fix(renderer): render errors after last part

lua/opencode/ui/formatter.lua

@@ -145,7 +145,7 @@ function M._format_revert_message(session_data, start_idx)
             virt_text_pos = 'inline',
             virt_text_win_col = col,
             priority = 1000,
-          })
+          } --[[@as OutputExtmark]])
           col = col + #diff + 1
         end
       end
@@ -270,9 +270,16 @@ function M.format_message_header(message)
     },
     virt_text_win_col = -3,
     priority = 10,
-  })
+  } --[[@as OutputExtmark]])
 
-  if role == 'assistant' and message.info.error and message.info.error ~= '' then
+  -- Only want to show the error if we have no parts. If we have parts, they'll
+  -- handle rendering the error
+  if
+    role == 'assistant'
+    and message.info.error
+    and message.info.error ~= ''
+    and (not message.parts or #message.parts == 0)
+  then
     local error = message.info.error
     local error_messgage = error.data and error.data.message or vim.inspect(error)
 
@@ -676,19 +683,24 @@ function M._add_vertical_border(output, start_line, end_line, hl_group, win_col)
       virt_text_pos = 'overlay',
       virt_text_win_col = win_col,
       virt_text_repeat_linebreak = true,
-    })
+    } --[[@as OutputExtmark]])
   end
 end
 
 ---Formats a single message part and returns the resulting output object
 ---@param part OpencodeMessagePart The part to format
 ---@param message? OpencodeMessage Optional message object to extract role and mentions from
+---@param is_last_part? boolean Whether this is the last part in the message, used to show an error if there is one
 ---@return Output
-function M.format_part(part, message)
+function M.format_part(part, message, is_last_part)
   local output = Output.new()
 
+  if not message or not message.info or not message.info.role then
+    return output
+  end
+
   local content_added = false
-  local role = message and message.info and message.info.role
+  local role = message.info.role
 
   if role == 'user' then
     if part.type == 'text' and part.text then
@@ -722,18 +734,14 @@ function M.format_part(part, message)
     output:add_empty_line()
   end
 
-  return output
-end
-
----@param error_text string
----@return Output
-function M.format_error_callout(error_text)
-  local temp_output = Output.new()
-
-  temp_output:add_empty_line()
-  M._format_callout(temp_output, 'ERROR', error_text)
+  if is_last_part and role == 'assistant' and message.info.error and message.info.error ~= '' then
+    local error = message.info.error
+    local error_messgage = error.data and error.data.message or vim.inspect(error)
+    M._format_callout(output, 'ERROR', error_messgage)
+    output:add_empty_line()
+  end
 
-  return temp_output
+  return output
 end
 
 return M

lua/opencode/ui/renderer.lua

@@ -450,15 +450,23 @@ function M.on_message_updated(message, revert_index)
   end
 
   if found_msg then
-    -- see if an error was added (or removed). have to check before we set
-    -- found_msg.info = message.info below
-    local rerender_message = not vim.deep_equal(found_msg.info.error, msg.info.error)
+    local error_changed = not vim.deep_equal(found_msg.info.error, msg.info.error)
 
     found_msg.info = msg.info
 
-    if rerender_message and not revert_index then
-      local header_data = formatter.format_message_header(found_msg)
-      M._replace_message_in_buffer(msg.info.id, header_data)
+    --- NOTE: error handling is a bit messy because errors come in on messages
+    --- but we want to display the error at the end. In this case, we an error
+    --- was added to this message. We find the last part and re-render it to
+    --- display the message. If there are no parts, we'll re-render the message
+
+    if error_changed and not revert_index then
+      local last_part_id = M._get_last_part_for_message(found_msg)
+      if last_part_id then
+        M._rerender_part(last_part_id)
+      else
+        local header_data = formatter.format_message_header(found_msg)
+        M._replace_message_in_buffer(msg.info.id, header_data)
+      end
     end
   else
     table.insert(state.messages, msg)
@@ -507,6 +515,9 @@ function M.on_part_updated(properties, revert_index)
   local part_data = M._render_state:get_part(part.id)
   local is_new_part = not part_data
 
+  local prev_last_part_id = M._get_last_part_for_message(message)
+  local is_last_part = is_new_part or (prev_last_part_id == part.id)
+
   if is_new_part then
     table.insert(message.parts, part)
   else
@@ -528,14 +539,33 @@ function M.on_part_updated(properties, revert_index)
     M._render_state:update_part_data(part)
   end
 
