feat(git): add --rename-threshold option to DiffviewOpen and DiffviewFileHistory (#301)

doc/diffview.txt

@@ -201,6 +201,14 @@ COMMANDS                                        *diffview-commands*
                         invocation; pass `--no-panel=false` to force the panel
                         shown.
 
+        --rename-threshold={n}
+                        Rename detection similarity, as an integer in [0, 100]
+                        (a trailing `%` is accepted). Overrides
+                        |diffview-config-rename_threshold| for this view.
+                        Invalid values are ignored with a warning.
+                        NOTE: This is Git-specific. For Jujutsu, this option
+                        is ignored with a warning.
+
                                                 *:DiffviewDiffFiles*
 :DiffviewDiffFiles {file1} {file2}
 
@@ -503,6 +511,14 @@ COMMANDS                                        *diffview-commands*
                 YYYY-mm-dd, YYYY-mm-dd HH:mm:ss, or natural language (for
                 instance "2 weeks 6 hours 12 minutes ago")
 
+        --rename-threshold={n}
+                Rename detection similarity, as an integer in [0, 100]
+                (a trailing `%` is accepted). Overrides
+                |diffview-config-rename_threshold| for this view.
+                Invalid values are ignored with a warning.
+                NOTE: This is Git-specific. For Jujutsu, this option is
+                ignored with a warning.
+
     Mercurial Options: ~
 
         --rev={rev}

lua/diffview/config.lua

@@ -795,6 +795,7 @@ M._config = M.defaults
 ---@field path_args string[]
 ---@field after? string
 ---@field before? string
+---@field rename_threshold? integer Per-view rename similarity threshold (0-100). Overrides |diffview-config-rename_threshold| for this view.
 
 ---@class HgLogOptions
 ---@field follow? string
@@ -842,6 +843,7 @@ M._config = M.defaults
 ---@field path_args? string[]
 ---@field after? string
 ---@field before? string
+---@field rename_threshold? integer Per-view rename similarity threshold (0-100). Overrides |diffview-config-rename_threshold| for this view.
 
 ---@class HgLogOptions.user
 ---@field follow? string
@@ -889,6 +891,7 @@ M.log_option_defaults = {
     G = nil,
     S = nil,
     path_args = {},
+    rename_threshold = nil,
   },
   ---@type HgLogOptions
   hg = {
@@ -1886,4 +1889,10 @@ function M.setup(user_config)
 end
 
 M.actions = actions
+
+-- Shared value validators. Used internally by `setup()` for the config schema,
+-- and re-exported for CLI arg parsing (e.g., `--rename-threshold`) so both
+-- surfaces produce the same warn-and-fallback behaviour.
+M.validate = validate
+
 return M

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

@@ -35,6 +35,7 @@ local same_rev = lazy.access(rev_lib, "same_rev") --[[@as fun(a: Rev?, b: Rev?):
 ---@field show_untracked? boolean
 ---@field selected_file? string Path to the preferred initially selected file.
 ---@field selected_row? integer Row to position the cursor on after opening the selected file.
+---@field rename_threshold? integer Per-view rename similarity threshold (0-100). Overrides |diffview-config-rename_threshold| for this view.
 
 ---@class DiffView : StandardView
 ---@operator call : DiffView

lua/diffview/tests/functional/git_adapter_spec.lua

@@ -4,6 +4,7 @@ local GitAdapter = require("diffview.vcs.adapters.git").GitAdapter
 local GitRev = require("diffview.vcs.adapters.git.rev").GitRev
 local Job = require("diffview.job").Job
 local RevType = require("diffview.vcs.rev").RevType
+local arg_parser = require("diffview.arg_parser")
 local test_utils = require("diffview.tests.helpers")
 
