feat(plugin): `opts_extend` can be a list of dotted keys that will be extended instead of merged

lua/lazy/core/plugin.lua

@@ -667,7 +667,27 @@ function M._values(root, plugin, prop, is_list)
   end
 
   values = type(values) == "table" and values or { values }
-  return is_list and Util.extend(ret, values) or Util.merge(ret, values)
+  if is_list then
+    return Util.extend(ret, values)
+  else
+    ---@type {path:string[], list:any[]}[]
+    local lists = {}
+    for _, key in ipairs(plugin[prop .. "_extend"] or {}) do
+      local path = vim.split(key, ".", { plain = true })
+      local r = Util.key_get(ret, path)
+      local v = Util.key_get(values, path)
+      if type(r) == "table" and type(v) == "table" then
+        lists[key] = { path = path, list = {} }
+        vim.list_extend(lists[key].list, r)
+        vim.list_extend(lists[key].list, v)
+      end
+    end
+    local t = Util.merge(ret, values)
+    for _, list in pairs(lists) do
+      Util.key_set(t, list.path, list.list)
+    end
+    return t
+  end
 end
 
 return M

lua/lazy/core/util.lua

@@ -428,4 +428,35 @@ function M.lazy_require(module)
     })
 end
 
+---@param t table
+---@param key string|string[]
+---@return any
+function M.key_get(t, key)
+  local path = type(key) == "table" and key or vim.split(key, ".", true)
+  local value = t
+  for _, k in ipairs(path) do
+    if type(value) ~= "table" then
+      return value
+    end
+    value = value[k]
+  end
+  return value
+end
+
+---@param t table
+---@param key string|string[]
+---@param value any
+function M.key_set(t, key, value)
+  local path = type(key) == "table" and key or vim.split(key, ".", true)
+  local last = t
+  for i = 1, #path - 1 do
+    local k = path[i]
+    if type(last[k]) ~= "table" then
+      last[k] = {}
+    end
+    last = last[k]
+  end
+  last[path[#path]] = value
+end
+
 return M