Linting

Variables, functions, methods, and parameters should use snake_case.

# Bad
let myVar = 10
def processData end

# Good
let my_var = 10
def process_data end

Classes and interfaces should use PascalCase.

# Bad
class my_class end
interface data_store end

# Good
class MyClass end
interface DataStore end

Blocks should not be empty. Add a comment or remove the block.

Lines should not exceed 120 characters.

Code after a return statement is unreachable and will never execute.

def example
  return 42
  print("never reached");  # Warning: unreachable code
end

Catch blocks should not be empty. Silently swallowing errors hides bugs.

# Bad - error silently ignored
try
  risky()catch e
end

# Good - at least log the error
try
  risky()catch e
  print("Error: " + str(e))
end

Nesting depth should not exceed 4 levels. Consider extracting logic into separate functions.

A class should not have two methods with the same name.

Calls to db_query_raw, Trusted.*, System.shell / System.shell_sync, or backtick command substitution from app/controllers/, app/middleware/, or app/views/. These primitives are powerful but become injection / traversal sinks when fed request-controlled data. The diagnostic spells out the safe alternative for each:

• db_query_raw → parameterised @sdbql{ ... #{value} ... } block, or Model.where("x = #{v}", { "v": v }).
• Trusted.* → jailed File.* (read/write/exists), which keeps every operation under the app root.
• System.shell / backticks → System.run(["prog", "arg1", ...]) with an argv array, which never invokes a shell.

Models, migrations, and tests are out of scope — those layers legitimately use these APIs against operator-controlled data.

Prefer .nil? / .present? over comparing to null.

# Bad
if user == null end
return user != null

# Good
if user.nil? end
return user.present?

Prefer .blank? / .present? over comparing to an empty string. .blank? also covers the nil case.

# Bad
if name == "" end

# Good
if name.blank? end

Replace a chain of 3+ comparisons of the same value with .includes?.

# Bad
status == "up" || status == "late" || status == "overdue"

# Good
["up", "late", "overdue"].includes?(status)

Model.find raises RecordNotFound on a miss (which the request handler turns into a 404), so a nil-check on its result never runs. Drop it, or use find_by / first_by when you want a nil result.

# Bad - dead code: .find already raised
post = Post.find(id)
return not_found() if post.nil?

# Good
post = Post.find(id)

A component's props(...) declaration must use string-literal names with no duplicates. Missing/unknown props are checked at render time in --dev, not by lint.

# Bad
props("title", "title")   # duplicate
props("title", x)         # not a string literal

# Good
props("title", "value")