fix(api): fix race condition in submit_input_prompt

As discussed in #95, there's a race condition if a display_route was
used and now we're submitting an input prompt.

To fix, we wait for the session to fully render before submitting the
input

Author: cameronr

lua/opencode/api.lua

@@ -274,7 +274,7 @@ function M.submit_input_prompt()
     -- we're displaying /help or something similar, need to clear that and refresh
     -- the session data before sending the command
     state.display_route = nil
-    ui.render_output()
+    ui.render_output(true)
   end
 
   input_window.handle_submit()

lua/opencode/core.lua

@@ -77,7 +77,7 @@ function M.open(opts)
         -- and the windows were closed so we need to do a full refresh. This mostly happens
         -- when opening the window after having closed it since we're not currently clearing
         -- the session on api.close()
-        ui.render_output(false)
+        ui.render_output()
       end
     end
   end

lua/opencode/ui/renderer.lua

@@ -114,12 +114,14 @@ local function fetch_session()
   return require('opencode.session').get_messages(session)
 end
 
+---Request all of the session data from the opencode server and render it
+---@return Promise<OpencodeMessage[]>
 function M.render_full_session()
   if not output_window.mounted() or not state.api_client then
-    return
+    return Promise.new():resolve(nil)
   end
 
-  fetch_session():and_then(M._render_full_session_data)
+  return fetch_session():and_then(M._render_full_session_data)
 end
 
 function M._render_full_session_data(session_data)

lua/opencode/ui/ui.lua

@@ -174,8 +174,16 @@ function M.clear_output()
   -- state.restore_points = {}
 end
 
-function M.render_output(_)
-  renderer.render_full_session()
+---Force a full rerender of the output buffer. Should be done synchronously if
+---called before submitting input or doing something that might generate events
+---from opencode
+---@param synchronous? boolean If true, waits until session is fully rendered
+function M.render_output(synchronous)
+  local ret = renderer.render_full_session()
+
+  if ret and synchronous then
+    ret:wait()
+  end
 end
 
 function M.render_lines(lines)