feat: add unified inline diff layout (ClaudeCodeBuffer) by spoloxs · Pull Request #300 · coder/claudecode.nvim

spoloxs · 2026-07-06T21:45:47Z

Summary

Adds a VS Code-style unified inline diff: a single persistent buffer (ClaudeCodeBuffer) that shows deleted lines in red/strikethrough and added lines in green, interleaved in one pane.

Zero-dependency engine: pure-Lua interleave on vim.text.diff/vim.diff (0.12 rename).
Persistent buffer: bufhidden="hide" buffer that can be opened anywhere.
Always toggleable: <leader>dt / open_inline_diff() opens the buffer whenever you want (creates empty one if none exists). <leader>dc / close_inline_diff() toggles it closed.
Keep-open on accept/reject: Accepting (:w) or rejecting (:q on window) does NOT close the window; the buffer stays open showing the reviewed file for continued viewing.

Usage

-- Add to your keymaps
vim.keymap.set('n', '<leader>dt',
  function() require('claudecode.diff_inline').open_inline_diff() end,
  { desc = 'Toggle open ClaudeCode diff buffer', silent = true })
vim.keymap.set('n', '<leader>dc',
  function() require('claudecode.diff_inline').close_inline_diff() end,
  { desc = 'Toggle close ClaudeCode diff buffer', silent = true })

Test plan

mise run check and mise run test.
Trigger a Claude Code edit → buffer is prepared silently.
Press <leader>dt → buffer opens in current tab.
:w → FILE_SAVED, buffer now shows the reviewed file (window stays).
<leader>dc → window closes, :w → opens again.

Related issues

Implements the unified path from #294 — related to #169 and #205.

Introduce a VS Code-style unified inline diff: a single persistent, read-only buffer (ClaudeCodeBuffer) showing deleted lines in red/ strikethrough and added lines in green, interleaved in one pane. - Pure-Lua interleave via vim.text.diff/vim.diff (zero external deps, coder#169) - Single reused buffer (bufhidden=hide) kept open showing the reviewed file after accept/reject, so it survives window/tab closes - Tears down any prior unified diff in the same buffer before rendering, preventing stale diffs from accumulating (fixes coder#205) - Wires ClaudeCodeDiffOpened/ClaudeCodeClosed User autocmds for the unified layout (noted in coder#294) - Tracks originating client_id so close_diffs_for_client can tear the diff down on disconnect (parity with the native path, coder#261) - Dispatch in diff.lua branches on layout == 'unified' Implements the unified inline diff layout described in coder#294.

Copilot

Pull request overview

Adds a new layout = "unified" diff mode that renders a VS Code–style unified inline diff into a single persistent ClaudeCodeBuffer, reusing/refreshing the same buffer between suggestions and integrating this mode into the diff lifecycle/cleanup paths.

Changes:

Introduces a persistent unified diff buffer (ClaudeCodeBuffer) with interleaved add/delete highlighting and stale-diff replacement logic.
Adds tab/window management helpers to better reuse a “diff tab” and avoid repeated splits in that tab.
Improves diff setup error handling/logging by formatting structured errors (and exposes the formatter for tests/debugging).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 6 comments.

File	Description
lua/claudecode/diff.lua	Adds unified-layout dispatch, diff-tab helpers, accept/deny cleanup calls, and error formatting changes.
lua/claudecode/diff_inline.lua	Implements the unified inline diff renderer around a persistent `ClaudeCodeBuffer` and updates setup/cleanup behavior.

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spoloxs · 2026-07-06T22:03:54Z

-      if setup_error.data then
-        error_msg = error_msg .. " (" .. setup_error.data .. ")"
-      end
+    error_msg = "Failed to setup diff operation: " .. format_error(setup_error)


Good catch — fixed. error_msg is now declared local in the setup error handler (the other call sites already used local), so it no longer leaks as a global or gets clobbered across concurrent/scheduled diff attempts.

spoloxs · 2026-07-06T22:04:06Z

-      error_msg = tostring(err)
-    end
-    logger.error("diff", "Diff setup failed for", '"' .. tab_name .. '"', "error:", error_msg)
+    logger.error("diff", "Diff setup failed for", '"' .. tab_name .. '"', "error:", format_error(err))


