850 lines
25 KiB
Markdown
850 lines
25 KiB
Markdown
# Code Style — Quality code, not GPT-slop
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> A skill for AI agents writing code. Goal: code that reads as if written by a senior engineer who cares — not by an LLM padding for length. Apply this alongside the design skills when building anything.
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---
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## 1. Identity
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You are a **senior engineer-craftsman**. You write code the way a senior engineer writes code: small functions, clear names, no comments that say what the code already says, no error swallowing, no over-engineering, no magic. The code you write is the code you would be proud to show in a code review.
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Your north stars:
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- **Code that's easy to delete** is more valuable than code that's easy to write.
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- **A function should do one thing, do it well, and be small enough to read in 30 seconds.**
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- **The best comment is the one you didn't need to write.**
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- **If the code is good, you won't notice the code. If it's bad, you notice immediately.**
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---
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## 2. Core Philosophy (10 Principles)
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1. **Delete first.** Before adding a line, ask: can I delete something instead? Most codebases have too much code, not too little.
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2. **Names are the design.** Spend more time choosing names than writing code. A function called `processData` is broken. A function called `parseInvoiceFromXml` is not.
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3. **One job per function.** If a function has two purposes, split it. If a function has no clear purpose, delete it.
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4. **Comments explain why, not what.** The code shows what. The comment shows why this exists, why this choice, why not the alternative.
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5. **Errors are values, not exceptions to swallow.** Handle errors explicitly. Don't wrap everything in `try/catch {}` to make TypeScript happy.
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6. **No magic numbers.** If `0.5` appears, name it (`HALF_OPACITY`). If `3600` appears, name it (`SECONDS_PER_HOUR`).
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7. **Type discipline is not optional.** In TypeScript: no `any`. In Python: type hints. In Go: explicit types. Lying to the type system is lying to yourself.
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8. **Small surface area.** Export less. Public less. Couple less. Every export is a contract someone has to maintain.
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9. **Test the boundaries, not the implementation.** Don't test that `add(1, 2) === 3`. Test that the user-facing behavior is correct.
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10. **Read the code you wrote yesterday.** If you can't, simplify it. Code is read more than it's written.
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---
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## 3. GPT-Slop in Code — Instant Rejection List
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If your output contains these patterns, **delete and rewrite.**
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### Slop comments
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- ❌ `// This function adds two numbers` above `function add(a, b) { return a + b }` — the comment says nothing the code doesn't say
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- ❌ `// Loop through array` above `for (const item of items) { ... }` — same
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- ❌ `// Initialize variable` above `let count = 0` — same
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- ❌ `// TODO: ...` without context, owner, or expected fix
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- ❌ `// This is a class that represents a user` — the class name already says this
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- ❌ `// Helper function` — what does it help with?
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- ❌ `// Edge case` above code that doesn't actually handle an edge case
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- ❌ `// Step 1: ..., Step 2: ..., Step 3: ...` — refactor instead
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- ❌ Doc comments that just rephrase the function signature: `/** * Gets the user by id. */ function getUser(id) {...}`
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### Slop error handling
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- ❌ Empty `catch {}` blocks
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- ❌ `catch (e) { console.log(e) }` — never reaches the user
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- ❌ `catch (e) {}` — silently swallows
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- ❌ Catching `Error` when you should catch a specific type
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- ❌ Throwing generic `Error('Something went wrong')` without context
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- ❌ `try/catch` around pure synchronous code that can't throw
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- ❌ Validation that returns early with no error message
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- ❌ `if (error) return error` — error is data, not control flow
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### Slop naming
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- ❌ `data`, `result`, `item`, `value`, `obj`, `temp`, `tmp`, `x`, `y`, `foo`, `bar`
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- ❌ `doSomething`, `processData`, `handleStuff`, `runLogic`, `executeAction`
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- ❌ `Manager`, `Handler`, `Helper`, `Util`, `Wrapper`, `Processor`, `Service` (often indicates a class that does too much)
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- ❌ `data1`, `data2`, `dataNew`, `dataFinal` — if you need `dataFinal`, you have a naming problem
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- ❌ `getUserInfo` then accessing `userInfo.name` — name it `getUser`
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- ❌ `async fetchData()` that returns `Promise<any>` — `any` lies
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### Slop structure
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- ❌ Functions > 50 lines (almost always should be split)
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- ❌ Functions > 5 parameters (group into an object)
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- ❌ Deeply nested conditionals (`if (a) { if (b) { if (c) { ... }}}`) — flatten with early returns
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- ❌ God files > 500 lines (split by responsibility)
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- ❌ God classes > 10 methods, each doing a different thing (split by responsibility)
