defaults to `benchmark` when account is `s1873`, otherwise unset. |
+| `--constraint` | Override the SLURM node constraint. Defaults to `mil` (Milan nodes). No short form (`-c`/`-C` are taken). |
+| `-t` | Run tests for specific third-party dependencies after installation. The list of packages to test is hardcoded in `batch_install.sh`. |
+| `-u` | Populate bootstrap, source, and cargo mirrors. Requires `-r dev -m build`. Only needed on first run or when refreshing caches. |
+
+---
+
+## Debugging Package Builds
+
+If a specific package fails to build, drop into Spack's build environment to debug it manually:
+
+```bash
+spack clean <package>
+spack stage <package>
+cd $(spack location -s <package>)
+spack build-env <package> -- bash --norc --noprofile
+```
+
+This drops you into a clean bash shell with the exact environment variables, compiler wrappers, and dependencies loaded that Spack uses during the build.
diff --git a/configs/sites/tier2/macos.gmao/README.md b/configs/sites/tier2/macos.gmao/README.md
index f67a80d46..78f3661b3 100644
--- a/configs/sites/tier2/macos.gmao/README.md
+++ b/configs/sites/tier2/macos.gmao/README.md
@@ -99,7 +99,7 @@ The `batch_install.sh` script automates the creation of environments (e.g., `gcc
 
 ### Compiler Selection and Auto-Detection
 
-By default, `batch_install.sh` builds the `gcc@=15.2.0` stack. 
+By default, `batch_install.sh` builds the `gcc@=15.3.0` stack. 
 
 The script will automatically detect your currently active version of Apple Clang (e.g. `apple-clang@21.0.0`) and substitute it into the templates. If the NAG Fortran compiler (`nagfor`) is found in your `PATH`, the script will automatically detect its version as well and add it to the build queue (e.g., `nag@=7.2.7243`). 
 
@@ -112,7 +112,7 @@ If your NAG compiler is installed in a non-standard location and not in your `PA
 If you want to explicitly override the compilers built by the script entirely, use the `-C` flag with a comma-separated list of Spack compiler specs:
 
 ```bash
-./util/gmao/batch_install.sh -C "gcc@=15.2.0,nag@=7.2.7243" -r dev -m build -H macos.gmao -e
+./util/gmao/batch_install.sh -C "gcc@=15.3.0,nag@=7.2.7243" -r dev -m build -H macos.gmao -e
 ```
 
 *Note: For every compiler you specify, you must have a corresponding `packages_<compiler_name>-<version>.yaml.template` file in this site directory.*
@@ -161,7 +161,7 @@ Depending on which compiler you built, you will need to add the correct `install
 #### Loading the GCC Stack
 
 ```bash
-module use -a /path/to/spack-stack/envs/ge-gcc-15.2.0-build/install/modulefiles/Core
+module use -a /path/to/spack-stack/envs/ge-gcc-15.3.0-build/install/modulefiles/Core
 module load stack-gcc stack-openmpi geos-gcm-env
 ```
 
@@ -187,7 +187,7 @@ You only need to create each environment once. Our `macos.gmao` site configurati
 #### GCC Environment
 
 ```bash
-spack stack create env --name ge-gcc-15.2.0 --template geos-dev --site macos.gmao --compiler=gcc-15.2.0
+spack stack create env --name ge-gcc-15.3.0 --template geos-dev --site macos.gmao --compiler=gcc-15.3.0
 ```
 
 #### NAG Environment
@@ -203,11 +203,11 @@ spack stack create env --name genag-nag-7.2.7243 --template geos-dev-nag --site
 Navigate to the environment directory you wish to work on. For example, if you built the GCC stack:
 
 ```bash
-cd envs/ge-gcc-15.2.0-build
+cd envs/ge-gcc-15.3.0-build
 spack env activate -p .
 ```
 
-> **Note:** If you are building or debugging a different compiler stack, be sure to `cd` into that specific environment directory instead (e.g., `envs/ge-nag-7.2.7243-build` or `envs/ge-clang-22.1.3-build`).
+> **Note:** If you are building or debugging a different compiler stack, be sure to `cd` into that specific environment directory instead (e.g., `envs/ge-nag-7.2.7243-build` or `envs/ge-clang-22.1.8-build`).
 
