What your stack says you are on the hook for
Paste a package.json, requirements.txt or go.mod. Every dependency you installed carries assumptions somebody has to own, and this names them and points at the day that teaches each one.
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10 dependencies read, 10 recognised
A package only claims a concept when using it seriously means owning that concept. Anything unrecognised is left alone rather than guessed at.
38
concepts under it
15
days that teach them
33
meant to be mastered
- D29Static typingMASTERTypeScript, and why static types exist
- D29InferenceTypeScript, and why static types exist
- D29Compile time and runtimeMASTERTypeScript, and why static types exist
- D30NarrowingMASTERInterfaces, unions, and generics in practice
- D32UI as a function of stateMASTERReact's mental model
- D32Components and propsMASTERReact's mental model
- D32State in ReactMASTERReact's mental model
- D32Why a component re-rendersMASTERReact's mental model
- D33File-based routingNext.js routing, layouts, server and client
- D33Server and client boundaryMASTERNext.js routing, layouts, server and client
- D33Server-side data fetchingMASTERNext.js routing, layouts, server and client
- D33LayoutsNext.js routing, layouts, server and client
- D37Trust boundariesMASTERValidation, serialization, and the trust boundary
- D37Defence in depthMASTERValidation, serialization, and the trust boundary
- D37Input validationMASTERValidation, serialization, and the trust boundary
- D37Serialising outwardMASTERValidation, serialization, and the trust boundary
- D38AuthenticationMASTERAuthentication versus authorization
- D39JWTsMASTERSessions, tokens, and what a JWT actually is
- D39TokensMASTERSessions, tokens, and what a JWT actually is
- D39The revocation tradeoffMASTERSessions, tokens, and what a JWT actually is
- D40Password hashingMASTERPassword hashing, CORS, and secrets
- D43Query planMASTERIndexes, and why a query goes from 4s to 4ms
- D45ORMsMASTERORMs, the N+1 problem, and SQL injection
- D45The N+1 problemMASTERORMs, the N+1 problem, and SQL injection
- D45What an abstraction hidesMASTERORMs, the N+1 problem, and SQL injection
- D47Unit testsMASTERTesting: what's worth testing, and what isn't
- D47Test doublesMASTERTesting: what's worth testing, and what isn't
- D47What coverage does not measureMASTERTesting: what's worth testing, and what isn't
- D48Where to spend testing effortMASTERIntegration and end-to-end tests
- D60RedisCaching: hits, misses, invalidation, and Redis
- D60Cache patternsMASTERCaching: hits, misses, invalidation, and Redis
- D60InvalidationMASTERCaching: hits, misses, invalidation, and Redis
- D60Cache failure modesMASTERCaching: hits, misses, invalidation, and Redis
- D68TokensMASTERTokens, context windows, and cost
- D68Context windowsMASTERTokens, context windows, and cost
- D68Token costMASTERTokens, context windows, and cost
- D69Calling an LLM APIMASTERCalling an LLM API, end to end
- D69Message rolesCalling an LLM API, end to end
The part worth repeating
This package.json rests on 38 concepts across 15 days of engineering.
Every dependency is somebody else's decisions, and they stay your problem at three in the morning. 33 of these are the ones worth being able to reason about rather than merely recognise.
The card shows the three counts. Your dependency list is never part of the link.
Installing a package is a decision to inherit its failure modes. An ORM makes the N plus one your problem. A JWT library makes revocation your problem, because a signed token nobody looks up is exactly the thing that cannot be withdrawn. Redis makes cache invalidation and the thundering herd your problem. None of that arrives with the install.
The mapping is deliberately narrow. A package claims a concept only when using it seriously means owning that concept, not when the two are merely adjacent, and anything unrecognised is left alone rather than guessed at. A short list you can trust is worth more than a long one you have to check.
The concepts marked to master are the ones the curriculum treats as load bearing: things you should be able to explain, apply, debug and argue the tradeoffs of, rather than merely recognise. Those are the rows worth being uncomfortable about.
Questions people arrive with
- What do my project's dependencies say I need to understand?
- More than most people check. Installing a JWT library makes token revocation your problem, an ORM makes the N+1 query your problem, and Redis makes cache invalidation and the thundering herd your problem. Paste a package.json, requirements.txt or go.mod above and every concept your own stack assumes is named.