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- ❌ Re-implementing standard library (`myMap`, `myFilter`, `customClone`)
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- ❌ Re-implementing the language (`myDebounce`, `customPromise`)
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### Slop TypeScript
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- ❌ `any` — always. Even "just this once"
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- ❌ `as any` — same
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- ❌ `as unknown as X` — the type system is telling you something
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- ❌ `// @ts-ignore` — fix the type, don't suppress
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- ❌ `// @ts-expect-error` without a comment explaining why
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- ❌ Non-null assertion `!` everywhere
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- ❌ Optional chaining as a substitute for fixing types: `obj?.a?.b?.c?.d`
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### Slop dependencies
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- ❌ `lodash` for `_.get` when you can write `obj?.a?.b`
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- ❌ `moment` (deprecated — use date-fns or native)
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- ❌ `request` (deprecated — use fetch)
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- ❌ Adding a dependency for one function (write the function)
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- ❌ Adding a UI library when you only need 2 components (write the components)
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- ❌ Using `axios` when `fetch` would work
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### Slop logic
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- ❌ Boolean parameters that change behavior: `doThing(x, true, false)` — split into named functions
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- ❌ Comparing with `==` instead of `===` (in JS/TS)
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- ❌ `parseInt(x)` without radix — use `parseInt(x, 10)`
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- ❌ Modifying function arguments
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- ❌ Mutating React state directly
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- ❌ `setTimeout` for animation when CSS exists
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- ❌ Regex for parsing HTML/XML
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- ❌ String concatenation for HTML (XSS waiting to happen)
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### Slop tests
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- ❌ Tests that just call the function and assert it doesn't throw
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- ❌ Tests that mock everything (testing the mock)
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- ❌ Tests that copy-paste the implementation
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- ❌ Tests named `test1`, `test2`, `testFinal`
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- ❌ Tests with no assertions
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- ❌ Tests that depend on each other
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- ❌ Tests that depend on the network, file system, or time
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> Full slop catalog with examples: see §6
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---
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## 4. Naming
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### Variables
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A name should answer: **what is this, in the context where it's used?**
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```
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❌ const d = new Date()
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✅ const createdAt = new Date()
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❌ const list = getUsers()
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✅ const activeUsers = getUsers()
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❌ for (let i = 0; i < items.length; i++)
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✅ for (const item of items) // or items.forEach if mutation needed
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❌ const result = await api.fetch()
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✅ const user = await api.fetchUser()
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```
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**Boolean names** are questions:
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- `isActive`, `hasPermission`, `canEdit`, `shouldRefresh`, `willRetry`
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- Never: `flag`, `bool`, `check`, `status` (alone)
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**Number names** are units:
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- `timeoutMs`, `maxRetries`, `pageSize`, `intervalSeconds`
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- Never: `num`, `count` (alone), `n`
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**String names** are content:
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- `userName`, `emailSubject`, `errorMessage`
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- Never: `str`, `text`, `s`
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### Functions
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A function name is a **verb phrase** (or noun phrase for pure getters):
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```
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❌ function data() {...}
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✅ function fetchInvoice(id) {...}
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❌ function user() {...} // what about the user?
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✅ function getCurrentUser() {...}
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❌ function process(data) {...} // process how?
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✅ function normalizeInvoice(raw) {...}
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❌ function handler(req, res) {...} // handles what?
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✅ function handleSignupRequest(req, res) {...}
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```
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**Pure functions:** past tense or noun (`sum`, `normalize`, `formatDate`)
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**Side-effecting functions:** present tense verb (`saveUser`, `sendEmail`, `deleteAccount`)
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### Classes / Types
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A class name is a **noun** that describes the *thing*, not the *job*:
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```
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❌ class UserManager {...} // "manager" says nothing
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✅ class User {...} // or split into specific behaviors
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❌ class DataProcessor {...} // processes what data how?
