diff --git a/.github/workflows/build-gersemi.yml b/.github/workflows/build-gersemi.yml
new file mode 100644
index 000000000000..9ef27bd6b2e9
--- /dev/null
+++ b/.github/workflows/build-gersemi.yml
@@ -0,0 +1,111 @@
+# SPDX-FileCopyrightText: 2026 The RISE Project
+# SPDX-License-Identifier: MIT
+---
+# This workflow is based on upstream's own wheel builder:
+#   https://github.com/BlankSpruce/gersemi/blob/0.28.1/.github/workflows/deploy.yml
+# gersemi is a setuptools-rust extension (gersemi_rust_backend); its Cargo.toml
+# enables pyo3's abi3 feature but the build never passes --py-limited-api, so
+# upstream's own published wheels are per-interpreter, not abi3.
+name: Build gersemi wheels (riscv64)
+
+on:
+  workflow_dispatch:
+    inputs:
+      version:
+        description: 'Version glob to (re)build; empty builds every version of docs/packages/gersemi.yaml not released yet'
+        required: false
+        default: ''
+  pull_request:
+    branches: [main]
+    paths:
+      - '.github/workflows/build-gersemi.yml'
+      - 'docs/packages/gersemi.yaml'
+  push:
+    branches: [main]
+    paths:
+      - '.github/workflows/build-gersemi.yml'
+      - 'docs/packages/gersemi.yaml'
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read  # to fetch code (actions/checkout)
+
+env:
+  MANYLINUX_RISCV64_IMAGE: quay.io/pypa/manylinux_2_39_riscv64
+
+jobs:
+  setup:
+    uses: $/.github/workflows/_setup.yml
+    with:
+      package: gersemi
+      version: ${{ inputs.version }}
+
+  build_wheels:
+    needs: [setup]
+    if: needs.setup.outputs.versions != '[]'
+    name: Build gersemi ${{ matrix.version }} ${{ matrix.python }}-manylinux_riscv64
+    runs-on: ubuntu-24.04-riscv
+    timeout-minutes: 60
+    strategy:
+      fail-fast: false
+      matrix:
+        version: ${{ fromJSON(needs.setup.outputs.versions) }}
+        python: ["cp312", "cp313", "cp314", "cp314t"]
+
+    env:
+      GERSEMI_VERSION: ${{ matrix.version }}
+
+    steps:
+      - name: Checkout gersemi v${{ env.GERSEMI_VERSION }}
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1  # v7.0.1
+        with:
+          repository: BlankSpruce/gersemi
+          ref: ${{ env.GERSEMI_VERSION }}
+          persist-credentials: false
+
+      - name: Build wheels
+        uses: pypa/cibuildwheel@1828c10ab37f080699c7b81cea34097c684a7074  # v4.2.0
+        with:
+          output-dir: wheelhouse/
+          only: ${{ matrix.python }}-manylinux_riscv64
+        env:
+          CIBW_MANYLINUX_RISCV64_IMAGE: ${{ env.MANYLINUX_RISCV64_IMAGE }}
+          CIBW_BEFORE_ALL_LINUX: >-
+            curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y
+          CIBW_ENVIRONMENT_LINUX: >-
+            PATH="$PATH:$HOME/.cargo/bin"
+            PIP_EXTRA_INDEX_URL=https://pypi.riseproject.dev/simple/
+          CIBW_TEST_REQUIRES: pytest pytest-clarity six pytest-xdist pytest-timeout pydantic
+          CIBW_TEST_SOURCES: tests .gersemirc.example extension-example gersemi/configuration.schema.json
+          # The test phase runs as root, which can still write the read-only cache
+          # test_when_cache_cant_be_modified_it_is_ignored sets up (gotcha 39); deselect it.
+          CIBW_TEST_COMMAND: >-
+            python -c "import gersemi_rust_backend as m; assert m.__file__.endswith('.so'), m.__file__" &&
+            python -m pytest tests -p no:terminalprogress --timeout=15 -n auto
+            --deselect tests/test_executable.py::test_when_cache_cant_be_modified_it_is_ignored
+
+      - uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a  # v7.0.1
+        with:
+          name: gersemi-${{ env.GERSEMI_VERSION }}-${{ matrix.python }}-manylinux_riscv64
+          path: wheelhouse/*.whl
+          if-no-files-found: error
+
+  publish:
+    name: Publish gersemi ${{ matrix.version }}
+    needs: [setup, build_wheels]
+    if: needs.setup.outputs.versions != '[]'
+    strategy:
+      fail-fast: false
+      matrix:
+        version: ${{ fromJSON(needs.setup.outputs.versions) }}
+    permissions:
+      contents: write
+      pull-requests: write
+    uses: $/.github/workflows/_publish-wheel.yml
+    secrets:
+      app-private-key: ${{ secrets.RISEPROJECT_APP_PRIVATE_KEY }}
+    with:
+      artifact-pattern: gersemi-${{ matrix.version }}-*-manylinux_riscv64
diff --git a/docs/packages/gersemi.yaml b/docs/packages/gersemi.yaml
new file mode 100644
index 000000000000..876248d14114
--- /dev/null
+++ b/docs/packages/gersemi.yaml
@@ -0,0 +1,5 @@
+package-name: gersemi
+source-code: https://github.com/BlankSpruce/gersemi
+license: MPL-2.0
+versions:
+- version: 0.28.1