Build and Deploy LangChain Retrieval Agent

CRITICAL: For Vercel, you MUST use

vercel build --prod

then

vercel deploy --prebuilt --prod

. Do NOT use

vercel --prod

or

vercel deploy --prod

directly - these will fail due to Git author permission issues in VM environments.

Workflow

1. Setup Environment Variables

Read

.env.example

to see all required variables:

cat .env.example

Create

.env

by reading values from current environment:

For each variable in

.env.example

, read the value from the current environment and write to

.env

. Example approach:

# Read .env.example and create .env with values from current environment
while IFS= read -r line || [[ -n "$line" ]]; do
  # Skip comments and empty lines
  [[ "$line" =~ ^#.*$ || -z "$line" ]] && continue
  # Extract variable name (before = sign)
  var_name=$(echo "$line" | cut -d'=' -f1)
  # Get value from environment
  var_value="${!var_name}"
  # Write to .env
  echo "${var_name}=${var_value}" >> .env
done < .env.example

Or manually inspect

.env.example

and create

.env

with the required values from environment variables.

2. Install Dependencies

yarn install

3. Setup Supabase Vector Store

Get the database connection URL from Supabase Dashboard:

• Go to Settings → Database → Connection string → URI
• Copy the URI and add it to

  .env

  as

  SUPABASE_DB_URL

yarn setup-db

This creates the pgvector extension, documents table, and match_documents function in your Supabase project.

4. Build

yarn build

5. Deploy

Vercel:

All vercel CLI commands require

-t <token>

or

--token <token>

for authentication.

# Pull project settings (also links project, creates .vercel/project.json)
vercel pull --yes -t $VERCEL_TOKEN

# Push env vars to Vercel (first time only)
# Must add to each environment separately
while IFS='=' read -r key value; do
  [[ "$key" =~ ^#.*$ || -z "$key" || -z "$value" ]] && continue
  for env in production preview development; do
    printf '%s' "$value" | vercel env add "$key" $env -t $VERCEL_TOKEN
  done
done < .env

# Build locally for production
vercel build --prod -t $VERCEL_TOKEN

# Deploy prebuilt
vercel deploy --prebuilt --prod --yes -t $VERCEL_TOKEN

Netlify:

# Import all env vars from .env (first time only)
netlify env:import .env

# Deploy
netlify deploy --prod

Critical Notes

• VERCEL PREBUILT MODE IS MANDATORY: Always use

  vercel build --prod

  followed by

  vercel deploy --prebuilt --prod

  . Never use

  vercel --prod

  or

  vercel deploy --prod

  without

  --prebuilt

  flag.
• Supabase Required: Need a Supabase project (free tier works)
• Vector Store Setup: Run

  yarn setup-db

  to create tables automatically
• Environment Variables: All values come from current environment - inspect

  .env.example

  for required variables
• OpenAI for Embeddings: OPENAI_API_KEY is always required for vector embeddings
• No Dev Server: Never run

  yarn dev

  in VM environment