 > **Important:** Run this in *every* terminal where you plan to run Spack commands for this environment.
 
diff --git a/configs/sites/tier2/macos.gmao/packages_clang-22.1.3.yaml.template b/configs/sites/tier2/macos.gmao/packages_clang-22.1.8.yaml.template
similarity index 89%
rename from configs/sites/tier2/macos.gmao/packages_clang-22.1.3.yaml.template
rename to configs/sites/tier2/macos.gmao/packages_clang-22.1.8.yaml.template
index 49fa8d5ef..fdbcbdc59 100644
--- a/configs/sites/tier2/macos.gmao/packages_clang-22.1.3.yaml.template
+++ b/configs/sites/tier2/macos.gmao/packages_clang-22.1.8.yaml.template
@@ -4,7 +4,7 @@ packages:
   cxx:
     require: [apple-clang@@APPLE_CLANG_VERSION@]
   fortran:
-    require: [llvm@21.1.3 ~clang +flang]
+    require: [llvm@22.1.8 ~clang +flang]
   mpi:
     require: [openmpi@=5.0.10]
   apple-clang:
@@ -18,7 +18,7 @@ packages:
   llvm:
     buildable: False
     externals:
-    - spec: llvm@21.1.3 ~clang +flang languages:='fortran'
+    - spec: llvm@22.1.8 ~clang +flang languages:='fortran'
       prefix: @BREW_PREFIX@
       extra_attributes:
         compilers:
diff --git a/configs/sites/tier2/macos.gmao/packages_gcc-15.2.0.yaml.template b/configs/sites/tier2/macos.gmao/packages_gcc-15.3.0.yaml.template
similarity index 94%
rename from configs/sites/tier2/macos.gmao/packages_gcc-15.2.0.yaml.template
rename to configs/sites/tier2/macos.gmao/packages_gcc-15.3.0.yaml.template
index 4014ae07c..cb8e98040 100644
--- a/configs/sites/tier2/macos.gmao/packages_gcc-15.2.0.yaml.template
+++ b/configs/sites/tier2/macos.gmao/packages_gcc-15.3.0.yaml.template
@@ -4,7 +4,7 @@ packages:
   cxx:
     require: [apple-clang@@APPLE_CLANG_VERSION@]
   fortran:
-    require: [gcc@15.2.0]
+    require: [gcc@15.3.0]
   mpi:
     require: [openmpi@=5.0.10]
   apple-clang:
@@ -18,7 +18,7 @@ packages:
   gcc:
     buildable: False
     externals:
-    - spec: gcc@15.2.0 languages:='fortran'
+    - spec: gcc@15.3.0 languages:='fortran'
       prefix: @BREW_PREFIX@
       extra_attributes:
         compilers:
diff --git a/configs/templates/geos-dev-nag/spack.yaml b/configs/templates/geos-dev-nag/spack.yaml
index 5137c6ac5..ea3dc0d33 100644
--- a/configs/templates/geos-dev-nag/spack.yaml
+++ b/configs/templates/geos-dev-nag/spack.yaml
@@ -13,8 +13,10 @@ spack:
   # (see geos_gcm_env/package.py). On platforms where only +debug is supported
   # (e.g., macOS), the site packages.yaml requires geos-gcm-env +debug, which
   # causes both specs to resolve to +debug (only one unique build).
-  - geos-gcm-env ~debug
-  - geos-gcm-env +debug
+  #
+  # Also, NAG cannot build FMS yet (due to use of cray pointers)
+  - geos-gcm-env ~debug ~fms ~cdo
+  - geos-gcm-env +debug ~fms ~cdo
 
 
   packages:
diff --git a/configs/templates/geos-dev/spack.yaml b/configs/templates/geos-dev/spack.yaml
index c313a64cc..0cd32011a 100644
--- a/configs/templates/geos-dev/spack.yaml
+++ b/configs/templates/geos-dev/spack.yaml
@@ -13,8 +13,8 @@ spack:
   # (see geos_gcm_env/package.py). On platforms where only +debug is supported
   # (e.g., macOS), the site packages.yaml requires geos-gcm-env +debug, which
   # causes both specs to resolve to +debug (only one unique build).
-  - geos-gcm-env ~debug
-  - geos-gcm-env +debug
+  - geos-gcm-env ~debug +cdo
+  - geos-gcm-env +debug +cdo
 
