Module 05: Autonomous Systems

Agentic AI, LangGraph & MCP Protocols

Interactive technical curriculum synthesized from FAANG and Tier-1 AI startup interview rounds.

Autonomous Agents, LangGraph Checkpointers & MCP Protocols

Comprehensive coverage of QA-03, QA-16, QA-26, and QA-45. Master state persistence in cyclic agent graphs, preventing duplicate payments, Model Context Protocol vs REST APIs, and zero-downtime agent migration.

Interactive LangGraph Checkpointer Lifecycle Walkthrough

Step through how a node failure replays code and why external APIs must be guarded with idempotent tokens:

Node Boundary Checkpoint
State saved in PostgreSQL / Redis

Mid-Node Network Timeout
External call succeeds, ACK lost

Unhandled Process Crash
Container dies, Kubernetes restarts

Replay from Checkpoint
Node re-executes from Line 1

Step 1: Checkpoint Saved at Node Boundary

LangGraph checkpointers (PostgresSaver / MemorySaver) serialize state only after a node returns cleanly.

# Initial State Saved
state = {
    "order_id": "ORD-9481",
    "amount": 150.00,
    "idempotency_token": "tx_a8f93e" # Pre-generated!
}

QA-03 • LangGraph Core

LangGraph Checkpointer Crash & Duplicate Payment Bug

Source: Naved Khan (LangGraph Core) • Track: AI Engineer • Difficulty: Hard

▼

The Bug: An autonomous agent calls Stripe to charge $150. Mid-node network drops. Checkpointer rolls back to beginning of node. Customer is charged twice.

The Solution:

Never generate idempotency tokens inside the mutation node!
State nodes must be pure. Generate the token in an upstream planning node and store it in state["idempotency_key"].
On checkpointer replay, the external API recognizes the identical token and returns the original transaction.

QA-26 • Protocols

Model Context Protocol (MCP) vs Traditional REST APIs

Source: Pavan Belagatti & Rohit Ghumare • Track: AI Engineer • Difficulty: Medium-Hard

▼

Dynamic Discovery: MCP clients query tool capabilities over JSON-RPC on demand, eliminating 15,000 prompt tokens of static Swagger schemas.
Transport Security: Runs over isolated stdio subprocesses or SSE with granular OAuth2 scopes.
Unified Ecosystem: Connects IDEs, AI coding assistants, and cloud platforms through a single standardized interface.