diff --git a/lua/anthropic/init.lua b/lua/anthropic/init.lua
index d5871d7..e2dd1c9 100644
--- a/lua/anthropic/init.lua
+++ b/lua/anthropic/init.lua
@@ -18,7 +18,16 @@ M.opts = {
   nerdfonts = false,
 }
 
-M.resources = {}
+M.resources = {
+  icons = {
+    user = "User:",
+    assistant = "Assistant:",
+  },
+  spinner = {
+    fps = 12,
+    parts = { "⠋", "⠙", "⠹", "⠸", "⠼", "⠴", "⠦", "⠧", "⠇", "⠏" },
+  },
+}
 
 function M.setup(opts)
   M.opts = vim.tbl_deep_extend("force", M.opts, opts)
@@ -38,17 +47,6 @@ function M.setup(opts)
         },
       },
     }
-  else
-    M.resources = {
-      icons = {
-        user = "User:",
-        assistant = "Assistant:",
-      },
-      spinner = {
-        fps = 12,
-        parts = { "⠋", "⠙", "⠹", "⠸", "⠼", "⠴", "⠦", "⠧", "⠇", "⠏" },
-      },
-    }
   end
 end
 
diff --git a/lua/anthropic/util/api.lua b/lua/anthropic/util/api.lua
index 8f59cc4..fddbe1e 100644
--- a/lua/anthropic/util/api.lua
+++ b/lua/anthropic/util/api.lua
@@ -1,4 +1,6 @@
 local VERSION = "2023-06-01"
+-- local USERAGENT = "anthropic.nvim/0.0.0"
+
 local opts = require("anthropic").opts
 
 local M = {}
@@ -13,7 +15,12 @@ function M.make_headers()
     return
   end
 
-  local headers = { ["content-type"] = "application/json", ["anthropic-version"] = VERSION, ["x-api-key"] = opts.token }
+  local headers = {
+    -- ["user-agent"] = USERAGENT,
+    ["content-type"] = "application/json",
+    ["anthropic-version"] = VERSION,
+    ["x-api-key"] = opts.token,
+  }
 
   return headers
 end
diff --git a/lua/anthropic/util/init.lua b/lua/anthropic/util/init.lua
index 9e46a21..498421d 100644
--- a/lua/anthropic/util/init.lua
+++ b/lua/anthropic/util/init.lua
@@ -1,3 +1,5 @@
+local session = require("anthropic.util.session")
+
 local M = {}
 
 function M.load_session()
@@ -5,10 +7,15 @@ function M.load_session()
   -- Redraw chat window with session
 end
 
-function M.chat_message()
-  -- Append user message to session
+--- # Message request wrapper function
+---
+--- Calls the Anthropic API and writes the response to the chatbox
+---@param message string
+function M.send_message(message)
+  session.add_message(message, "user")
   -- Call API with session
-  -- Stream response to chat window and session
+  -- Stream response to chat window and
+  -- Update session
 end
 
 return M
diff --git a/lua/anthropic/util/session.lua b/lua/anthropic/util/session.lua
index 3497edd..e0769cc 100644
--- a/lua/anthropic/util/session.lua
+++ b/lua/anthropic/util/session.lua
@@ -25,6 +25,7 @@ function M.save()
 end
 
 --- # Load session from file
+---
 ---@param name string
 function M.load(name)
   local path = filename(name)
@@ -47,6 +48,7 @@ function M.load(name)
 end
 
 --- # List saved session names
+---
 ---@return string[]
 function M.list()
   local sessions = vim.fn.glob(session_dir .. "/*.json", false, true)
@@ -56,4 +58,18 @@ function M.list()
   return sessions
 end
 
+--- # Add a message to the session
+---
+---@param message string
+---@param role "user" | "assistant"
+function M.add_message(message, role)
+  local msgs = M.session.messages
+  if msgs[#msgs - 1].role == role then
+    vim.notify("anthropic: " .. role .. " message added after a " .. role .. " message", vim.log.levels.ERROR)
+    return
+  end
+
+  table.insert(msgs, { role = role, content = message })
+end
+
 return M