| name | clean-code-skill |
| description | Write clean, human-readable code with proper naming, small functions, self-documenting patterns, and object calisthenics - language-agnostic |
| license | Apache-2.0 |
| compatibility | opencode |
| metadata | {"audience":"developers","workflow":"code-quality","languages":["language-agnostic"],"protocol":"autoresearch-opt-in"} |
What I do
I help you write clean, maintainable code that is easy to understand and change:
- Improve Naming: Apply consistent, understandable, specific, and searchable naming conventions
- Reduce Function Size: Keep functions small (under 10 lines) with single responsibility
- Apply Object Calisthenics: Follow the 9 rules for better object-oriented design
- Eliminate Comments: Replace comments with self-documenting code
- Improve Formatting: Apply consistent code structure and organization
- Reduce Cognitive Load: Write code that tells a story
When to use me
Use this skill when:
- Code is hard to understand even though it works
- Functions are long and do multiple things
- Names are vague, inconsistent, or misleading
- Code requires extensive comments to explain what it does
- Reviewing code for readability and maintainability
- Onboarding new developers who struggle with the codebase
- Setting up coding standards for a team
- Refactoring legacy code for better maintainability
Prerequisites
- Code to analyze or write
- Understanding of basic programming concepts
- Willingness to refactor for readability
- Knowledge of the domain/business context for naming
What is Clean Code?
Code that is:
- Easy to understand - reveals intent clearly
- Easy to change - modifications are localized
- Easy to test - dependencies are injectable
- Simple - no unnecessary complexity
The Human-Centered Approach
Code has THREE consumers:
- Users - get their needs met
- Customers - make or save money
- Developers - must maintain it
Design for all three, but remember: developers read code 10x more than they write it.
Naming Principles
Priority Order for Naming
- Consistency & Uniqueness (HIGHEST PRIORITY)
- Understandability
- Specificity
- Brevity
- Searchability
- Pronounceability
- Austerity
1. Consistency & Uniqueness
Same concept = same name everywhere. One name per concept.
get_user_by_id(id)
fetch_customer_by_id(id)
retrieve_client_by_id(id)
get_user(id)
get_order(id)
get_product(id)
2. Understandability
Use domain language, not technical jargon.
const arr = users.filter(u => u.isActive);
const activeCustomers = users.filter(user => user.isActive);
3. Specificity
Avoid vague names: data, info, manager, handler, processor, utils
class DataManager:
pass
def process_info(data):
pass
class OrderRepository:
pass
def validate_payment(payment):
pass
4. Brevity (but not at cost of clarity)
Short names are good only if meaning is preserved.
const usrLst = getUsrs();
const listOfAllActiveUsersInTheSystem = getActiveUsers();
const activeUsers = getActiveUsers();
5. Searchability
Names should be unique enough to grep/search.
data = fetch()
order_summary = fetch_order_summary()
6. Pronounceability
You should be able to say it in conversation.
const genymdhms = generateYearMonthDayHourMinuteSecond();
const timestamp = generateTimestamp();
7. Austerity
Avoid unnecessary filler words.
user_data = user
class UserClass:
pass
user = user
class User:
pass
Learning: method-name-reuse-different-semantics
A method name reused across classes with DIFFERENT semantics violates the principle of least surprise — process() on OrderService mutates state, process() on PaymentGateway makes a network call, and process() on ReportBuilder returns a new immutable value. The reader assumes one meaning; the code does another. Before naming a method, grep for the proposed name across the codebase. If it exists elsewhere, either verify the semantic meaning is IDENTICAL, or include the specific condition/context in the name (process_for_refund, build_draft).
class OrderService:
def process(self, order):
order.status = "processed"
db.commit()
class PaymentGateway:
def process(self, amount):
return self.client.charge(amount)
class ReportBuilder:
def process(self, rows):
return Report(rows)
class OrderService:
def mark_processed(self, order): ...
class PaymentGateway:
def charge_card(self, amount) -> bool: ...
class ReportBuilder:
def build_from_rows(self, rows) -> Report: ...
