ElixirLS uses git root instead of opened Mix app in Elixir monorepos

[0xSSDD]

Description

Problem

When OpenCode is started in a nested Elixir app inside a git monorepo, ElixirLS appears to attach to the git root instead of the opened app root.

That breaks Elixir navigation in the subproject:

• document-symbols returns [] for valid .ex files
• some runs time out during ElixirLS initialize
• sessions keep the correct directory, but the resolved project root stays the monorepo root

Why this looks like the root cause

I started OpenCode in a nested Mix app:

opencode /path/to/monorepo/apps/example_app

But the local API still resolves the current project to the git root:

curl -s http://127.0.0.1:4099/project/current

{
  "id": "<project-id>",
  "worktree": "/path/to/monorepo",
  "vcs": "git"
}

At the same time, sessions keep the nested app as their directory:

curl -s 'http://127.0.0.1:4099/experimental/session?directory=/path/to/monorepo/apps/example_app&roots=true'

Example response shape:

{
  "directory": "/path/to/monorepo/apps/example_app",
  "project": {
    "worktree": "/path/to/monorepo"
  }
}

So OpenCode distinguishes directory from project.worktree, but ElixirLS appears to follow the git-root project.

Expected behavior

If I open:

opencode /path/to/monorepo/apps/example_app

then ElixirLS should attach to:

/path/to/monorepo/apps/example_app

or at least to the nearest ancestor containing mix.exs, not to:

/path/to/monorepo

Actual behavior

For valid Elixir files inside the nested app:

opencode debug lsp document-symbols file:///path/to/monorepo/apps/example_app/lib/example_app/application.ex

returns:

[]

And:

opencode debug lsp diagnostics /path/to/monorepo/apps/example_app/lib/example_app/application.ex

returns:

{
  "/path/to/monorepo/apps/example_app/lib/example_app/application.ex": []
}

Environment

• OpenCode 1.2.24
• macOS
• Elixir 1.15.6-otp-26
• Erlang 26.1.2

Notes

The nested app itself is valid:

• it has its own mix.exs
• it has its own .tool-versions
• it already has .elixir_ls/

This looks like an OpenCode workspace/project-root issue rather than an ElixirLS project setup issue.

Plugins

No response

OpenCode version

1.2.24

Steps to reproduce

Minimal reproduction

Repo shape:

• /path/to/monorepo/.git
• /path/to/monorepo/apps/example_app/mix.exs

Commands:

opencode /path/to/monorepo/apps/example_app
opencode debug lsp document-symbols file:///path/to/monorepo/apps/example_app/lib/example_app/application.ex

Screenshot and/or share link

No response

Operating System

macOS

Terminal

cmux

[github-actions]

This issue might be a duplicate of existing issues. Please check:

• LSP detection in monorepo not working #7690: LSP detection in monorepo not working — same root cause (LSP server attaches to git root instead of opened subdirectory), reported for JS/TS LSPs
• ElixirLS: LSP client spawns new process per request, causing timeout and process leak #12596: ElixirLS LSP client spawns new process per request, causing timeout and process leak — different symptom but also affects ElixirLS initialization and root resolution