Question library
Explained questions for the decisions developers make.
When would you avoid LangChain?
For a small direct API call with clear validation, plain SDK code may be easier to understand and maintain. I adopt abstractions when they reduce actual integration complexity and keep provider requests, costs, and failures inspectable.
What are nodes, edges, and state?
Nodes are steps that perform work, edges choose what runs next, and state carries the information needed by those steps. Nodes can be ordinary code or model calls, so the graph can be deterministic or hybrid.
Deterministic versus agentic workflow?
Deterministic transitions follow defined code and recorded outcomes. Agentic transitions delegate some next-step choices to a model. I use AI for language uncertainty and deterministic control for business invariants.
Why isn't normal unit testing enough?
Model outputs vary and can be plausible but wrong. I still unit-test deterministic code, but also evaluate representative tasks, support from evidence, tool behavior, and safe failure using versioned datasets and rubrics.
The API returned 200 but the user got no complete answer. Why?
Streaming headers may have been sent before an error or disconnect. I inspect terminal events and run/message status rather than HTTP code alone, then check provider completion, validation, cancellation, and persistence spans.
What questions come before architecture?
What task should succeed, which data is authoritative, who may access it, what errors are costly, how fast it must respond, expected load, and available budget. Then decide whether deterministic code or AI is needed.
A concrete architecture proposal template
For a client, write: Outcome and scope; users and permissions; authoritative data; ordinary-code baseline; AI responsibilities; controlled workflow and approvals; tools/data contracts; failure and reconciliation policy; evaluations; telemetry/audit;…
Questions to ask before choosing architecture
What successful outcome does the client need, and can ordinary code provide it?
Final interview advice
Explain the approach before coding.
Best Java DSA interview practice list
Must know
What should I study first?
Preparation works best when later topics build on earlier ones. JavaScript scope and async behavior support Node and React; database rules support backend correctness and system design. Follow the sequence, but spend extra time where you cannot yet explain a concept without reading the answer.
How can I reduce dependence on AI?
Reducing AI dependence means being able to understand, test and change a solution without treating generated output as authority. Use AI as a source of candidate ideas, then establish correctness through your own reasoning and evidence. The goal is independent judgment, not avoiding useful tools entirely.
What is scope? What does lexical mean?
Scope is the part of a program where a variable can be accessed. JavaScript uses lexical scope, which means the available outer variables depend on where a function was defined, not where it is later called. The engine searches outward through surrounding scopes when a name is not found locally.
What are unknown, any and never?
any allows operations without normal type checking, while unknown accepts any value but requires checks before use. never represents a situation where no value is possible, such as the result of a function that always throws. These types describe different levels of knowledge and should not be used interchangeably.
HTTP/1.1 vs HTTP/2 vs HTTP/3?
HTTP versions preserve the basic request/response model but change how messages travel over the network. HTTP/2 multiplexes streams over one TCP connection, while HTTP/3 uses QUIC to avoid some transport-level blocking between streams. These improvements affect connection efficiency, not the need for correct API semantics.
What makes a backend ready for production?
Production readiness means an application can be operated, monitored and recovered under normal load and failure. Working business logic is only one part; configuration, resource limits, startup, shutdown and observability also affect users. A ready service should fail clearly and avoid accepting work it cannot safely complete.
What are WebSockets, microservices and CQRS used for?
WebSockets maintain a two-way connection for ongoing messages, microservices split an application into separately operated services, and CQRS separates command/write handling from query/read handling. These solve different problems and can be used independently. Each adds complexity that should be justified by a concrete requirement.
How do I fix slow aggregation, pagination or N+1 queries?
Query performance depends on how much data is scanned, joined, sorted and returned for each useful result. Slow pagination and N+1 patterns often do repeated work that grows with result size. The best fix usually reduces that work before increasing hardware or connection limits.
Difficulty is an editorial estimate. Completion means you chose to mark a question as understood.