Detection:
rg 'def (\w+)\(self' --type py --type ts -o --no-filename | sort | uniq -c | sort -rn | head -30
Rule: Before naming a method, grep the codebase for the proposed name. If it exists elsewhere, confirm the semantic contract is identical, or qualify the name with the specific condition. Never let one name mean two different things.
Object Calisthenics (9 Rules)
Exercises to improve OO design. Follow strictly during practice, relax slightly in production.
Rule 1: One Level of Indentation per Method
def process(orders):
for order in orders:
if order.is_valid():
for item in order.items:
if item.in_stock:
def process(orders):
for order in orders:
if order.is_valid():
process_order(order)
def process_order(order):
for item in order.items:
if item.in_stock:
process_item(item)
Rule 2: Don't Use the ELSE Keyword
Use early returns, guard clauses, or polymorphism.
Learning: duplicate-service-account-check
Don't call the same expensive method twice in one function. Extract to a local variable — single call, clear intent, no redundant work.
def process_payment(self, order):
if self.auth_service.get_service_account() is None:
raise NoServiceAccount()
account = self.auth_service.get_service_account()
self.charge(account, order.total)
def process_payment(self, order):
account = self.auth_service.get_service_account()
if account is None:
raise NoServiceAccount()
self.charge(account, order.total)
Rule 2 continued: Don't Use the ELSE Keyword
function getDiscount(user: User): number {
if (user.isPremium) {
return 20;
} else {
return 0;
}
}
function getDiscount(user: User): number {
if (user.isPremium) return 20;
return 0;
}
Rule 3: Wrap All Primitives and Strings
Primitives should be wrapped in domain objects when they have meaning.
def create_user(email: str, age: int):
pass
class Email:
def __init__(self, value: str):
if not self._is_valid(value):
raise InvalidEmail()
self._value = value
def _is_valid(self, email: str) -> bool:
return '@' in email
class Age:
def __init__(self, value: int):
if value < 0 or value > 150:
raise InvalidAge()
self._value = value
def create_user(email: Email, age: Age):
pass
Rule 4: First-Class Collections
Any class with a collection should have no other instance variables.
class Order {
items: Item[] = [];
customerId: string;
total: number;
}
class OrderItems {
constructor(private items: Item[] = []) {}
add(item: Item): void { }
total(): Money { }
isEmpty(): boolean { }
}
class Order {
constructor(
private items: OrderItems,
private customerId: CustomerId
) {}
}
Rule 5: One Dot per Line (Law of Demeter)
Don't chain through object graphs.
city = order.customer.address.city
city = order.get_shipping_city()
Rule 6: Don't Abbreviate
If a name is too long to type, the class is doing too much.
const custRepo = new CustRepo();
const ord = new Ord();
const customerRepository = new CustomerRepository();
const order = new Order();
Rule 7: Keep All Entities Small
- Classes: < 50 lines
- Methods: < 10 lines
- Files: < 100 lines
If larger, it's probably doing too much. Split it.
Rule 8: No Classes with More Than Two Instance Variables
Forces small, focused classes.
class Order:
def __init__(self):
self.id = None
self.customer_id = None
self.items = []
self.total = 0
self.status = None
class Order:
def __init__(self, order_id, details):
self._id = order_id
self._details = details
class OrderDetails:
def __init__(self, customer, line_items):
self._customer = customer
self._line_items = line_items
Rule 9: No Getters/Setters/Properties
Objects should have behavior, not just data. Tell objects what to do.
class Account {
getBalance(): number { return this.balance; }
setBalance(value: number) { this.balance = value; }
}
if (account.getBalance() >= amount) {
account.setBalance(account.getBalance() - amount);
}
class Account {
withdraw(amount: Money): WithdrawResult {
if (!this.canWithdraw(amount)) {
return WithdrawResult.insufficientFunds();
}
this.balance = this.balance.subtract(amount);
return WithdrawResult.success();
}
}
const result = account.withdraw(amount);
Learning: two-phase-dataclass-initialization
A function returns an object with sentinel/placeholder values (0.0, None, "") that the caller must separately patch. If the second call is forgotten, the result is silently wrong — not an error, just incorrect data.
