feat: add Jujutsu (jj) VCS adapter

Add a full JjAdapter for DiffviewOpen with rev parsing, bookmark
handling, main→master fallback, merge-base resolution via triple-dot,
refresh-revs support, and working-tree diff content refresh.

Includes documentation, tests, and the force parameter on
FileEntry:destroy() needed by the replace-noop refresh path.

Cherry-picked from vramana/diffview.nvim (commits 600a120..fda5b1a).

Author: vramana

.gitignore

@@ -1,3 +1,4 @@
 /doc/tags
 /.tests/
 /.dev/
+/.nvimlog

README.md

@@ -13,12 +13,13 @@ for any git rev.
 Vim's diff mode is pretty good, but there is no convenient way to quickly bring
 up all modified files in a diffsplit. This plugin aims to provide a simple,
 unified, single tabpage interface that lets you easily review all changed files
-for any git rev.
+for any VCS rev.
 
 ## Requirements
 
 - Git ≥ 2.31.0 (for Git support)
 - Mercurial ≥ 5.4.0 (for Mercurial support)
+- Jujutsu ≥ 0.38.0 (for `:DiffviewOpen` support)
 - Neovim ≥ 0.10.0 (with LuaJIT)
 - [nvim-web-devicons](https://github.com/nvim-tree/nvim-web-devicons) or [mini.icons](https://github.com/echasnovski/mini.nvim/blob/main/readmes/mini-icons.md) (optional) for file icons
 
@@ -82,11 +83,11 @@ For more info, see `:h :DiffviewFileHistory`.
 
 ## Usage
 
-### `:DiffviewOpen [git rev] [options] [ -- {paths...}]`
+### `:DiffviewOpen [rev] [options] [ -- {paths...}]`
 
-Calling `:DiffviewOpen` with no args opens a new Diffview that compares against
-the current index. You can also provide any valid git rev to view only changes
-for that rev.
+Calling `:DiffviewOpen` with no args opens a new Diffview for the current
+working copy (the exact baseline depends on VCS adapter). You can also provide
+any valid rev/range accepted by your active adapter.
 
 Examples:
 
@@ -97,6 +98,9 @@ Examples:
 - `:DiffviewOpen d4a7b0d^!`
 - `:DiffviewOpen d4a7b0d..519b30e`
 - `:DiffviewOpen origin/main...HEAD`
+- `:DiffviewOpen @-` (Jujutsu)
+- `:DiffviewOpen main..@` (Jujutsu)
+- `:DiffviewOpen main...@` (Jujutsu)
 
 You can also provide additional paths to narrow down what files are shown:
 
@@ -105,6 +109,10 @@ You can also provide additional paths to narrow down what files are shown:
 For information about additional `[options]`, visit the
 [documentation](https://github.com/sindrets/diffview.nvim/blob/main/doc/diffview.txt).
 
+Jujutsu currently supports only `:DiffviewOpen`. The options `--cached`,
+`--staged`, and `--imply-local` are Git-only and are ignored by the Jujutsu
+adapter with a warning.
+
 Additional commands for convenience:
 
 - `:DiffviewClose`: Close the current diffview. You can also use `:tabclose`.
@@ -188,6 +196,7 @@ require("diffview").setup({
   enhanced_diff_hl = false, -- See |diffview-config-enhanced_diff_hl|
   git_cmd = { "git" },      -- The git executable followed by default args.
   hg_cmd = { "hg" },        -- The hg executable followed by default args.
+  jj_cmd = { "jj" },        -- The jj executable followed by default args.
   rename_threshold = nil,   -- Integer 0-100 for rename detection similarity. Nil uses git default (50%). Invalid values are ignored.
   use_icons = true,         -- Requires nvim-web-devicons or mini.icons
   show_help_hints = true,   -- Show hints for how to open the help panel

doc/diffview.txt

@@ -50,13 +50,14 @@ Visit the help page for more info.
 COMMANDS                                        *diffview-commands*
 
