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Module 2: Semantic Router

What you're building

Your agent currently answers everything, even off-topic questions like "Why is the sky blue?" In this module you'll add a semantic router that filters queries before they reach the AI.

You'll define two lists of example queries: an allow list for questions your agent should handle, and a deny list for ones it should block.

Setup

Enable the Semantic Router in your .env file:

GUARDRAIL_ENABLED=true

Exercise

  1. Open exercises/banking/semantic_router.py in your IDE.
  2. Add 2-3 more references to each route to improve classification. Each Route has:
Field What it does
name "allow_list" lets queries through, "deny_list" blocks them
references Example queries that represent this category
distance_threshold How close a match must be (lower = stricter) 
Route(
    name="allow_list",
    references=[
        "What are my account balances?",
        "Fixed deposit rate FD6",
        "Waive annual card fee",
        "Branch hours Tampines",
        "What accounts do I have?",
        "Early withdrawal penalty",
        "Can you help me?",
        "What do you know about me?",
        # Add 2-3 more banking queries...
    ],
    distance_threshold=0.7,
),
Route(
    name="deny_list",
    references=[
        "Why is the sky blue?",
        "Tell me a joke",
        "How do I cook pasta?",
        # Add 2-3 more off-topic queries...
    ],
    distance_threshold=0.5,
),
Click for a hint

For the allow list, think about accounts, fixed deposits, card fees, branches, or greetings like "Hello". For the deny list, think about cooking, trivia, coding help, or creative writing.

Verify

Stop the running server (Ctrl+C) and restart:

make dev

.\workshop.ps1 dev

Open localhost:3040.

  • Ask: "What accounts do I have and what are my current balances?" and click Semantic-router in the right activity panel to see it pass through
  • Ask: "Why is the sky blue?" and see it get blocked with a redirect message