Go Code Quality & Idioms

Enforces canonical Go idioms: context.Context propagation as the first parameter, small interfaces defined by consumers, explicit error wrapping (fmt.Errorf("%w", err)), and goroutine cancellation.

1. Purpose

Refactor Go code into idiomatic, robust implementations. "Interface Segregation" means declaring 1-2 method interfaces at consumer sites rather than large producer interfaces.

2. When to Use

Use this skill when:

• Adding cancellation and timeouts to long-running Go operations via context.Context.
• Wrapping errors with %w for errors.Is() and errors.As().
• Preventing goroutine leaks by ensuring channels have exits.

3. When Not to Use

• Do not use for testing; use go-testing.

4. Required Inputs

• target_file: Path to the Go file to improve.

5. Missing-Input Behavior

1. If target_file is missing: ask for target file.
2. Never introduce panics for standard operational errors; use error returns.

6. Procedure

Follow these numbered actions:

1. Action 1: Check Context Propagation
   • Ensure ctx context.Context is the first parameter of I/O functions.
2. Action 2: Check Error Wrapping
   • Replace generic string formatting with fmt.Errorf("failed action: %w", err).
3. Action 3: Audit Goroutine Lifecycles
   • Ensure every go func() has a termination condition via ctx.Done().
4. Action 4: Verify Compilation & Tests
   • Run go build ./... and go test ./....

7. Decision Rules

• Accept interfaces, return structs.
• Never use panic() in package libraries.

8. Output Format

Emit the report using this template:

### Go Code Quality Report: [File]

- **File Modified**: `[path]`
- **Patterns Applied**: [e.g. Context Propagation, Error Wrapping]
- **Compile Status**: PASS
- **Test Status**: PASS

#### Improvements Made
- [Detail 1]
- [Detail 2]

9. Verification Checklist

• ctx context.Context is first parameter on network/db functions.
• Errors wrapped using %w.
• No goroutine leaks.
• go test ./... passes.

10. Common Failures and Recovery

11. Stop or Escalation Conditions

Stop and ask the user when:

• Changing function signatures affects exported public package APIs.

12. Examples

Example 1: Successful Execution

Input:

File: internal/fetcher.go
Goal: Add context cancellation to FetchUser

Output:

### Go Code Quality Report: internal/fetcher.go

- **File Modified**: `internal/fetcher.go`
- **Patterns Applied**: Context Propagation & Error Wrapping
- **Compile Status**: PASS
- **Test Status**: PASS

#### Improvements Made
- Updated signature: `func FetchUser(ctx context.Context, id string) (*User, error)`
- Wrapped HTTP request with `http.NewRequestWithContext(ctx, ...)`.
- Wrapped error: `fmt.Errorf("fetching user %s: %w", id, err)`.

Example 2: Ambiguous or Missing Input

Input:

Fix go idioms.

Output:

### Go Code Quality Report: Halted - No Target

- **Status**: Halted

Please specify the target Go file to inspect.

Example 3: Expected Final Output

Output:

### Go Code Quality Report: internal/storage.go

- **File Modified**: `internal/storage.go`
- **Patterns Applied**: Consumer-Defined Interface
- **Compile Status**: PASS
- **Test Status**: PASS