diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
new file mode 100644
index 0000000..e4cbad7
--- /dev/null
+++ b/.github/workflows/tests.yml
@@ -0,0 +1,47 @@
+name: Source compatibility
+
+on: [push, pull_request]
+
+permissions:
+  contents: read
+
+jobs:
+  test:
+    name: ${{ matrix.os }} / Python ${{ matrix.python-version }}
+    runs-on: ${{ matrix.os }}
+    timeout-minutes: 15
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-22.04, windows-2022]
+        python-version: ['3.7', '3.8', '3.9', '3.10', '3.11', '3.12', '3.13', '3.14']
+    steps:
+      - name: Check out source
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          persist-credentials: false
+      - name: Set up Python
+        id: python
+        uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97 # v7.0.0
+        with:
+          python-version: ${{ matrix.python-version }}
+          architecture: x64
+      - name: Record interpreter
+        shell: python
+        run: |
+          import platform
+          import struct
+          import sys
+          import tempfile
+          from pathlib import Path
+
+          print(sys.version)
+          print(platform.platform())
+          print('Architecture bits:', struct.calcsize('P') * 8)
+          print('Temporary directory:', tempfile.gettempdir())
+          print('Resolved temporary directory:', Path(tempfile.gettempdir()).resolve())
+      - name: Run source tests
+        run: python -m unittest discover -s tests -v
+      - name: Check source syntax
+        if: ${{ !cancelled() && steps.python.outcome == 'success' }}
+        run: python -m compileall -q MHTMLExtractor.py mhtmlextractor
diff --git a/AGENTS.md b/AGENTS.md
index d52da09..9949d4b 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -3,6 +3,8 @@
 ## Install
 
 - Use Python 3.7 or newer.
+- Source CI covers x64 CPython 3.7 through 3.14 on Windows and Linux. Keep the minimum at 3.7 and do not add an upper installation cap.
+- Project compatibility testing does not imply upstream maintenance of end-of-life Python versions.
 - From the repository root, install normally with `python -m pip install .`.
 - For local development, install editable with `python -m pip install -e .`.
 - After installation, confirm the command surface with `mhtml-extract --help`.
@@ -39,10 +41,14 @@ Use `MHTMLExtractor` or `mhtml-extract` when you need files written to disk.
 
 ## Test
 
+- `.github/workflows/tests.yml` runs the source suite and syntax check on pushes and pull requests across Windows Server 2022 / Ubuntu 22.04 and CPython 3.7-3.14.
+- Source tests use only the standard library and run without a package installation.
 - Run tests with `python -m unittest discover -s tests`.
+- CI adds `-v` to expose skips: the TOML metadata test skips below 3.11, and symlink coverage may skip when the platform cannot create symlinks.
 - Run a syntax check with `python -m compileall -q MHTMLExtractor.py mhtmlextractor`.
 - Do not use `python -m py_compile mhtmlextractor\*.py` in PowerShell; the wildcard can be passed literally.
 - For installability changes, verify an editable install and run `mhtml-extract --help`.
+- Source and editable-install checks do not replace separate clean wheel/sdist installation validation.
 
 ## Avoid Unsafe Assumptions
 
diff --git a/README.md b/README.md
index a96144f..39c688f 100644
--- a/README.md
+++ b/README.md
@@ -10,6 +10,12 @@ The project uses only Python's standard library.
 
 - Python 3.7 or newer
 
+The source compatibility CI matrix covers x64 CPython 3.7 through 3.14 on
+Windows and Linux. The package has no upper Python version cap; versions beyond
+this matrix are not yet verified. Compatibility testing of older Python versions
+does not imply upstream maintenance. See the
+[official Python version status](https://devguide.python.org/versions/).
+
 ## Installation
 
 From the repository root:
@@ -307,12 +313,24 @@ objects.
 
 ## Development
 
-Run the test suite:
+The [source compatibility workflow](.github/workflows/tests.yml) runs on pushes
+and pull requests using Windows Server 2022 and Ubuntu 22.04, with x64 CPython
+3.7 through 3.14. It runs the source tests and syntax check directly from the
+checkout using only the standard library; no package installation is required.
+Each matrix job reports its interpreter version and runs independently so one
+failure does not cancel the other versions.
+
+Run the same test suite locally:
 
 ```bash
 python -m unittest discover -s tests
 ```
 
+CI adds `-v` to show individual tests and skip reasons. The TOML metadata test
+skips on Python 3.7 through 3.10 because `tomllib` is available from Python 3.11;
+the extraction tests still run. A symlink test may skip when the platform cannot
+create symlinks.
+
 Run a package syntax check:
 
 ```bash
@@ -325,6 +343,9 @@ Check the installed command surface from a local editable install:
 mhtml-extract --help
 ```
 
+Source compatibility and editable-install checks do not verify installed wheel
+or source-distribution behavior; those require separate clean installations.
+
 ## License
 
 MHTMLExtractor is released under the MIT License. See `LICENSE`.
diff --git a/pyproject.toml b/pyproject.toml
index 9d53463..c150c3c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -35,6 +35,7 @@ classifiers = [
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
     "Programming Language :: Python :: 3.13",
+    "Programming Language :: Python :: 3.14",
     "Topic :: Internet :: WWW/HTTP",
     "Topic :: System :: Archiving",
     "Topic :: Utilities",
diff --git a/tests/test_duplicate_parts.py b/tests/test_duplicate_parts.py
index cfb3b31..f77bb94 100644
--- a/tests/test_duplicate_parts.py
+++ b/tests/test_duplicate_parts.py
@@ -36,7 +36,8 @@ class DuplicatePartTests(unittest.TestCase):
     def setUp(self):
         temporary = tempfile.TemporaryDirectory(prefix="mhtml-duplicates-")
         self.addCleanup(temporary.cleanup)
-        self.root = Path(temporary.name)
+        # Match the extractor's canonical paths when TEMP contains an alias.
+        self.root = Path(temporary.name).resolve()
 
     def archive(self, parts, name="input"):
         payload = [b'Content-Type: multipart/related; boundary="duplicates"\r\n\r\n']
diff --git a/tests/test_file_safety.py b/tests/test_file_safety.py
index 03431c3..043efe0 100644
--- a/tests/test_file_safety.py
+++ b/tests/test_file_safety.py
@@ -117,7 +117,8 @@ class FileSafetyTests(unittest.TestCase):
     def setUp(self):
         self.temporary = tempfile.TemporaryDirectory(prefix="mhtml-a61-")
         self.addCleanup(self.temporary.cleanup)
-        self.root = Path(self.temporary.name)
+        # Match the extractor's canonical paths when TEMP contains an alias.
+        self.root = Path(self.temporary.name).resolve()
 
     def archive_and_output(self, name="case", **options):
         case = self.root / name
diff --git a/tests/test_static_references.py b/tests/test_static_references.py
index 866b617..3226003 100644
--- a/tests/test_static_references.py
+++ b/tests/test_static_references.py
@@ -53,7 +53,8 @@ class StaticReferenceTests(unittest.TestCase):
     def setUp(self):
         temporary = tempfile.TemporaryDirectory(prefix="mhtml-static-refs-")
         self.addCleanup(temporary.cleanup)
-        self.root = Path(temporary.name)
+        # Match the extractor's canonical paths when TEMP contains an alias.
+        self.root = Path(temporary.name).resolve()
         self.case_number = 0
 
     def archive(self, parts, outer_location=None):