diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index d81e637..daac1f6 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -25,20 +25,27 @@ jobs:
         uses: actions/setup-python@v5
         with:
           python-version: "3.14"
+          cache: 'pip'
 
-      - name: Cache pip dependencies
+      - name: Cache full virtual environment
         uses: actions/cache@v4
-        id: pip-cache
+        id: cache-venv
         with:
-          path: ~/.cache/pip
-          key: ${{ runner.os }}-pip-${{ hashFiles('pyproject.toml', 'requirements*.txt') }}
+          path: .venv
+          key: ${{ runner.os }}-py3.14-venv-${{ hashFiles('pyproject.toml') }}
           restore-keys: |
-            ${{ runner.os }}-pip-
+            ${{ runner.os }}-py3.14-venv-
 
       - name: Install dependencies
+        if: steps.cache-venv.outputs.cache-hit != 'true'
         run: |
+          python -m venv .venv
+          source .venv/bin/activate
           python -m pip install --upgrade pip
-          pip install ".[dev]"
+          pip install --no-cache-dir ".[dev]"
+
+      - name: Activate virtual environment
+        run: echo "$GITHUB_WORKSPACE/.venv/bin" >> $GITHUB_PATH
 
       - name: Run Ruff linter
         run: ruff check .
diff --git a/.github/workflows/docker-publish.yml b/.github/workflows/docker-publish.yml
index 4f72757..489070c 100644
--- a/.github/workflows/docker-publish.yml
+++ b/.github/workflows/docker-publish.yml
@@ -20,19 +20,27 @@ jobs:
         uses: actions/setup-python@v5
         with:
           python-version: "3.14"
+          cache: 'pip'
 
-      - name: Cache pip dependencies
+      - name: Cache full virtual environment
         uses: actions/cache@v4
+        id: cache-venv
         with:
-          path: ~/.cache/pip
-          key: ${{ runner.os }}-pip-${{ hashFiles('pyproject.toml', 'requirements*.txt') }}
+          path: .venv
+          key: ${{ runner.os }}-py3.14-venv-${{ hashFiles('pyproject.toml') }}
           restore-keys: |
-            ${{ runner.os }}-pip-
+            ${{ runner.os }}-py3.14-venv-
 
       - name: Install dependencies
+        if: steps.cache-venv.outputs.cache-hit != 'true'
         run: |
+          python -m venv .venv
+          source .venv/bin/activate
           python -m pip install --upgrade pip
-          pip install ".[dev]"
+          pip install --no-cache-dir ".[dev]"
+
+      - name: Activate virtual environment
+        run: echo "$GITHUB_WORKSPACE/.venv/bin" >> $GITHUB_PATH
 
       - name: Run Ruff linter
         run: ruff check .
diff --git a/pyproject.toml b/pyproject.toml
index 2bb8efb..3dd286c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -48,6 +48,7 @@ dependencies = [
 
   # RAG
   "tiktoken>=0.7",
+  "nltk>=3.8.1",
 
   # Storage
   "sqlalchemy>=2.0",