diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 772ef98..fdc94a3 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -15,10 +15,27 @@ permissions:
 
 jobs:
   quality:
-    name: Format, lint, typecheck, tests, and coverage
+    name: Format, lint, typecheck, tests, and coverage (py${{ matrix.python-version }})
     runs-on: ubuntu-latest
     timeout-minutes: 15
 
+    strategy:
+      fail-fast: false
+      matrix:
+        # 3.12 is the `requires-python` floor; 3.14 is the interpreter the
+        # container actually ships (docker/Dockerfile). Both ends are tested so a
+        # base-image bump can never ship an interpreter CI has not exercised.
+        python-version: ["3.12", "3.14"]
+
+    env:
+      # Without this the matrix is a lie. `uv` resolves its interpreter from
+      # `.python-version` (pinned to 3.12 for local dev) *before* it looks at
+      # PATH, so `setup-python` installing 3.14 changes nothing: both legs would
+      # build a 3.12 environment and the "3.14" leg would test the floor twice.
+      # `UV_PYTHON` outranks `.python-version`, and applies to every `uv run`
+      # inside `make ci-local`, not just the explicit `uv sync` below.
+      UV_PYTHON: ${{ matrix.python-version }}
+
     steps:
       - name: Checkout
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
@@ -26,7 +43,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97 # v7.0.0
         with:
-          python-version: "3.12"
+          python-version: ${{ matrix.python-version }}
 
       - name: Set up uv
         uses: astral-sh/setup-uv@c771a70e6277c0a99b617c7a806ffedaca235ff9 # v9.0.0
@@ -44,5 +61,5 @@ jobs:
       # Coverage gate runs only on push to main to avoid a second full test run on
       # every PR iteration (concurrency-cancel + this split are the compute savers).
       - name: Coverage gate
-        if: github.event_name == 'push'
+        if: github.event_name == 'push' && matrix.python-version == '3.14'
         run: make test-cov
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3295bcd..4eb8c11 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,32 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [4.1.2] - 2026-07-30
+
+### Changed
+
+- **CI tests the interpreter that actually ships.** The `quality` job now runs
+  on a `["3.12", "3.14"]` matrix instead of 3.12 only. `docker/Dockerfile` ships
+  `python:3.14-slim`, so until now the test suite was never exercised on the
+  interpreter that reaches production — only the image itself was, via
+  `container-ci`/`conformance`. A 3.14-only stdlib or typing regression would
+  have shipped uncaught. 3.12 stays in the matrix because it is the declared
+  `requires-python` floor; dropping it would make that floor a false claim. The
+  coverage gate still runs once (on 3.14, push to `main`). `requires-python`,
+  ruff `target-version` and mypy `python_version` are deliberately unchanged at
+  3.12.
+- **The matrix is forced with `UV_PYTHON`, not just `setup-python`.** `uv`
+  resolves its interpreter from `.python-version` (pinned to 3.12 for local dev)
+  *before* it consults `PATH`, so `actions/setup-python` alone does not move it:
+  both legs would have built a 3.12 environment and the "3.14" leg would have
+  tested the floor twice — green, and meaningless. The job now exports
+  `UV_PYTHON: ${{ matrix.python-version }}`, which outranks `.python-version`
+  and applies to every `uv run` inside `make ci-local`.
+- **New guard `tests/unit/test_ci_python_matrix.py`.** Pins the matrix against
+  `pyproject.toml`'s floor and the Dockerfile's `FROM python:<x.y>-slim`, so a
+  base-image bump that is not mirrored into CI fails instead of silently
+  re-opening the blind spot.
+
 ## [4.1.1] - 2026-07-30
 
