From cc-skills-golang
Adds structured error handling to Go projects using samber/oops — error builders, stack traces, error codes, context attributes, user-facing vs developer messages, panic recovery, and logger integration.
How this skill is triggered — by the user, by Claude, or both
Slash command
/cc-skills-golang:golang-samber-oopsThis skill is limited to the following tools:
The summary Claude sees in its skill listing — used to decide when to auto-load this skill
**Persona:** You are a Go engineer who treats errors as structured data. Every error carries enough context — domain, attributes, trace — for an on-call engineer to diagnose the problem without asking the developer.
Persona: You are a Go engineer who treats errors as structured data. Every error carries enough context — domain, attributes, trace — for an on-call engineer to diagnose the problem without asking the developer.
samber/oops is a drop-in replacement for Go's standard error handling that adds structured context, stack traces, error codes, public messages, and panic recovery. Variable data goes in .With() attributes (not the message string), so APM tools (Datadog, Loki, Sentry) can group errors properly. Unlike the stdlib approach (adding slog attributes at the log site), oops attributes travel with the error through the call stack.
Standard Go errors lack context — you see connection failed but not which user triggered it, what query was running, or the full call stack. samber/oops provides:
.With() attributes, not the message string, so APM tools group errors properlyThis skill is not exhaustive. Please refer to library documentation and code examples for more information. Context7 can help as a discoverability platform. For Go package docs, versions, symbols, and known vulnerabilities, → See samber/cc-skills-golang@golang-pkg-go-dev skill.
All oops errors use a fluent builder pattern:
err := oops.
In("user-service"). // domain/feature
Tags("database", "postgres"). // categorization
Code("network_failure"). // machine-readable identifier
User("user-123", "email", "[email protected]"). // user context
With("query", query). // custom attributes
Errorf("failed to fetch user: %s", "timeout")
Terminal methods:
.Errorf(format, args...) — create a new error.Wrap(err) — wrap an existing error.Wrapf(err, format, args...) — wrap with a message.Join(err1, err2, ...) — combine multiple errors.Recover(fn) / .Recoverf(fn, format, args...) — convert panic to error| Methods | Use case |
|---|---|
.With("key", value) | Add custom key-value attribute (lazy func() any values supported) |
.WithContext(ctx, "key1", "key2") | Extract values from Go context into attributes (lazy values supported) |
.In("domain") | Set the feature/service/domain |
.Tags("auth", "sql") | Add categorization tags (query with err.HasTag("tag")) |
.Code("iam_authz_missing_permission") | Set machine-readable error identifier/slug |
.Public("Could not fetch user.") | Set user-safe message (separate from technical details) |
.Hint("Runbook: https://doc.acme.org/doc/abcd.md") | Add debugging hint for developers |
.Owner("team/slack") | Identify responsible team/owner |
.User(id, "k", "v") | Add user identifier and attributes |
.Tenant(id, "k", "v") | Add tenant/organization context and attributes |
.Trace(id) | Add trace / correlation ID (default: ULID) |
.Span(id) | Add span ID representing a unit of work/operation (default: ULID) |
.Time(t) | Override error timestamp (default: time.Now()) |
.Since(t) | Set duration based on time since t (exposed via err.Duration()) |
.Duration(d) | Set explicit error duration |
.Request(req, includeBody) | Attach *http.Request (optionally including body) |
.Response(res, includeBody) | Attach *http.Response (optionally including body) |
oops.FromContext(ctx) | Start from an OopsErrorBuilder stored in a Go context |
func (r *UserRepository) FetchUser(id string) (*User, error) {
query := "SELECT * FROM users WHERE id = $1"
row, err := r.db.Query(query, id)
if err != nil {
return nil, oops.
In("user-repository").
Tags("database", "postgres").
With("query", query).
With("user_id", id).
Wrapf(err, "failed to fetch user from database")
}
// ...
}
func (h *Handler) CreateUser(w http.ResponseWriter, r *http.Request) {
userID := getUserID(r)
err := h.service.CreateUser(r.Context(), userID)
if err != nil {
err = oops.
In("http-handler").
Tags("endpoint", "/users").
Request(r, false).
User(userID).
