fix: keep WebSocket subscription changes in sync and send them promptly

.github/workflows/test.yml

@@ -14,7 +14,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, windows-latest]
-        python-version: ['3.10', '3.11']
+        python-version: ['3.10', '3.11', '3.12', '3.13', '3.14']
     runs-on: ${{ matrix.os }}
     name: ${{ matrix.os }} Unit test ${{ matrix.python-version }}
     steps:
@@ -32,3 +32,41 @@ jobs:
         run: poetry install
       - name: Unit tests
         run: make test
+  test-free-threaded:
+    strategy:
+      fail-fast: false
+      matrix:
+        python-version: ['3.13t', '3.14t']
+    runs-on: ubuntu-latest
+    name: ubuntu-latest Unit test ${{ matrix.python-version }} (PYTHON_GIL=0)
+    steps:
+      - uses: actions/checkout@v3
+      - name: Setup Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+      - name: Setup Poetry
+        # pipx is Poetry's recommended installation method, and it keeps Poetry
+        # on the runner's regular Python, independent of the interpreter under test
+        run: pipx install poetry
+      - name: Install pypi deps
+        # the dev group (linters, docs, orjson for the examples) is not needed
+        # to run the tests, and orjson does not support free-threaded Python
+        run: |
+          poetry env use python${{ matrix.python-version }}
+          poetry install --only main,test
+      - name: Unit tests
+        env:
+          PYTHON_GIL: '0'
+        run: |
+          poetry run python - <<'EOF'
+          import sys, sysconfig
+          state = (
+              f"version={sys.version!r} "
+              f"Py_GIL_DISABLED={sysconfig.get_config_var('Py_GIL_DISABLED')!r} "
+              f"_is_gil_enabled={sys._is_gil_enabled()!r}"
+          )
+          print(state)
+          assert not sys._is_gil_enabled(), f"the GIL is enabled: {state}"
+          EOF
+          make test

docs/source/WebSocket.rst

@@ -34,6 +34,16 @@ Unsubscribe
 ============================
 .. automethod:: massive.WebSocketClient.unsubscribe
 
+============================
+Set subscriptions
+============================
+.. automethod:: massive.WebSocketClient.set_subscriptions
+
+============================
+Resubscribe
+============================
+.. automethod:: massive.WebSocketClient.resubscribe
+
 ============================
 Close
 ============================