RAG & Agent System Design is a core part of the Cognition Forward Deployed Engineer loop. Retrieval pipelines, chunking, reranking, tool-using agents, guardrails, multi-tenancy and eval harnesses: the modal FDE design round at OpenAI, Anthropic, Sierra, Glean and Scale. Below are the rag & agent system design questions to prepare, the ones tagged to Cognition first, then the highest-signal questions from our RAG & Agent System Design track, each with an answer written to a senior-engineer bar.

WHAT COGNITION LOOKS FOR HERE · Candidate guides report that the forward deployed loop drops the traditional coding round and the system-design round; technical ability is read from the Devin exercise and the project walkthrough instead. See the full Cognition interview process →

RAG & Agent System Design questions tagged to Cognition

More RAG & Agent System Design questions for Cognition's loop

The highest-signal rag & agent system design questions candidates rate most useful, modeled on what Cognition's Forward Deployed Engineer loop tests.

Concepts behind Cognition's RAG & Agent System Design round

The vocabulary and mental models these questions assume. Start with the foundations free; the deeper, interview-defining ideas are part of premium.

FoundationalRetrieval-Augmented Generation (RAG)RAG grounds a language model in your own data by retrieving relevant passages at query time and putting them in the prompt, so the model answers from real sources instead of memory. It is the default pattern for almost every enterprise FDE deployment, which is why nearly every loop tests it.

FoundationalVector DatabasesA vector database stores embeddings alongside metadata and answers nearest-neighbor queries fast using approximate indexes. The real interview question is not how they work but when you actually need one instead of a library or plain Postgres with pgvector.

CoreSign inHybrid Search (Lexical + Vector)Hybrid search runs a keyword retriever (BM25) and a dense vector retriever side by side, then merges their result lists, because each one misses cases the other catches. Vectors lose exact codes and rare jargon, BM25 loses paraphrase, and combining them with Reciprocal Rank Fusion usually beats either alone.

CoreSign inChunking StrategiesChunking is how you split documents into the units you embed and retrieve, and it quietly sets the recall ceiling for your entire RAG system. Get the size, boundaries, and metadata wrong and no reranker or prompt can recover the answer that never got retrieved.

CoreSign inReranking and Two-Stage RetrievalTwo-stage retrieval pairs a cheap recall-heavy first stage that pulls dozens of candidates with a precise reranker that re-scores each one against the query. It is the standard fix when vector search returns relevant-ish chunks but the right one is not in the top few, and it trades a little latency for a lot of precision.

CoreSign inApproximate Nearest Neighbor (ANN)Brute-force vector search is O(N*d) per query and falls apart at millions of vectors, so ANN trades a sliver of recall for orders-of-magnitude speed. The two dominant families are IVF (cluster then probe nearby cells) and HNSW (walk a navigable graph), with product quantization to shrink memory. The non-negotiable habit is measuring recall@k against a brute-force baseline.

FoundationalAI Agents and Tool UseAn agent is a language model wrapped in a loop that lets it choose tools, act, observe the result, and decide what to do next. The skill interviewers test is judgment: knowing when that loop earns its unpredictability and when a fixed pipeline is cheaper, faster, and safer.

Advanced🔒 PremiumAgent MemoryAgent memory is how an agent carries state across turns and sessions. Short-term memory is the conversation and scratchpad living inside the context window, bounded and expensive. Long-term memory is an external store the agent writes to and retrieves from on demand, usually via RAG, so it can recall facts from last week without holding them in the prompt. FDE loops probe this because the hard parts, summarization, what to persist, and stale or contradictory memory, are where agents quietly break.

Cognition's Forward Deployed Engineer loop draws rag & agent system design questions such as "An agentic loop runs forever on long-horizon tasks. Propose an algorithmic change to stop the looping and evaluate it offline.", "Design a Planner-Coder-Reviewer-Tester system that turns a Jira ticket into tested code and fixes its own bugs.", "A coding agent passes every test but the feature is wrong: it gamed the verifier. How do you build a verifier it can't hack?". Retrieval pipelines, chunking, reranking, tool-using agents, guardrails, multi-tenancy and eval harnesses: the modal FDE design round at OpenAI, Anthropic, Sierra, Glean and Scale. The full set, ordered easy to hard with expert answers, is below.

Work the rag & agent system design questions on this page in order, study the underlying concepts linked below, then review Cognition's full interview process for how this round fits the loop. For Cognition specifically, interviewers weight this: Candidate guides report that the forward deployed loop drops the traditional coding round and the system-design round; technical ability is read from the Devin exercise and the project walkthrough instead.

Yes, under more than one title. Cognition posts Forward Deployed Engineer and Applied AI Engineer roles that put Devin into customer engineering teams. The Applied AI Engineer posting frames it bluntly: you do not demo Devin, you deploy it, embedding with engineering teams and driving measurable productivity gains until adoption sticks.

Expect practical coding, system and agent design, and past-project deep dives, plus evidence of successful enterprise deployments. Candidate guides describe the forward deployed loop differently: a hands-on take-home inside Devin rather than an algorithms round, a project presentation judged on business impact, an executive pitch, and a timed simulated customer call. Loops differ by title, so confirm yours with the recruiter.

Other Cognition interview rounds

The other tracks Cognition's Forward Deployed Engineer loop tests.

Prep the whole Cognition Forward Deployed Engineer loop

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