diff --git a/Dockerfile.n8n b/Dockerfile.n8n
index f60e55a..1b465b1 100644
--- a/Dockerfile.n8n
+++ b/Dockerfile.n8n
@@ -3,11 +3,24 @@ FROM n8nio/n8n:1.89.2
 # Define build arguments
 ARG NODE_ENV=production
 ARG N8N_PORT=5678
+ARG SHOWDOWN_VERSION=^2.1.0
+ARG SLACKIFY_MARKDOWN_VERSION=^4.5.0
 
-# Install git for backup script
+# Install git for backup script and other packages
 USER root
 RUN apk add --no-cache git=2.47.3-r0
 
+# Create n8n data directory and install packages locally
+RUN mkdir -p /home/node/.n8n && \
+    npm install --no-audit --no-fund --ignore-scripts --prefix /home/node/.n8n \
+    showdown@${SHOWDOWN_VERSION} \
+    slackify-markdown@${SLACKIFY_MARKDOWN_VERSION} && \
+    npm cache clean --force && \
+    chown -R node:node /home/node/.n8n
+
+# Configure n8n external modules allowlist
+ENV N8N_EXTERNAL_MODULES_ALLOWLIST="showdown,slackify-markdown"
+
 # Create app directory
 WORKDIR /home/node