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Your First Contract in 5 Minutes

1. Create a Contract​

mkdir my-escrow && cd my-escrow
modal contract create

This creates a .contract/ directory to track commits.

2. Create Identities​

modal id create --path alice.passfile
modal id create --path bob.passfile

3. Initialize State​

modal c checkout
mkdir -p state rules

# Add party identities
modal c set /parties/alice.id $(modal id get --path ./alice.passfile)
modal c set /parties/bob.id $(modal id get --path ./bob.passfile)

4. Define the Model​

Create model/escrow.modality:

model escrow {
  states { pending, funded, delivered, released, refunded }
  initial pending
  terminal released, refunded
  
  transition DEPOSIT: pending -> funded
    +signed_by(/parties/alice.id)
  
  transition DELIVER: funded -> delivered
    +signed_by(/parties/bob.id)
  
  transition RELEASE: delivered -> released
    +signed_by(/parties/alice.id)
  
  transition REFUND: funded -> refunded
    +signed_by(/parties/bob.id)
}

5. Add Protection Rules​

Rules constrain who can commit based on contract state. Create rules/buyer-protection.modality:

export default rule {
  starting_at $PARENT
  formula {
    signed_by(/parties/alice.id) | signed_by(/parties/bob.id)
  }
}

This says: "Every commit must be signed by Alice or Bob."

For state-dependent authorization:

export default rule {
  starting_at $PARENT
  formula {
    // Only buyer can commit when not yet delivered
    !bool_true(/status/delivered.bool) -> signed_by(/parties/buyer.id)
  }
}

6. Commit and Verify​

# Commit all changes
modal c commit --all --sign alice.passfile -m "Initial escrow setup"

# Check status
modal c status

What's Next?​