diff --git a/.github/workflows/_checks.yml b/.github/workflows/_checks.yml
index ac9d235..f78d92d 100644
--- a/.github/workflows/_checks.yml
+++ b/.github/workflows/_checks.yml
@@ -99,10 +99,10 @@ jobs:
           cache-dependency-glob: "**/pyproject.toml"
       - run: uv python install ${{ matrix.python-version }}
       - run: uv python pin ${{ matrix.python-version }}
-      # --no-build so a floor with no wheel for this interpreter fails here instead of
-      # quietly compiling its sdist; --no-install-project because that flag would refuse to
-      # build this project too, and the tests import it from the checkout.
-      - run: uv sync --all-extras --no-install-project --resolution lowest-direct --no-build
+      - run: uv venv
+      # Pinned with builds allowed, so a floor with no wheel fails the wheel-only install below.
+      - run: uv pip compile pyproject.toml --all-extras --no-deps --resolution lowest-direct -o floors.txt
+      - run: uv pip install -r pyproject.toml --all-extras --group dev --constraints floors.txt --no-build
       - run: uv run --no-sync pytest
         env:
           PYTHONDONTWRITEBYTECODE: 1
diff --git a/pyproject.toml b/pyproject.toml
index 73ccb28..e5f1428 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -31,10 +31,11 @@ dependencies = [
     # 4.12.2, not 4.12.0: pydantic requires >=4.12.2 on 3.13+, and pinning 4.12.0 drags pydantic
     # back to a build whose pydantic-core has no cp313 wheel either.
     "typing-extensions>=4.12.2",
+    # pydantic 2.12, the 3.14 floor above, requires >=4.14.1.
+    "typing-extensions>=4.14.1; python_version >= '3.14'",
 ]
 
 [dependency-groups]
-# Floored so `uv sync --resolution lowest-direct` resolves a usable harness, not each name's first release.
 dev = [
     "pytest>=8",
     "pytest-asyncio>=0.24",