 Dependabot onboarding plus the accumulated dependency sweep it had been hiding.
diff --git a/CITATION.cff b/CITATION.cff
index d309f24..475e8be 100644
--- a/CITATION.cff
+++ b/CITATION.cff
@@ -13,7 +13,7 @@ authors:
   given-names: Bernt
   email: bernt.popp@charite.de
   affiliation: Charité – Universitätsmedizin Berlin
-version: 4.1.1
+version: 4.1.2
 license: MIT
 repository-code: https://github.com/berntpopp/stringdb-link
 url: https://genefoundry.org
diff --git a/pyproject.toml b/pyproject.toml
index d7c1072..df141c8 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "stringdb-link"
-version = "4.1.1"
+version = "4.1.2"
 description = "High-performance unified API server for STRING protein-protein interaction database with MCP integration"
 readme = "README.md"
 license = { text = "MIT" }
diff --git a/tests/unit/test_ci_python_matrix.py b/tests/unit/test_ci_python_matrix.py
new file mode 100644
index 0000000..bbe99dc
--- /dev/null
+++ b/tests/unit/test_ci_python_matrix.py
@@ -0,0 +1,78 @@
+"""CI must run the test suite on the interpreter the container actually ships.
+
+``docker/Dockerfile`` ships ``python:3.14-slim``, but the CI test job ran only on
+Python 3.12. ``container-ci``/``conformance`` exercise the *image* on 3.14; the
+unit and API suites never did, so a 3.14-only stdlib or typing regression could
+ship uncaught.
+
+Both ends of the matrix are required. 3.12 is the declared ``requires-python``
+floor -- drop it and the floor is a false claim. 3.14 is what reaches
+production. And ``UV_PYTHON`` is load-bearing: ``uv`` resolves its interpreter
+from ``.python-version`` *before* it consults ``PATH``, so ``setup-python``
+alone would leave both matrix legs on 3.12 -- green, and meaningless.
+"""
+
+from __future__ import annotations
+
+import re
+import tomllib
+from pathlib import Path
+from typing import Any
+
+import yaml
+
+ROOT = Path(__file__).resolve().parents[2]  # tests/unit/ -> repo root
+WORKFLOW = ROOT / ".github" / "workflows" / "ci.yml"
+DOCKERFILE = ROOT / "docker" / "Dockerfile"
+
+
+def _quality_job() -> dict[str, Any]:
+    workflow = yaml.safe_load(WORKFLOW.read_text(encoding="utf-8"))
+    return dict(workflow["jobs"]["quality"])
+
+
+def _matrix_versions() -> list[str]:
+    return [str(v) for v in _quality_job()["strategy"]["matrix"]["python-version"]]
+
+
+def _requires_python_floor() -> str:
+    pyproject = tomllib.loads((ROOT / "pyproject.toml").read_text(encoding="utf-8"))
+    return str(pyproject["project"]["requires-python"]).removeprefix(">=")
+
+
+def _dockerfile_python_version() -> str:
+    match = re.search(
+        r"^FROM python:(\d+\.\d+)-slim", DOCKERFILE.read_text(encoding="utf-8"), re.MULTILINE
+    )
+    assert match is not None, "docker/Dockerfile must pin a python:<major>.<minor>-slim base"
+    return match.group(1)
+
+
+def test_ci_tests_the_requires_python_floor() -> None:
+    assert _requires_python_floor() in _matrix_versions(), (
+        "the declared requires-python floor must stay under test, or it is a false claim"
+    )
+
+
+def test_ci_tests_the_interpreter_the_container_ships() -> None:
+    assert _dockerfile_python_version() in _matrix_versions(), (
+        "docker/Dockerfile ships a CPython the test matrix never runs"
+    )
+
+
+def test_matrix_forces_uv_to_the_matrix_interpreter() -> None:
+    assert (ROOT / ".python-version").exists()
+    assert _quality_job()["env"]["UV_PYTHON"] == "${{ matrix.python-version }}", (
+        "uv reads .python-version before PATH, so without UV_PYTHON both matrix "
+        "legs build a 3.12 environment and the matrix silently tests the floor twice"
+    )
+
+
+def test_coverage_gate_runs_once_not_per_matrix_leg() -> None:
+    steps = _quality_job()["steps"]
+    coverage = [step for step in steps if step.get("run") == "make test-cov"]
+
+    assert len(coverage) == 1
+    assert "matrix.python-version == '3.14'" in coverage[0]["if"], (
+        "the coverage gate must run on one interpreter, not once per matrix leg"
+    )
diff --git a/uv.lock b/uv.lock
index 3efbc08..97169ff 100644
--- a/uv.lock
+++ b/uv.lock
@@ -1739,7 +1739,7 @@ wheels = [
 
 [[package]]
 name = "stringdb-link"
-version = "4.1.1"
+version = "4.1.2"
 source = { editable = "." }
 dependencies = [
     { name = "asgi-correlation-id" },