Rule: Every function must return a complete object. If a field cannot be computed at construction time, make it Optional[None] so the type system surfaces the incompleteness.
def create_template(name: str) -> Template:
return Template(name=name, mean=0.0, stddev=0.0, low=0.0, high=0.0)
tpl = create_template("sensor")
tpl.compute_bounds(data)
def create_empty_template(name: str) -> Template:
"""Returns template with None bounds — caller MUST call populate()."""
return Template(name=name, mean=None, stddev=None, low=None, high=None)
def populate_template(tpl: Template, data: list[float]) -> Template:
"""Returns a NEW template with computed bounds."""
return Template(name=tpl.name, mean=mean(data), stddev=stdev(data), ...)
Detection: Look for functions returning objects with hardcoded 0.0, "", None, [] defaults that have companion compute_* or populate_* methods.
Learning: parallel-hierarchies-for-report-type-variants
When two container+hook+component trees are near-identical for different report types (e.g. FinancialReportContainer + useFinancialReport + FinancialReportTable vs OperationalReportContainer + useOperationalReport + OperationalReportTable), and the similarity is >70% (same fetch → transform → render lifecycle, same state machine, only the data shape differs), maintaining them as parallel trees is a duplication smell. Every bug fix must be applied twice and drifts silently on the second pass. Extract the shared container/hook structure and parameterize the report type via a strategy or a config object, so there is exactly one tree driven by a ReportType discriminator.
type ReportType = 'financial' | 'operational'
const REPORT_CONFIG: Record<ReportType, {
endpoint: string
transform: (raw: unknown) => ReportRow[]
columns: Column[]
}> = {
financial: { endpoint: '/api/financial-reports', transform: toFinancialRows, columns: FINANCIAL_COLUMNS },
operational: { endpoint: '/api/operational-reports', transform: toOperationalRows, columns: OPERATIONAL_COLUMNS },
}
function useReport(type: ReportType, id: string) {
const { endpoint, transform } = REPORT_CONFIG[type]
return useFetchReport(endpoint, id, transform)
}
function ReportContainer({ type, id }: { type: ReportType; id: string }) {
const { data, isLoading } = useReport(type, id)
const { columns } = REPORT_CONFIG[type]
return <ReportTable rows={data} columns={columns} loading={isLoading} />
}
Detection:
rg -l 'use[A-Z]\w+Report' --type ts --type tsx | xargs -I{} basename {} | sort
Rule: When two container+hook+component trees for different report types share >70% of their structure, extract a single parameterized tree driven by a ReportType discriminator and a config object. Maintaining parallel trees guarantees drift on the second copy.
Comments
When to Write Comments
Only write comments to explain WHY, not WHAT or HOW.
Code explains what and how. Comments explain business reasons, non-obvious decisions, or warnings.
counter += 1
counter += 1
Prefer Self-Documenting Code
Instead of commenting, rename to make intent clear.
if (user.subscriptionLevel >= 2 && !user.isBanned) { }
if (user.canAccessPremiumFeatures()) { }
Learning: self-documented-duplication
Comments like # could be replaced by X, tracked as follow-up or # TODO: extract this into a shared helper are permanent confessions — the follow-up ticket is never filed and the comment ships to production as a badge of known debt. A self-documenting comment that describes duplication without eliminating it is worse than no comment at all: it makes the duplication feel deliberate. Convert every "could be replaced by" or "should extract" comment into a JIRA or GitHub ticket immediately, and either delete the comment or replace it with a reference to the ticket (# See PROJ-1234 for extraction plan).
def validate_email(email: str) -> bool:
return "@" in email
def validate_email(email: str) -> bool:
return "@" in email
from shared_validation import validate_email
Detection:
rg "could be replaced|should be extracted|tracked as follow-up|TODO.*extract|FIXME.*duplicate" --type py --type ts --type tsx
Rule: "Could be replaced by" and "should extract" comments are debt that never ships. Either file a ticket and reference it in the comment, or eliminate the duplication now. Never let a confession comment ship as if the duplication were intentional.