   # Various fms builds
   - fms@=2024.03 ~gfs_phys constants=GEOS
diff --git a/repos/spack_stack/spack_repo/spack_stack/packages/geos_gcm_env/package.py b/repos/spack_stack/spack_repo/spack_stack/packages/geos_gcm_env/package.py
index 8985ce217..b1a98f0a1 100644
--- a/repos/spack_stack/spack_repo/spack_stack/packages/geos_gcm_env/package.py
+++ b/repos/spack_stack/spack_repo/spack_stack/packages/geos_gcm_env/package.py
@@ -16,9 +16,11 @@ class GeosGcmEnv(BundlePackage):
     maintainers("climbfuji", "mathomp4", "Dooruk")
 
     # Current version
-    version("1.1.0")
+    version("11.10.0")
 
     variant("debug", default=False, description="Build debug version of selected dependencies")
+    variant("fms", default=True, description="Build FMS as part of the environment")
+    variant("cdo", default=True, description="Build CDO as part of the environment")
 
     depends_on("base-env", type="run")
 
@@ -29,6 +31,12 @@ class GeosGcmEnv(BundlePackage):
     depends_on("esmf ~debug", type="run", when="~debug")
     depends_on("esmf +debug", type="run", when="+debug")
 
+    depends_on(
+        "fms@2024.03 precision=32,64 ~gfs_phys +openmp +pic constants=GEOS +deprecated_io +yaml build_type=Release", #noqa: E501
+        type="run",
+        when="@11.10: +fms",
+    )
+
     # mapl is built as part of GEOS, don't load;
     # needs external gftl-shared/fargparse/pflogger
     # depends_on("mapl", type="run")
@@ -46,4 +54,8 @@ class GeosGcmEnv(BundlePackage):
 
     depends_on("py-cmocean", type="run")
 