 local run = test_utils.run
@@ -1847,4 +1848,177 @@ describe("diffview.vcs.adapters.git", function()
       end)
     )
   end)
+
+  describe("diffview_options --rename-threshold", function()
+    it(
+      "parses an integer value onto DiffViewOptions",
+      test_utils.async_test(function()
+        local repo, adapter = make_repo_and_adapter()
+
+        local ok, err = pcall(function()
+          local argo = arg_parser.parse({ "--rename-threshold=40" })
+          local opt = adapter:diffview_options(argo)
+          assert.is_not_nil(opt)
+          assert.equals(40, opt.options.rename_threshold)
+        end)
+
+        vim.schedule(function()
+          pcall(vim.fn.delete, repo, "rf")
+        end)
+        async.await(async.scheduler())
+
+        if not ok then
+          error(err)
+        end
+      end)
+    )
+
+    it(
+      "accepts a trailing percent sign",
+      test_utils.async_test(function()
+        local repo, adapter = make_repo_and_adapter()
+
+        local ok, err = pcall(function()
+          local argo = arg_parser.parse({ "--rename-threshold=30%" })
+          local opt = adapter:diffview_options(argo)
+          assert.is_not_nil(opt)
+          assert.equals(30, opt.options.rename_threshold)
+        end)
+
+        vim.schedule(function()
+          pcall(vim.fn.delete, repo, "rf")
+        end)
+        async.await(async.scheduler())
+
+        if not ok then
+          error(err)
+        end
+      end)
+    )
+
+    it(
+      "leaves DiffViewOptions.rename_threshold nil for invalid values",
+      test_utils.async_test(function()
+        local repo, adapter = make_repo_and_adapter()
+
+        local ok, err = pcall(function()
+          -- Out of range and non-numeric both fall back to nil (with a warning).
+          for _, bad in ipairs({ "abc", "-5", "150", "12.5" }) do
+            local argo = arg_parser.parse({ "--rename-threshold=" .. bad })
+            local opt = adapter:diffview_options(argo)
+            assert.is_not_nil(opt)
+            assert.is_nil(opt.options.rename_threshold)
+          end
+        end)
+
+        vim.schedule(function()
+          pcall(vim.fn.delete, repo, "rf")
+        end)
+        async.await(async.scheduler())
+
+        if not ok then
+          error(err)
+        end
+      end)
+    )
+
+    it(
+      "leaves DiffViewOptions.rename_threshold nil when the flag is absent",
+      test_utils.async_test(function()
+        local repo, adapter = make_repo_and_adapter()
+
+        local ok, err = pcall(function()
+          local argo = arg_parser.parse({})
+          local opt = adapter:diffview_options(argo)
+          assert.is_not_nil(opt)
+          assert.is_nil(opt.options.rename_threshold)
+        end)
+
+        vim.schedule(function()
+          pcall(vim.fn.delete, repo, "rf")
+        end)
+        async.await(async.scheduler())
+
+        if not ok then
+          error(err)
+        end
+      end)
+    )
+
+    it(
+      "leaves DiffViewOptions.rename_threshold nil for a bare or empty value",
+      test_utils.async_test(function()
+        local repo, adapter = make_repo_and_adapter()
+
+        local ok, err = pcall(function()
+          -- Bare `--rename-threshold` (arg_parser records the value as "true"
+          -- and casts it to boolean) and an explicitly-empty `--rename-threshold=`
+          -- both distinct from "flag absent"; the parser warns and drops them.
+          for _, args in ipairs({ { "--rename-threshold" }, { "--rename-threshold=" } }) do
+            local argo = arg_parser.parse(args)
+            local opt = adapter:diffview_options(argo)
+            assert.is_not_nil(opt)
+            assert.is_nil(opt.options.rename_threshold)
+          end
+        end)
+
+        vim.schedule(function()
+          pcall(vim.fn.delete, repo, "rf")
+        end)
+        async.await(async.scheduler())
+
+        if not ok then
+          error(err)
+        end
+      end)
+    )
+  end)
+
+  describe("file_history_options --rename-threshold", function()
+    it(
+      "parses an integer value onto GitLogOptions",
+      test_utils.async_test(function()
+        local repo, adapter = make_repo_and_adapter()
+
+        local ok, err = pcall(function()
+          local argo = arg_parser.parse({ "--rename-threshold=40" })
+          local log_opt = adapter:file_history_options(nil, { "init.txt" }, argo)
+          assert.is_not_nil(log_opt)
+          assert.equals(40, log_opt.rename_threshold)
+        end)
+
+        vim.schedule(function()
+          pcall(vim.fn.delete, repo, "rf")
+        end)
+        async.await(async.scheduler())
+
+        if not ok then
+          error(err)
+        end
+      end)
+    )
+
+    it(
+      "leaves GitLogOptions.rename_threshold nil for invalid values",
+      test_utils.async_test(function()
+        local repo, adapter = make_repo_and_adapter()
+
+        local ok, err = pcall(function()
+          local argo = arg_parser.parse({ "--rename-threshold=nope" })
+          local log_opt = adapter:file_history_options(nil, { "init.txt" }, argo)
+          assert.is_not_nil(log_opt)
+          assert.is_nil(log_opt.rename_threshold)
+        end)
+
+        vim.schedule(function()
+          pcall(vim.fn.delete, repo, "rf")
+        end)
+        async.await(async.scheduler())
+
+        if not ok then
+          error(err)
+        end
+      end)
+    )
+  end)
 end)