                                                 *:DiffviewOpen*
-:DiffviewOpen [git-rev] [options] [ -- {paths...}]
+:DiffviewOpen [rev] [options] [ -- {paths...}]
 
-        Opens a new Diffview that compares against [git-rev]. If no [git-rev]
-        is given, defaults to comparing against the index. Additional
-        {paths...} may be provided to narrow down what files are shown. If the
-        `-C` flag is not defined, the git top-level is determined from the
-        current buffer when possible. Otherwise it's determined from the cwd.
+        Opens a new Diffview that compares against [rev]. If no [rev] is
+        given, defaults to comparing against the working copy baseline for the
+        active adapter. Additional {paths...} may be provided to narrow down
+        what files are shown. If the `-C` flag is not defined, the adapter
+        repository top-level is determined from the current buffer when
+        possible. Otherwise it's determined from the cwd.
 
         Examples: >vim
 
@@ -78,6 +79,11 @@ COMMANDS                                        *diffview-commands*
             " Diff HEAD against it's merge base in origin/main:
             :DiffviewOpen origin/main...HEAD
 
+            " Jujutsu examples:
+            :DiffviewOpen @-
+            :DiffviewOpen main..@
+            :DiffviewOpen main...@
+
             " Limit the scope to the given paths:
             :DiffviewOpen HEAD~2 -- lua/diffview plugin
 
@@ -143,8 +149,10 @@ COMMANDS                                        *diffview-commands*
                           • `true`, `normal`, `all` Show untracked.
                           • `false`, `no` Don't show untracked.
         --cached, --staged
-                        Diff staged changes against [git-rev]. If no [git-rev]
+                        Diff staged changes against [rev]. If no [rev]
                         is given, defaults to `HEAD`.
+                        NOTE: This is Git-specific. For Jujutsu, this option is
+                        ignored with a warning.
 
         --imply-local   If a range rev is provided and either end of the range
                         points to `HEAD`: point that end to local files
@@ -153,6 +161,8 @@ COMMANDS                                        *diffview-commands*
                         (triple-dot), but you want to be able to utilize the
                         LSP features that are not available while you're
                         viewing files created from git.
+                        NOTE: This is Git-specific. For Jujutsu, this option is
+                        ignored with a warning.
 
         -C{path}        Run as if git was started in {path} instead of the
                         current working directory.
@@ -169,6 +179,8 @@ COMMANDS                                        *diffview-commands*
         given paths. This is a porcelain interface for git-log. Both [paths]
         and [options] may be specified in any order, even interchangeably.
 
+        NOTE: The Jujutsu adapter currently supports only |:DiffviewOpen|.
+
         If no [paths] are given, defaults to the top-level of the working
         tree. The top-level will be inferred from the current buffer when
         possible, otherwise the cwd is used. Multiple [paths] may be provided
@@ -444,6 +456,13 @@ hg_cmd                                          *diffview-config-hg_cmd*
         If your Mercurial install bundles the `chg` binary, this can be
         configured here to have a significant performance boost.
 
+jj_cmd                                          *diffview-config-jj_cmd*
+        Type: `string[]`, Default: `{ "jj" }`
+
+        This table forms the first part of all Jujutsu commands used
+        internally in the plugin. The first element should be the Jujutsu
+        binary. The subsequent elements are passed as arguments.
+
 rename_threshold                                *diffview-config-rename_threshold*
         Type: `integer?`, Default: `nil`
 

doc/diffview_defaults.txt

@@ -7,6 +7,7 @@ DEFAULT CONFIG                                  *diffview.defaults*
     enhanced_diff_hl = false, -- See |diffview-config-enhanced_diff_hl|
     git_cmd = { "git" },      -- The git executable followed by default args.
     hg_cmd = { "hg" },        -- The hg executable followed by default args.
+    jj_cmd = { "jj" },        -- The jj executable followed by default args.
     p4_cmd = { "p4" },        -- The p4 executable followed by default args.
     rename_threshold = nil,   -- Integer 0-100 for rename detection similarity. Nil uses git default (50%). Invalid values are ignored.
     use_icons = true,         -- Requires nvim-web-devicons or mini.icons