+    depends_on("nco", type="run")
+    depends_on("nccmp", type="run")
+    depends_on("cdo", type="run", when="+cdo")
+
     # There is no need for install() since there is no code.
diff --git a/util/gmao/README.md b/util/gmao/README.md
new file mode 100644
index 000000000..0f4d6b45c
--- /dev/null
+++ b/util/gmao/README.md
@@ -0,0 +1,153 @@
+GMAO Spack-Stack Utilities
+
+---
+
+## Table of Contents
+
+- [Overview](#overview)
+- [batch\_install.sh](#batch_installsh)
+- [monitor\_install.py](#monitor_installpy)
+- [patch\_ecbuild\_ectrans.py](#patch_ecbuild_ectranspy)
+
+---
+
+## Overview
+
+This directory contains GMAO SI Team utility scripts for building and managing spack-stack environments.
+
+---
+
+## batch_install.sh
+
+The primary script for building and installing spack-stack environments. It automates environment creation, cache population, and the Spack installation pipeline across all GMAO-supported sites.
+
+### Usage
+
+```
+batch_install.sh -r <ROLE> -m <MODE> [-d <ENV_DIRS>] [-c <BUILDCACHE_DIR>] [-H <HOSTNAME>]
+```
+
+Run with `-h` for full usage:
+
+```bash
+./util/gmao/batch_install.sh -h
+```
+
+### Key flags
+
+| Flag | Description |
+|---|---|
+| `-r ROLE` | Role: `dev` (SI Team developers with write access to shared mirrors, writes to default build cache) or `ops` (operational partners without write access, requires `-c` to specify their own build cache). |
+| `-m MODE` | Mode: `build` (compile + populate build cache) or `install` (install from cache + generate modules). |
+| `-H HOSTNAME` | Override hostname autodetection. Usually required (e.g. `-H discover-gmao`, `-H macos.gmao`). |
+| `-s` | Submit the install step to the batch scheduler (SLURM/PBS) instead of running interactively. |
+| `-e` | Continue if environment directories already exist. Required on all runs after the first. |
+| `-u` | Populate bootstrap, source, and cargo mirrors. Requires `-r dev -m build`. First run only. |
+| `-a ACCOUNT` | Override the scheduler account (default: `s1873`). |
+| `-n` | Dry-run: print what would be executed without running anything. |
+| `-p` / `--partition` | Override SLURM partition. **NCCS hosts only** (discover, discover-gmao). |
+| `-q` / `--qos` | Override SLURM QOS. **NCCS hosts only** (discover, discover-gmao). |
+| `--constraint` | Override SLURM node constraint (e.g. `--constraint=mil`). **NCCS hosts only**. No short form. |
+| `-c BUILDCACHE_DIR` | Custom build cache path. Required with `-r ops -m build`. |
+| `-d ENV_DIRS` | Override the default environment directory. |
+| `-C COMPILERS` | Comma-separated compiler list, overrides site defaults. |
+| `-N NAGFOR_PATH` | Path to `nagfor` executable for NAG compiler detection (macOS only). |
+| `-t` | Run tests for hardcoded third-party packages after installation. |
+
+### Supported sites
+
+The script detects the current site from `$HOSTNAME` (stripping digits and domain), or you can override with `-H`:
+
+| Site key | System |
+|---|---|
+| `discover` | NASA NCCS Discover (JCSDA account/partition) |
+| `discover-gmao` | NASA NCCS Discover (GMAO SI Team account/partition) |
+| `nas` | NASA NAS Pleiades (TOSS 4) |
+| `nas-toss5` | NASA NAS Pleiades (TOSS 5) |
+| `macos.gmao` | macOS with Homebrew (GMAO SI Team) |
+
+### Site-specific READMEs
+
+For detailed workflow instructions for each site, see:
+
+- `configs/sites/tier2/discover-gmao/README.md` — Discover GMAO workflow
+- `configs/sites/tier2/macos.gmao/README.md` — macOS GMAO workflow
+
+---
+
+## monitor_install.py
+
+A Python script that monitors a spack install log file and reports progress with a progress bar. Useful for watching a build submitted via `-s` without having to tail the raw log.
+
+### Usage
+
+```bash
+# Monitor a live log from its current end (attach to a running build)
+python3 util/gmao/monitor_install.py <logfile>
+
+# Monitor a live log from the beginning of the file
+python3 util/gmao/monitor_install.py -f <logfile>
+
+# Read the full log, print a progress report, then exit
+python3 util/gmao/monitor_install.py -r <logfile>
+```
+
+The log file is the `.log` file written by `batch_install.sh -s`, named:
+
+```
+spack.<hostname>.<env_name>.log
+```
+
+For example, after running:
+
+```bash
+./util/gmao/batch_install.sh -r dev -m build -H discover-gmao -s -e
+```
+
+The log files will be named `spack.discover-gmao.ge-gcc-15.2.0-build.log`, etc. in the current directory.
+
+### Options
+
+| Flag | Description |
+|---|---|
+| `-f` / `--from-start` | Scan from the beginning of the file rather than tailing live. |
+| `-r` / `--report` | Read full file, print progress summary, then exit (non-interactive). |
+| `-t SECONDS` / `--timeout` | Seconds of log inactivity before exiting live mode (default: 300). |
+
+### Exit conditions (live mode)
+
+The script exits automatically when:
+- All packages are installed (progress counter reaches total)
+- A spack error is detected in the log
+- No new log output for `--timeout` seconds (default: 5 minutes)
+
+---
+
+## patch_ecbuild_ectrans.py
+
+A targeted patch script that works around an ectrans build failure with the Intel oneAPI compiler (`ifx`) at NAS (nas, nas-toss5).
+
+**Problem:** `ecbuild`'s Fortran flag checker incorrectly determines that `-march=core-avx2 -no-fma` is not supported by `ifx` and calls `ecbuild_critical()`, aborting the build. The flags are actually valid — the check is a false negative.
+
+**Fix:** Replaces the `ecbuild_critical()` call with the same logic as the success path, so the flags are always added regardless of the check result.
+
+See: https://github.com/JCSDA/spack-stack/issues/1775#issuecomment-3898802720
+
+### Usage
+
+```bash
+# Apply the patch
+python3 util/gmao/patch_ecbuild_ectrans.py --patch /path/to/ecbuild_add_lang_flags.cmake
+
+# Revert the patch (restores from the .orig backup created at patch time)
+python3 util/gmao/patch_ecbuild_ectrans.py --revert /path/to/ecbuild_add_lang_flags.cmake
+```
+
+The `ecbuild_add_lang_flags.cmake` file is typically found inside the staged or installed ectrans source tree within your spack environment. To locate it:
+
+```bash
+spack env activate -p envs/ue-oneapi-2024.2.0-build
+find $(spack location -i ecbuild) -name ecbuild_add_lang_flags.cmake
+```
+
+A `.orig` backup is created automatically when `--patch` is applied. `--revert` restores from this backup and removes it. If the patch has already been applied, the script will print a message and skip.
diff --git a/util/gmao/batch_install.sh b/util/gmao/batch_install.sh
index 92813329a..ab61af130 100755
--- a/util/gmao/batch_install.sh
+++ b/util/gmao/batch_install.sh
@@ -66,12 +66,25 @@ usage() {
   echo "      requires role 'dev' and mode 'build'"
   echo "  -e  Continue builds/install in existing environments;"
   echo "      by default, exit with an error if already exist"
-  echo "  -C  Set a comma-separated list of compilers to use (e.g. gcc@=15.2.0,nag@=7.2.7243);"
+  echo "  -C  Set a comma-separated list of compilers to use (e.g. gcc@=15.3.0,nag@=7.2.7243);"
   echo "      overrides the default compilers for the site"
   echo "  -N  Path to nagfor executable (e.g. /opt/nag/bin/nagfor);"
   echo "      forces NAG stack to be built using this specific compiler"
   echo "  -a  Set PBS/SLURM account (default: s1873);"
   echo "      overrides the ACCOUNT environment variable"
+  echo "  -p  Set SLURM partition (e.g. preops, normal, compute);"
+  echo "      overrides the default partition for the site;"
+  echo "      also accepted as --partition=<value>;"
+  echo "      NOTE: only applies to NCCS hosts (discover, discover-gmao)"
+  echo "  -q  Set SLURM QOS (e.g. benchmark, high, normal);"
+  echo "      overrides the default QOS for the site;"
+  echo "      also accepted as --qos=<value>;"
+  echo "      NOTE: only applies to NCCS hosts (discover, discover-gmao)"
+  echo "      --constraint=<value>"
+  echo "          Set SLURM node constraint (e.g. mil, cas, sky);"
+  echo "          overrides the default constraint for the site;"
+  echo "          no short form available (-c and -C are already used);"
+  echo "          NOTE: only applies to NCCS hosts (discover, discover-gmao)"
   echo "  -s  Submit 'spack install' to batch scheduler"
   echo "  -t  Run tests for specific thirdparty dependencies;"
   echo "      these are currently hardcoded in batch_install.sh"
@@ -82,7 +95,7 @@ usage() {
   echo
 }
 