Learning: brittle-single-strategy-data-extraction
Hardcoding a single extraction path silently returns null when it fails — the caller never knows why. Implement multi-strategy extraction with ordered fallbacks and a clear error when all strategies fail.
def extract_report_id(response: requests.Response) -> str | None:
try:
return response.json()["data"]["report_id"]
except (KeyError, ValueError):
return None
def extract_report_id(response: requests.Response) -> str:
strategies = [
lambda: response.json()["data"]["report_id"],
lambda: response.headers["Location"].rstrip("/").split("/")[-1],
lambda: response.json()["report_id"],
]
for strategy in strategies:
try:
return strategy()
except (KeyError, IndexError, ValueError, TypeError):
continue
raise ExtractionError(
f"Could not extract report_id from response "
f"(status={response.status_code}, body={response.text[:200]})"
)
Learning: inline-imports-in-functions
Imports inside function bodies (lazy imports) hide the module's true dependencies from static analysis tools (mypy, pylint, IDE go-to-definition) and mask circular-import problems that should be fixed by restructuring the module graph. When from heavy_sdk import Client lives inside process(), the import graph looks clean in pydeps output but is actually broken. Fix the architecture — split the module, extract an interface, or move the import to module level. Lazy imports are acceptable ONLY for optional/heavy imports behind feature flags (e.g. import torch only when GPU inference is requested) where the dependency is genuinely conditional.
def process_payment(order):
from services.audit import log_event
from heavy_payment_sdk import Client
client = Client()
log_event("payment_started")
return client.charge(order.total)
from services.audit import log_event
from heavy_payment_sdk import Client
def process_payment(order):
client = Client()
log_event("payment_started")
return client.charge(order.total)
def run_inference(model_path: str):
if not settings.GPU_ENABLED:
raise RuntimeError("GPU inference disabled")
import torch
return torch.load(model_path)
Detection:
rg "^\s+(import|from)\s" --type py
Rule: Module-level imports are the default. Inline imports hide dependencies from static analysis and mask circular-import bugs — fix the architecture instead. Exception: genuinely conditional/heavy dependencies behind feature flags.
Error Handling
Learning: broad-except-masks-bugs
Suggestion #1 + #8 merged — same root cause observed across 3 projects (Python async, Python DSP, TypeScript sequential async).
Narrow catches handle expected transport errors; broad except Exception masks programming bugs as service outages. Expected errors (ConnectError, TimeoutException, HTTPStatusError) are caught and degraded. Unexpected errors (AttributeError, KeyError, TypeError) must propagate as 500s so monitoring surfaces them — they are never "service unreachable."
try:
result = await client.call()
except Exception:
logger.warning("Service unreachable, degrading...")
return fallback
try:
result = await client.call()
except (ConnectError, TimeoutException, HTTPStatusError):
logger.warning("Service unreachable, degrading...")
return fallback
Detection:
rg 'except Exception\b|except:' --type py -l
rg 'except Exception' --type py -g '*dsp*' -g '*audio*' -g '*process*'
Rule: Define a domain exception hierarchy for expected failures. Never catch Exception or bare except: in code paths that process external data — you will mask genuine bugs as degraded results.
Learning: silent-failure-sequential-async
A critical async operation that catches its own failure and logs only console.error (or logger.error) prevents the caller from detecting the failure. The caller continues with stale or missing data, entering an inconsistent state with no feedback.
Rule: Sequential async operations must either:
- Throw on failure — let the caller decide whether to degrade, or
- Return a discriminated union —
Result[T, E] type so the caller explicitly handles both paths.
async def sync_engine_to_cds():
try:
data = await engine.get_data()
await cds.upload(data)
except Exception:
logger.error("Sync failed")
async def sync_engine_to_cds() -> None:
data = await engine.get_data()
await cds.upload(data)
toast.promise(apiCall(), {
error: "Failed",
})
await apiCall()
try {
const result = await apiCall()
toast.success("Done")
} catch (e) {
toast.error("Failed")
}
Detection:
rg 'except.*:\s*\n\s*(logger|console)\.(error|warning)' --type py --type ts -U
Frontend Patterns
Learning: scattered-z-index-magic-numbers
Symptom: Z-index values hardcoded in 10+ CSS/TSX files, making layering impossible to reason about. Two developers adding modals both pick 9999; the second one wins; the first one's modal is now buried.
