diff --git a/careless/README.md b/careless/README.md
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+# careless
+
+Scaling and merging of X-ray diffraction data with approximate Bayesian
+inference (variational merging), built on TensorFlow.
+
+- Upstream: https://github.com/rs-station/careless
+- License: MIT
+
+## How it is built
+
+Upstream recommends a fresh conda env, but repo.anaconda.com is not
+reachable from Ra, so the build uses uv instead: it fetches a standalone
+Python 3.12 into `$PREFIX/python` (upstream supports >=3.9,<3.13), creates
+`$PREFIX/venv`, and runs `uv pip install careless[cuda]==<version>` into
+it. The `[cuda]` extra pulls the NVIDIA libraries as pip wheels, so the
+same install works on GPU and CPU-only Ra nodes.
+
+`uv` must be on PATH on the build host (e.g. `pip install --user uv`).
+
+Loading the module puts the venv's `bin/` on `PATH` (the `careless`
+command is directly available, no activation needed) and sets
+`CARELESS_ENV` to the venv path.
+
+## Verifying the install
+
+Run on a Ra login node after building (in order, cheap to expensive):
+
+```sh
+# 1. module is visible and loads
+module search careless
+module load careless/<version>
+
+# 2. modulefile wiring: PATH + CARELESS_ENV
+which careless          # -> .../careless/<version>/venv/bin/careless
+echo $CARELESS_ENV      # -> .../venv
+
+# 3. venv is self-contained: must resolve inside the module PREFIX,
+#    not the builder's home cache (which may be cleaned later)
+readlink -f "$CARELESS_ENV/bin/python"
+
+# 4. CLI entry point; imports the full TensorFlow stack
+careless --help          # usage text, no traceback
+
+# 5. installed version matches the one requested
+"$CARELESS_ENV/bin/python" -c "import careless; print(careless.__version__)"
+
+# 6. GPU pickup (GPU node only; [] on a CPU node is fine)
+"$CARELESS_ENV/bin/python" -c "import tensorflow as tf; print(tf.config.list_physical_devices('GPU'))"
+```
+
+Optional end-to-end smoke test with a small unmerged mtz (a few seconds;
+proves the TF graph builds and the optimizer steps):
+
+```sh
+careless mono dHKL <file.mtz> /tmp/careless_test --iterations 10
+```
+
+## Adding a new version
+
+Add the version under `versions:` in `files/config.yaml`, then on a Ra
+login node: `modbuild build <version>` (modbuild/2.1.2).
diff --git a/careless/build b/careless/build
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+#!/usr/bin/env modbuild
+
+pbuild::prep() {
+    :
+}
+
+pbuild::configure() {
+    # repo.anaconda.com is unreachable from Ra (GnuTLS error), so no conda.
+    # uv fetches a standalone CPython instead; keep it inside PREFIX so the
+    # venv's interpreter symlinks don't depend on the builder's home cache.
+    # modbuild's shell strips ~/.local/bin from PATH; override with UV=/path/to/uv if needed
+    UV="${UV:-$HOME/.local/bin/uv}"
+    # ~/.cache/uv hits the home disk quota; cache under PREFIX (removed after install)
+    export UV_CACHE_DIR="/opt/psi/MX/.uv-cache"
+    export UV_PYTHON_INSTALL_DIR="$PREFIX/python"
+    "$UV" venv --python 3.12 "$PREFIX/venv"
+}
+
+pbuild::compile() {
+    :
+}
+
+pbuild::install() {
+    UV="${UV:-$HOME/.local/bin/uv}"
+    export UV_CACHE_DIR="/opt/psi/MX/.uv-cache"
+    # [cuda] extra ships the NVIDIA libs via pip wheels; works on CPU-only nodes too
+    "$UV" pip install --python "$PREFIX/venv/bin/python" "careless[cuda]==${V_PKG}"
+}
diff --git a/careless/files/config.yaml b/careless/files/config.yaml
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+++ b/careless/files/config.yaml
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+---
+format: 1
+careless:
+  defaults:
+    group: MX
+    overlay: base
+    relstage: unstable
+  versions:
+    0.5.4:
+      config:
+        relstage: unstable
diff --git a/careless/modulefile b/careless/modulefile
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+++ b/careless/modulefile
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+#%Module1.0
+
+module-whatis       "careless - merging crystallography data with variational inference"
+module-url          "https://github.com/rs-station/careless"
+module-license      "MIT"
+module-maintainer   "MX Data <jiaxin.duan@psi.ch>"
+
+module-help     "
+careless: scaling and merging of X-ray diffraction data using
+approximate Bayesian inference (TensorFlow). Installed with the
+[cuda] extra, so it uses NVIDIA GPUs when available and falls
+back to CPU otherwise.
+"
+
+setenv          CARELESS_ENV    $PREFIX/venv
+prepend-path    PATH            $PREFIX/venv/bin