diff --git a/.github/workflows/build-wheels.yml b/.github/workflows/build-wheels.yml
new file mode 100644
index 00000000..6cd90d6c
--- /dev/null
+++ b/.github/workflows/build-wheels.yml
@@ -0,0 +1,159 @@
+name: Build wheels
+
+# Reusable wheel-build matrix shared by:
+#   - publish.yml   (on release: builds the full matrix, then uploads to PyPI)
+#   - release-build-check.yml (on PR: build-only smoke of the release path)
+# Keeping the build jobs in ONE place means the pre-merge guard can never
+# drift from what actually publishes.
+on:
+  workflow_call:
+    inputs:
+      linux_only:
+        description: "Build only the manylinux Linux wheels (PR-guard mode); skip macOS/Windows/sdist."
+        type: boolean
+        default: false
+
+permissions:
+  contents: read
+
+jobs:
+  # Build wheels on Linux using manylinux containers
+  build-linux:
+    name: Build Linux ${{ matrix.arch }} wheels
+    runs-on: ${{ matrix.runner }}
+    container: ${{ matrix.container }}
+    strategy:
+      matrix:
+        include:
+          - arch: x86_64
+            runner: ubuntu-latest
+            container: quay.io/pypa/manylinux_2_28_x86_64
+            artifact: wheels-linux-x86_64
+          - arch: aarch64
+            runner: ubuntu-24.04-arm
+            container: quay.io/pypa/manylinux_2_28_aarch64
+            artifact: wheels-linux-aarch64
+    steps:
+      - uses: actions/checkout@v7
+
+      - name: Install system dependencies
+        run: dnf install -y openssl-devel perl-IPC-Cmd openblas-devel
+
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@stable
+
+      - name: Install maturin
+        run: /opt/python/cp312-cp312/bin/pip install maturin
+
+      - name: Build wheels
+        run: |
+          expected=0
+          for pyver in 39 310 311 312 313 314; do
+            pybin="/opt/python/cp${pyver}-cp${pyver}/bin/python"
+            if [ ! -f "$pybin" ]; then
+              echo "ERROR: Expected Python interpreter not found: $pybin"
+              exit 1
+            fi
+            /opt/python/cp312-cp312/bin/maturin build --release --out dist -i "$pybin" --features extension-module,openblas
+            expected=$((expected + 1))
+          done
+          actual=$(find dist -maxdepth 1 -name '*.whl' | wc -l)
+          echo "Built $actual wheels (expected $expected)"
+          if [ "$actual" -ne "$expected" ]; then
+            echo "ERROR: Expected $expected wheels but found $actual"
+            exit 1
+          fi
+
+      - name: Upload wheels
+        uses: actions/upload-artifact@v7
+        with:
+          name: ${{ matrix.artifact }}
+          path: dist/*.whl
+
+  # Build wheels on macOS ARM64 (native build)
+  # Note: macOS x86_64 skipped - Intel runners retired, users can install from sdist
+  build-macos-arm:
+    name: Build macOS ARM64 wheels
+    if: ${{ !inputs.linux_only }}
+    runs-on: macos-14
+    strategy:
+      matrix:
+        python-version: ['3.9', '3.10', '3.11', '3.12', '3.13', '3.14']
+    steps:
+      - uses: actions/checkout@v7
+
+      - name: Set up Python
+        uses: actions/setup-python@v6
+        with:
+          python-version: ${{ matrix.python-version }}
+
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@stable
+
+      - name: Install maturin
+        run: pip install maturin
+
+      - name: Build wheel
+        run: maturin build --release --out dist --features extension-module,accelerate
+
+      - name: Upload wheels
+        uses: actions/upload-artifact@v7
+        with:
+          name: wheels-macos-arm64-py${{ matrix.python-version }}
+          path: dist/*.whl
+
+  # Build wheels on Windows
+  build-windows:
+    name: Build Windows wheels
+    if: ${{ !inputs.linux_only }}
+    runs-on: windows-latest
+    strategy:
+      matrix:
+        python-version: ['3.9', '3.10', '3.11', '3.12', '3.13', '3.14']
+    steps:
+      - uses: actions/checkout@v7
+
+      - name: Set up Python
+        uses: actions/setup-python@v6
+        with:
+          python-version: ${{ matrix.python-version }}
+
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@stable
+
+      - name: Install maturin
+        run: pip install maturin
+
+      - name: Build wheel
+        run: maturin build --release --out dist --features extension-module
+
+      - name: Upload wheels
+        uses: actions/upload-artifact@v7
+        with:
+          name: wheels-windows-py${{ matrix.python-version }}
+          path: dist/*.whl
+
+  # Build source distribution
+  build-sdist:
+    name: Build source distribution
+    if: ${{ !inputs.linux_only }}
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v7
+
+      - name: Set up Python
+        uses: actions/setup-python@v6
+        with:
+          python-version: '3.11'
+
+      - name: Install maturin
+        run: pip install maturin
+
+      - name: Build sdist
+        run: maturin sdist --out dist
+
+      - name: Upload sdist
+        uses: actions/upload-artifact@v7
+        with:
+          name: sdist
+          path: dist/*.tar.gz
diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml
index daccec67..303354b1 100644
--- a/.github/workflows/publish.yml
+++ b/.github/workflows/publish.yml
@@ -8,148 +8,14 @@ permissions:
   contents: read
 
