Extra } inserted in .kts files on save

[yamad07]

When working with .kts files in Zed using the Kotlin extension, an extra closing brace (}) is added automatically upon saving the file. This behavior does not occur with regular .kt files. The issue causes compilation errors as the resulting script contains mismatched braces.

zed-kts.mov

Environment

• Zed 0.167.2
• Kotlin v0.1.1

[reecelikesramen]

From my experience it's not just that it adds a closing brace, it's just arbitrary text addition/removal on save. Should have the option to disable LSP formatting and just use prettier for formatting KTS files

[notpeter]

1. Do either of you have trivial example repo and steps so I can try and reproduce this (I'm not a Kotlin dev, so could use a little hand holding)

2. Do you have any formatter settings defined in your Zed user settings / Zed project settings? (check both global "formatter" and "formatter" under languauges.Kotlin)? E.g. are you using any code_actions, are you invoking ktfmt as an external formatter, etc?

3. I believe fwcd/kotlin-language-server uses ktfmt under the hood.

4. @reecelikesramen Zed extensions can use prettier by adding a couple keys to the extensions config.toml (untested):```
   prettier_parser_name = "kotlin"
   prettier_plugins = ["prettier-plugin-kotlin"]

So it should be possible to support using prettier instead of the language server.

[reecelikesramen]

Reproducible example that I just tried:

• open new zed project in empty folder
• create test.kts:

println("hello world")

fun test(str: String) {
    println(str)
}

val i = 2

fun test2(str: String) {
    println(str)
}

• do a formatless save (super+k s)
• ensure language server is running (restart language server for me)
• insert this below val i = 2:

val j = 2
val k = 2
val l = 2

• do a regular save or just format

What I notice is that inserting at the end of the file maybe trims a line or something, but adding code in arbitrary places in the file really messes up the formatting.

I don't have the ability to annotate key presses, but here's a video where I alternate between doing a formatless save, putting in new code, and attempting to format:

Screen.Recording.2025-04-10.at.3.30.10.PM.mov

[notpeter]

I can reproduce with your steps. I think this is likely an upstream issue.

I don't think kotlin-language-server has proper support for KotlinScript:

• Support official Kotlin scripting API fwcd/kotlin-language-server#134
• KotlinScript Support fwcd/kotlin-language-server#354

Looks like kotlin-language-server vendored a fork of ktfmt to alias some namespaces.

• Vendored: fwcd/ktfmt@b5d31d1 (2022-03-18)
• Forked from upstream: facebook/ktfmt@f3c2964 (2022-03-18)
• That upstream commit was after v0.34 and before v0.35. v0.54 is current.

Looks like it has never been updated since.

• [Deps] Investigate ways of integrating ktfmt fwcd/kotlin-language-server#338

As a workaround, can you try manually download and configure ktfmt as an external formatter which worked for me:

curl -L -O $(curl -s "https://api.github.com/repos/facebook/ktfmt/releases/latest" | jq -r '.assets[] | select(.name | test("ktfmt-.*-jar-with-dependencies\\.jar")) | .browser_download_url') 

And drop this into .zed/settings.json inside your project

{
  "languages": {
    "Kotlin": {
      "formatter": {
        "external": {
          "command": "java",
          "arguments": [
            "-jar",
            "./ktfmt-0.54-jar-with-dependencies.jar",
            // "--meta-style",      // Use 2-space block indenting (default)
            // "--google-style",    // Google internal style (2 spaces)
            // "--kotlinlang-style" // Kotlin language guidelines style (4 spaces)
            "--stdin-name={buffer_path}",
            "-"
          ]
        }
      }
    }
  }
}

Let me know if that works and I'll update the docs.

Would love someone with more Kotlin knowledge to help kotlin-language-server improve their formatter.
The repro above was the first lines of kotlin I've ever written :P

Update: ktfmt is available via brew install ktfmt too.