Agent-skills-standard flutter-error-handling

Implement functional error recovery with Either/Failure patterns. Use when writing repositories, handling exceptions, defining failures, or using Either in any Flutter layer. (triggers: lib/domain/**, lib/infrastructure/**, Either, fold, Left, Right, Failure, dartz)

install

source · Clone the upstream repo

git clone https://github.com/HoangNguyen0403/agent-skills-standard

Claude Code · Install into ~/.claude/skills/

T=$(mktemp -d) && git clone --depth=1 https://github.com/HoangNguyen0403/agent-skills-standard "$T" && mkdir -p ~/.claude/skills && cp -r "$T/skills/flutter/flutter-error-handling" ~/.claude/skills/hoangnguyen0403-agent-skills-standard-flutter-error-handling && rm -rf "$T"

manifest: skills/flutter/flutter-error-handling/SKILL.md

source content

Error Handling

Priority: P1 (HIGH)

Implementation Workflow

Define failures — Create domain-specific failures using
```
@freezed
```
unions (e.g.,
```
UnauthorizedFailure
```
,
```
OutOfStockFailure
```
).
Return Either — Repositories return
```
Either<Failure, T>
```
. No exceptions in UI/BLoC.
Catch in Infrastructure only — Infrastructure catches exceptions (e.g.,
```
DioException
```
) and returns
```
Left(Failure)
```
. Never rethrow to UI.
Fold in BLoC — Use
```
.fold(failure, success)
```
in BLoC to emit corresponding states. Remove try/catch from BLoC.
Localize messages — Use
```
failure.failureMessage
```
(returns
```
TRObject
```
or localized string) for UI-safe text.
Log with stable templates — Use low-cardinality message templates; pass variable data via metadata/context.
No Silent Catch: Never swallow errors without logging or documented retry.
Crashlytics Routing: All UI/BLoC
```
catch
```
blocks MUST route errors via
```
AppLogger.error(AppException.fromException(e).message, error: e, stackTrace: st)
```
for observability and type-safe UI messages.

Repository & BLoC Examples

See implementation examples for repository error mapping and BLoC consumption patterns.

Reference & Examples

For Failure definitions and API error mapping: See references/REFERENCE.md.

Anti-Patterns

No Try-Catch in BLoC: BLoC receives
```
Either
```
and
```
folds
```
; try/catch belongs in Infrastructure
No Plain String Failures: Define typed
```
@freezed
```
Failure subclasses instead of
```
Left('Something went wrong')
```
No Empty Catch Blocks: Always log and propagate; never swallow errors silently
No Repositories Throwing Status: Return
```
Left(Failure)
```
instead of throwing
```
Exception
```
No Missing Log Registration: Use
```
AppLogger.error
```
in BLoC/UI
```
catch
```
to ensure Crashlytics tracking and type-safe UI messages