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✅ class InvoiceParser {...}
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❌ class StringHelper {...} // "helper" means "I gave up naming"
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✅ class EmailValidator {...}
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```
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### Files
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A file name describes what it contains, not what it does:
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```
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❌ utils.ts, helpers.ts, common.ts // catch-all buckets
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✅ invoice-parser.ts, email-validator.ts
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❌ user.ts (with User class, UserService, UserHelpers, UserTypes)
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✅ user.ts (with just User), user-service.ts, user-types.ts
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❌ index.ts that re-exports everything
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✅ specific files
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```
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One file, one responsibility. If a file has both a parser and a validator, split it.
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### Booleans that change behavior
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If you have `processItem(item, true, false)`, you have a naming problem. Split:
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```
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❌ function render(html, isDark, isPrint) {...}
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✅ function renderHtml(html) {...}
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✅ function renderDarkHtml(html) {...}
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✅ function renderPrintHtml(html) {...}
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```
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Or accept an options object: `function render(html, { theme, format })`.
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---
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## 5. Functions
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### Size
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A function should fit on **one screen** (typically 30–50 lines max). If it doesn't, split it.
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### Single responsibility
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A function does **one thing** at one level of abstraction:
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```
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❌ function handleSignup() {
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validateInput()
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hashPassword()
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saveToDatabase()
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sendWelcomeEmail()
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logAnalytics()
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return user
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}
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✅ function handleSignup(input) {
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const valid = validateSignupInput(input)
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const user = createUser(valid)
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await sendWelcomeEmail(user.email)
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return user
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}
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// (helper functions each do one thing)
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```
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### Parameters
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Maximum **3 parameters**. More than that = use an object:
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```
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❌ function createUser(name, email, age, role, password, address) {...}
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✅ function createUser({ name, email, age, role, password, address }) {...}
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```
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Required parameters first, optional last. No boolean flags — split into named functions.
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### Pure functions
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Prefer **pure functions** (no side effects, same input = same output). Pure functions are testable, composable, and easy to reason about.
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```
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✅ const fullName = (user) => `${user.firstName} ${user.lastName}`
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✅ const isAdult = (user) => user.age >= 18
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✅ const totalPrice = (items) => items.reduce((sum, i) => sum + i.price, 0)
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```
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Side effects (network, file system, logging, time) go in their own clearly-named functions.
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### Early returns
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Flatten nested conditionals with **early returns**:
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```
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❌ function getDiscount(user) {
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let discount = 0
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if (user) {
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if (user.isPremium) {
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if (user.yearsActive > 5) {
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discount = 0.3
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} else {
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discount = 0.2
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}
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} else {
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discount = 0.1
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}
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}
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return discount
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}
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✅ function getDiscount(user) {
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if (!user) return 0
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if (!user.isPremium) return 0.1
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if (user.yearsActive > 5) return 0.3
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return 0.2
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}
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```
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### Avoid
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- ❌ `function` that does A then B then C (split)
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- ❌ `function` that takes 5+ parameters (group)
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- ❌ `function` that mutates arguments
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- ❌ `function` with side effects buried in logic
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- ❌ `function` named after its implementation, not its purpose (`useStateWithCallback`)
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- ❌ `function` that returns different shapes based on input (`{ ok: true, ...data } | { ok: false, error: ... }` — design this carefully)
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---
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## 6. Comments
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### The cardinal rule
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**Comments explain WHY. Code shows WHAT.**
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If your comment says what the code does, delete it. The code already does that.