 jobs:
-  # Build wheels on Linux using manylinux containers
-  build-linux:
-    name: Build Linux ${{ matrix.arch }} wheels
-    runs-on: ${{ matrix.runner }}
-    container: ${{ matrix.container }}
-    strategy:
-      matrix:
-        include:
-          - arch: x86_64
-            runner: ubuntu-latest
-            container: quay.io/pypa/manylinux_2_28_x86_64
-            artifact: wheels-linux-x86_64
-          - arch: aarch64
-            runner: ubuntu-24.04-arm
-            container: quay.io/pypa/manylinux_2_28_aarch64
-            artifact: wheels-linux-aarch64
-    steps:
-      - uses: actions/checkout@v7
-
-      - name: Install system dependencies
-        run: dnf install -y openssl-devel perl-IPC-Cmd openblas-devel
-
-      - name: Install Rust
-        uses: dtolnay/rust-toolchain@stable
-
-      - name: Install maturin
-        run: /opt/python/cp312-cp312/bin/pip install maturin
-
-      - name: Build wheels
-        run: |
-          expected=0
-          for pyver in 39 310 311 312 313 314; do
-            pybin="/opt/python/cp${pyver}-cp${pyver}/bin/python"
-            if [ ! -f "$pybin" ]; then
-              echo "ERROR: Expected Python interpreter not found: $pybin"
-              exit 1
-            fi
-            /opt/python/cp312-cp312/bin/maturin build --release --out dist -i "$pybin" --features extension-module,openblas
-            expected=$((expected + 1))
-          done
-          actual=$(ls dist/*.whl 2>/dev/null | wc -l)
-          echo "Built $actual wheels (expected $expected)"
-          if [ "$actual" -ne "$expected" ]; then
-            echo "ERROR: Expected $expected wheels but found $actual"
-            exit 1
-          fi
-
-      - name: Upload wheels
-        uses: actions/upload-artifact@v7
-        with:
-          name: ${{ matrix.artifact }}
-          path: dist/*.whl
-
-  # Build wheels on macOS ARM64 (native build)
-  # Note: macOS x86_64 skipped - Intel runners retired, users can install from sdist
-  build-macos-arm:
-    name: Build macOS ARM64 wheels
-    runs-on: macos-14
-    strategy:
-      matrix:
-        python-version: ['3.9', '3.10', '3.11', '3.12', '3.13', '3.14']
-    steps:
-      - uses: actions/checkout@v7
-
-      - name: Set up Python
-        uses: actions/setup-python@v6
-        with:
-          python-version: ${{ matrix.python-version }}
-
-      - name: Install Rust
-        uses: dtolnay/rust-toolchain@stable
-
-      - name: Install maturin
-        run: pip install maturin
-
-      - name: Build wheel
-        run: maturin build --release --out dist --features extension-module,accelerate
-
-      - name: Upload wheels
-        uses: actions/upload-artifact@v7
-        with:
-          name: wheels-macos-arm64-py${{ matrix.python-version }}
-          path: dist/*.whl
-
-  # Build wheels on Windows
-  build-windows:
-    name: Build Windows wheels
-    runs-on: windows-latest
-    strategy:
-      matrix:
-        python-version: ['3.9', '3.10', '3.11', '3.12', '3.13', '3.14']
-    steps:
-      - uses: actions/checkout@v7
-
-      - name: Set up Python
-        uses: actions/setup-python@v6
-        with:
-          python-version: ${{ matrix.python-version }}
-
-      - name: Install Rust
-        uses: dtolnay/rust-toolchain@stable
-
-      - name: Install maturin
-        run: pip install maturin
-
-      - name: Build wheel
-        run: maturin build --release --out dist --features extension-module
-
-      - name: Upload wheels
-        uses: actions/upload-artifact@v7
-        with:
-          name: wheels-windows-py${{ matrix.python-version }}
-          path: dist/*.whl
-
-  # Build source distribution
-  build-sdist:
-    name: Build source distribution
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v7
-
-      - name: Set up Python
-        uses: actions/setup-python@v6
-        with:
-          python-version: '3.11'
-
-      - name: Install maturin
-        run: pip install maturin
-
-      - name: Build sdist
-        run: maturin sdist --out dist
-
-      - name: Upload sdist
-        uses: actions/upload-artifact@v7
-        with:
-          name: sdist
-          path: dist/*.tar.gz
+  # Build the full wheel matrix via the shared reusable workflow.
+  build:
+    uses: ./.github/workflows/build-wheels.yml
 
