fix(explorer): ignore stale same-path selections

lua/codediff/ui/explorer/render.lua

@@ -188,6 +188,7 @@ function M.create(status_result, git_root, tabpage, width, base_revision, target
     current_file_path = nil, -- Track currently selected file
     current_file_group = nil, -- Track currently selected file's group (staged/unstaged)
     current_selection = nil, -- Full file selection used to replay current state
+    selection_generation = 0, -- Reject async work superseded by a newer selection of the same path
     is_hidden = explorer_config.hidden, -- Track visibility state
     visible_groups = vim.deepcopy(explorer_config.visible_groups or { staged = true, unstaged = true, conflicts = true }),
   }
@@ -203,6 +204,11 @@ function M.create(status_result, git_root, tabpage, width, base_revision, target
     local old_path = file_data.old_path -- For renames: path in original revision
     local group = file_data.group or "unstaged"
     local jump = not opts.no_jump and config.options.diff.jump_to_first_change
+    local selection_generation = explorer.selection_generation
+
+    local function selection_is_current()
+      return explorer.selection_generation == selection_generation and explorer.current_file_path == file_path
+    end
 
     -- Emit CodeDiffFileSelect User autocmd
     vim.api.nvim_exec_autocmds("User", {
@@ -234,7 +240,7 @@ function M.create(status_result, git_root, tabpage, width, base_revision, target
       end
 
       vim.schedule(function()
-        if explorer.current_file_path ~= file_path then
+        if not selection_is_current() then
           return
         end
         ---@type SessionConfig
@@ -256,7 +262,7 @@ function M.create(status_result, git_root, tabpage, width, base_revision, target
     -- Handle untracked files: show file without diff
     if file_data.status == "??" then
       vim.schedule(function()
-        if explorer.current_file_path ~= file_data.path then
+        if not selection_is_current() then
           return
         end
         local sess = lifecycle.get_session(tabpage)
@@ -274,7 +280,7 @@ function M.create(status_result, git_root, tabpage, width, base_revision, target
     -- Handle added files: only one side has the file
     if file_data.status == "A" then
       vim.schedule(function()
-        if explorer.current_file_path ~= file_data.path then
+        if not selection_is_current() then
           return
         end
         local sess = lifecycle.get_session(tabpage)
@@ -318,7 +324,7 @@ function M.create(status_result, git_root, tabpage, width, base_revision, target
     -- Handle deleted files: show old content without diff
     if file_data.status == "D" then
       vim.schedule(function()
-        if explorer.current_file_path ~= file_data.path then
+        if not selection_is_current() then
           return
         end
         local sess = lifecycle.get_session(tabpage)
@@ -409,7 +415,7 @@ function M.create(status_result, git_root, tabpage, width, base_revision, target
       -- Two revision mode: Compare base vs target
       vim.schedule(function()
         -- Ignore stale async: see comment on the base_revision branch below.
-        if explorer.current_file_path ~= file_path then
+        if not selection_is_current() then
           return
         end
         ---@type SessionConfig
@@ -429,6 +435,9 @@ function M.create(status_result, git_root, tabpage, width, base_revision, target
     -- Use base_revision if provided, otherwise default to HEAD
     local target_revision_single = base_revision or "HEAD"
     git.resolve_revision(target_revision_single, git_root, function(err_resolve, commit_hash)
+      if not selection_is_current() then
+        return
+      end
       if err_resolve then
         vim.schedule(function()
           vim.notify(err_resolve, vim.log.levels.ERROR)
@@ -443,7 +452,7 @@ function M.create(status_result, git_root, tabpage, width, base_revision, target
           -- scheduled callback ran, `view.update` on the old target would
           -- clobber the newer selection (buffers get swapped, virtual buffers
           -- with `bufhidden=wipe` get destroyed mid-load, single_pane resets).
-          if explorer.current_file_path ~= file_path then
+          if not selection_is_current() then
             return
           end
           ---@type SessionConfig
@@ -462,7 +471,7 @@ function M.create(status_result, git_root, tabpage, width, base_revision, target
         -- Position controlled by config.diff.conflict_ours_position (absolute screen position)
         vim.schedule(function()
           -- Ignore stale async: see comment on the base_revision branch above.
-          if explorer.current_file_path ~= file_path then
+          if not selection_is_current() then
             return
           end
           -- Determine conflict buffer positions based on config
@@ -499,7 +508,7 @@ function M.create(status_result, git_root, tabpage, width, base_revision, target
         -- No pre-fetching needed, virtual files will load via BufReadCmd
         vim.schedule(function()
           -- Ignore stale async: see comment on the base_revision branch above.
-          if explorer.current_file_path ~= file_path then
+          if not selection_is_current() then
             return
           end
           ---@type SessionConfig
@@ -533,7 +542,7 @@ function M.create(status_result, git_root, tabpage, width, base_revision, target
           -- Ignore stale async: if a newer selection superseded us before this
           -- scheduled callback ran, `view.update` on the old target would
           -- clobber the newer one (resetting single_pane, layout.arrange).
-          if explorer.current_file_path ~= file_path then
+          if not selection_is_current() then
             return
           end
           ---@type SessionConfig
@@ -553,6 +562,7 @@ function M.create(status_result, git_root, tabpage, width, base_revision, target
 
