fix(diff): invalidate stage buffers when a newly added file is unstaged

lua/diffview/scene/file_entry.lua

@@ -192,9 +192,13 @@ function FileEntry:validate_stage_buffers(stat)
           local is_modified = vim.bo[f.bufnr].modified
 
           if f.blob_hash then
+            -- `new_hash` is nil when the path no longer has a stage-0 blob at
+            -- all (e.g. a newly added file that was unstaged, leaving it
+            -- untracked). That is a content change like any other: the buffer
+            -- still shows the old staged blob and must be invalidated.
             local new_hash = self.adapter:file_blob_hash(f.path)
 
-            if new_hash and new_hash ~= f.blob_hash then
+            if new_hash ~= f.blob_hash then
               if is_modified then
                 utils.warn(
                   (

lua/diffview/scene/views/diff/diff_view.lua

@@ -828,6 +828,25 @@ local update_files_impl = debounce.debounce_trailing(
               )
             end
 
+            -- A status change can flip a side's nulled state even when the
+            -- revs are identical (e.g. unstaging a newly added file: the
+            -- working entry goes "M" -> "?" and its a-side no longer has a
+            -- stage-0 blob). The NOOP path only copies `status` onto the old
+            -- entry; the Files' `nulled` flags are fixed at construction, so
+            -- the old a-side would keep showing — and try to reload — a blob
+            -- that no longer exists. Replace the entry instead.
+            if not replace_noop then
+              for _, sym in ipairs({ "a", "b", "c", "d" }) do
+                local of = old_file.layout:get_file_for(sym)
+                local nf = new_file.layout:get_file_for(sym)
+
+                if (of and of.nulled or false) ~= (nf and nf.nulled or false) then
+                  replace_noop = true
+                  break
+                end
+              end
+            end
+
             if replace_noop then
               if self.panel.cur_file == old_file then
                 self.panel:set_cur_file(new_file)

lua/diffview/vcs/adapters/git/init.lua

@@ -1843,17 +1843,21 @@ end
 ---@param rev_arg string?
 ---@return string?
 function GitAdapter:file_blob_hash(path, rev_arg)
+  -- Empty output with exit code 0 is a real outcome, not a failure: the path
+  -- has no blob at that rev (e.g. a newly added file that was unstaged no
+  -- longer exists in the index at all). `fail_on_empty` would burn retries
+  -- and spam the log for it; instead let the empty result through and map it
+  -- to nil so callers can distinguish "no blob" from a blob hash.
   local out, code = self:exec_sync({
     "rev-parse",
     "--revs-only",
     fmt("%s:%s", rev_arg or "", path),
   }, {
     cwd = self.ctx.toplevel,
     retry = 2,
-    fail_on_empty = true,
   })
 
-  if code ~= 0 then
+  if code ~= 0 or not out[1] or vim.trim(out[1]) == "" then
     return
   end