lua/diffview/vcs/adapter.lua

@@ -23,6 +23,7 @@ local M = {}
 ---@field pin_local? boolean # When true, file-history entries are constructed with revs.b = LOCAL so the b-window can pin to the working-tree file.
 ---@field pinned_path? string # Working-tree path used for the b-side File when `pin_local` is true for a single-file history; preserves the pin across renames in older commits.
 ---@field pinned_b_file_for? fun(path: string): vcs.File # Resolves the shared, view-owned working-tree File for a given path. Set by `FileHistoryPanel` when `pin_local` is active so adapters can hand the same `vcs.File` instance to every entry's b-side; see `FileHistoryView:get_pinned_b_file`. The returned file outlives entry/log destruction (its layout symbol lives in `Diff2*Pinned.shared_symbols`), so adapters must not destroy it.
+---@field rename_threshold? integer # Per-view rename similarity threshold (0-100) forwarded from `DiffViewOptions.rename_threshold`. Overrides the global config for this view's diff calls; adapters that don't support rename detection ignore it.
 
 ---@class vcs.adapter.VCSAdapter.Bootstrap
 ---@field done boolean # Did the bootstrapping

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

@@ -28,6 +28,32 @@ local uv = vim.uv
 
 local M = {}
 
+---Parse a `--rename-threshold` CLI value.
+---Accepts `"40"` or `"40%"` (trailing `%` matches git's own `--find-renames`
+---spelling); the value must be an integer in [0, 100]. On invalid input warns
+---and returns nil so the caller falls back to the global config. `nil` (flag
+---absent) is the only silent return path; bare `--rename-threshold` (boolean
+---`true` from `arg_parser`), an empty value (`--rename-threshold=`), and any
+---non-integer or out-of-range string all warn via `config.validate.integer`.
+---@param raw string[]|string|boolean|nil
+---@return integer?
+local function parse_rename_threshold_flag(raw)
+  if raw == nil then
+    return nil
+  end
+  -- `tonumber("40%")` returns nil, so strip a trailing `%` before delegating
+  -- to `validate.integer`. Non-string inputs (e.g., a boolean from a bare
+  -- flag) pass through and the validator warns as expected.
+  local wrap = { v = type(raw) == "string" and (raw:gsub("%%$", "")) or raw }
+  config.validate.integer(wrap, "v", nil, {
+    min = 0,
+    max = 100,
+    nilable = true,
+    path = "--rename-threshold",
+  })
+  return wrap.v --[[@as integer? ]]
+end
+
 ---@class GitAdapter : VCSAdapter
 ---@operator call : GitAdapter
 local GitAdapter = oop.create_class("GitAdapter", VCSAdapter)
@@ -575,7 +601,7 @@ function GitAdapter:stream_fh_data(state)
       "--no-show-signature",
       "--pretty=format:%x00%n" .. GitAdapter.COMMIT_PRETTY_FMT,
       (function()
-        local t = config.get_config().rename_threshold
+        local t = state.log_options.rename_threshold or config.get_config().rename_threshold
         return t and ("-M" .. t .. "%") or nil
       end)(),
       "--numstat",
@@ -877,6 +903,7 @@ function GitAdapter:file_history_options(range, paths, argo)
     ---@diagnostic disable-next-line: assign-type-mismatch
     log_options[key] = v
   end
+  log_options.rename_threshold = parse_rename_threshold_flag(argo:get_flag("rename-threshold"))
 