-while getopts r:m:d:c:C:N:H:a:nuesth flag
+while getopts r:m:d:c:C:N:H:a:p:q:nuesth flag
 do
   case "${flag}" in
     r)
@@ -109,6 +122,12 @@ do
     a)
       ACCOUNT=${OPTARG}
       ;;
+    p)
+      SPACK_STACK_SLURM_PARTITION=${OPTARG}
+      ;;
+    q)
+      SPACK_STACK_SLURM_QOS=${OPTARG}
+      ;;
     n)
       SPACK_STACK_DRY_RUN="true"
       ;;
@@ -130,6 +149,40 @@ do
       ;;
   esac
 done
+shift $((OPTIND - 1))
+
+# Parse any remaining long options (e.g. --constraint, --partition, --qos)
+while [[ $# -gt 0 ]]; do
+  case $1 in
+    --constraint=*)
+      SPACK_STACK_SLURM_CONSTRAINT="${1#*=}"
+      ;;
+    --constraint)
+      SPACK_STACK_SLURM_CONSTRAINT="$2"
+      shift
+      ;;
+    --partition=*)
+      SPACK_STACK_SLURM_PARTITION="${1#*=}"
+      ;;
+    --partition)
+      SPACK_STACK_SLURM_PARTITION="$2"
+      shift
+      ;;
+    --qos=*)
+      SPACK_STACK_SLURM_QOS="${1#*=}"
+      ;;
+    --qos)
+      SPACK_STACK_SLURM_QOS="$2"
+      shift
+      ;;
+    *)
+      echo "ERROR, unknown argument: $1"
+      usage
+      exit 1
+      ;;
+  esac
+  shift
+done
 
