fix: address Copilot feedback on diff tests and implementation

- Add temp_file field to mocked _open_native_diff implementation
- Ensure error case returns temp_file = nil explicitly
- Add comprehensive error validation in tests
- Improve test robustness and consistency

docs: add terminal-based diff acceptance/rejection option

- Document that users can accept/reject diffs from Claude Code terminal
- Provide alternative workflow for terminal-focused users

Change-Id: I5bee1fffb5cec40d0d593795ec1d8bb2dd2208be
Signed-off-by: Thomas Kosiewski <[email protected]>

Author: ThomasK33

README.md

@@ -151,6 +151,10 @@ Both methods signal Claude Code to apply the changes to your file, after which t
 
 When you reject changes, the diff view closes and the original file remains unchanged.
 
+### Accepting/Rejecting from Claude Code Terminal
+
+You can also navigate to the Claude Code terminal window and accept or reject diffs directly from within Claude's interface. This provides an alternative way to manage diffs without using the Neovim-specific keymaps.
+
 ### How It Works
 
 The plugin uses a signal-based approach where accepting or rejecting a diff sends a message to Claude Code rather than directly modifying files. This ensures consistency and allows Claude Code to handle the actual file operations while the plugin manages the user interface and buffer reloading.

lua/claudecode/diff.lua

@@ -231,7 +231,7 @@ function M._open_native_diff(old_file_path, new_file_path, new_file_contents, ta
   local new_filename = vim.fn.fnamemodify(new_file_path, ":t") .. ".new"
   local tmp_file, err = create_temp_file(new_file_contents, new_filename)
   if not tmp_file then
-    return { provider = "native", tab_name = tab_name, success = false, error = err }
+    return { provider = "native", tab_name = tab_name, success = false, error = err, temp_file = nil }
   end
 
   local target_win = find_main_editor_window()

tests/unit/diff_spec.lua

@@ -92,6 +92,7 @@ describe("Diff Module", function()
       expect(result.success).to_be_false()
       expect(result.error).to_be_string()
       expect(result.error:find("Failed to create temporary file", 1, true)).not_to_be_nil()
+      expect(result.temp_file).to_be_nil() -- Ensure no temp_file is created on failure
 
       rawset(io, "open", old_io_open)
     end)
@@ -263,6 +264,7 @@ describe("Diff Module", function()
           success = true,
           provider = "native",
           tab_name = tab_name,
+          temp_file = "/mock/temp/file.new",
         }
       end