   # Publish to PyPI
   publish:
     name: Publish to PyPI
-    needs: [build-linux, build-macos-arm, build-windows, build-sdist]
+    needs: build
     runs-on: ubuntu-latest
     environment: pypi
     permissions:
diff --git a/.github/workflows/release-build-check.yml b/.github/workflows/release-build-check.yml
new file mode 100644
index 00000000..ee7c4dd5
--- /dev/null
+++ b/.github/workflows/release-build-check.yml
@@ -0,0 +1,36 @@
+name: Release build check
+
+# Pre-merge guard for the PyPI release build path. publish.yml only runs on
+# `release: published`, so its manylinux container build (checkout@v7 inside
+# glibc-2.28, openblas, py3.9-3.14) is never exercised by PR CI. This calls the
+# SAME reusable workflow build-only (no PyPI upload) so a PR that would break our
+# ability to mint a release fails here instead of at release time.
+#
+# On PRs it builds only the manylinux leg (the gap rust-test.yml doesn't cover);
+# `workflow_dispatch` runs the full matrix as a manual pre-release rehearsal.
+on:
+  pull_request:
+    branches: [main]
+    types: [opened, synchronize, reopened, labeled, unlabeled]
+    paths:
+      - 'rust/**'
+      - 'pyproject.toml'
+      - '.github/workflows/build-wheels.yml'
+      - '.github/workflows/publish.yml'
+      - '.github/workflows/release-build-check.yml'
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  release-build:
+    # Skip unrelated label churn: a non-ready-for-ci label add/remove won't run this job.
+    if: >-
+      github.event_name != 'pull_request'
+      || (contains(github.event.pull_request.labels.*.name, 'ready-for-ci')
+      && (github.event.action != 'labeled' && github.event.action != 'unlabeled'
+      || github.event.label.name == 'ready-for-ci'))
+    uses: ./.github/workflows/build-wheels.yml
+    with:
+      linux_only: ${{ github.event_name == 'pull_request' }}
diff --git a/.github/workflows/rust-test.yml b/.github/workflows/rust-test.yml
index ef12a463..3908f293 100644
--- a/.github/workflows/rust-test.yml
+++ b/.github/workflows/rust-test.yml
@@ -20,6 +20,7 @@ on:
       - '.github/workflows/docs-tests.yml'
       - '.github/workflows/notebooks.yml'
       - '.github/workflows/ci-gate.yml'
+      - '.github/workflows/release-build-check.yml'
       # The AI-review surfaces below are tested by
       # tests/test_openai_review.py (TestWorkflowPromptHardening,
       # TestAdaptReviewCriteria, etc.). Without these path filters, a
@@ -47,6 +48,7 @@ on:
       - '.github/workflows/docs-tests.yml'
       - '.github/workflows/notebooks.yml'
       - '.github/workflows/ci-gate.yml'
+      - '.github/workflows/release-build-check.yml'
       - '.github/workflows/ai_pr_review.yml'
       - '.github/codex/prompts/pr_review.md'
       - '.claude/scripts/openai_review.py'
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1d8fcbec..61140c38 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -17,6 +17,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   `maturin develop --features accelerate` against the pinned `ndarray 0.17`, the Rust unit
   tests, and the full Python⇄Rust equivalence suite (`tests/test_rust_backend.py`).
 