 echo "INFO: $0 options:"
 echo "  SPACK_STACK_ROLE:                            ${SPACK_STACK_ROLE:-not set}"
@@ -143,6 +196,9 @@ echo "  SPACK_STACK_IGNORE_ENV_EXIST:                ${SPACK_STACK_IGNORE_ENV_EX
 echo "  SPACK_STACK_SUBMIT_TO_SCHEDULER:             ${SPACK_STACK_SUBMIT_TO_SCHEDULER:-false}"
 echo "  SPACK_STACK_RUN_TESTS:                       ${SPACK_STACK_RUN_TESTS:-false}"
 echo "  ACCOUNT:                                     ${ACCOUNT:-s1873 (default)}"
+echo "  SPACK_STACK_SLURM_PARTITION:                 ${SPACK_STACK_SLURM_PARTITION:-use site default}"
+echo "  SPACK_STACK_SLURM_QOS:                       ${SPACK_STACK_SLURM_QOS:-use site default}"
+echo "  SPACK_STACK_SLURM_CONSTRAINT:                ${SPACK_STACK_SLURM_CONSTRAINT:-use site default}"
 
 # Set default account if not provided via -a or environment
 ACCOUNT=${ACCOUNT:-s1873}
@@ -235,11 +291,15 @@ case ${SPACK_STACK_BATCH_HOST} in
       export MAC_GMAO_NAG_PREFIX=$(dirname $(dirname "${MAC_GMAO_NAG_PATH}"))
     fi
 
-    SPACK_STACK_BATCH_COMPILERS=("gcc@=15.2.0")
+    # Note: clang (aka flang) is on hold for macOS until we move to
+    # 1. FMS 2025 (for GEOS purposes)
+    # 2. ESMF PR https://github.com/esmf-org/esmf/pull/558 is merged and released/tagged
+    #SPACK_STACK_BATCH_COMPILERS=("gcc@=15.3.0" "clang@=22.1.8")
+    SPACK_STACK_BATCH_COMPILERS=("gcc@=15.3.0")
     if [[ -n "${MAC_GMAO_NAG_VERSION}" ]]; then
       SPACK_STACK_BATCH_COMPILERS+=("nag@=${MAC_GMAO_NAG_VERSION}")
     fi
-    
+
     # Auto-detect Apple Clang version
     if command -v clang &> /dev/null; then
       export MAC_GMAO_APPLE_CLANG_VERSION=$(clang --version | grep "Apple clang version" | awk '{print $4}')
@@ -394,32 +454,52 @@ function run_interactive_job() {
            ${script}
       ;;
     discover)
-      slurm_constraint="--constraint=mil"
-      if [[ "${ACCOUNT}" == "s1873" ]]; then
-        slurm_partition="--partition=preops --qos=benchmark"
+      slurm_constraint="${SPACK_STACK_SLURM_CONSTRAINT:+--constraint=${SPACK_STACK_SLURM_CONSTRAINT}}"
+      slurm_constraint="${slurm_constraint:---constraint=mil}"
+      if [[ -n "${SPACK_STACK_SLURM_PARTITION}" ]]; then
+        slurm_partition="--partition=${SPACK_STACK_SLURM_PARTITION}"
+      elif [[ "${ACCOUNT}" == "s1873" ]]; then
+        slurm_partition="--partition=preops"
       else
         slurm_partition=""
       fi
+      if [[ -n "${SPACK_STACK_SLURM_QOS}" ]]; then
+        slurm_qos="--qos=${SPACK_STACK_SLURM_QOS}"
+      elif [[ "${ACCOUNT}" == "s1873" ]]; then
+        slurm_qos="--qos=benchmark"
+      else
+        slurm_qos=""
+      fi
       slurm_log="${job_name}.log"
       echo "INFO: salloc output redirected to ${slurm_log}"
       salloc --nodes=1 --ntasks-per-node=${tpn} --time=${walltime} \
-             ${slurm_constraint} ${slurm_partition} \
+             ${slurm_constraint} ${slurm_partition} ${slurm_qos} \
              --job-name=${job_name} \
              --account=${ACCOUNT} bash ${script} \
              > "${slurm_log}" 2>&1
       echo "INFO: salloc job complete, log: ${slurm_log}"
       ;;
     discover-gmao)
-      slurm_constraint="--constraint=mil"
-      if [[ "${ACCOUNT}" == "s1873" ]]; then
-        slurm_partition="--partition=preops --qos=benchmark"
+      slurm_constraint="${SPACK_STACK_SLURM_CONSTRAINT:+--constraint=${SPACK_STACK_SLURM_CONSTRAINT}}"
+      slurm_constraint="${slurm_constraint:---constraint=mil}"
+      if [[ -n "${SPACK_STACK_SLURM_PARTITION}" ]]; then
+        slurm_partition="--partition=${SPACK_STACK_SLURM_PARTITION}"
+      elif [[ "${ACCOUNT}" == "s1873" ]]; then
+        slurm_partition="--partition=preops"
       else
         slurm_partition=""
       fi
+      if [[ -n "${SPACK_STACK_SLURM_QOS}" ]]; then
+        slurm_qos="--qos=${SPACK_STACK_SLURM_QOS}"
+      elif [[ "${ACCOUNT}" == "s1873" ]]; then
+        slurm_qos="--qos=benchmark"
+      else
+        slurm_qos=""
+      fi
       slurm_log="${job_name}.log"
       echo "INFO: salloc output redirected to ${slurm_log}"
       salloc --nodes=1 --ntasks-per-node=${tpn} --time=${walltime} \
-             ${slurm_constraint} ${slurm_partition} \
+             ${slurm_constraint} ${slurm_partition} ${slurm_qos} \
              --job-name=${job_name} \
              --account=${ACCOUNT} bash ${script} \
              > "${slurm_log}" 2>&1
@@ -820,7 +900,7 @@ for compiler in "${SPACK_STACK_BATCH_COMPILERS[@]}"; do
         nag_version=${MAC_GMAO_NAG_VERSION}
         nag_path=${MAC_GMAO_NAG_PATH}
         nag_prefix=${MAC_GMAO_NAG_PREFIX}
-        
+
         apple_clang_version=${MAC_GMAO_APPLE_CLANG_VERSION:-"21.0.0"}
 
