fix(expert): default PATH lookup to noninteractive login shell

apps/expert/lib/expert/port.ex

@@ -278,7 +278,7 @@ defmodule Expert.Port do
 
         _ ->
           cmd = "cd #{directory} && printf \"#{@path_marker}:%s:#{@path_marker}\" \"$PATH\""
-          ["-i", "-l", "-c", cmd]
+          path_lookup_args(cmd)
       end
 
     {output, exit_code} = System.cmd(shell, args, env: env)
@@ -288,7 +288,21 @@ defmodule Expert.Port do
         clean_path
 
       _ ->
-        output |> String.trim() |> String.split("\n") |> List.last()
+        output
+        |> String.trim()
+        |> String.split("\n")
+        |> List.last()
+    end
+  end
+
+  defp path_lookup_args(cmd) do
+    case System.get_env("EXPERT_PATH_SHELL_MODE", "login") do
+      # Some users configure version managers or PATH mutations only in
+      # interactive shell startup files. Keep an escape hatch for those
+      # environments, but default to non-interactive login shells so LSP
+      # startup avoids shell UI side effects like zle/fzf or job-control noise.
+      "interactive" -> ["-i", "-l", "-c", cmd]
+      _ -> ["-l", "-c", cmd]
     end
   end
 

apps/expert/test/expert/port_test.exs

@@ -0,0 +1,85 @@
+defmodule Expert.PortTest do
+  use ExUnit.Case, async: false
+
+  alias Expert.Port
+  alias Forge.Test.Fixtures
+
+  setup do
+    original_env = %{
+      "SHELL" => System.get_env("SHELL"),
+      "EXPERT_PATH_SHELL_MODE" => System.get_env("EXPERT_PATH_SHELL_MODE"),
+      "EXPERT_ARGS_FILE" => System.get_env("EXPERT_ARGS_FILE")
+    }
+
+    on_exit(fn ->
+      Enum.each(original_env, fn {key, value} ->
+        if value do
+          System.put_env(key, value)
+        else
+          System.delete_env(key)
+        end
+      end)
+    end)
+
+    :ok
+  end
+
+  if match?({:unix, _}, :os.type()) do
+    @tag :tmp_dir
+    test "uses a non-interactive login shell by default", %{tmp_dir: tmp_dir} do
+      args = capture_lookup_args(tmp_dir)
+
+      assert ["-l", "-c", _cmd] = args
+    end
+
+    @tag :tmp_dir
+    test "supports interactive shell lookup as an opt-in", %{tmp_dir: tmp_dir} do
+      System.put_env("EXPERT_PATH_SHELL_MODE", "interactive")
+
+      args = capture_lookup_args(tmp_dir)
+
+      assert ["-i", "-l", "-c", _cmd] = args
+    end
+
+    @tag :tmp_dir
+    test "falls back to non-interactive login shell for unknown shell mode", %{tmp_dir: tmp_dir} do
+      System.put_env("EXPERT_PATH_SHELL_MODE", "bogus")
+
+      args = capture_lookup_args(tmp_dir)
+
+      assert ["-l", "-c", _cmd] = args
+    end
+  end
+
+  defp capture_lookup_args(tmp_dir) do
+    args_file = Path.join(tmp_dir, "shell-args.txt")
+    shell_path = write_shell_probe(tmp_dir)
+
+    System.put_env("EXPERT_ARGS_FILE", args_file)
+    System.put_env("SHELL", shell_path)
+
+    project = Fixtures.project()
+
+    assert {:ok, _elixir, _env} = Port.find_project_executable(project, "elixir")
+
+    args_file
+    |> File.read!()
+    |> String.split("\n", trim: true)
+  end
+
+  defp write_shell_probe(tmp_dir) do
+    shell_path = Path.join(tmp_dir, "zsh")
+
+    File.write!(
+      shell_path,
+      """
+      #!/bin/sh
+      printf '%s\\n' "$@" > "$EXPERT_ARGS_FILE"
+      printf '__EXPERT_PATH__:%s:__EXPERT_PATH__' "$PATH"
+      """
+    )
+
+    File.chmod!(shell_path, 0o755)
+    shell_path
+  end
+end