AI Architecture Patterns: Series Overview

Most AI demos teach you a trick. This series teaches you the decisions.

You’ve seen the tutorials: hook up an API key, paste a prompt, get a chatbot. They’re not wrong, exactly — but they skip the part that actually matters in production: why this architecture, not that one, and what breaks when a second team, a stricter schema, or a real cost constraint shows up.

This series is the opposite bet. 16 patterns, one continuous story — a payment-support assistant at a fictional bank — starting as simple as “one model call” and accumulating exactly the complexity a real system would, in the order a real one would need it.

Why payment support, specifically

Banking and payments give every pattern a concrete stake: a wrong answer here isn’t a quirky chatbot mistake, it’s a customer being told the wrong thing about their money. That stakes-level is what makes guardrails, validation, and escalation paths feel necessary rather than decorative — the same techniques would feel like over-engineering in a toy demo.

Pattern 01 sets up the cast: a customer asking about a pending card payment, a synthetic transaction store, a small local knowledge base of policy documents. Every later pattern reuses this same world and extends it — a second team’s data breaks an unwritten assumption (Pattern 02), the model’s output needs to validate against a schema (Pattern 03), and so on through production hardening and the final fine-tuning-vs-RAG decision (Pattern 16). By the later patterns, this is one coherent system, not sixteen disconnected demos.

Two rules that hold across all 16 patterns

Research the official AWS documentation before writing any code. Not from memory, not from a tutorial — the actual current docs and API reference for the service in question. This series has already caught real mistakes this way: an assumption that Bedrock Prompt Management used Python-style templates (it doesn’t — {{double-brace}} syntax, a genuine two-step create-then-version flow), and a misconception that a Lambda function sits inside a Bedrock Knowledge Base retrieval call (it doesn’t — RetrieveAndGenerate is called directly).
Every pattern’s code runs with zero AWS credentials by default. A local mock mirrors the real service’s request/response shape closely enough that swapping in boto3 later is a drop-in replacement, never a rewrite. Anyone can clone the repo and follow along for free — that’s the actual design, not a fallback.

What’s new: a real AWS path, deliberately cheap

Every pattern now also ships a documented path to deploy the real thing — AWS Console click-through steps and an AWS CLI script, alongside the free local mock. The model choice is deliberate too: Amazon Nova Micro, the cheapest model in Bedrock, is the default recommendation across the series — fractions of a cent per recording session, not the most capable (or most expensive) model by default. A full pattern, deployed and torn down on real AWS, typically costs under $1.

This isn’t the default experience — the free local mock still is — but it’s there for anyone who wants the credibility of “I built this on real AWS,” not just a local simulation.

The locked roadmap

Week	Pattern	What’s New This Week	AWS Service
1	Grounded RAG For Payment Support	One retrieve→generate call	— (local-only by design)
2	Prompt And Context Contract	Same call, formalize the input/output contract	Bedrock Prompt Management
3	Structured Output And Validation	Same call, output must now validate against a schema	Bedrock Structured Outputs
4	Evaluator Optimizer	First second LLM call — a judge over the first call’s output	Bedrock Model Evaluation (LLM-as-a-Judge)
5	Tool Calling	First non-talk action — model requests a read-only lookup	Bedrock Agents action groups
6	Memory Pattern	First cross-turn state — conversation now has continuity	Bedrock AgentCore memory
7	Workflow Orchestration	First explicit multi-step pipeline	AWS Step Functions
8	Agentic RAG And Query Planning	Retrieval itself becomes a planned, multi-step process	Bedrock Knowledge Bases + query reformulation
9	Router Pattern	First branching — choose path/model/tool at runtime	Bedrock intelligent prompt routing
10	Human-In-The-Loop Approval	First human gate in the flow, not just code	Step Functions + SNS approval queue
11	AI Gateway And Policy Enforcement	Centralize policy/logging across everything built so far	Bedrock Guardrails + API Gateway
12	Supervisor Worker Agents	First multi-agent coordination — genuine complexity jump	Bedrock AgentCore multi-agent / Strands
13	Observability And Evaluation	Harden: traces + test sets across the whole system	CloudWatch GenAI observability
14	Semantic Cache And Cost Control	Harden: reuse safely, control cost	Bedrock prompt caching
15	Fallback And Graceful Degradation	Harden: handle failure and uncertainty	Bedrock Cross-Region Inference + circuit breaker
16	Fine-Tuning Vs RAG Decision Pattern	Capstone: when to graduate beyond everything built so far	SageMaker fine-tuning vs. Bedrock Knowledge Bases

Learn it yourself before teaching it

Every pattern ships two parallel code folders: starter/ (the core logic stubbed out with TODO markers, tests failing until filled in) and solution/ (the finished, working version). The intended order: read the pattern’s plan, attempt starter/ by hand, compare against solution/. This series follows that same discipline before presenting any pattern publicly — running the code and hitting the failure mode firsthand, not reading a summary of it.

What every pattern produces

A problem statement, the real situation it solves, and an honest AWS-vs-alternative design comparison — including the tradeoffs, not just the winner.
starter/ and solution/ code, plus editable architecture diagrams.
A local demo UI — one continuous scroll: Problem → Architecture → Resources → Use cases → Demo → Guardrails → Lesson.
This blog post, and a video walkthrough.

Start here

Pattern 01: Grounded RAG For Payment Support is the foundation — the first pattern, the smallest possible implementation, and the one this whole series builds on.

[!TIP] Star the GitHub repo and follow along — every pattern’s full reasoning, code, and diagrams live there, not just this post’s summary.

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