diff --git a/.github/workflows/publish-pypi.yml b/.github/workflows/publish-pypi.yml
index 8731a73..7129679 100644
--- a/.github/workflows/publish-pypi.yml
+++ b/.github/workflows/publish-pypi.yml
@@ -5,6 +5,14 @@ on:
     tags:
       - "v*"
   workflow_dispatch:
+  pull_request:
+    paths:
+      - ".github/workflows/publish-pypi.yml"
+      - "Cargo.toml"
+      - "Cargo.lock"
+      - "pyproject.toml"
+      - "src/**"
+      - "python/**"
 
 permissions:
   contents: read
@@ -51,6 +59,7 @@ jobs:
           PY
 
   manylinux:
+    if: github.event_name != 'pull_request'
     name: manylinux ${{ matrix.target }}
     needs: validate
     runs-on: ubuntu-latest
@@ -90,6 +99,7 @@ jobs:
           if-no-files-found: error
 
   musllinux:
+    if: github.event_name != 'pull_request'
     name: musllinux ${{ matrix.target }}
     needs: validate
     runs-on: ubuntu-latest
@@ -124,7 +134,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["3.10", "3.11", "3.12", "3.13", "3.14"]
+        python-version: ["3.10", "3.11", "3.12", "3.13", "3.14", "3.15", "3.14t", "3.15t"]
     steps:
       - uses: actions/checkout@v7
 
@@ -132,6 +142,7 @@ jobs:
         with:
           python-version: ${{ matrix.python-version }}
           architecture: x64
+          allow-prereleases: true
 
       - name: Build wheel
         uses: PyO3/maturin-action@v1
@@ -142,11 +153,46 @@ jobs:
           args: >-
             --release --locked --compatibility pypi --interpreter python --out dist
 
-      - name: Test wheel
+      - name: Validate wheel tags and test in a clean interpreter
+        shell: bash
+        env:
+          EXPECTED_PYTHON: ${{ matrix.python-version }}
         run: |
-          python -m pip install pytest
-          python -m pip install --no-index --no-deps --force-reinstall --find-links dist fasttime-rs
-          python -m pytest python/tests
+          python -m venv wheel-test
+          wheel-test/Scripts/python -m pip install pytest packaging
+          wheel-test/Scripts/python - <<'PY'
+          import os
+          from pathlib import Path
+          import struct
+          import sys
+          import sysconfig
+          import zipfile
+          from packaging.tags import Tag
+          from packaging.utils import parse_wheel_filename
+
+          version = os.environ["EXPECTED_PYTHON"]
+          free_threaded = version.endswith("t")
+          major, minor = map(int, version.removesuffix("t").split("."))
+          assert sys.version_info[:2] == (major, minor), sys.version
+          assert struct.calcsize("P") == 8, "Expected a 64-bit interpreter"
+          assert bool(sysconfig.get_config_var("Py_GIL_DISABLED")) == free_threaded
+          python_tag = f"cp{major}{minor}"
+          abi_tag = python_tag + ("t" if free_threaded else "")
+          expected = Tag(python_tag, abi_tag, "win_amd64")
+          wheels = list(Path("dist").glob("*.whl"))
+          assert len(wheels) == 1, wheels
+          wheel = wheels[0]
+          assert parse_wheel_filename(wheel.name)[3] == {expected}, wheel.name
+          with zipfile.ZipFile(wheel) as archive:
+              metadata = [name for name in archive.namelist() if name.endswith(".dist-info/WHEEL")]
+              assert len(metadata) == 1, metadata
+              tags = [line[5:] for line in archive.read(metadata[0]).decode().splitlines()
+                      if line.startswith("Tag: ")]
+          assert tags == [str(expected)], tags
+          print(f"Validated {wheel.name}: {expected}; interpreter={sys.version}")
+          PY
+          wheel-test/Scripts/python -m pip install --no-index --no-deps --find-links dist fasttime-rs
+          wheel-test/Scripts/python -m pytest python/tests
 
       - name: Upload wheel
         uses: actions/upload-artifact@v6
@@ -156,6 +202,7 @@ jobs:
           if-no-files-found: error
 
   macos:
+    if: github.event_name != 'pull_request'
     name: macOS ${{ matrix.platform.target }} CPython ${{ matrix.python-version }}
     needs: validate
     runs-on: ${{ matrix.platform.runner }}
@@ -198,6 +245,7 @@ jobs:
           if-no-files-found: error
 
   sdist:
+    if: github.event_name != 'pull_request'
     name: Source distribution
     needs: validate
     runs-on: ubuntu-latest