Question library
Explained questions for the decisions developers make.
Authentication, authorization, and permissions
Authentication establishes who a client/user is; authorization determines what that identity may do. MCP connection authorization and downstream business authorization are separate concerns. A valid connection does not automatically permit every customer's…
Moderation and PII detection
Content moderation categorizes content that may violate a product policy. PII detection identifies potentially private identity-linked information for masking, routing, or restricted handling. Both can use rules and models, and neither is perfectly accurate.
Traces, agent runs, LLM/tool calls, and state transitions
A trace connects the operations serving one request or task. Each timed operation is a span, such as an LLM call, retrieval, or tool execution. An agent run may include several spans and persisted state transitions across multiple requests.
Langfuse, LangSmith, OpenTelemetry, and Sentry
Langfuse and LangSmith provide AI-oriented trace and experiment views. OpenTelemetry standardizes telemetry instrumentation and export across services. Sentry provides application error and performance investigation capabilities; exact AI-specific…
LiteLLM, Portkey, and cloud AI gateways
LiteLLM provides model-access abstraction and proxy/gateway capabilities. Portkey provides an AI gateway and operational controls. Cloud gateways can apply access and model traffic policies within an existing cloud API-management environment; exact AI…
AWS Bedrock, Lambda, ECS, S3, OpenSearch, and IAM
Bedrock provides managed access to supported foundation models and related capabilities. Lambda runs event-driven functions; ECS orchestrates containers; S3 stores objects such as original PDFs. OpenSearch provides search infrastructure, while IAM controls…
Multi-tenancy and comparison with PostgreSQL + pgvector
Multi-tenancy supports several organizations while preventing cross-organization access. MongoDB often fits flexible document records; PostgreSQL provides relational constraints, joins, transactions, and optional row-level security with pgvector. Both require…
Scalability, availability, reliability, and latency
Scalability handles growing load. Availability means the system is accessible when needed; reliability means tasks produce correct, durable outcomes despite failures. Latency measures waiting, including queue time and user-visible completion.
Which parts are deterministic and which are agentic?
Agentic portion: interpreting wording, gathering missing information, and choosing among bounded read/search actions. Workflow portion: identity, required fields, approvals, transaction order, retries, and durable outcomes. LangGraph can coordinate the…
Tools and their safe contracts
Never accept a model's customerId as proof of the current customer. Never let the model supply an unrestricted email URL, SQL query, database filter, or role field.
Project 1 — Basic LLM chatbot
Build in this order. Each project extends a capability, not necessarily a separate repository. These are future learning projects; the notes remain in this one file. Move forward when you can explain the trade-offs and demonstrate the acceptance criteria,…
Project 2 — Streaming AI chatbot
Requirements: Show progress/text incrementally, allow cancellation, and distinguish completion from stream failure. Preserve final message state.
Project 5 — Tool-calling agent
Requirements: Read claim status, lookup policy, retrieve instructions, ask for missing IDs, and escalate. Start read-only.
Guardrails
Beginner — What is a guardrail?
Evaluation
Beginner — Why isn't normal unit testing enough?
Python
Beginner — Why learn Python as a MERN engineer?
AI system design
Beginner — What questions come before architecture?
How do you design degraded behavior?
Define acceptable alternatives per task: verified templates, search results, paused durable work, or staff escalation. Preserve data/permission/quality contracts and distinguish missing evidence, service failure, and unknown commit outcomes explicitly.
Difficulty is an editorial estimate. Completion means you chose to mark a question as understood.