fix(renderer): handle error rendering

Required adding support for replacing messages... fortunately, that was
straightforward to add.

Also disable session.error reporting for now (except when debug is
enabled) as those errors seem duplicative?

Author: cameronr

lua/opencode/ui/formatter.lua

@@ -220,9 +220,8 @@ function M._format_error(output, message)
 end
 
 ---@param message OpencodeMessage
----@param msg_idx number Message index in the session
 ---@return Output
-function M.format_message_header(message, msg_idx)
+function M.format_message_header(message)
   local output = Output.new()
 
   output:add_lines(M.separator)
@@ -236,7 +235,6 @@ function M.format_message_header(message, msg_idx)
   local debug_text = config.debug and ' [' .. message.info.id .. ']' or ''
 
   output:add_empty_line()
-  output:add_metadata({ msg_idx = msg_idx, part_idx = 1, role = role, type = 'header' })
 
   local display_name
   if role == 'assistant' then
@@ -246,7 +244,7 @@ function M.format_message_header(message, msg_idx)
     else
       -- For the most recent assistant message, show current_mode if mode is missing
       -- This handles new messages that haven't been stamped yet
-      local is_last_message = msg_idx == #state.messages
+      local is_last_message = #state.messages == 0 or message.info.id == state.messages[#state.messages].info.id
       if is_last_message and state.current_mode and state.current_mode ~= '' then
         display_name = state.current_mode:upper()
       else
@@ -270,6 +268,14 @@ function M.format_message_header(message, msg_idx)
     priority = 10,
   })
 
+  if 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)
+
+    output:add_line('')
+    M._format_callout(output, 'ERROR', error_messgage)
+  end
+
   output:add_line('')
   return output
 end

lua/opencode/ui/renderer.lua

@@ -137,12 +137,6 @@ function M._render_full_session_data(session_data)
     for j, part in ipairs(msg.parts or {}) do
       M.on_part_updated({ part = part })
     end
-
-    -- FIXME: not sure how this error rendering code works when streaming
-    -- if msg.info.error and msg.info.error ~= '' then
-    --   vim.notify('calling _format_error')
-    --   M._format_error(output, msg.info)
-    -- end
   end
 
   M._scroll_to_bottom()
@@ -316,6 +310,37 @@ function M._remove_message_from_buffer(message_id)
   M._render_state:remove_message(message_id)
 end
 
+---Replace existing message header in buffer
+---@param message_id string Message ID
+---@param formatted_data Output Formatted header as Output object
+---@return boolean Success status
+function M._replace_message_in_buffer(message_id, formatted_data)
+  vim.notify('replacing message in buffer')
+  local cached = M._render_state:get_message(message_id)
+  if not cached or not cached.line_start or not cached.line_end then
+    return false
+  end
+
+  local new_lines = formatted_data.lines
+  local new_line_count = #new_lines
+
+  output_window.clear_extmarks(cached.line_start, cached.line_end + 1)
+  output_window.set_lines(new_lines, cached.line_start, cached.line_end + 1)
+  output_window.set_extmarks(formatted_data.extmarks, cached.line_start)
+
+  local old_line_end = cached.line_end
+  local new_line_end = cached.line_start + new_line_count - 1
+
+  M._render_state:set_message(message_id, cached.message, cached.line_start, new_line_end)
+
+  local delta = new_line_end - old_line_end
+  if delta ~= 0 then
+    M._render_state:shift_all(old_line_end + 1, delta)
+  end
+
+  return true
+end
+
 ---Event handler for message.updated events
 ---Creates new message or updates existing message info
 ---@param message {info: MessageInfo} Event properties
@@ -334,11 +359,20 @@ function M.on_message_updated(message)
   local found_msg = rendered_message and rendered_message.message
 
   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, message.info.error)
+
     found_msg.info = message.info
+
+    if rerender_message then
+      local header_data = formatter.format_message_header(found_msg)
+      M._replace_message_in_buffer(message.info.id, header_data)
+    end
   else
     table.insert(state.messages, message)
 
-    local header_data = formatter.format_message_header(message, #state.messages)
+    local header_data = formatter.format_message_header(message)
     local range = M._write_formatted_data(header_data)
 
     if range then
@@ -508,13 +542,19 @@ function M.on_session_error(properties)
     return
   end
 
-  local error_data = properties.error
-  local error_message = error_data.data and error_data.data.message or vim.inspect(error_data)
+  -- NOTE: we're handling message errors so session errors seem duplicative
 
-  local formatted = formatter.format_error_callout(error_message)
+  if config.debug.enabled then
+    vim.notify('Session error: ' .. vim.inspect(properties.error))
+  end
 
-  M._write_formatted_data(formatted)
-  M._scroll_to_bottom()
+  -- local error_data = properties.error
+  -- local error_message = error_data.data and error_data.data.message or vim.inspect(error_data)
+  --
+  -- local formatted = formatter.format_error_callout(error_message)
+  --
+  -- M._write_formatted_data(formatted)
+  -- M._scroll_to_bottom()
 end
 
 ---Event handler for permission.updated events