fix(acp): return JSON-RPC error for fs/read_text_file on missing files (#2849)

Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>

lua/avante/libs/acp_client.lua

@@ -195,19 +195,21 @@ local ACPClient = {}
 
 -- ACP Error codes
 ACPClient.ERROR_CODES = {
-  TRANSPORT_ERROR = -32000,
-  PROTOCOL_ERROR = -32001,
-  TIMEOUT_ERROR = -32002,
-  AUTH_REQUIRED = -32003,
-  SESSION_NOT_FOUND = -32004,
-  PERMISSION_DENIED = -32005,
-  INVALID_REQUEST = -32006,
+  -- JSON-RPC 2.0
+  PARSE_ERROR = -32700,
+  INVALID_REQUEST = -32600,
+  METHOD_NOT_FOUND = -32601,
+  INVALID_PARAMS = -32602,
+  INTERNAL_ERROR = -32603,
+  -- ACP
+  AUTH_REQUIRED = -32000,
+  RESOURCE_NOT_FOUND = -32002,
 }
 
 ---@class ACPHandlers
 ---@field on_session_update? fun(update: avante.acp.UserMessageChunk | avante.acp.AgentMessageChunk | avante.acp.AgentThoughtChunk | avante.acp.ToolCallUpdate | avante.acp.PlanUpdate | avante.acp.AvailableCommandsUpdate)
 ---@field on_request_permission? fun(tool_call: table, options: table[], callback: fun(option_id: string | nil)): nil
----@field on_read_file? fun(path: string, line: integer | nil, limit: integer | nil, callback: fun(content: string)): nil
+---@field on_read_file? fun(path: string, line: integer | nil, limit: integer | nil, callback: fun(content: string), error_callback: fun(message: string, code: integer|nil)): nil
 ---@field on_write_file? fun(path: string, content: string, callback: fun(error: string|nil)): nil
 ---@field on_error? fun(error: table)
 
@@ -562,7 +564,7 @@ end
 ---@param code? number
 ---@return nil
 function ACPClient:_send_error(id, message, code)
-  code = code or self.ERROR_CODES.TRANSPORT_ERROR
+  code = code or self.ERROR_CODES.INTERNAL_ERROR
   local msg = { jsonrpc = "2.0", id = id, error = { code = code, message = message } }
 
   local data = vim.json.encode(msg)
@@ -666,7 +668,10 @@ function ACPClient:_handle_read_text_file(message_id, params)
   local session_id = params.sessionId
   local path = params.path
 
-  if not session_id or not path then return end
+  if not session_id or not path then
+    self:_send_error(message_id, "Invalid fs/read_text_file params", ACPClient.ERROR_CODES.INVALID_PARAMS)
+    return
+  end
 
   if self.config.handlers and self.config.handlers.on_read_file then
     vim.schedule(function()
@@ -674,9 +679,12 @@ function ACPClient:_handle_read_text_file(message_id, params)
         path,
         params.line ~= vim.NIL and params.line or nil,
         params.limit ~= vim.NIL and params.limit or nil,
-        function(content) self:_send_result(message_id, { content = content }) end
+        function(content) self:_send_result(message_id, { content = content }) end,
+        function(err, code) self:_send_error(message_id, err or "Failed to read file", code) end
       )
     end)
+  else
+    self:_send_error(message_id, "fs/read_text_file handler not configured", ACPClient.ERROR_CODES.METHOD_NOT_FOUND)
   end
 end
 
@@ -688,7 +696,10 @@ function ACPClient:_handle_write_text_file(message_id, params)
   local path = params.path
   local content = params.content
 
-  if not session_id or not path or not content then return end
+  if not session_id or not path or not content then
+    self:_send_error(message_id, "Invalid fs/write_text_file params", ACPClient.ERROR_CODES.INVALID_PARAMS)
+    return
+  end
 
   if self.config.handlers and self.config.handlers.on_write_file then
     vim.schedule(function()
@@ -698,6 +709,8 @@ function ACPClient:_handle_write_text_file(message_id, params)
         function(error) self:_send_result(message_id, error == nil and vim.NIL or error) end
       )
     end)
+  else
+    self:_send_error(message_id, "fs/write_text_file handler not configured", ACPClient.ERROR_CODES.METHOD_NOT_FOUND)
   end
 end
 

lua/avante/llm.lua

@@ -1238,9 +1238,16 @@ function M._stream_acp(opts)
             permission_options = options,
           }, opts.session_ctx, tool_call.kind)
         end,
-        on_read_file = function(path, line, limit, callback)
+        on_read_file = function(path, line, limit, callback, error_callback)
           local abs_path = Utils.to_absolute_path(path)
-          local lines = Utils.read_file_from_buf_or_disk(abs_path)
+          local lines, err, errname = Utils.read_file_from_buf_or_disk(abs_path)
+          if err then
+            if error_callback then
+              local code = errname == "ENOENT" and ACPClient.ERROR_CODES.RESOURCE_NOT_FOUND or nil
+              error_callback(err, code)
+            end
+            return
+          end
           lines = lines or {}
           if line ~= nil and limit ~= nil then lines = vim.list_slice(lines, line, line + limit) end
           local content = table.concat(lines, "\n")

lua/avante/utils/init.lua

@@ -1383,6 +1383,7 @@ end
 ---@param filepath string
 ---@return string[]|nil lines
 ---@return string|nil error
+---@return string|nil errname
 function M.read_file_from_buf_or_disk(filepath)
   local abs_path = filepath:sub(1, 7) == "term://" and filepath or M.join_paths(M.get_project_root(), filepath)
   --- Lookup if the file is loaded in a buffer
@@ -1391,12 +1392,13 @@ function M.read_file_from_buf_or_disk(filepath)
     if bufnr ~= -1 and vim.api.nvim_buf_is_loaded(bufnr) then
       -- If buffer exists and is loaded, get buffer content
       local lines = vim.api.nvim_buf_get_lines(bufnr, 0, -1, false)
-      return lines, nil
+      return lines, nil, nil
     end
   end
 
-  local stat = vim.uv.fs_stat(abs_path)
-  if stat and stat.type == "directory" then return {}, "Cannot read a directory as file" .. filepath end
+  local stat, stat_err, stat_errname = vim.uv.fs_stat(abs_path)
+  if not stat then return {}, stat_err, stat_errname end
+  if stat.type == "directory" then return {}, "Cannot read a directory as file" .. filepath, nil end
 
   -- Fallback: read file from disk
   local file, open_err = io.open(abs_path, "r")
@@ -1404,9 +1406,9 @@ function M.read_file_from_buf_or_disk(filepath)
     local content = file:read("*all")
     file:close()
     content = content:gsub("\r\n", "\n")
-    return vim.split(content, "\n"), nil
+    return vim.split(content, "\n"), nil, nil
   else
-    return {}, open_err
+    return {}, open_err, nil
   end
 end