fix: anthropic adapter with multiple consecutive user prompts

lua/codecompanion/adapters/anthropic.lua

@@ -8,6 +8,46 @@ local function get_system_prompt(tbl)
   end
 end
 
+local function merge_messages(messages)
+  local new_messages = {}
+  local temp_content = {} -- Temporary storage for consecutive "user" messages content
+  local last_role = nil -- Track the last role we encountered
+
+  for _, message in ipairs(messages) do
+    if message.role == "user" then
+      if last_role == "user" then
+        -- If the last role was also "user", we continue accumulating the content
+        table.insert(temp_content, message.content)
+      else
+        -- If we encounter "user" after a different role, start a new accumulation
+        temp_content = { message.content }
+      end
+    else
+      -- For any non-user message:
+      if last_role == "user" then
+        -- If the last message was a user message, we need to insert the accumulated content first
+        table.insert(new_messages, {
+          role = "user",
+          content = table.concat(temp_content, " "),
+        })
+      end
+      -- Insert the current non-user message
+      table.insert(new_messages, message)
+    end
+    last_role = message.role
+  end
+
+  -- After looping, check if the last messages were from "user" and need to be inserted
+  if last_role == "user" then
+    table.insert(new_messages, {
+      role = "user",
+      content = table.concat(temp_content, " "),
+    })
+  end
+
+  return new_messages
+end
+
 ---@class CodeCompanion.Adapter
 ---@field name string
 ---@field url string
@@ -56,23 +96,8 @@ return {
         table.remove(messages, system_prompt_index)
       end
 
-      -- Combine user prompts into a single prompt
-      local user_role_content = {}
-      for i = #messages, 1, -1 do
-        local message = messages[i]
-        if message.role == "user" then
-          table.insert(user_role_content, 1, message.content)
-          table.remove(messages, i)
-        end
-      end
-      local output = table.concat(user_role_content, " ")
-
-      if output ~= "" then
-        table.insert(messages, {
-          role = "user",
-          content = output,
-        })
-      end
+      -- Combine consecutive user prompts into a single prompt
+      messages = merge_messages(messages)
 
       return { messages = messages }
     end,