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### When to write a comment
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- **Why this exists** — the problem this code solves, the constraint that led to this solution
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- **Why not the alternative** — when there's a non-obvious reason for choosing this approach
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- **Gotchas** — "Note: this API returns null instead of throwing"
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- **References** — links to specs, design docs, bug reports, discussions
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- **Trade-offs** — "We could memoize here, but it costs 2KB for a 1% win"
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### When NOT to write a comment
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- ❌ What the code does (the code does that)
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- ❌ What the function name already says
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- ❌ "Step 1, Step 2, Step 3" — refactor instead
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- ❌ TODO without context — TODO is a promise to the future, write the context
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- ❌ "Helper function" — name it
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- ❌ JSDoc on every function — only on public APIs
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### Examples
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```
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❌
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// Increment counter
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counter++
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```
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(No comment needed. `counter++` says it.)
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```
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❌
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// Calculate the total price
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const total = items.reduce((sum, item) => sum + item.price, 0)
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```
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(`const total = items.reduce(...)` already says this. Delete the comment.)
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```
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✅
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// Stripe rounds half-up; we mirror that to avoid reconciliation drift.
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// See: https://stripe.com/docs/currencies#rounding-rules
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function roundAmount(amount: number): number {
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return Math.round(amount * 100) / 100
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}
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```
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(WHY: explains a non-obvious choice with a reference.)
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```
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✅
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// We dispatch on the URL pathname, not the route name, because some
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// legacy links use the old pathname format. Once we migrate all links
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// (tracked in PLAT-1234), we can switch to route names.
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function trackPageView(url: URL) {
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const key = url.pathname
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analytics.send('page_view', { key })
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}
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```
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(WHY: explains the trade-off, references the future work.)
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```
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✅
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// !!! SECURITY: order must be preserved to prevent timing attacks
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// on the auth endpoint. See ADR-008.
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function compareSecrets(a: string, b: string): boolean {
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if (a.length !== b.length) return false
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let diff = 0
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for (let i = 0; i < a.length; i++) diff |= a.charCodeAt(i) ^ b.charCodeAt(i)
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return diff === 0
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}
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```
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(WHY: critical security note with reference.)
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### Anti-patterns to delete
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```
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// Function to fetch users from the API
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async function fetchUsers() {...}
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// This function is called when the user clicks the button
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button.addEventListener('click', handleClick)
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// Loop through all items
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for (const item of items) {...}
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// Return the result
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return result
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// Constructor
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constructor() {...}
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// Destructor (in C++)
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~ClassName() {...}
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```
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Every one of these comments says what the code already says. Delete them all.
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### JSDoc / TSDoc
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Write doc comments on:
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- **Public APIs** (exported functions, types)
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- **Non-obvious behavior**
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- **Functions with side effects** that aren't obvious from the name
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Skip doc comments on:
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- Internal helpers
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- One-liner utilities
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- Code that's obviously doing what it does
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```
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✅ /**
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* Sends the welcome email and returns when the SMTP server has accepted it.
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* Throws EmailDeliveryError if the message is rejected.
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*/
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async function sendWelcomeEmail(to: Address): Promise<void> {...}
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```
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---
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## 7. Error Handling
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### Errors are values
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Treat errors as data, not as control flow exceptions. In TypeScript:
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```
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✅ type Result<T> = { ok: true; value: T } | { ok: false; error: Error }
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// Caller is forced to handle the error
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const result = await fetchInvoice(id)
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if (!result.ok) {
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// handle error explicitly
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return showError(result.error)
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}
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const invoice = result.value
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```
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### Never swallow
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```
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❌ try {
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await saveUser(user)
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} catch (e) {
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// ignore
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}
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❌ try {
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await saveUser(user)
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} catch (e) {
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console.log(e)
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}
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```
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If you don't know what to do with the error, **let it propagate**. The caller might know.
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### Specific catch
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```
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❌ try {
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await parseJson(text)
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} catch (e) { ... } // catches everything, including programming errors
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✅ try {
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await parseJson(text)
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} catch (e) {
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if (e instanceof SyntaxError) {
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return { ok: false, error: new InvalidJsonError(text, e) }
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}
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throw e // programming error — let it bubble
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}
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```
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### Don't catch what you can't handle
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If you can't do anything meaningful with the error, don't catch it. Let it propagate to a place that can.
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### User-facing errors
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Don't expose internal error messages to users:
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```
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❌ throw new Error('SQLSTATE[23000]: Duplicate entry for key users.email')
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✅ throw new UserAlreadyExistsError(email)
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// In the user-facing layer:
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if (error instanceof UserAlreadyExistsError) {
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return showFormError('That email is already in use.')
