Feature: opt-in gate on Spring Boot project detection before starting LSP

[fobbyal]

Use case

I work in a polyglot Java environment where some projects are Spring Boot,
many are Jersey / plain libraries, and others are mixed-language repos
that happen to have a few .java and .yaml files. spring-boot.nvim's
current behaviour is to start the (fairly heavy) Spring Boot LSP for
every java and yaml buffer, regardless of whether the project
actually uses Spring Boot.

For Spring-only environments this is fine. For polyglot setups it's
expensive — booting a JVM-based language server you'll never use, plus
the LSP attaches to unrelated YAML buffers (docker-compose.yml,
.gitlab-ci.yml, helm values, etc.).

Current behaviour

The plugin registers an autocmd (group spring_boot_ls) that
unconditionally starts the Spring Boot LSP on BufRead / BufNewFile of
java and yaml filetypes.

Proposed behaviour (opt-in)

A setup({ ... }) option such as:

require('spring-boot.nvim').setup({
  -- default false (current behaviour preserved)
  require_spring_boot_project = true,
})

When true, before starting the LSP, walk up from the buffer's path
looking for pom.xml / build.gradle[.kts], then grep that file for
spring-boot. Only start the LSP if found.

The existing default stays unchanged, so this is non-breaking.

Prototype

I'm already using a local wrapper that does exactly this — it overrides
the spring_boot_ls autocmd group with a gated version. Sketch:

local function is_spring_project(bufnr)
  local root = vim.fs.root(bufnr or 0, {
    'pom.xml', 'build.gradle', 'build.gradle.kts',
    'settings.gradle', 'settings.gradle.kts',
  })
  if not root then return false end
  for _, fname in ipairs({ 'pom.xml', 'build.gradle', 'build.gradle.kts' }) do
    local p = root .. '/' .. fname
    if vim.fn.filereadable(p) == 1 then
      for _, line in ipairs(vim.fn.readfile(p, '', 500)) do
        if line:match('spring%-boot') then return true end
      end
    end
  end
  return false
end

-- Replace each existing 'spring_boot_ls' autocmd callback with one that
-- bails early when is_spring_project(bufnr) is false.

It works well for me but it's brittle — it depends on your group name
staying spring_boot_ls and the autocmd shape staying the same. A
proper opt-in inside the plugin would be more robust and benefit other
polyglot users.

Questions

• Would you be open to a PR adding this as an opt-in option?
• If yes, do you have a preferred name for the option? require_spring_boot_project,
  gate_on_project_detection, auto_detect, something else?
• Does the file scan (grep pom.xml / build.gradle for spring-boot)
  feel right, or would you prefer a stricter check (e.g. dependency
  resolution via maven-resolver)?

Happy to send a PR once we agree on the shape.

---

🤖 Filed via Claude Code on behalf of @fobbyal