lua/diffview/config.lua

@@ -41,6 +41,7 @@ M.defaults = {
   enhanced_diff_hl = false,
   git_cmd = { "git" },
   hg_cmd = { "hg" },
+  jj_cmd = { "jj" },
   rename_threshold = nil, -- Similarity threshold for rename detection (e.g. 40 for 40%). Nil uses git default (50%).
   use_icons = true,
   show_help_hints = true,
@@ -619,6 +620,14 @@ function M.setup(user_config)
     M._config.git_cmd = M.defaults.git_cmd
   end
 
+  if #M._config.hg_cmd == 0 then
+    M._config.hg_cmd = M.defaults.hg_cmd
+  end
+
+  if #M._config.jj_cmd == 0 then
+    M._config.jj_cmd = M.defaults.jj_cmd
+  end
+
   if #M._config.p4_cmd == 0 then
     M._config.p4_cmd = M.defaults.p4_cmd
   end

lua/diffview/health.lua

@@ -66,6 +66,7 @@ function M.check()
 
     local has_valid_adapter = false
     local adapter_kinds = {
+      { class = require("diffview.vcs.adapters.jj").JjAdapter, name = "Jujutsu" },
       { class = require("diffview.vcs.adapters.git").GitAdapter, name = "Git" },
       { class = require("diffview.vcs.adapters.hg").HgAdapter, name = "Mercurial" },
       { class = require("diffview.vcs.adapters.p4").P4Adapter, name = "Perforce" },

lua/diffview/scene/file_entry.lua

@@ -89,9 +89,10 @@ function FileEntry:init(opt)
   self.opened = false
 end
 
-function FileEntry:destroy()
+---@param force? boolean
+function FileEntry:destroy(force)
   for _, f in ipairs(self.layout:files()) do
-    f:destroy()
+    f:destroy(force)
   end
 
   self.layout:destroy()

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

@@ -27,6 +27,24 @@ local pl = lazy.access(utils, "path") ---@type PathLib
 
 local M = {}
 
+---@param a Rev?
+---@param b Rev?
+---@return boolean
+local function same_rev(a, b)
+  if a == nil and b == nil then
+    return true
+  end
+
+  if a == nil or b == nil then
+    return false
+  end
+
+  return a.type == b.type
+    and a.commit == b.commit
+    and a.stage == b.stage
+    and a.track_head == b.track_head
+end
+
 ---@class DiffViewOptions
 ---@field show_untracked? boolean
 ---@field selected_file? string Path to the preferred initially selected file.
@@ -368,6 +386,17 @@ DiffView.update_files = debounce.debounce_trailing(
     local perf = PerfTimer("[DiffView] Status Update")
     self:ensure_layout()
 
+    local new_left, new_right = self.adapter:refresh_revs(self.rev_arg, self.left, self.right)
+    if new_left and new_right then
+      self.left = new_left
+      self.right = new_right
+
+      if not self.rev_arg then
+        self.panel.rev_pretty_name = self.adapter:rev_to_pretty_string(self.left, self.right)
+      end
+    end
+    perf:lap("refreshed revs")
+
     -- If left is tracking HEAD and right is LOCAL: Update HEAD rev.
     local new_head
     if self.left.track_head and self.right.type == RevType.LOCAL then
@@ -428,26 +457,49 @@ DiffView.update_files = debounce.debounce_trailing(
 
       for _, opr in ipairs(script) do
         if opr == EditToken.NOOP then
-          -- Update status and stats
-          -- Guard against nil entries that can occur during async race conditions (#395).
-          local cur_file = v.cur_files[ai]
+          local old_file = v.cur_files[ai]
           local new_file = v.new_files[bi]
 