Fixed. format_error was wrongly nested inside _setup_blocking_diff; I hoisted it to module scope (and moved M._format_error to module scope too), so open_diff_blocking's error path can call it without raising a secondary error.

spoloxs · 2026-07-06T22:04:08Z

    else
      error({
        code = -32000,
        message = "Error setting up diff",
-        data = tostring(err),
+        data = format_error(err),
      })


Same root cause as the previous one — fixed by hoisting format_error to module scope. This call now resolves correctly and error propagation works.

spoloxs · 2026-07-06T22:04:09Z

+  local function get_or_create_diff_tab()
+    local tabs = vim.api.nvim_list_tabpages()
+    if #tabs >= 2 then
+      return tabs[2]
+    end
+    vim.cmd("tabnew")
+    mark_tabnew_buffer_ephemeral()
+    return vim.api.nvim_get_current_tabpage()
+  end


Fixed. get_or_create_diff_tab now always does :tabnew instead of reusing tabs[2], so _cleanup_diff_state can never close an unrelated user tab when open_in_new_tab is set.

spoloxs · 2026-07-06T22:04:11Z

  local editor_win
  local fallback_window
-  if created_new_tab then
-    local tab_wins = vim.api.nvim_tabpage_list_wins(0)
-    for _, w in ipairs(tab_wins) do
-      if w ~= terminal_win_in_new_tab then
-        editor_win = w
-        break
-      end
-    end
-    -- Fallback to first window in the new tab
-    if not editor_win and #tab_wins > 0 then
-      editor_win = tab_wins[1]
-    end
+  local diff_win = reuse_or_open_diff_window()
+


Fixed. reuse_or_open_diff_window now only reuses a window that lives in the current tabpage (verified via nvim_tabpage_list_wins(0)); otherwise it returns nil and the normal fallback-window path runs. This avoids nvim_set_current_win on, or hijacking of, another tab.

spoloxs · 2026-07-06T22:04:12Z

@@ -1863,6 +1969,7 @@
 M._detect_filetype = detect_filetype
 M._get_autocmd_group = get_autocmd_group
 M._display_terminal_in_new_tab = display_terminal_in_new_tab
+M.get_or_create_editor_win_in_diff_tab = get_or_create_editor_win_in_diff_tab



Fixed. Renamed the internal export to M._get_or_create_editor_win_in_diff_tab (underscore prefix, matching the other internal helpers in that block) and updated the caller in diff_inline.lua.

- Hoist format_error to module scope so the open_diff_blocking error path can use it (it was defined inside _setup_blocking_diff and raised a secondary error, obscuring the original failure). - Declare error_msg as local (was implicitly a global). - Stop reusing tabs[2] in get_or_create_diff_tab; always :tabnew so cleanup never closes an unrelated user tab (issue flagged by reviewer). - Rename the internal export get_or_create_editor_win_in_diff_tab -> _get_or_create_editor_win_in_diff_tab for API consistency. - Guard reuse_or_open_diff_window to only reuse a window in the current tabpage, avoiding hijacking/switching to an unrelated tab.

…ffer in current tab - The unified diff no longer auto-opens a window or creates tab 2. - prepares silently. - Added and for user-initiated buffer access (works in any tab, creates a vsplit if needed). - Cleanup closes any window showing and keeps the buffer alive showing the reviewed file. - Removed , , tab2 logic from this path; those remain for native diff. This eliminates the tab-3 confusion: the diff always lives in and the user decides where to view it.

Copilot AI review requested due to automatic review settings July 6, 2026 21:45

Copilot started reviewing on behalf of spoloxs July 6, 2026 21:46 View session

spoloxs mentioned this pull request Jul 6, 2026

feat: streaming 'typing' reveal for the unified inline diff #301

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feat: add unified inline diff layout (ClaudeCodeBuffer)#300

feat: add unified inline diff layout (ClaudeCodeBuffer)#300
spoloxs wants to merge 3 commits into
coder:mainfrom
spoloxs:feat/unified-inline-diff

spoloxs commented Jul 6, 2026 •

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spoloxs commented Jul 6, 2026 •

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