Auto-indent wants to sometimes use tab_size 4 no matter what the user setting is

[ArttuLai]

I have following configuration in Zed:

// settings.json
{
  "tab_size": 2
}

also tried this, which didn't help:

// settings.json
{
  "languages": {
    "Lua": {
      "tab_size": 2
    }
  }
}

However, auto-indent in Lua files sometimes acts like I have 4. For example, if I have my cursor at |:

local tab = {|}

Pressing <Enter> turns into (looking good so far):

local tab = {
··|
}

I type something (still looking good):

local tab = {
··a = 1,|
}

But after I press <Enter>, it indents the first line inside the table to 4:

local tab = {
····a = 1,
··|
}

Same goes for functions, if statements, etc:

local function fn()
··local a = 1|
end

<Enter>:

local function fn()
····local a = 1
··|
end

If I set tab_size to 4, there's no issue, because in that case, that's where you want the indents to go.

[notpeter]

I can reproduce.

Screen.Recording.2026-07-28.at.10.46.46.mov

Looking at language server logs, it appears this change is coming from lua-language-server in response to the the textDocument/onTypeFormatting issued by Zed. Not sure whether that's a bug in lua-language-server (not respecting tabSize?) or something else (missing initialization_options/settings, etc).

// Send:
{"jsonrpc":"2.0","method":"textDocument/didChange","params":{"textDocument":{"uri":"file:///Users/peter/oxide/rustfmt-wrapper/foo.lua","version":124},"contentChanges":[{"range":{"start":{"line":8,"character":10},"end":{"line":8,"character":10}},"text":"\n    "}]}}
{"jsonrpc":"2.0","id":412,"method":"textDocument/onTypeFormatting","params":{"textDocument":{"uri":"file:///Users/peter/oxide/rustfmt-wrapper/foo.lua"},"position":{"line":9,"character":4},"ch":"\n","options":{"tabSize":2,"insertSpaces":true,"trimTrailingWhitespace":true,"insertFinalNewline":true,"trimFinalNewlines":true}}}

// Receive (took 174.5ms):
{"id":412,"jsonrpc":"2.0","result":[{"newText":"    a = 1,\n","range":{"end":{"character":0,"line":9},"start":{"character":0,"line":8}}}]}

[ArttuLai]

After digging some more, there actually is a setting (Zed settings reference) that works around this:

// settings.json
{
  "languages": {
    "Lua": {
      "use_on_type_format": false
    }
  }
}