-  local formatted = formatter.format_part(part, message)
+  local formatted = formatter.format_part(part, message, is_last_part)
 
   if revert_index and is_new_part then
     return
   end
 
   if is_new_part then
     M._insert_part_to_buffer(part.id, formatted)
+
+    if message.info.error then
+      --- NOTE: More error display code. As mentioned above, errors come in on messages
+      --- but we want to display them after parts so we tack the error onto the last
+      --- part. When a part is added and there's an error, we need to rerender
+      --- previous last part so it doesn't also display the message. If there was no previous
+      --- part, then we need to rerender the header so it doesn't display the error
+
+      vim.notify('new part and error: ' .. part.id)
+
+      if not prev_last_part_id then
+        -- no previous part, we're the first part, re-render the message header
+        -- so it doesn't also display the error
+        local header_data = formatter.format_message_header(message)
+        M._replace_message_in_buffer(part.messageID, header_data)
+      elseif prev_last_part_id ~= part.id then
+        M._rerender_part(prev_last_part_id)
+      end
+    end
   else
     M._replace_part_in_buffer(part.id, formatted)
   end
@@ -737,6 +767,24 @@ function M._find_text_part_for_message(message)
   return nil
 end
 
+---Find the last part in a message
+---@param message OpencodeMessage The message containing the parts
+---@return string? last_part_id The ID of the last part
+function M._get_last_part_for_message(message)
+  if not message or not message.parts or #message.parts == 0 then
+    return nil
+  end
+
+  for i = #message.parts, 1, -1 do
+    local part = message.parts[i]
+    if part.type ~= 'step-start' and part.type ~= 'step-finish' and part.id then
+      return part.id
+    end
+  end
+
+  return nil
+end
+
 ---Re-render existing part with current state
 ---Used for permission updates and other dynamic changes
 ---@param part_id string Part ID to re-render
@@ -753,7 +801,9 @@ function M._rerender_part(part_id)
   end
 
   local message = rendered_message.message
-  local formatted = formatter.format_part(part, message)
+  local last_part_id = M._get_last_part_for_message(message)
+  local is_last_part = (last_part_id == part_id)
+  local formatted = formatter.format_part(part, message, is_last_part)
 
   M._replace_part_in_buffer(part_id, formatted)
 end

tests/data/api-abort.expected.json

@@ -0,0 +1 @@
+{"timestamp":1761606463,"extmarks":[[1,2,0,{"virt_text_win_col":-3,"virt_text_hide":false,"virt_text_repeat_linebreak":false,"right_gravity":true,"priority":10,"ns_id":3,"virt_text":[["▌󰭻 ","OpencodeMessageRoleUser"],[" "],["USER","OpencodeMessageRoleUser"],["","OpencodeHint"],[" (2025-10-27 22:44:29)","OpencodeHint"],[" [msg_a27d8299d001nchmBunYlZcPyL]","OpencodeHint"]],"virt_text_pos":"win_col"}],[2,3,0,{"virt_text_win_col":-3,"virt_text_hide":false,"virt_text_repeat_linebreak":true,"right_gravity":true,"priority":4096,"ns_id":3,"virt_text":[["▌","OpencodeMessageRoleUser"]],"virt_text_pos":"win_col"}],[3,4,0,{"virt_text_win_col":-3,"virt_text_hide":false,"virt_text_repeat_linebreak":true,"right_gravity":true,"priority":4096,"ns_id":3,"virt_text":[["▌","OpencodeMessageRoleUser"]],"virt_text_pos":"win_col"}],[4,5,0,{"virt_text_win_col":-3,"virt_text_hide":false,"virt_text_repeat_linebreak":true,"right_gravity":true,"priority":4096,"ns_id":3,"virt_text":[["▌","OpencodeMessageRoleUser"]],"virt_text_pos":"win_col"}],[5,6,0,{"virt_text_win_col":-3,"virt_text_hide":false,"virt_text_repeat_linebreak":true,"right_gravity":true,"priority":4096,"ns_id":3,"virt_text":[["▌","OpencodeMessageRoleUser"]],"virt_text_pos":"win_col"}],[6,9,0,{"virt_text_win_col":-3,"virt_text_hide":false,"virt_text_repeat_linebreak":false,"right_gravity":true,"priority":10,"ns_id":3,"virt_text":[[" ","OpencodeMessageRoleAssistant"],[" "],["PLAN","OpencodeMessageRoleAssistant"],[" gpt-4.1","OpencodeHint"],[" (2025-10-27 22:44:29)","OpencodeHint"],[" [msg_a27d829f9002sfUFPslHq5P2b4]","OpencodeHint"]],"virt_text_pos":"win_col"}]],"lines":["","----","","","can generate 10 numbers?","","[a-empty.txt](a-empty.txt)","","----","","","You asked if I can generate 10 numbers, and you referenced reading an empty file (`a-empty.txt`). However, I'm currently in \"plan mode,\" which means I cannot write or modify any files—I'm only allowed to read, observe,","","> [!ERROR] The operation was aborted.",""],"actions":[]}