-          if cur_file and new_file then
-            local a_stats = cur_file.stats
-            local b_stats = new_file.stats
+          -- Guard against nil entries that can occur during async race conditions (#395).
+          if old_file and new_file then
+            local replace_noop = self.adapter:force_entry_refresh_on_noop(self.left, self.right)
+
+            -- Even with a stable path, rev endpoints can change on refresh
+            -- (e.g. symbolic revs like `master...@`). Replace the entry so
+            -- the displayed content comes from the latest rev pair.
+            if not replace_noop then
+              replace_noop = not (
+                same_rev(utils.tbl_access(old_file, "revs.a"), utils.tbl_access(new_file, "revs.a"))
+                and same_rev(utils.tbl_access(old_file, "revs.b"), utils.tbl_access(new_file, "revs.b"))
+                and same_rev(utils.tbl_access(old_file, "revs.c"), utils.tbl_access(new_file, "revs.c"))
+                and same_rev(utils.tbl_access(old_file, "revs.d"), utils.tbl_access(new_file, "revs.d"))
+              )
+            end
+
+            if replace_noop then
+              if self.panel.cur_file == old_file then
+                self.panel:set_cur_file(new_file)
+              end
 
-            if a_stats then
-              cur_file.stats = vim.tbl_extend("force", a_stats, b_stats or {})
+              old_file:destroy(true)
+              v.cur_files[ai] = new_file
             else
-              cur_file.stats = new_file.stats
-            end
+              -- Update status and stats
+              local a_stats = old_file.stats
+              local b_stats = new_file.stats
 
-            cur_file.status = new_file.status
-            cur_file:validate_stage_buffers(index_stat)
+              if a_stats then
+                old_file.stats = vim.tbl_extend("force", a_stats, b_stats or {})
+              else
+                old_file.stats = new_file.stats
+              end
 
-            if new_head then
-              cur_file:update_heads(new_head)
+              old_file.status = new_file.status
+              old_file:validate_stage_buffers(index_stat)
+
+              if new_head then
+                old_file:update_heads(new_head)
+              end
             end
           end
 

lua/diffview/tests/functional/file_entry_spec.lua

@@ -1,9 +1,12 @@
+local helpers = require("diffview.tests.helpers")
 local FileEntry = require("diffview.scene.file_entry").FileEntry
 local Diff2Hor = require("diffview.scene.layouts.diff_2_hor").Diff2Hor
 local RevType = require("diffview.vcs.rev").RevType
 local GitRev = require("diffview.vcs.adapters.git.rev").GitRev
 
-describe("diffview.file_entry", function()
+local eq = helpers.eq
+
+describe("diffview.scene.file_entry", function()
   it("convert_layout skips null entries without error (#612)", function()
     local adapter = { ctx = { toplevel = vim.uv.cwd() } }
     local entry = FileEntry.new_null_entry(adapter)
@@ -48,4 +51,45 @@ describe("diffview.file_entry", function()
     assert.is_not_nil(captured)
     assert.False(captured.b.nulled)
   end)
+
+  it("forwards force flag to contained files when destroyed", function()
+    local seen = {}
+    local layout_destroyed = false
+
+    local layout = {
+      files = function()
+        return {
+          {
+            destroy = function(_, force)
+              seen[#seen + 1] = force
+            end,
+          },
+          {
+            destroy = function(_, force)
+              seen[#seen + 1] = force
+            end,
+          },
+        }
+      end,
+      destroy = function()
+        layout_destroyed = true
+      end,
+    }
+
+    local entry = FileEntry({
+      adapter = { ctx = { toplevel = "/tmp" } },
+      path = "a.txt",
+      oldpath = nil,
+      revs = {},
+      layout = layout,
+      status = "M",
+      stats = {},
+      kind = "working",
+    })
+
+    entry:destroy(true)
+
+    eq({ true, true }, seen)
+    eq(true, layout_destroyed)
+  end)
 end)