16 section

Case Studies

Fifteen full designs, each starting from the constraint that makes it hard: 100ms fraud decisions, HIPAA-bound voice notes, two direct competitors on one vector database.

15 pages 79 min 16,843 words

01 the section

What is in here

Every case study runs the same arc — problem, constraints, architecture, the two or three decisions that actually mattered, cost, and how to present it in an interview. Chapters 01 through 05 are the long-form builds with full component deep-dives; 06 through 15 are tighter, more heavily diagrammed, and closer to what a 45-minute round demands. Read one in your own domain first, then one far outside it, because the transfer is the point.

01 9 min Enterprise RAG A financial firm's 500,000-document search, where daily updates, department permissions and mandatory citations drive the shift from small-chunk RAG to million-token balanced context. case-studyragretrieval 02 7 min Conversational Support Agent 500,000 monthly tickets for a B2B SaaS platform, with the design centered on confidence-based escalation: knowing when the agent should stop talking and fetch a human. case-studyagentsreliability 03 8 min Financial Analysis with Ensemble Verification Equity research where one hallucinated EPS figure is a regulatory problem, so drafting is followed by a reasoning-model audit and a multi-agent fact debate. case-studyensemblesfintech 04 8 min AI Code Assistant An IDE extension that must return a completion in under 200 milliseconds, so the design is context assembly, layered caching and speculative decoding on the hot path. case-studycoding-agentslatency 05 8 min Content Moderation at Scale Ten million posts a day funneled through hash matching, multimodal classifiers and LLM review, where the real work is adversarial evasion and false-positive cost. case-studyguardrailsmultimodal 06 3 min Real-Time AI Search Engine Market intelligence with a five-minute freshness guarantee: Kafka ingestion into paired vector and full-text indexes, RRF fusion, sourced answers inside three seconds. case-studyretrievalfintech 07 4 min Autonomous Coding Agent A planner-coder-debugger loop running inside an E2B sandbox on thousand-file repos, iterating until the test suite passes, for under fifty cents a task. case-studycoding-agentsagents 08 4 min Multi-Tenant AI SaaS Coca-Cola and Pepsi on shared infrastructure: hybrid namespace-versus-dedicated-pod isolation, defense in depth on every query, and GDPR deletion that truly removes embeddings. case-studymulti-tenancysecurity 09 4 min Customer Support Automation Two million e-commerce tickets a month in twelve languages, resolved by tool calls against order APIs rather than free generation, with a safety check before send. case-studyagentsorchestration 10 4 min Document Intelligence Pipeline Fifty thousand contracts a month turned into JSON by parallel field extractors, with vision-LLM OCR for scans and cross-field validation catching the disagreements. case-studydocument-processingmultimodal 11 4 min Recommendation Engine Fifty million users served inside 200 milliseconds by matrix factorization and ANN search, with the LLM confined to writing cached, per-title explanations. case-studyretrievallatency 12 4 min Regulatory Compliance Automation Pharma marketing review where a missed violation is unacceptable, so claims are extracted first, checked against CFR Title 21 and warning-letter precedent, then cited. case-studycompliancerag 13 4 min Voice AI for Healthcare Nurses dictating into an EHR, which forces on-premise Whisper for HIPAA, speaker diarization to separate nurse from patient, and FHIR write-back after review. case-studymultimodalcompliance 14 4 min Real-Time Fraud Detection Ten million card transactions a day scored under 100 milliseconds by an XGBoost ensemble plus rules, with the LLM only writing the human-readable reason. case-studyfintechlatency 15 4 min Enterprise Knowledge Management Two million consulting documents across fifteen sources, where permission tags travel with every chunk and stale methodologies get ranked down instead of quietly winning. case-studyragaccess-control