fix(nvim): skip Mason install for tools already on PATH

Mason's installer tries one source per package. For tools that we
already provide via the system package manager (Arch pkgs on the
host) or nix-profile (on the remote-dev VM), Mason will keep trying
to (re-)install via cargo/pip/etc. and report failures — but
conform.nvim/nvim-lint resolve their binary from PATH anyway, so
the Mason install is redundant.

Filter ensure_installed at startup against vim.fn.executable(). Keeps
behaviour identical on a fresh host (Mason still pulls everything),
but silences spurious failures for tools that the user has chosen to
provide system-wide (shellharden via nix-profile being the immediate
case).

1 files changed, 57 insertions, 44 deletions

diff --git a/dot_config/nvim/lua/plugins/lsp.lua b/dot_config/nvim/lua/plugins/lsp.lua
index 1a115db..69f8163 100644
--- a/dot_config/nvim/lua/plugins/lsp.lua
+++ b/dot_config/nvim/lua/plugins/lsp.lua
@@ -19,50 +19,63 @@ require("mason-lspconfig").setup({
   },
 })
 require("mason-tool-installer").setup({
-  ensure_installed = {
-    "actionlint",
-    "autotools-language-server",
-    "basedpyright",
-    "bash-language-server",
-    "clangd",
-    "codelldb",
-    "codespell",
-    "css-lsp",
-    "dockerfile-language-server",
-    "gh",
-    "gh-actions-language-server",
-    "groovy-language-server",
-    "hadolint",
-    "html-lsp",
-    "jq",
-    "json-lsp",
-    "jsonlint",
-    "just-lsp",
-    "lua-language-server",
-    "markdownlint",
-    "mdformat",
-    "neocmakelsp",
-    "nginx-config-formatter",
-    "nginx-language-server",
-    "npm-groovy-lint",
-    "prettier",
-    "ruff",
-    "rust-analyzer",
-    "selene",
-    "shellcheck",
-    "shellharden",
-    "shfmt",
-    "stylelint",
-    "stylua",
-    "systemd-lsp",
-    "systemdlint",
-    "taplo",
-    "typescript-language-server",
-    "typos",
-    "yaml-language-server",
-    "yamllint",
-    "yq",
-  },
+  ensure_installed = (function()
+    local tools = {
+      "actionlint",
+      "autotools-language-server",
+      "basedpyright",
+      "bash-language-server",
+      "clangd",
+      "codelldb",
+      "codespell",
+      "css-lsp",
+      "dockerfile-language-server",
+      "gh",
+      "gh-actions-language-server",
+      "groovy-language-server",
+      "hadolint",
+      "html-lsp",
+      "jq",
+      "json-lsp",
+      "jsonlint",
+      "just-lsp",
+      "lua-language-server",
+      "markdownlint",
+      "mdformat",
+      "neocmakelsp",
+      "nginx-config-formatter",
+      "nginx-language-server",
+      "npm-groovy-lint",
+      "prettier",
+      "ruff",
+      "rust-analyzer",
+      "selene",
+      "shellcheck",
+      "shellharden",
+      "shfmt",
+      "stylelint",
+      "stylua",
+      "systemd-lsp",
+      "systemdlint",
+      "taplo",
+      "typescript-language-server",
+      "typos",
+      "yaml-language-server",
+      "yamllint",
+      "yq",
+    }
+    -- Skip Mason install when the tool is already on PATH from the system
+    -- (e.g. shellharden via nix-profile on the remote-dev VM, where Mason's
+    -- cargo-build install path would fail). Mason's runners still discover
+    -- PATH binaries, so conform.nvim/nvim-lint keep working.
+    local filtered = {}
+    for _, name in ipairs(tools) do
+      if vim.fn.executable(name) ~= 1 then
+        table.insert(filtered, name)
+      end
+    end
+    return filtered
+  end)(),
 })
 
 vim.api.nvim_create_autocmd("LspAttach", {