   -- Wrap on_file_select to track current file and group
   explorer.on_file_select = function(file_data, opts)
+    explorer.selection_generation = explorer.selection_generation + 1
     explorer.current_file_path = file_data.path
     explorer.current_file_group = file_data.group
     explorer.current_selection = vim.deepcopy(file_data)

tests/ui/explorer/stale_same_path_selection_spec.lua

@@ -0,0 +1,114 @@
+-- Regression: async work for an older selection must not overwrite a newer
+-- staged/unstaged selection of the same path. A path-only stale check cannot
+-- distinguish those two explorer entries.
+
+local h = dofile("tests/helpers.lua")
+h.ensure_plugin_loaded()
+
+local lifecycle = require("codediff.ui.lifecycle")
+
+local function setup_command()
+  local commands = require("codediff.commands")
+  vim.api.nvim_create_user_command("CodeDiff", function(opts)
+    commands.vscode_diff(opts)
+  end, { nargs = "*", bang = true })
+end
+
+describe("explorer stale same-path selections", function()
+  local repo
+  local original_cwd
+  local git
+  local view
+  local real_resolve_revision
+  local real_update
+
+  before_each(function()
+    require("codediff").setup({ explorer = { auto_refresh = false } })
+    setup_command()
+    original_cwd = vim.fn.getcwd()
+    repo = h.create_temp_git_repo()
+
+    repo.write_file("race.lua", { "local value = 1", "return value" })
+    repo.git("add race.lua")
+    repo.git("commit -m initial")
+    repo.write_file("race.lua", { "local value = 2", "return value" })
+    repo.git("add race.lua")
+    repo.write_file("race.lua", { "local value = 2", "return value + 1" })
+
+    git = require("codediff.core.git")
+    view = require("codediff.ui.view")
+    real_resolve_revision = git.resolve_revision
+    real_update = view.update
+  end)
+
+  after_each(function()
+    git.resolve_revision = real_resolve_revision
+    view.update = real_update
+    pcall(function()
+      vim.cmd("tabnew")
+      vim.cmd("tabonly")
+    end)
+    vim.fn.chdir(original_cwd)
+    if repo then
+      repo.cleanup()
+    end
+  end)
+
+  it("ignores an older callback when the same path changes group", function()
+    vim.fn.chdir(repo.dir)
+    vim.cmd("edit " .. repo.path("race.lua"))
+    vim.cmd("CodeDiff")
+
+    local explorer
+    assert.is_true(
+      vim.wait(10000, function()
+        for _, tabpage in ipairs(vim.api.nvim_list_tabpages()) do
+          local session = lifecycle.get_session(tabpage)
+          if
+            session
+            and session.explorer
+            and session.explorer.current_file_path == "race.lua"
+            and session.original_revision == ":0"
+            and session.modified_revision == nil
+            and session.stored_diff_result
+            and session.stored_diff_result.changes
+          then
+            explorer = session.explorer
+            return true
+          end
+        end
+        return false
+      end, 20),
+      "CodeDiff explorer did not become ready"
+    )
+
+    local callbacks = {}
+    git.resolve_revision = function(_, _, callback)
+      callbacks[#callbacks + 1] = callback
+    end
+
+    local updates = {}
+    view.update = function(_, session_config)
+      updates[#updates + 1] = session_config
+      return true
+    end
+
+    local common = { path = "race.lua", status = "M", git_root = explorer.git_root }
+    explorer.on_file_select(vim.tbl_extend("force", common, { group = "unstaged" }), { force = true })
+    explorer.on_file_select(vim.tbl_extend("force", common, { group = "staged" }), { force = true })
+    assert.equal(2, #callbacks)
+
+    local head = vim.trim(repo.git("rev-parse HEAD"))
+    callbacks[2](nil, head) -- Newer staged selection completes first.
+    callbacks[1](nil, head) -- Older unstaged selection completes last.
+
+    assert.is_true(
+      vim.wait(1000, function()
+        return #updates > 0
+      end, 10),
+      "the current selection did not update the view"
+    )
+    assert.equal(1, #updates, "stale same-path callback also updated the view")
+    assert.equal(":0", updates[1].modified_revision, "the staged selection should be the only update")
+  end)
+end)