How to Debug Outdated Go Code Generated by AI Agents: 5 Systematic Strategies

Use the JetBrains go-modern-guidelines repository to detect your target Go version, validate generated code against a JSON guideline catalog, and iteratively refine AI prompts to eliminate stale language patterns.

When an AI agent produces Go code using deprecated idioms, you need a deterministic debugging workflow rather than manual inspection. The JetBrains/go-modern-guidelines repository provides a self-contained CLI, embedded guideline definitions, and automated analyzers that enable you to catch and correct outdated constructs before they reach production.

Detect the Target Go Version

Before validating any AI output, determine the exact Go version your project expects. The CLI in internal/cli/cli.go reads the go.mod file and falls back to runtime build information using debug.ReadBuildInfo():

// internal/cli/cli.go – line 41
info, ok := debug.ReadBuildInfo()
if ok {
    fmt.Printf("Running with Go %s\n", info.GoVersion)
}

Run the CLI command to surface the version constraint that AI agents should respect:

go-modern-guidelines version

This prints the detected version (e.g., go1.27) from internal/goversion/goversion.go, establishing the baseline for all modern feature checks. When you know the target version, you can reject AI suggestions that use language features introduced in later releases or fall back to pre-module legacy patterns.

Validate AI-Generated Code Against the Guideline Catalog

The repository ships with a machine-readable catalog at internal/guidelines/guidelines.json. The guidelines package loads this schema and exposes lookup helpers in internal/guidelines/guidelines.go:

// internal/guidelines/guidelines.go
func Load() (*Guidelines, error) { … }
func (g *Guidelines) FindByFeature(name string) (*Feature, bool) { … }

Write a validator that parses AI-generated source files using the go/ast package, extracts used features (such as errors.AsType or slices.Contains), and checks whether each construct is permitted for your detected Go version:

package main

import (
    "fmt"
    "log"
    "go/ast"
    "go/parser"
    "go/token"

    "github.com/JetBrains/go-modern-guidelines/internal/guidelines"
)

func main() {
    g, err := guidelines.Load()
    if err != nil { log.Fatal(err) }

    src := []byte(`// AI-generated snippet …`)
    fset := token.NewFileSet()
    file, _ := parser.ParseFile(fset, "tmp.go", src, 0)

    ast.Inspect(file, func(n ast.Node) bool {
        // Detect calls to outdated constructs
        // Return false to stop traversal on violation
        return true
    })

    fmt.Println("All used features are up-to-date.")
}

This approach gives immediate feedback about which constructs violate the schema defined in internal/guidelines/schema/schema.go, letting you pinpoint exactly which lines need modernization.

Automate Refactoring with the Modernize Analyzer

For systematic cleanup, leverage the modernize static analyzer that complements the embedded guidelines. First install the analyzer:

go install golang.org/x/tools/go/analysis/passes/modernize@latest

Then run it against the AI-generated package:

modernize ./...

The tool flags patterns such as manual for i := 0; i < n; i++ loops that should use for i := range n, or verbose error type assertions that should use errors.AsType[T]. These concrete suggestions provide actionable data you can feed back into the AI context window or apply directly via automated fixes.

Verify Changes with Unit Tests

The repository includes comprehensive tests that exercise version detection and guideline loading logic. Run these against your AI-generated modules to ensure modern idioms do not break existing behavior:

go test ./...

Key test files validate the pipeline:

• internal/cli/cli_test.go – Confirms version detection logic correctly parses go.mod and runtime build info.
• internal/guidelines/guidelines_test.go – Validates the JSON loader and feature lookup mechanisms.

If tests fail after modernizing AI-generated code, inspect the diffs to identify which modern idioms conflict with your project's constraints. This feedback loop prevents regressions while enforcing current language standards.

Refine AI Prompts Based on Concrete Feedback

Once the validator and analyzer identify specific outdated patterns, encode those findings into your prompt engineering. Instead of vague instructions, provide exact replacements:

"Generate Go 1.26 code. Replace manual type assertions with errors.AsType[T]. Use slices.Contains instead of for loops for membership checks. Avoid ioutil.ReadAll; use io.ReadAll."

Include the output from modernize or your custom validator as negative examples in the prompt context. This iterative approach—generate, validate, refine—trains the AI agent to produce code that passes the go-modern-guidelines checks on the first attempt.

Summary

• Pin the Go version using internal/cli/cli.go and internal/goversion/goversion.go to establish a compatibility baseline.
• Parse and validate AI output against internal/guidelines/guidelines.json using the Load() and FindByFeature() helpers.
• Automate detection of stale patterns with the modernize analyzer from golang.org/x/tools.
• Protect against regressions by running the repository's *_test.go files against generated code.
• Close the loop by feeding concrete violations back into AI prompts to improve future generations.

Frequently Asked Questions

How does the CLI detect which Go version the project uses?

The CLI first inspects the go.mod file through internal/goversion/goversion.go, then falls back to runtime/debug.ReadBuildInfo() as shown in internal/cli/cli.go at line 41. This dual approach ensures accurate version detection whether you are inside a module context or running standalone.

What specific outdated patterns does the guideline catalog cover?

The internal/guidelines/guidelines.json file tracks modern features such as errors.AsType, slices.Contains, and maps.Copy, mapping each to the Go version where it became available. The schema in internal/guidelines/schema/schema.go defines the structure that the Load() function parses.

Can I integrate these checks into a CI pipeline?

Yes. Run go-modern-guidelines version to verify the target version, then execute your validator script using the guidelines package to parse AI-generated files. Finally, invoke modernize ./... and go test ./... to block merges containing outdated idioms.

How do I programmatically check if a specific feature is available for my Go version?

Use the FindByFeature() method in internal/guidelines/guidelines.go after calling Load(). Pass the feature name (e.g., "errors.AsType") and check the returned struct's Since field against your detected version to determine compatibility.

{
  "mcpServers": {
    "instagit": {
      "command": "npx",
      "args": ["-y", "instagit@latest"]
    }
  }
}