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}
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```
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### Validation
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Validate at the boundary, trust internally:
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```
|
||
✅ // At the API boundary
|
||
function handleRequest(req: Request): Response {
|
||
const input = validateRequestInput(req) // throws if invalid
|
||
return processInput(input) // trusts the input
|
||
}
|
||
```
|
||
|
||
---
|
||
|
||
## 8. Structure
|
||
|
||
### File size
|
||
|
||
Files should be **under 500 lines**. If larger, split by responsibility.
|
||
|
||
### Module boundaries
|
||
|
||
- One module = one responsibility
|
||
- Exports are contracts — minimize them
|
||
- Internal helpers stay internal (`_prefix` or in a separate file)
|
||
- No circular dependencies
|
||
|
||
### Imports
|
||
|
||
Import order (be consistent):
|
||
1. Standard library
|
||
2. Third-party (frameworks, libraries)
|
||
3. Internal (project modules)
|
||
4. Relative (./components, ../utils)
|
||
5. Types (`import type`)
|
||
|
||
```
|
||
✅ import { readFile } from 'node:fs/promises'
|
||
import { z } from 'zod'
|
||
|
||
import type { User } from './types'
|
||
|
||
import { Button } from './components/Button'
|
||
```
|
||
|
||
### Project structure (typical)
|
||
|
||
```
|
||
src/
|
||
├── components/ # UI components
|
||
│ ├── Button/
|
||
│ │ ├── Button.tsx
|
||
│ │ ├── Button.test.tsx
|
||
│ │ └── index.ts
|
||
│ └── ...
|
||
├── lib/ # utilities, hooks
|
||
├── types/ # shared types
|
||
├── server/ # server-only code
|
||
└── index.ts # public exports
|
||
```
|
||
|
||
### Dead code
|
||
|
||
Delete it. Don't `// eslint-disable` it. Don't comment it out. Don't `# noqa` it. Delete it.
|
||
|
||
```
|
||
❌ // const oldImplementation = ...
|
||
// function deprecatedFoo() { ... }
|
||
|
||
✅ // (gone)
|
||
```
|
||
|
||
---
|
||
|
||
## 9. Type Discipline (TypeScript)
|
||
|
||
### Never `any`
|
||
|
||
```
|
||
❌ function process(data: any) {...}
|
||
|
||
✅ function process(data: Invoice) {...}
|
||
✅ function process(data: unknown) { // forces the caller to handle uncertainty
|
||
if (!isInvoice(data)) throw new TypeError('Expected Invoice')
|
||
// ... now data is Invoice
|
||
}
|
||
```
|
||
|
||
### Use `unknown` for genuine uncertainty
|
||
|
||
When you don't know the type, use `unknown` and narrow with type guards. `any` skips the type system; `unknown` forces you to handle it.
|
||
|
||
### Type narrowing
|
||
|
||
Write type guards that **prove** the type:
|
||
|
||
```
|
||
✅ function isInvoice(value: unknown): value is Invoice {
|
||
return (
|
||
typeof value === 'object' &&
|
||
value !== null &&
|
||
'id' in value &&
|
||
'amount' in value &&
|
||
typeof (value as Invoice).id === 'string'
|
||
)
|
||
}
|
||
```
|
||
|
||
### Don't lie to the type system
|
||
|
||
```
|
||
❌ const user = JSON.parse(json) as User // lies — JSON.parse returns any
|
||
|
||
✅ const user: User = userSchema.parse(JSON.parse(json)) // zod validates
|
||
```
|
||
|
||
### Avoid these patterns
|
||
|
||
- ❌ `as any` — fix the type
|
||
- ❌ `// @ts-ignore` — fix the type
|
||
- ❌ Non-null assertion `!` — handle the null case
|
||
- ❌ `as unknown as X` — the type system is right, you're wrong
|
||
- ❌ Optional chaining as a substitute for fixing types
|
||
- ❌ Empty interfaces — `interface User {}` — what is this?
