diff --git a/.github/workflows/publish-python-packages.yaml b/.github/workflows/publish-python-packages.yaml
index c2502297e..1c4a9802c 100644
--- a/.github/workflows/publish-python-packages.yaml
+++ b/.github/workflows/publish-python-packages.yaml
@@ -79,6 +79,16 @@ jobs:
         id: get-code-artifact-params
         uses: ./.github/actions/code-artifact
 
+      # overture-schema-pyspark ships generated validation expressions that are
+      # not committed to git -- they are regenerated on demand from the Pydantic
+      # models. `uv build` packages whatever is on disk under the module root, so
+      # the tree must be generated here before the build, or the published wheel
+      # ships without its `expressions/generated/` modules and validate_model()
+      # discovers nothing to run.
+      - name: Generate PySpark expressions before build
+        if: matrix.package == 'overture-schema-pyspark'
+        run: make generate-pyspark
+
       - name: Publish package ${{ matrix.package }} version ${{ matrix.after }} to PyPI
         env:
           CA_TOKEN: ${{ steps.get-code-artifact-params.outputs.token }}
@@ -94,6 +104,14 @@ jobs:
             echo "    Wheel file [$wheel] not found. Aborting!"
             exit 1
           fi
+          # Guard against a silently empty wheel: if the generate step above ever
+          # regresses, overture-schema-pyspark would publish with no validation
+          # expressions. Fail loudly instead of shipping a hollow package.
+          if [ "$PACKAGE" = "overture-schema-pyspark" ] && \
+             ! unzip -l "$wheel" | grep -q 'expressions/generated/.*\.py'; then
+            echo "    Wheel [$wheel] has no generated expressions -- codegen did not run. Aborting!"
+            exit 1
+          fi
           tarball="dist/${PACKAGE//-/_}-${AFTER}.tar.gz"
           if [ ! -f "$tarball" ]; then
             echo "    Source tarball file [$tarball] not found. Aborting!"
diff --git a/packages/overture-schema-pyspark/changelog.d/625.bugfix.md b/packages/overture-schema-pyspark/changelog.d/625.bugfix.md
new file mode 100644
index 000000000..67d1c8953
--- /dev/null
+++ b/packages/overture-schema-pyspark/changelog.d/625.bugfix.md
@@ -0,0 +1 @@
+Fixed published wheels and sdists shipping without the generated validation expressions, which left an installed `validate_model()` unable to discover any models.