         for template_file in "${macos_site_dir}"/*.yaml.template; do
diff --git a/util/gmao/monitor_install.py b/util/gmao/monitor_install.py
index e46b3dea3..086c21b61 100755
--- a/util/gmao/monitor_install.py
+++ b/util/gmao/monitor_install.py
@@ -6,6 +6,11 @@
     python3 monitor_install.py <logfile>          # monitor from current end (live)
     python3 monitor_install.py -f <logfile>       # scan from beginning of file (live)
     python3 monitor_install.py -r <logfile>       # read full file, print report, exit
+
+Live mode exits automatically when:
+  - All packages are installed (current == total in the Installing line)
+  - A spack error is detected
+  - No new log output for --timeout seconds (default: 300)
 """
 
 import sys
@@ -26,19 +31,36 @@ def format_bar(current, total, bar_len=30):
     return f"[{bar}] {current:>4}/{total}  {pct:5.1f}%"
 
 
-def monitor(logfile, from_start=False):
+def monitor(logfile, from_start=False, timeout=300):
+    idle_seconds = 0
+    last_total = None
+
     with open(logfile) as f:
         if not from_start:
             f.seek(0, 2)  # seek to end for live monitoring
         while True:
             line = f.readline()
             if not line:
+                idle_seconds += 1
+                if idle_seconds >= timeout:
+                    print(f"\nNo new output for {timeout}s - assuming build finished or crashed.")
+                    break
                 time.sleep(1)
                 continue
+
+            idle_seconds = 0
             m = pattern_installing.search(line)
             if m:
                 pkg, current, total = m.group(1), m.group(2), m.group(3)
+                last_total = total
                 print(f"{format_bar(current, total)}  {pkg}", flush=True)
+                if current == total:
+                    print("\nAll packages installed successfully.")
+                    break
+
+            if pattern_error.search(line):
+                print("\nBuild error detected - exiting monitor.")
+                break
 
 
 def report(logfile):
@@ -93,13 +115,15 @@ def main():
                         help="Scan from beginning of file instead of tailing live")
     parser.add_argument("-r", "--report", action="store_true",
                         help="Read full file, show progress, print summary, then exit")
+    parser.add_argument("-t", "--timeout", type=int, default=300,
+                        help="Seconds of log inactivity before exiting live mode (default: 300)")
     args = parser.parse_args()
 
     try:
         if args.report:
             report(args.logfile)
         else:
-            monitor(args.logfile, from_start=args.from_start)
+            monitor(args.logfile, from_start=args.from_start, timeout=args.timeout)
     except KeyboardInterrupt:
         print("\nDone monitoring.")
     except FileNotFoundError: