LLM engineering guides by experienced practitioners, including builders from leading AI and tech companies: RAG, agents, streaming UX, evals, and cost and scaling.https://fieldjournal.ai/https://fieldjournal.ai/blog/context-engineering-for-internal-assistants/https://fieldjournal.ai/blog/context-engineering-for-internal-assistants/Internal assistants fail less when context is assembled deliberately instead of dumped wholesale into the model. Here is a practical context-engineering approach: task framing, scope, retrieval, compression, and provenance.Sat, 04 Apr 2026 00:00:00 GMTGuidesContext EngineeringRAGAgentsArchitectureSearchhttps://fieldjournal.ai/blog/prompt-caching-for-llm-apps/https://fieldjournal.ai/blog/prompt-caching-for-llm-apps/Prompt caching only pays when your reusable prefix is stable, versioned, and safe to share. The hard part is not turning it on; it is deciding what may be cached.Sat, 28 Mar 2026 00:00:00 GMTGuidesCachingLLMsLatencyCostArchitectureObservabilityhttps://fieldjournal.ai/blog/mcp-servers-in-production/https://fieldjournal.ai/blog/mcp-servers-in-production/MCP works when you treat servers as trust boundaries, not generic adapters. Narrow resource scope, explicit consent, and auditability matter more than broad connectivity.Sat, 21 Mar 2026 00:00:00 GMTGuidesMCPAgentsSecurityTool CallingArchitectureObservabilityhttps://fieldjournal.ai/blog/system-prompts-vs-app-logic/https://fieldjournal.ai/blog/system-prompts-vs-app-logic/System prompts are for steering behavior. Authorization, state changes, retries, and data access belong in the app and server layers where they can be enforced.Sat, 14 Mar 2026 00:00:00 GMTOpinionPromptingArchitectureReliabilityAgentsPolicyhttps://fieldjournal.ai/blog/what-to-log-for-llm-apps/https://fieldjournal.ai/blog/what-to-log-for-llm-apps/A concrete logging model for LLM apps: traces, tool calls, approvals, versioned context, and the minimum metadata needed to reconstruct failure.Sat, 07 Mar 2026 00:00:00 GMTGuidesObservabilityLLMsTracingAgentsSecurityCosthttps://fieldjournal.ai/blog/human-approvals-for-agents/https://fieldjournal.ai/blog/human-approvals-for-agents/A concrete guide to approval boundaries for agents: side effects, trust boundaries, ambiguous decisions, and the audit trail that makes the approval real.Sat, 28 Feb 2026 00:00:00 GMTGuidesAgentsApprovalsSecurityUXTool Callinghttps://fieldjournal.ai/blog/queue-design-for-long-running-agents/https://fieldjournal.ai/blog/queue-design-for-long-running-agents/How to design durable queues for agent jobs: state machines, idempotency, checkpoints, cancellation, and the failure modes SQS and Temporal force you to handle.Sat, 21 Feb 2026 00:00:00 GMTGuidesAgentsQueuesReliabilityArchitectureAsynchttps://fieldjournal.ai/blog/internal-assistant-auth-boundaries/https://fieldjournal.ai/blog/internal-assistant-auth-boundaries/Internal assistants usually fail where identity, permissions, and retrieval meet. Here is why broad access feels productive at first, and why scoped identity design matters more than another prompt tweak.Sat, 14 Feb 2026 00:00:00 GMTOpinionSecurityRAGPermissionsIdentityEnterprisehttps://fieldjournal.ai/blog/when-to-fine-tune-vs-retrieve-vs-prompt/https://fieldjournal.ai/blog/when-to-fine-tune-vs-retrieve-vs-prompt/Fine-tuning, retrieval, and prompt engineering solve different failure modes. Here is the decision framework I use when a team asks how to make an LLM app more accurate, cheaper, or easier to operate.Sat, 07 Feb 2026 00:00:00 GMTGuidesFine-TuningRAGPromptingArchitectureLLMshttps://fieldjournal.ai/blog/how-openclaw-works/https://fieldjournal.ai/blog/how-openclaw-works/OpenClaw (formerly Clawdbot, then Moltbot) is a personal AI assistant that runs on your devices. Here is the architecture: the Gateway control plane, channels, sessions, tools, skills, and the agent loop.Sat, 31 Jan 2026 00:00:00 GMTGuidesAgentsTool CallingArchitectureSecurityCLIPluginsObservabilityhttps://fieldjournal.ai/blog/shipping-safe-tooling-for-tool-calling-agents/https://fieldjournal.ai/blog/shipping-safe-tooling-for-tool-calling-agents/A production guide to tool calling safety: designing tight tool contracts, validating outputs, limiting agency, and handling retries, idempotency, and audit logs for tool-using agents.Sat, 31 Jan 2026 00:00:00 GMTGuidesAgentsTool CallingSecurityValidationReliabilityObservabilityAPI Designhttps://fieldjournal.ai/blog/the-return-of-rag-in-2026/https://fieldjournal.ai/blog/the-return-of-rag-in-2026/RAG is back in 2026 because long context did not solve freshness, permissions, or reliability. Modern RAG looks like search engineering: hybrid retrieval, reranking, and tight evals.Thu, 29 Jan 2026 00:00:00 GMTGuidesRAGRetrievalSearchRerankingEmbeddingsLong ContextArchitecturehttps://fieldjournal.ai/blog/why-frontier-models-are-getting-more-restrictive/https://fieldjournal.ai/blog/why-frontier-models-are-getting-more-restrictive/Moderation is no longer a thin filter on top of a chatbot. For frontier labs, it is becoming an end-to-end product and risk system shaped by capability jumps, regulation, and enterprise expectations.Wed, 28 Jan 2026 00:00:00 GMTOpinionModerationPolicySafetyRegulationGovernanceFrontier ModelsGrokhttps://fieldjournal.ai/blog/llm-evals-for-chat-and-tool-agents/https://fieldjournal.ai/blog/llm-evals-for-chat-and-tool-agents/A production-first guide to evaluating chat assistants and tool-using agents with a small, reliable eval suite: datasets, grader types, flake reduction, and CI gates.Tue, 27 Jan 2026 00:00:00 GMTGuidesEvalsAgentsTool CallingTestingQualitySafetyObservabilityhttps://fieldjournal.ai/blog/voice-pipelines-vs-speech-to-speech-models/https://fieldjournal.ai/blog/voice-pipelines-vs-speech-to-speech-models/A practical comparison of cascaded voice pipelines (ASR→LLM→TTS) versus speech-to-speech models, with examples, trade-offs, and code patterns.Mon, 26 Jan 2026 00:00:00 GMTGuidesVoiceAudioAgentsRealtimeWebRTCASRTTSLatencyPricingGroqCerebrashttps://fieldjournal.ai/blog/codex-cli-vs-claude-code/https://fieldjournal.ai/blog/codex-cli-vs-claude-code/Claude Code is the safe bet. Codex CLI came in strong and is already close in UX. Here is the harness-level comparison: approvals, sandboxing, context, and extensibility.Sun, 25 Jan 2026 00:00:00 GMTGuidesAgentsDeveloper ToolsCodexClaudeMCPSandboxingSecurityhttps://fieldjournal.ai/blog/llm-cost-and-scaling-playbook/https://fieldjournal.ai/blog/llm-cost-and-scaling-playbook/A practical, production-first guide to reducing LLM spend with model routing, token discipline, caching, batching, and rate-limit aware throughput.Sun, 25 Jan 2026 00:00:00 GMTGuidesLLMsCostScalingCachingBatchingRAGObservabilityhttps://fieldjournal.ai/blog/stop-defaulting-to-python-for-llm-apps/https://fieldjournal.ai/blog/stop-defaulting-to-python-for-llm-apps/If streaming is the default UX, TypeScript is the pragmatic default stack.Sat, 24 Jan 2026 00:00:00 GMTOpinionTypeScriptStreamingSSEAgentsArchitecture