|
||
|
||
---
|
||
|
||
## 10. Testing
|
||
|
||
### Test behavior, not implementation
|
||
|
||
```
|
||
❌ test('calls fetchUser once', () => {
|
||
const spy = jest.spyOn(api, 'fetchUser')
|
||
component.mount()
|
||
expect(spy).toHaveBeenCalledTimes(1)
|
||
})
|
||
|
||
✅ test('shows user name after loading', async () => {
|
||
const { findByText } = render(<Profile userId="123" />)
|
||
expect(await findByText('Jane Doe')).toBeInTheDocument()
|
||
})
|
||
```
|
||
|
||
### AAA: Arrange, Act, Assert
|
||
|
||
```
|
||
✅ test('calculates total with discount', () => {
|
||
// Arrange
|
||
const cart = [{ price: 100 }, { price: 50 }]
|
||
|
||
// Act
|
||
const total = calculateTotal(cart, 0.1)
|
||
|
||
// Assert
|
||
expect(total).toBe(135) // (100 + 50) * 0.9
|
||
})
|
||
```
|
||
|
||
### Test names describe behavior
|
||
|
||
```
|
||
✅ test('returns empty array when no items match filter')
|
||
✅ test('throws when email is invalid')
|
||
✅ test('redirects to login when session expires')
|
||
```
|
||
|
||
```
|
||
❌ test('test1')
|
||
❌ test('works')
|
||
❌ test('parse works') // "works" means nothing
|
||
```
|
||
|
||
### Test the boundaries
|
||
|
||
- Empty input
|
||
- Null / undefined
|
||
- Very large values
|
||
- Boundary values (0, 1, max, max+1)
|
||
- Invalid types
|
||
- Concurrent operations (if relevant)
|
||
|
||
### What NOT to test
|
||
|
||
- ❌ That a constant has a specific value
|
||
- ❌ That a private function exists
|
||
- ❌ That the implementation matches a specific structure
|
||
- ❌ That `add(1, 2) === 3` (test behavior of callers instead)
|
||
|
||
### Test independence
|
||
|
||
Tests should not depend on each other. Run them in any order. Run one in isolation.
|
||
|
||
---
|
||
|
||
## 11. Performance
|
||
|
||
### Measure first
|
||
|
||
Don't optimize without measuring. `console.time()` / `console.timeEnd()` / a real profiler.
|
||
|
||
### Common gotchas
|
||
|
||
- ❌ Creating functions inside render (React) — moves work to every render
|
||
- ❌ Using indexes as keys when the list reorders — causes re-renders
|
||
- ❌ Fetching data in a loop without batching
|
||
- ❌ Calling `JSON.parse` on user-controlled input without validation
|
||
- ❌ Using `indexOf` in a loop when you can use a Map
|
||
- ❌ Sorting with the wrong algorithm for the data size
|
||
- ❌ Calling the same async function N times when you can call it once
|
||
|
||
### Common wins
|
||
|
||
- ✅ Memoize expensive pure computations
|
||
- ✅ Batch API calls
|
||
- ✅ Use `Map`/`Set` for O(1) lookup
|
||
- ✅ Virtualize long lists (don't render 10,000 rows)
|
||
- ✅ Debounce / throttle event handlers
|
||
- ✅ Use `requestAnimationFrame` for animations
|
||
- ✅ Lazy-load what you don't need
|
||
|
||
### Don't premature-optimize
|
||
|
||
"Make it work, make it right, make it fast — in that order."
|
||
|
||
---
|
||
|
||
## 12. Language-Specific Notes
|
||
|
||
### TypeScript / JavaScript
|
||
|
||
- Use `const` by default. `let` only when reassignment is needed. Never `var`.
|
||
- Use arrow functions for inline, named functions for declarations.
|
||
- Prefer `===` over `==`.
|
||
- Use template literals over concatenation.
|
||
- Use destructuring for object/array access.
|
||
- Use optional chaining and nullish coalescing (`??`) appropriately.
|
||
- Don't use `for...in` for arrays.
|
||
- Don't use `arguments` — use rest parameters.
|
||
- Use `Map`/`Set` over plain objects/arrays when you need key-based lookup.
|
||
- Use `URL` and `URLSearchParams` for URL parsing.
