Applications and Integration is 33.1 percent of the Claude Certified Developer Foundations exam and Model Selection and Optimization is another 16.8 percent, so this one course covers just under half of every question you will see. It is built around the facts that are counterintuitive enough to be worth testing: that strict tool use goes on the tool definition and not on tool_choice, that assistant prefill on the last turn now returns 400, that citations and structured outputs together return 400, that temperature is rejected on Opus 4.7 and later, and that the prompt cache minimum runs 512, 1024, 2048, 4096 tokens in an order that is not monotonic with model age. Exact model ids, exact prices per million tokens, exact beta header strings, exact platform gaps. No hand-waving, because the whole point of a lookup-able number is that getting it wrong is unforgivable.
Pick a real integration you would actually ship. A support triage bot, a document extractor, an internal research agent, whatever. Then write a one page spec that names, with a reason attached to each:
The model id, in full, with its context and output limits and its per-million-token price. Why that model and not the one a tier cheaper.
The build shape: Client SDK with your own loop, Tool Runner, the Claude Agent SDK, or Managed Agents. Say what you are giving up by not picking the other three.
Every beta header the design requires, spelled exactly, with the feature it unlocks. If the answer is none, say none and mean it.
The caching plan: what is stable enough to sit in the cached prefix, whether that prefix clears your chosen model's minimum, which TTL, and the break-even reuse count at 1.25 times write and 0.1 times read.
Whether any of it can go through Batches for half price, and what that does to your latency story.
The platform: first-party API, Bedrock, Vertex, or Foundry, cross-checked against the availability gaps so you do not discover in staging that Files API is not there.
Then the part that matters most. Write down every request in your design that would return 400, and why. If you cannot find one, you have not read the deprecation lesson carefully enough.