Wrapf(err, "create user failed")
http.Error(w, oops.GetPublic(err, "Internal server error"), http.StatusInternalServerError)
return
}
w.WriteHeader(http.StatusCreated)
}
func (s *UserService) CreateOrder(ctx context.Context, req CreateOrderRequest) error {
builder := oops.
In("order-service").
Tags("orders", "checkout").
Tenant(req.TenantID, "plan", req.Plan).
User(req.UserID, "email", req.UserEmail)
product, err := s.catalog.GetProduct(ctx, req.ProductID)
if err != nil {
return builder.
With("product_id", req.ProductID).
Wrapf(err, "product lookup failed")
}
if product.Stock < req.Quantity {
return builder.
Code("insufficient_stock").
Public("Not enough items in stock.").
With("requested", req.Quantity).
With("available", product.Stock).
Errorf("insufficient stock for product %s", req.ProductID)
}
return nil
}
// ✓ Good — Wrap returns nil if err is nil
return oops.Wrapf(err, "operation failed")
// ✗ Bad — unnecessary nil check
if err != nil {
return oops.Wrapf(err, "operation failed")
}
return nil
Each architectural layer SHOULD add context via Wrap/Wrapf — at least once per package boundary (not necessarily at every function call).
// ✓ Good — each layer adds relevant context
func Controller() error {
return oops.In("controller").Trace(traceID).Wrapf(Service(), "user request failed")
}
func Service() error {
return oops.In("service").With("op", "create_user").Wrapf(Repository(), "db operation failed")
}
func Repository() error {
return oops.In("repository").Tags("database", "postgres").Errorf("connection timeout")
}
Error messages MUST be low-cardinality for APM aggregation. Interpolating variable data into the message breaks grouping in Datadog, Loki, Sentry.
// ✗ Bad — high-cardinality, breaks APM grouping
oops.Errorf("failed to process user %s in tenant %s", userID, tenantID)
// ✓ Good — static message + structured attributes
oops.With("user_id", userID).With("tenant_id", tenantID).Errorf("failed to process user")
oops.Recover() MUST be used in goroutine boundaries. Convert panics to structured errors:
func ProcessData(data string) (err error) {
return oops.
In("data-processor").
Code("panic_recovered").
Hint("Check input data format and dependencies").
With("input_data", data).
Recover(func() {
riskyOperation(data)
})
}
samber/oops errors implement the standard error interface. Access additional info:
if oopsErr, ok := err.(oops.OopsError); ok {
fmt.Println("Code:", oopsErr.Code())
fmt.Println("Domain:", oopsErr.Domain())
fmt.Println("Tags:", oopsErr.Tags())
fmt.Println("Context:", oopsErr.Context())
fmt.Println("Stacktrace:", oopsErr.Stacktrace())
}
// Get public-facing message with fallback
publicMsg := oops.GetPublic(err, "Something went wrong")
fmt.Printf("%+v\n", err) // verbose with stack trace
bytes, _ := json.Marshal(err) // JSON for logging
slog.Error(err.Error(), slog.Any("error", err)) // slog integration
Carry error context through Go contexts:
func middleware(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
builder := oops.
In("http").
Request(r, false).
Trace(r.Header.Get("X-Trace-ID"))
ctx := oops.WithBuilder(r.Context(), builder)
next.ServeHTTP(w, r.WithContext(ctx))
})
}
func handler(ctx context.Context) error {
return oops.FromContext(ctx).Tags("handler", "users").Errorf("something failed")
}
For assertions, configuration, and additional logger examples, see Advanced patterns.
samber/cc-skills-golang@golang-error-handling skill for general error handling patternssamber/cc-skills-golang@golang-observability skill for logger integration and structured loggingnpx claudepluginhub fyrsmithlabs/marketplace --plugin cc-skills-golangIdiomatic Go error handling — creation, wrapping with %w, errors.Is/As/Join, custom types, sentinels, panic/recover, slog logging, HTTP middleware, and samber/oops for production errors. Apply when creating, wrapping, inspecting, or logging errors in Go codebases.
Provides Go error handling patterns: basic errors, wrapping with %w, sentinel errors, custom types, errors.Is, and Unwrap for robust apps.
Implements and reviews Go error handling: creates/wraps errors with fmt.Errorf, checks via errors.Is/As/Join, uses sentinels/custom types, logs with slog. Audits codebases and PRs.