.modal-overlay { z-index: 9999; }
.dropdown-menu { z-index: 1000; }
.toast { z-index: 8000; }
.sidebar { z-index: 500; }
:root {
--z-sidebar: 100;
--z-dropdown: 200;
--z-sticky: 300;
--z-modal-backdrop: 400;
--z-modal: 500;
--z-popover: 600;
--z-toast: 700;
}
.modal-overlay { z-index: var(--z-modal-backdrop); }
.dropdown-menu { z-index: var(--z-dropdown); }
.toast { z-index: var(--z-toast); }
.sidebar { z-index: var(--z-sidebar); }
Detection:
rg 'z-index:\s*\d+' --type css --type tsx -c | rg '[3-9]|[1-9][0-9]+'
Rule: Z-index values MUST be centralized as CSS custom properties (or a TypeScript constants file). Hardcoded numeric values drift across files and create layering races that are nearly impossible to debug after the fact.
Formatting
Vertical Spacing
- Related code together
- Blank lines between concepts
- Most important/public at top
Horizontal Spacing
- Consistent indentation
- Space around operators
- Max line length ~80-120 characters
Storytelling
Code should read top-to-bottom like a story. High-level at top, details below.
class OrderProcessor:
def process(self, order):
self._validate(order)
self._calculate_totals(order)
return self._save(order)
def _validate(self, order):
pass
def _calculate_totals(self, order):
pass
def _save(self, order):
pass
Steps
Step 1: Analyze Current Code
- Read the code as if you're seeing it for the first time
- Note areas that require mental effort to understand
- Identify long functions (>10 lines)
- Find vague or inconsistent names
- Locate comments that explain WHAT
Step 2: Improve Naming
- Apply the 7 naming principles in priority order
- Use domain language, not technical jargon
- Ensure consistency across the codebase
- Make names searchable and pronounceable
Step 3: Reduce Function Size
- Apply Rule 1 (one level of indentation)
- Extract methods to achieve <10 lines per function
- Ensure each function does one thing
- Use early returns to avoid else
Step 4: Apply Object Calisthenics
- Review against all 9 rules
- Focus on the most impactful violations first
- Refactor incrementally
- Keep tests passing after each change
Step 5: Eliminate Unnecessary Comments
- Replace WHAT comments with better naming
- Keep WHY comments that explain business reasons
- Add warnings for non-obvious edge cases
- Document public APIs with proper documentation
Best Practices
General Clean Code Practices
- Meaningful Names: Spend time on naming, it pays off
- Small Functions: If you can't see the whole function, it's too long
- Do One Thing: Each function/class should have one purpose
- DRY (Don't Repeat Yourself): But wait for Rule of Three
- KISS (Keep It Simple): Simplest solution that works
Code Review Checklist
Common Issues
Over-Abstraction
Issue: Creating too many small classes/methods for simple logic
Solution:
- Apply clean code when you feel pain
- Rule of Three for abstractions
- Keep related code together
Inconsistent Naming
Issue: Same concept has different names across codebase
Solution:
- Create a project glossary
- Use consistent naming conventions
- Review naming in code reviews
Too Many Small Functions
Issue: Code becomes hard to navigate with too many tiny functions
Solution:
- Group related functions in classes
- Use clear naming to show relationships
- Keep related code physically close
Verification Commands
After applying clean code principles:
find src -name "*.py" -exec grep -c "def " {} \;
grep -r "data\|info\|manager\|handler\|utils" src/ --include="*.py"
find src -name "*.py" -exec wc -l {} \; | sort -rn | head -20
grep -r "TODO\|FIXME" src/ --include="*.py"
Clean Code Verification Checklist:
Iteration Protocol (opt-in)
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Prompt-injection boundary
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Bounded-by-default
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