openidea/plugins/README.md

Writing OpenIDEA plugins

OpenIDEA plugins are sandboxed WebAssembly components (wasmtime, component model, WASI preview 2), in the style of Zed extensions. A plugin can register commands (they become IDE actions you can search for and bind to keys), read project files, insert text into the editor, show notifications and contribute themes and languages. Plugins that only contribute themes or languages need no code at all.

plugins/
├─ build.sh                 # builds Rust plugins into components
├─ hello/                   # Rust plugin: two commands
├─ theme-solarized/         # manifest-only: Solarized Light / Dark themes
├─ theme-one/               # manifest-only: One Light / Dark themes
└─ language-toy/            # manifest-only: a language definition

The API is defined in wit/plugin.wit (openidea:plugin/plugin@0.1.0).

1. The package

A plugin is a directory with a plugin.toml:

id = "hello"                    # [a-z0-9][a-z0-9_-]*, unique
name = "Hello"
version = "0.1.0"               # semver
description = "Inserts today's date and counts words."
authors = ["You <you@example.com>"]
homepage = "https://example.com" # optional
openidea-api = "0.1"                # API version this plugin targets
wasm = "dist/plugin.wasm"       # omit for contribution-only plugins
permissions = ["project-read", "editor-read", "editor-write"]

# Optional static contributions (active even before / without code):
[[contributes.commands]]
id = "insert-date"              # [a-z0-9][a-z0-9._-]*
title = "Hello: Insert Date"
category = "Hello"              # group in Search Everywhere / Keymap

[[contributes.themes]]
path = "themes/my-theme.json"

[[contributes.languages]]
path = "languages/my-lang.toml"

All paths are relative to the package directory and may not leave it.

Permissions

Permission	Unlocks
project-read	workspace-root, read-file (project root only)
editor-read	active-file
editor-write	insert-text, replace-selection

log, register-command, show-notification, register-language and register-theme are always available. Calling a gated function without its permission traps: the plugin is stopped and the user is told which permission is missing.

2. Writing code (Rust)

wasm32-wasip2 produces a component directly, so all you need is rustup:

rustup target add wasm32-wasip2

Cargo.toml:

[package]
name = "my-plugin"
version = "0.1.0"
edition = "2024"

[workspace]              # keep it out of any parent workspace

[lib]
crate-type = ["cdylib"]

[dependencies]
wit-bindgen = "0.63"

[profile.release]
opt-level = "s"
lto = true
strip = true
panic = "abort"

src/lib.rs:

wit_bindgen::generate!({ world: "plugin", path: "path/to/openidea/wit" });

use openidea::plugin::host::{self, LogLevel, NotificationLevel};

struct MyPlugin;

impl Guest for MyPlugin {
    fn activate(_ctx: Context) -> Result<(), String> {
        host::register_command("shout", "My Plugin: Shout Selection", Some("My Plugin"));
        Ok(())
    }

    fn deactivate() {}

    fn run_command(id: String, arg: Option<String>) -> Result<Option<String>, String> {
        match id.as_str() {
            "shout" => {
                host::replace_selection(&arg.unwrap_or_default().to_uppercase());
                Ok(None)
            }
            _ => Err(format!("unknown command {id}")),
        }
    }
}

export!(MyPlugin);

Build (copy build.sh or run it with your plugin's path):

plugins/build.sh hello                 # → plugins/hello/dist/plugin.wasm
plugins/build.sh /path/to/my-plugin

Any language with component-model tooling works (e.g. componentize-py, jco componentize, TinyGo): the only contract is the plugin world.

Host functions

Function	Notes
log(level, msg)	Goes to the IDE log, tagged with the plugin id. eprintln! output is logged too and shown when the plugin crashes.
register-command(id, title, category?)	Becomes action plugin.<plugin-id>.<id>; call again to rename. Max 256 commands.
show-notification(level, title, body)	Balloon in the invoking window.
workspace-root()	Root of the project the command runs in.
active-file()	Absolute path of the focused editor's file.
read-file(path)	Absolute or project-relative; ../symlinks escaping the root are rejected; UTF-8 only, ≤ 16 MiB. Unsaved editor contents win over disk.
insert-text(text)	Inserts at every cursor of the active editor (cursor ends after the text).
replace-selection(text)	Replaces every selection and selects the new text.
register-language(toml)	Same format as languages/<id>.toml.
register-theme(json)	See Themes below.

run-command receives an optional string argument: executeAction("plugin.hello.insert-date", "arg") from another feature, or nothing when run from Search Everywhere / a shortcut. Returning Err(msg) shows "