   if range then
     paths, rel_paths = {}, {}
@@ -1707,6 +1734,7 @@ function GitAdapter:diffview_options(argo)
       or nil
     ) --[[@as string? ]],
     selected_row = tonumber(argo:get_flag("selected-row", { no_empty = true })),
+    rename_threshold = parse_rename_threshold_flag(argo:get_flag("rename-threshold")),
   }
 
   return { left = left, right = right, options = options }
@@ -2260,7 +2288,7 @@ GitAdapter.tracked_files = async.wrap(function(self, left, right, args, kind, op
   ---@type FileEntry[]
   local conflicts = {}
   local log_opt = { label = "GitAdapter:tracked_files()" }
-  local rename_threshold = config.get_config().rename_threshold
+  local rename_threshold = opt.rename_threshold or config.get_config().rename_threshold
   local rename_flag = rename_threshold and ("-M" .. rename_threshold .. "%") or nil
 
   local namestat_job = Job({
@@ -2776,6 +2804,7 @@ function GitAdapter:init_completion()
   end)
   self.comp.open:put({ "selected-row" })
   self.comp.open:put({ "no-panel" })
+  self.comp.open:put({ "rename-threshold" }, {})
 
   self.comp.file_history:put({ "base" }, function(_, arg_lead)
     return utils.vec_join("LOCAL", self:rev_candidates(arg_lead))
@@ -2819,6 +2848,7 @@ function GitAdapter:init_completion()
   self.comp.file_history:put({ "-S" }, {})
   self.comp.file_history:put({ "--after", "--since" }, {})
   self.comp.file_history:put({ "--before", "--until" }, {})
+  self.comp.file_history:put({ "--rename-threshold" }, {})
 end
 
 M.GitAdapter = GitAdapter

lua/diffview/vcs/adapters/jj/init.lua

@@ -732,6 +732,10 @@ function JjAdapter:diffview_options(argo)
 
   logger:fmt_debug("Parsed revs: left = %s, right = %s", left, right)
 
+  if argo:get_flag("rename-threshold") then
+    utils.warn("The '--rename-threshold' option is not supported for Jujutsu. Ignoring.")
+  end
+
   local options = {
     show_untracked = arg_parser.ambiguous_bool(
       argo:get_flag({ "u", "untracked-files" }, { plain = true }),
@@ -833,6 +837,10 @@ function JjAdapter:file_history_options(range, paths, argo)
     return
   end
 
+  if argo:get_flag("rename-threshold") then
+    utils.warn("The '--rename-threshold' option is not supported for Jujutsu. Ignoring.")
+  end
+
   local rel_paths = vim.tbl_map(function(v)
     return v == "." and "." or pl:relative(v, ".")
   end, paths) --[[@as string[] ]]

lua/diffview/vcs/utils.lua

@@ -156,6 +156,12 @@ M.diff_file_list = async.wrap(function(adapter, left, right, path_args, dv_opt,
   local files = FileDict()
   local rev_args = adapter:rev_to_args(left, right)
   local errors = {}
+
+  -- Forward the CLI `--rename-threshold` override into the per-view `opt` so
+  -- `tracked_files` picks it up without widening its signature.
+  if dv_opt.rename_threshold then
+    opt.rename_threshold = dv_opt.rename_threshold
+  end
   (function()
     local err, tfiles, tconflicts = await(
       adapter:tracked_files(left, right, utils.vec_join(rev_args, "--", path_args), "working", opt)