Skills for writing modern Go code

JetBrains released a set of guidelines for code agents to write modern Go code, covering features from Go 1.0 through 1.27, including Go 1.26 additions like `new(42)` and `errors.AsType[T]`. The guidelines, available for Junie, Claude Code, Codex, and Cursor, aim to counter training data lag and frequency bias that cause agents to generate outdated Go code. They align with the Go team's `modernize` analyzer and require Go 1.25 or newer.

This repository contains guidelines https://github.com/JetBrains/go-modern-guidelines/blob/main/plugin/skills/use-modern-go/SKILL.md for code agents that help them write modern Go code. For example, an agent with these guidelines uses max a, b instead of an if-else block, slices.Contains instead of a manual loop, cmp.Or a, b, c instead of a chain of nil checks. It also knows about recent additions like new 42 to get a pointer to a value and errors.AsType T err for type-safe error matching—both from Go 1.26. The guidelines cover the most useful features from Go 1.0 through Go 1.27, including everything targeted by the modernize analyzer. An agent will: - Detect the project's Go version from go.mod - Use language features and stdlib additions available up to and including that version - Prefer modern idioms over older patterns All coding agents tend to generate outdated Go. Two reasons: - Training data lag. Models don't know about features added after their training cutoff. They can't use errors.AsType T Go 1.26 if they've never seen it. - Frequency bias. Even for features the model knows, it often picks older patterns. There's more for i := 0; i < n; i++ in the training data than for i := range n , so that's what comes out. These guidelines fix both problems by giving the agent an explicit reference. This aligns with the Go team's direction. The modernize analyzer exists to automatically update existing code to use newer idioms see this talk https://www.youtube.com/watch?v= VePjjjV9JU from the Go team . These guidelines serve the same goal for new code: agents write modern Go from the start, so there's less to fix later. The marketplace integrations run a small CLI that is installed on first use with go install . Because of that, the Go toolchain https://go.dev/dl/ must be installed and available on your PATH . The CLI is installed into a local cache for example ~/.cache/go-modern-guidelines and never modifies your project. It targets Go 1.25 or newer ; on an older Go it still works as long as automatic toolchain switching is enabled GOTOOLCHAIN=auto , the default , which lets Go fetch a compatible toolchain on first run. The guidelines are available for Junie, Claude Code, Codex, and Cursor, and for other agents via skills.sh. Run the following commands inside a Junie CLI session. - Add this repository as a marketplace: /extensions marketplace add JetBrains/go-modern-guidelines - Install the extension: /extensions install modern-go-guidelines Junie invokes the skill automatically when it is relevant to a Go task. Update the installed extension from inside a Junie CLI session: /extensions update modern-go-guidelines Run the following commands inside a Claude Code session. - Add this repository as a marketplace: /plugin marketplace add JetBrains/go-modern-guidelines - Install the plugin: /plugin install modern-go-guidelines@goland-claude-marketplace Claude Code invokes the skill automatically when it is relevant to a Go task. To invoke it explicitly: /modern-go-guidelines:use-modern-go Claude Code can update the marketplace and installed plugin automatically at startup. Automatic updates are disabled by default for third-party marketplaces, so enable them once: - Run /plugin . - Open Marketplaces and select goland-claude-marketplace . - Select Enable auto-update . When Claude Code reports that the plugin was updated, apply the new version to the current session with: /reload-plugins To update it manually instead, run these commands in a terminal: claude plugin marketplace update goland-claude-marketplace claude plugin update modern-go-guidelines@goland-claude-marketplace Run the following commands in a terminal. - Add this repository as a marketplace: codex plugin marketplace add JetBrains/go-modern-guidelines - Install the plugin: codex plugin add modern-go-guidelines@goland-codex-marketplace Refresh the marketplace and reinstall the plugin so Codex replaces its cached copy: codex plugin marketplace upgrade goland-codex-marketplace codex plugin remove modern-go-guidelines@goland-codex-marketplace codex plugin add modern-go-guidelines@goland-codex-marketplace For convenience, the guidelines are distributed as a Cursor plugin. - Add this repository as a marketplace by running the following command in a terminal: cursor-agent plugin marketplace add https://github.com/JetBrains/go-modern-guidelines - Install the plugin with the /plugins command inside a Cursor session. Refresh the marketplace from Git and reopen Cursor so it can pick up the new plugin version: cursor-agent plugin marketplace update goland-cursor-marketplace If the installed plugin is still on the previous version, reinstall it with the /plugins command. Cursor does not currently provide a non-interactive CLI command for updating an installed plugin. Other Agents via skills.sh https://skills.sh The same skill package works across other agents such as OpenCode. Install it with: npx skills add JetBrains/go-modern-guidelines --skill use-modern-go installs only this skill. Update the project-installed skill with: npx skills update use-modern-go -p -y For a globally installed skill, replace -p with -g . To try changes to the CLI in your agent, build this checkout into the tool's cache: make dev-install Then set GO MODERN GUIDELINES DEV=1 in the environment your agent runs in. With it set, any agent using the plugin runs your local build instead of the released version, the same way across Claude Code, Codex, and Cursor. Export it before launching the agent so the agent process inherits it: export GO MODERN GUIDELINES DEV=1 After editing the CLI, run make dev-install again to rebuild; the next call picks it up. To go back to the released version, unset the variable or run make dev-uninstall to remove the build : make dev-uninstall This requires the Go toolchain. The dev build is stored in the tool's cache directory $XDG CACHE HOME/go-modern-guidelines or ~/.cache/go-modern-guidelines . The build is driven by scripts/dev-install.sh , which is intentionally separate from the agent-facing wrapper so an agent can never trigger a build. Without make for example on Windows you can run it directly: sh scripts/dev-install.sh install or: uninstall pwsh scripts/dev-install.ps1 install PowerShell equivalent