diff --git a/Dockerfile b/Dockerfile
index 9e30e09..848178d 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -32,6 +32,14 @@ COPY open_notebook/__init__.py ./open_notebook/__init__.py
 # Install dependencies with optimizations (this layer will be cached unless dependencies change)
 RUN uv sync --frozen --no-dev
 
+# Pre-download tiktoken encoding so the app works offline (issue #264).
+# /app/tiktoken-cache is intentionally outside /app/data/ so that volume mounts
+# of /app/data (for user data persistence) do not hide the pre-baked encoding.
+# config.py reads TIKTOKEN_CACHE_DIR from the environment to pick up this path.
+ENV TIKTOKEN_CACHE_DIR=/app/tiktoken-cache
+RUN mkdir -p /app/tiktoken-cache && \
+    .venv/bin/python -c "import tiktoken; tiktoken.get_encoding('o200k_base')"
+
 # Copy the rest of the application code
 COPY . /app
 
@@ -72,9 +80,14 @@ COPY --from=builder /app/.venv /app/.venv
 # Copy the source code (the rest)
 COPY . /app
 
+# Copy pre-downloaded tiktoken encoding from builder (outside /data/ — volume-mount safe)
+COPY --from=builder /app/tiktoken-cache /app/tiktoken-cache
+
 # Ensure uv uses the existing venv without attempting network operations
 ENV UV_NO_SYNC=1
 ENV VIRTUAL_ENV=/app/.venv
+# Point the app at the pre-baked tiktoken encoding (see open_notebook/config.py)
+ENV TIKTOKEN_CACHE_DIR=/app/tiktoken-cache
 
 # Bind Next.js to all interfaces (required for Docker networking and reverse proxies)
 ENV HOSTNAME=0.0.0.0
diff --git a/Dockerfile.single b/Dockerfile.single
index 32ddd28..1eb5e80 100644
--- a/Dockerfile.single
+++ b/Dockerfile.single
@@ -33,6 +33,14 @@ COPY open_notebook/__init__.py ./open_notebook/__init__.py
 # Install dependencies
 RUN uv sync --frozen --no-dev
 
+# Pre-download tiktoken encoding so the app works offline (issue #264).
+# /app/tiktoken-cache is intentionally outside /app/data/ so that volume mounts
+# of /app/data (for user data persistence) do not hide the pre-baked encoding.
+# config.py reads TIKTOKEN_CACHE_DIR from the environment to pick up this path.
+ENV TIKTOKEN_CACHE_DIR=/app/tiktoken-cache
+RUN mkdir -p /app/tiktoken-cache && \
+    .venv/bin/python -c "import tiktoken; tiktoken.get_encoding('o200k_base')"
+
 # Stage 5: Runtime
 FROM python:3.12-slim-bookworm AS runtime
 
@@ -57,6 +65,9 @@ WORKDIR /app
 COPY --from=backend-builder /app/.venv /app/.venv
 COPY . /app/
 
+# Copy pre-downloaded tiktoken encoding from builder (outside /data/ — volume-mount safe)
+COPY --from=backend-builder /app/tiktoken-cache /app/tiktoken-cache
+
 # Copy built frontend from standalone output
 COPY --from=frontend-builder /app/frontend/.next/standalone /app/frontend/
 COPY --from=frontend-builder /app/frontend/.next/static /app/frontend/.next/static
@@ -64,6 +75,8 @@ COPY --from=frontend-builder /app/frontend/public /app/frontend/public
 
 # Bind Next.js to all interfaces (required for Docker networking and reverse proxies)
 ENV HOSTNAME=0.0.0.0
+# Point the app at the pre-baked tiktoken encoding (see open_notebook/config.py)
+ENV TIKTOKEN_CACHE_DIR=/app/tiktoken-cache
 
 # Setup directories and permissions
 RUN mkdir -p /app/data /mydata
diff --git a/open_notebook/config.py b/open_notebook/config.py
index 00d64cb..2db8f74 100644
--- a/open_notebook/config.py
+++ b/open_notebook/config.py
@@ -13,5 +13,8 @@ UPLOADS_FOLDER = f"{DATA_FOLDER}/uploads"
 os.makedirs(UPLOADS_FOLDER, exist_ok=True)
 
 # TIKTOKEN CACHE FOLDER
-TIKTOKEN_CACHE_DIR = f"{DATA_FOLDER}/tiktoken-cache"
+# Reads TIKTOKEN_CACHE_DIR from the environment so Docker can redirect the cache
+# to a path outside /data/ (which is typically volume-mounted and would hide the
+# pre-baked encoding baked into the image at build time).
+TIKTOKEN_CACHE_DIR = os.environ.get("TIKTOKEN_CACHE_DIR", "").strip() or f"{DATA_FOLDER}/tiktoken-cache"
 os.makedirs(TIKTOKEN_CACHE_DIR, exist_ok=True)
diff --git a/open_notebook/utils/token_utils.py b/open_notebook/utils/token_utils.py
index 9b4a9ea..fd77592 100644
--- a/open_notebook/utils/token_utils.py
+++ b/open_notebook/utils/token_utils.py
@@ -28,8 +28,15 @@ def token_count(input_string: str) -> int:
         encoding = tiktoken.get_encoding("o200k_base")
         tokens = encoding.encode(input_string)
         return len(tokens)
-    except ImportError:
-        # Fallback: simple word count estimation
+    except Exception:
+        # Fallback: handles ImportError (not installed) AND network errors
+        # (e.g., offline environments that can't download encoding from internet)
+        from loguru import logger
+
+        logger.warning(
+            "tiktoken unavailable (not installed or offline); "
+            "falling back to word-count estimation."
+        )
         return int(len(input_string.split()) * 1.3)
 
 
diff --git a/tests/test_utils.py b/tests/test_utils.py
index e686826..389e2b9 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -151,6 +151,28 @@ class TestTokenUtilities:
             assert isinstance(count, int)
             assert count > 0
 
+    def test_token_count_network_error_fallback(self):
+        """Test fallback when tiktoken raises a network error (issue #264).
+
+        In offline environments tiktoken.get_encoding() tries to download the
+        encoding file and raises a URLError/OSError, not an ImportError.
+        The except clause must catch Exception (not only ImportError) so that
+        these network failures also fall through to the word-count estimate.
+        """
+        import urllib.error
+        from unittest.mock import patch
+
+        with patch(
+            "tiktoken.get_encoding",
+            side_effect=urllib.error.URLError("No network (simulated offline)"),
+        ):
+            text = "one two three four five"
+            count = token_count(text)
+
+            # Must not raise; must return a positive int via the fallback
+            assert isinstance(count, int)
+            assert count > 0
+
 
 # ============================================================================
 # TEST SUITE 3: Version Utilities