Support loading ACP sessions if agent can (#2889)

lua/avante/llm.lua

@@ -1320,8 +1320,7 @@ function M._stream_acp(opts)
       if not session_id then
         M._create_acp_session_and_continue(opts, acp_client)
       else
-        if opts.just_connect_acp_client then return end
-        M._continue_stream_acp(opts, acp_client, session_id)
+        M._load_acp_session_and_continue(opts, acp_client, session_id)
       end
     end)
     return
@@ -1357,6 +1356,23 @@ function M._create_acp_session_and_continue(opts, acp_client)
   end)
 end
 
+---@param opts AvanteLLMStreamOptions
+---@param acp_client avante.acp.ACPClient
+---@param session_id string
+function M._load_acp_session_and_continue(opts, acp_client, session_id)
+  local project_root = Utils.root.get()
+  acp_client:load_session(session_id, project_root, {}, function(_, err)
+    if err then
+      -- Failed to load session, create a new one. It happens after switching acp providers
+      M._create_acp_session_and_continue(opts, acp_client)
+      return
+    end
+
+    if opts.just_connect_acp_client then return end
+    M._continue_stream_acp(opts, acp_client, session_id)
+  end)
+end
+
 ---@param opts AvanteLLMStreamOptions
 ---@param acp_client avante.acp.ACPClient
 ---@param session_id string