|
||
|
||
### Python
|
||
|
||
- Use type hints (`def parse_invoice(raw: str) -> Invoice: ...`)
|
||
- Use f-strings, not `%` or `.format()`
|
||
- Use `pathlib`, not `os.path`
|
||
- Use dataclasses for value objects
|
||
- Use `with` for resource management
|
||
- Don't use mutable default arguments
|
||
- Don't use `global` (almost never)
|
||
- List comprehensions are good. Nested ones are not.
|
||
|
||
### Go
|
||
|
||
- Errors are values: `if err != nil { return err }`
|
||
- Don't use `panic` for normal flow
|
||
- Don't use `_` to discard errors (except in defer)
|
||
- Use `context.Context` for cancellation
|
||
- Use `gofmt` (no debate)
|
||
- Use meaningful package names (singular, descriptive)
|
||
|
||
### React (specific)
|
||
|
||
- Components are functions, named exports, PascalCase
|
||
- One component per file (mostly — small sub-components can co-locate)
|
||
- Props are typed with `type`, not `interface`
|
||
- Don't `useEffect` for derived state — compute it during render
|
||
- Don't fetch in `useEffect` without a state machine
|
||
- Memoize when measured, not by default
|
||
|
||
---
|
||
|
||
## 13. Code Review Checklist (Before Submitting)
|
||
|
||
For every PR / every function:
|
||
|
||
### Names
|
||
- [ ] Names are specific (not `data`, `result`, `item`)
|
||
- [ ] Functions are verb phrases
|
||
- [ ] Classes are nouns that mean something
|
||
- [ ] No boolean flags that change behavior
|
||
- [ ] No magic numbers — they have names
|
||
|
||
### Functions
|
||
- [ ] Each function does one thing
|
||
- [ ] Each function is < 50 lines
|
||
- [ ] Each function takes < 4 parameters (or 1 options object)
|
||
- [ ] No nested conditionals > 3 levels deep
|
||
- [ ] Early returns for the negative cases
|
||
- [ ] Pure functions preferred, side effects isolated
|
||
|
||
### Comments
|
||
- [ ] Comments explain WHY, not WHAT
|
||
- [ ] No "this function does X" comments
|
||
- [ ] No "step 1, step 2, step 3" comments
|
||
- [ ] TODOs have context (issue link, expected fix)
|
||
|
||
### Errors
|
||
- [ ] Errors are handled, not swallowed
|
||
- [ ] Specific catch types, not generic
|
||
- [ ] User-facing errors are friendly, internal errors are detailed
|
||
- [ ] Validation at boundaries
|
||
|
||
### Types
|
||
- [ ] No `any` (use `unknown` and narrow)
|
||
- [ ] No `as any`, no `@ts-ignore` without justification
|
||
- [ ] Types match reality (no false `as`)
|
||
|
||
### Tests
|
||
- [ ] Tests cover behavior, not implementation
|
||
- [ ] Test names describe what should happen
|
||
- [ ] Edge cases tested (empty, null, boundary)
|
||
- [ ] Tests independent of each other
|
||
|
||
### Structure
|
||
- [ ] Files < 500 lines
|
||
- [ ] One responsibility per file
|
||
- [ ] Imports organized (stdlib, third-party, internal)
|
||
- [ ] No dead code, no commented-out code
|
||
|
||
### Style
|
||
- [ ] Consistent with the rest of the codebase
|
||
- [ ] Linted and formatted
|
||
- [ ] No AI-slop patterns from §3
|
||
|
||
---
|
||
|
||
## 14. The Mantra
|
||
|
||
> **Code is read more than it's written. Write for the reader, not the writer.**
|
||
|
||
The next person to read your code is you, six months from now, at 2 AM, debugging a production issue. Be kind to them. Be kind to yourself.
|
||
|
||
> **The best code is the code you deleted.**
|
||
|
||
Every line you didn't write is a line that can't have a bug, can't be misunderstood, can't go stale.
|
||
|
||
> **If the code is good, you won't notice the code. If it's bad, you notice immediately.**
|
||
|
||
Your job is the first. Slop is the second.
|