So I added this line to "file_types" section in Zed settings: "CMake": ["CMakeLists.txt"],
And it worked. I suppose the fix is to add this to Zed default settings.

I could make a PR, but first I would like to know if I should add "cmake" to "CMake" file_type like this "Cmake": ["CMakeLists.txt", "cmake"]. It seems unnecessary but could be nice

This fixed issue for me

diff --git a/assets/settings/default.json b/assets/settings/default.json
index a59e115901..49cd414b66 100644
--- a/assets/settings/default.json
+++ b/assets/settings/default.json
@@ -843,6 +843,7 @@
   // }
   //
   "file_types": {
+    "CMake": ["CMakeLists.txt", "cmake"],
     "Plain Text": ["txt"],
     "JSON": ["flake.lock"],
     "JSONC": [

Also added this to my fork. If everything is fine I'm ready to open PR https://github.com/k0tran/zed/tree/main

I think I likely broke this in:

• Detect txt files as Plain Text #18334

Relevant lines from default.json with the "txt" line:

  "file_types": {
    "Plain Text": ["txt"],
    "JSONC": ["**/.zed/**/*.json", "**/zed/**/*.json", "**/Zed/**/*.json", "**/.vscode/**/*.json"],
    "Shell Script": [".env.*"]
  },

Currently here is the order of file_type overrides: (top wins)

• ~/.zed/settings.json
• zed default.json (bundled)
• config.toml in extension/built-in languages

As we don't ship default.json settings Languages provided by 3rd party extensions, for the moment you'll have to manually add this to your settings:

"file_types": {
    "CMake": [
      "CMakeLists.txt"
    ]
}

The longer term fix is perhaps to populate the Plain Text language with txt as an extension instead of using default.json, but this may require some work.

My apologies for breaking this.

there is another issue with the with Cmake extension.
when changing manually to the cmake filetype. and write some cmake command (add_executable or something in the CMakeLists.txt file) it seem to remove the added file and reset it to the previous state .

@regisx001 Please file that upstream on k0tran/zed_neocmake