A small Neovim helper that opens GitHub references under the cursor (or visual selection) in a browser. This is editor-native. No plugins, no API calls, no Tree-sitter, no LSP. Just Lua.

github_ref.lua

--[[
github_ref.lua

A small, editor-native Neovim helper for opening GitHub references found
under the cursor or in a visual selection.

This file intentionally avoids plugins, GitHub API calls, Tree-sitter,
LSP integration, or background jobs. It is designed to be fast, predictable,
and usable anywhere text appears (code, documentation, comments, or notes).

Usage
-----

Press <leader>gb in normal or visual mode on any of the following patterns:

  `org/repo` - Opens the repository

  `org/repo@ref` - Opens a branch, tag, or commit
      (shorhand sha and full branch names with slashes are supported)

  `org/repo#123` - Opens issue #123 (or PR via GitHub redirect)

  `#123` - Resolves the issue via the current git remote and opens it

The mapping works in any buffer and does not depend on filetype.

Visual mode
-----------

When a visual selection is active, the first valid GitHub reference found
in the selection is used. If no selection is active, the WORD under the
cursor is used instead.

Configuration
-------------

By default, links are opened against https://github.com.

For GitHub Enterprise or self-hosted GitHub instances:

  require("config.github_ref").setup({
    github_base_url = "https://github.mycompany.com",
  })

Git remotes using HTTPS and SSH are supported.

Design notes
------------

- No GitHub API usage (issues vs PRs are not distinguished)
- No network requests
- No assumptions about language or filetype
- Deterministic behavior over heuristics
- NB!: Pull requests are opened via /issues/<id> and allowed to redirect naturally

This file is intended to be easy to copy, modify, or later extract into a
proper Neovim plugin if desired.
]]

local M = {}

M.config = {
  github_base_url = "https://github.com",
}

local function open_url(url)
  if vim.fn.has("mac") == 1 then
    vim.fn.jobstart({ "open", url }, { detach = true })
  elseif vim.fn.has("unix") == 1 then
    vim.fn.jobstart({ "xdg-open", url }, { detach = true })
  elseif vim.fn.has("win32") == 1 then
    vim.fn.jobstart({ "cmd.exe", "/c", "start", url }, { detach = true })
  end
end

local function get_git_remote()
  local handle = io.popen("git config --get remote.origin.url 2>/dev/null")
  if not handle then return nil end
  local result = handle:read("*a")
  handle:close()
  return result and result:gsub("%s+", "") or nil
end

local function parse_remote(remote)
  if not remote then return nil end

  -- git@github.com:org/repo.git
  local path = remote:match("^git@[^:]+:(.+)$")
  if path then
    return path:gsub("%.git$", "")
  end

  -- ssh://git@github.com/org/repo.git
  local path2 = remote:match("^ssh://git@[^/]+/(.+)$")
  if path2 then
    return path2:gsub("%.git$", "")
  end

  -- https://github.com/org/repo.git
  local path3 = remote:match("^https?://[^/]+/(.+)$")
  if path3 then
    return path3:gsub("%.git$", "")
  end

  return nil
end

local function get_visual_selection()
  local _, ls, cs = unpack(vim.fn.getpos("'<"))
  local _, le, ce = unpack(vim.fn.getpos("'>"))
  if ls == 0 then return nil end

  local lines = vim.api.nvim_buf_get_lines(0, ls - 1, le, false)
  if #lines == 0 then return nil end

  lines[#lines] = string.sub(lines[#lines], 1, ce)
  lines[1] = string.sub(lines[1], cs)

  return table.concat(lines, " ")
end

local function get_token_under_cursor()
  local token = vim.fn.expand("<cWORD>")
  token = token:gsub("^[%(%[%{\"']+", "")
  token = token:gsub("[%]%)}\"',%.]+$", "")
  return token
end

local function parse_github(text)
  local base = M.config.github_base_url

  -- org/repo#123
  local org, repo, issue = text:match("([%w%-_.]+)/([%w%-_.]+)#(%d+)")
  if org then
    return base .. "/" .. org .. "/" .. repo .. "/issues/" .. issue
  end

  -- #123 (resolve via git remote)
  local issue_only = text:match("^#(%d+)$")
  if issue_only then
    local remote = get_git_remote()
    local repo_path = parse_remote(remote)
    if not repo_path then
      vim.notify("Cannot resolve #"..issue_only.." (no git remote)", vim.log.levels.ERROR)
      return nil
    end
    return base .. "/" .. repo_path .. "/issues/" .. issue_only
  end

  -- org/repo@ref (ref may contain slashes)
  local org2, repo2, ref = text:match("([%w%-_.]+)/([%w%-_.]+)@(.+)")
  if org2 then
    return base .. "/" .. org2 .. "/" .. repo2 .. "/tree/" .. ref
  end

  -- org/repo
  local org3, repo3 = text:match("([%w%-_.]+)/([%w%-_.]+)")
  if org3 then
    return base .. "/" .. org3 .. "/" .. repo3
  end

  return nil
end

local function open_github_ref()
  local text = nil

  if vim.fn.mode():match("[vV]") then
    text = get_visual_selection()
  end

  if not text or text == "" then
    text = get_token_under_cursor()
  end

  local url = parse_github(text)

  if not url then
    vim.notify("No GitHub reference found", vim.log.levels.WARN)
    return
  end

  open_url(url)
end

-- =========================
-- Keymaps
-- =========================

vim.keymap.set({ "n", "v" }, "<leader>gb", open_github_ref, {
  desc = "Open GitHub reference",
})

-- =========================
-- Optional: public setup
-- =========================

function M.setup(opts)
  M.config = vim.tbl_deep_extend("force", M.config, opts or {})
end

return M