Dart

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Iron law

Null safety is not optional. Await failures. Don't catch everything.

Tooling / verify

dart test
# or flutter test when the package is Flutter
dart analyze

Idioms a linter misses

• Sound null safety. No ! without an invariant.
• final default. Prefer immutability on public types.
• async/await over raw then chains unless the file is already that style.
• Libraries: show / hide exports so the public surface is small.

Errors

• Typed errors or the project's result type.
• No empty catch (e) {}. Don't catch Error.

Concurrency

• Isolates for CPU. Don't block the UI isolate with heavy work.
• Unawaited futures in app code are bugs (unawaited only when the file already documents fire-and-forget).

Testing

• package:test or flutter_test as the package already uses.

PR review

• New dynamic on a public API: reject.
• New !: named invariant or reject.
• Flutter widgets: this skill stays on Dart. Do not invent a BLoC religion.

Security

• No concatenated SQL or process strings.
• Path joins inside an allowlisted root.
• Secrets not in pubspec or source.

Always

• Null-safe types. Awaited futures. Tests.

Ask first

• Adding Flutter to a pure Dart package.
• A new state-management package.

Never

• Empty catch.
• dynamic as an escape hatch on public APIs.
• Concatenated SQL or process strings.

Red flags

• "dynamic is faster to write"
• "I'll unawait it, it's just logging"