+### Security
+- **Bumped the Rust backend's `pyo3` and `numpy` crates 0.28 → 0.29.** Resolves two RustSec
+  advisories in `pyo3 < 0.29` — RUSTSEC-2026-0176 (out-of-bounds read in `PyList`/`PyTuple`
+  `nth`/`nth_back`, High) and RUSTSEC-2026-0177 (missing `Sync` bound on
+  `PyCFunction::new_closure`, Medium). Neither vulnerable path was reachable in this crate
+  (no `PyList`/`PyTuple` iteration, no `new_closure`, no free-threaded wheels); `numpy` 0.29 is
+  bumped in lockstep because it requires `pyo3` ^0.29. No API or numerical change — both crates
+  are FFI/binding layers, and the math/RNG crates (`ndarray`, `faer`, `rand`, `rand_xoshiro`)
+  are unchanged.
+
 ## [3.5.3] - 2026-06-25
 
 ### Added
@@ -43,16 +53,6 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   `treatment_fraction` remains inert (balanced 2×2×2); pass `group_frac`/`partition_frac`
   via `data_generator_kwargs`. See `docs/methodology/REGISTRY.md` §PowerAnalysis.
 
-### Security
-- **Bumped the Rust backend's `pyo3` and `numpy` crates 0.28 → 0.29.** Resolves two RustSec
-  advisories in `pyo3 < 0.29` — RUSTSEC-2026-0176 (out-of-bounds read in `PyList`/`PyTuple`
-  `nth`/`nth_back`, High) and RUSTSEC-2026-0177 (missing `Sync` bound on
-  `PyCFunction::new_closure`, Medium). Neither vulnerable path was reachable in this crate
-  (no `PyList`/`PyTuple` iteration, no `new_closure`, no free-threaded wheels); `numpy` 0.29 is
-  bumped in lockstep because it requires `pyo3` ^0.29. No API or numerical change — both crates
-  are FFI/binding layers, and the math/RNG crates (`ndarray`, `faer`, `rand`, `rand_xoshiro`)
-  are unchanged.
-
 ## [3.5.2] - 2026-06-08
 
 ### Added
diff --git a/tests/test_openai_review.py b/tests/test_openai_review.py
index e9cd8055..3ae27dde 100644
--- a/tests/test_openai_review.py
+++ b/tests/test_openai_review.py
@@ -2084,6 +2084,7 @@ def test_rust_test_yml_pr_filter_covers_ai_review_surfaces(self, workflow_paths)
         ".github/workflows/docs-tests.yml",
         ".github/workflows/notebooks.yml",
         ".github/workflows/ci-gate.yml",
+        ".github/workflows/release-build-check.yml",
     )
 
     def test_rust_test_yml_push_filter_covers_guarded_workflows(self, workflow_paths):
@@ -2128,6 +2129,9 @@ class TestCiWorkflowLabelEventGuard:
         "rust-test.yml": ("rust-tests", "python-tests", "python-fallback"),
         "notebooks.yml": ("execute-notebooks",),
         "docs-tests.yml": ("doc-snippets", "sphinx-build", "docs-deps-py39-smoke"),
+        # release-build-check.yml is a single reusable-workflow caller job gated on
+        # ready-for-ci (it build-tests the PyPI release path on PRs); lock its guard too.
+        "release-build-check.yml": ("release-build",),
     }
 
     # The exact guard every gated job must carry (folded to one line). Asserting