Experiments and learnings in AI engineeringhttps://jaykim88.github.io/https://jaykim88.github.io/learnings/2026-03-14-optimizing-guest-to-login-data-transfer/https://jaykim88.github.io/learnings/2026-03-14-optimizing-guest-to-login-data-transfer/How reordering async operations, splitting API calls, and deferring storage moves eliminated a 4-second login delay and fixed missing chat history.Sat, 14 Mar 2026 00:00:00 GMTreactasync-operationsperformancefastapibackground-tasksrace-conditionsupabasehttps://jaykim88.github.io/learnings/2026-03-03-python-fastapi-lifespan-asynccontextmanager/https://jaykim88.github.io/learnings/2026-03-03-python-fastapi-lifespan-asynccontextmanager/How @asynccontextmanager and yield divide startup/shutdown in FastAPI lifespan, and how dunder methods __aenter__/__aexit__ work as Python's context manager protocol.Tue, 03 Mar 2026 00:00:00 GMTpythonfastapiasynccontextmanagerlifespanuvicorndunder-methodscontext-managerhttps://jaykim88.github.io/learnings/2026-03-02-llm-fundamentals-parameters-embeddings-attention/https://jaykim88.github.io/learnings/2026-03-02-llm-fundamentals-parameters-embeddings-attention/How LLM parameters encode meaning, what embedding dimensions actually represent, and why Transformer attention is computed in parallel.Mon, 02 Mar 2026 00:00:00 GMTllmembeddingsattentiontransformerragpgvectorai-engineeringhttps://jaykim88.github.io/learnings/2026-02-28-genai-design-patterns-and-career-positioning/https://jaykim88.github.io/learnings/2026-02-28-genai-design-patterns-and-career-positioning/A structured map of GenAI application patterns and a practical framework for deciding how deep to go — calibrated to AI Product Engineer vs AI Engineer roles.Sat, 28 Feb 2026 00:00:00 GMTgenai-patternsragagent-patternscareerai-product-engineerprompt-engineeringtool-usehttps://jaykim88.github.io/learnings/2026-02-27-ai-pipeline-patterns-lingua-rag/https://jaykim88.github.io/learnings/2026-02-27-ai-pipeline-patterns-lingua-rag/A comprehensive breakdown of AI pipeline concepts learned building LinguaRAG — a Korean-German textbook AI tutor using RAG, SSE streaming, multi-layer prompts, and pgvector.Fri, 27 Feb 2026 00:00:00 GMTragllm-streamingprompt-engineeringpgvectorfastapissevector-searchcontext-managementhttps://jaykim88.github.io/learnings/2026-02-27-pdf-rag-indexing-unit-detection/https://jaykim88.github.io/learnings/2026-02-27-pdf-rag-indexing-unit-detection/How to reliably detect structured unit boundaries in a bilingual PDF and prevent boilerplate text from polluting RAG vector chunks.Fri, 27 Feb 2026 00:00:00 GMTragpdf-processingpdftotextregexvector-searchpythonpgvectorhttps://jaykim88.github.io/learnings/2026-02-27-pdf-unit-detection-indexing-guards/https://jaykim88.github.io/learnings/2026-02-27-pdf-unit-detection-indexing-guards/Hard-won lessons from building a robust PDF chunker for a Korean-German textbook: multiple detection guards, line-level copyright stripping, and RAG behavior verification.Fri, 27 Feb 2026 00:00:00 GMTpdf-parsingragregextext-extractionpgvectorindexingdebugginghttps://jaykim88.github.io/learnings/2026-02-27-supabase-auth-jwt-es256-fastapi/https://jaykim88.github.io/learnings/2026-02-27-supabase-auth-jwt-es256-fastapi/New Supabase projects sign JWTs using the ES256 algorithm. How to verify with PyJWT + JWKS client and how to resolve macOS Python SSL issues.Fri, 27 Feb 2026 00:00:00 GMTsupabasefastapijwtoauthpythonnext-jsauthenticationhttps://jaykim88.github.io/learnings/2026-02-25-rag-architecture-lingua-rag/https://jaykim88.github.io/learnings/2026-02-25-rag-architecture-lingua-rag/Core RAG concepts understood while planning LinguaRAG: offline/online phase separation, SSE streaming mechanics, prompt assembly, and the role of pgvector.Wed, 25 Feb 2026 00:00:00 GMTragfastapisse-streamingpgvectorembeddingclaude-apillmhttps://jaykim88.github.io/digests/2026-02-23-ai-agent-era-software-survival/https://jaykim88.github.io/digests/2026-02-23-ai-agent-era-software-survival/YC's philosophy has shifted from "Make something people want" to **"Make something agents want"**. In an era where agents choose, recommend, and deploy, the value axis of software has fundamentally moved. YC Lightcone,...Mon, 23 Feb 2026 00:00:00 GMTaiagent-economysoftware-strategyyca16zharnessvertical-saashttps://jaykim88.github.io/learnings/2026-02-20-ai-engineering-fundamentals-en/https://jaykim88.github.io/learnings/2026-02-20-ai-engineering-fundamentals-en/Every concept in this document is explained through a single real-world app -- **"SupportBot" (AI-powered customer support system)**. Each section...Fri, 20 Feb 2026 00:00:00 GMThttps://jaykim88.github.io/learnings/2026-02-03-spec-interview-plugin-implementation/https://jaykim88.github.io/learnings/2026-02-03-spec-interview-plugin-implementation/A new Claude Code plugin that collects requirements by having **the AI interview the user**.Tue, 03 Feb 2026 00:00:00 GMThttps://jaykim88.github.io/digests/2026-01-27-ai-context-engineering-anthropic/https://jaykim88.github.io/digests/2026-01-27-ai-context-engineering-anthropic/Anthropic's context engineering guide covers strategies for optimizing AI agent performance through deliberate token management — moving beyond simple prompt engineering to optimize the entire information ecosystem, including system instructions, tools, external data, and message history.Tue, 27 Jan 2026 00:00:00 GMTaicontext-engineeringai-agentsllmanthropichttps://jaykim88.github.io/learnings/2026-01-18-ai-pe-learning-agent-project-setup/https://jaykim88.github.io/learnings/2026-01-18-ai-pe-learning-agent-project-setup/Building AI agents to learn AI engineering - the tool creation process itself becomes the learning journey. Instead of following tutorials, you solve...Sun, 18 Jan 2026 00:00:00 GMTmeta-learningmulti-agentlanggraphproject-setupportfoliohttps://jaykim88.github.io/learnings/2026-01-18-claude-code-marketplace-and-plugins/https://jaykim88.github.io/learnings/2026-01-18-claude-code-marketplace-and-plugins/Claude Code's marketplace is a **decentralized system**, not a centralized App Store.Sun, 18 Jan 2026 00:00:00 GMT