diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 7527ac9..0d32f28 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -4,9 +4,24 @@ on:
   push:
   workflow_dispatch:
 
+permissions: {}
+
+# Cancel superseded runs on PR branches; never cancel main, since a
+# mid-flight publish would orphan the tag from the PyPI upload and the
+# next run would skip publish because the tag already exists.
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ github.ref != 'refs/heads/main' }}
+
+env:
+  PYTHON_VERSION: "3.10"
+  POETRY_VERSION: "1.5.1"
+
 jobs:
   compile:
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
 
     steps:
       - name: Checkout repo
@@ -15,11 +30,11 @@ jobs:
       - name: Set up python
         uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6
         with:
-          python-version: "3.10"
+          python-version: ${{ env.PYTHON_VERSION }}
 
       - name: Bootstrap poetry
         run: |
-          curl -sSL https://install.python-poetry.org | python - -y --version 1.5.1
+          curl -sSL https://install.python-poetry.org | python - -y --version "${{ env.POETRY_VERSION }}"
 
       - name: Install dependencies
         run: poetry install
@@ -30,6 +45,9 @@ jobs:
   test:
     needs: [ compile ]
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
+
     steps:
       - name: Checkout repo
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
@@ -37,11 +55,11 @@ jobs:
       - name: Set up python
         uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6
         with:
-          python-version: "3.10"
+          python-version: ${{ env.PYTHON_VERSION }}
 
       - name: Bootstrap poetry
         run: |
-          curl -sSL https://install.python-poetry.org | python - -y --version 1.5.1
+          curl -sSL https://install.python-poetry.org | python - -y --version "${{ env.POETRY_VERSION }}"
 
       - name: Install dependencies
         run: poetry install
@@ -68,7 +86,7 @@ jobs:
       # version tagged but unpublished, and subsequent runs would skip
       # publish because the tag already exists.
       - name: Verify bundled OpenAPI spec
-        uses: PhenoML/sdk-shared-actions/verify-openapi-spec@1.0.2
+        uses: PhenoML/sdk-shared-actions/verify-openapi-spec@1.0.3
         with:
           spec-path: src/phenoml/openapi/openapi.json
 
@@ -94,12 +112,11 @@ jobs:
             --title "${{ steps.check.outputs.version }}" \
             --generate-notes
 
-  publish:
-    needs: [ compile, test, tag ]
+  build-artifact:
+    needs: [ tag ]
     if: needs.tag.outputs.should_publish == 'true'
     runs-on: ubuntu-latest
     permissions:
-      id-token: write
       contents: read
 
     steps:
@@ -109,14 +126,44 @@ jobs:
       - name: Set up python
         uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6
         with:
-          python-version: "3.10"
+          python-version: ${{ env.PYTHON_VERSION }}
 
       - name: Bootstrap poetry
         run: |
-          curl -sSL https://install.python-poetry.org | python - -y --version 1.5.1
+          curl -sSL https://install.python-poetry.org | python - -y --version "${{ env.POETRY_VERSION }}"
 
       - name: Build distribution
         run: poetry build
 
+      - name: Upload artifact
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
+        with:
+          name: python-dist
+          path: dist/
+          if-no-files-found: error
+          retention-days: 1
+
+  publish:
+    needs: [ tag, build-artifact ]
+    if: needs.tag.outputs.should_publish == 'true'
+    runs-on: ubuntu-latest
+    # Environment-scoped OIDC: the environment's deployment branch rule
+    # restricts this job to refs/heads/main, and the PyPI Trusted Publisher
+    # binding requires this environment name — so a publish from any other
+    # ref or workflow is rejected end-to-end.
+    environment: pypi-production
+    permissions:
+      id-token: write
+      contents: read
+
+    steps:
+      # download-artifact verifies the downloaded bundle against GitHub's
+      # recorded digest by default (digest-mismatch: error).
+      - name: Download artifact
+        uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
+        with:
+          name: python-dist
+          path: dist
+
       - name: Publish to PyPI
         uses: pypa/gh-action-pypi-publish@cef221092ed1bacb1cc03d23a2d87d1d172e277b # v1.14.0
diff --git a/.github/workflows/sync-fern-artifacts.yml b/.github/workflows/sync-fern-artifacts.yml
index 301b0a1..0a4a39b 100644
--- a/.github/workflows/sync-fern-artifacts.yml
+++ b/.github/workflows/sync-fern-artifacts.yml
@@ -20,6 +20,6 @@ jobs:
   sync:
     permissions:
       contents: write
-    uses: PhenoML/sdk-shared-actions/.github/workflows/sync-fern-artifacts.yml@1.0.2
+    uses: PhenoML/sdk-shared-actions/.github/workflows/sync-fern-artifacts.yml@1.0.3
     with:
       spec-path: src/phenoml/openapi/openapi.json