# Case Study: A Customer-Support Agent Team — LangGraph Agents & Multi-Agent Systems

Source: https://www.geekswithgeeks.com/en/langgraph-agents/z-case

> Design a supervised team with approvals, memory and limits.

## The design

Goal: handle support tickets with a team of agents. **Entry**: a `classify` node (small model) labels the ticket billing, technical or other. **Supervisor**: routes to workers via `Command(goto=...)` and ends when `resolution` is set or after 8 steps. **Workers**: *billing* (tools: `get_invoice`, `propose_refund`), *technical* (tools: `search_docs`, `get_account_status`), *writer* (drafts the reply from verified facts only). **Approval**: any refund above a threshold hits `interrupt()` for a human, with the proposed amount and evidence shown. **Memory**: Postgres checkpointer with `thread_id` from the session; a store keeps the customer's language and plan; long histories are trimmed with a summary. **Reliability**: retry policy on tool nodes, error field in state routing to a human queue, recursion limit 25, per-run cost cap. **Testing**: scripted-model tests for every route and the cap; a 100-ticket evaluation set scoring outcome, tool trajectory and safety; tracing with redaction. **Security**: least-privilege read-only tools except `propose_refund`, validated arguments, ticket text treated as data.

## A bounded, resumable, observable agent

State, routing, tools, memory, approval and tests combine into a dependable agent system.

![Four habits: bound, persist, approve, test.](assets/figures/langgraph-agents/section-8-map.svg) — Figure 8.1 — Bound, persist, approve and test.

## The design on one page

Each line maps to a section of this course.

```text
START -> classify -> supervisor <-> {billing, technical} -> writer -> supervisor -> END   (Sec 1, 2, 6)
billing.propose_refund -> interrupt() -> human approves / rejects                                    (Sec 5)
state: messages (add_messages), route, resolution, error, hops (counters)                            (Sec 1)
memory: Postgres checkpointer (thread_id from session) + store for language/plan; trim+summary       (Sec 4)
limits: step cap 8, recursion_limit 25, retry policy on tools, cost cap per run                       (Sec 2, 3, 5)
quality: scripted tests per route; 100-ticket eval (outcome + trajectory + safety); traces           (Sec 7)
```

**Quiz:** Why is the refund step behind an interrupt?

- [ ] Interrupts make tools faster
- [x] It is costly and irreversible, so a human should approve it
- [ ] Refunds are free
- [ ] To avoid state

*Answer:* It is costly and irreversible, so a human should approve it. Human approval limits the damage of a wrong or manipulated action.