Feat: Add jumpable commit view hunk navigation

- Allow jumping from commit view hunks to worktree or committed file content
- Share jump logic via new lib/jump helpers and extra tests
- Make commit-view "open file" mapping configurable
- Document commit view mappings and behavior

Author: txemaotero

doc/neogit.txt

@@ -391,6 +391,10 @@ The following mappings can all be customized via the setup function.
         ["<c-c><c-k>"] = "Abort",
       }
 
+      commit_view = {
+        ["a"]          = "OpenFileInWorktree",
+      }
+
       rebase_editor = {
         ["p"]          = "Pick",
         ["r"]          = "Reword",
@@ -2171,7 +2175,32 @@ Reflog Buffer                                             *neogit_reflog_buffer*
 
 ==============================================================================
 Commit Buffer                                             *neogit_commit_buffer*
-(TODO)
+The commit buffer shows a single commit, including metadata, summary, and an
+inline diff. It opens via |:NeogitCommit|, from log/graph views, or when
+pressing `<cr>` on a commit hash elsewhere in Neogit.
+
+Mappings (normal mode):
+  • `a`          (|neogit_setup_mappings|: "OpenFileInWorktree" in commit_view)
+                 On a diff hunk, try to jump to that location in the worktree
+                 (i.e. current version of the file).
+                 Note: it can fail if the file no longer exists or it can take
+                 you to a wrong location in the file if the lines have been
+                 moved around.
+  • `<cr>`       On a diff hunk, open the file contents from the commit in a
+                 temporary read-only tab, or the parent revision for deleted
+                 lines; on a filepath line, jump to that file's diff section
+                 within the buffer.
+  • `o`          Open the commit in the configured git service (requires
+                 Neovim >= 0.10 for |vim.ui.open|).
+  • `{` / `}`    Jump to previous/next hunk or diff header.
+  • `q` / `<esc>` Close the commit buffer (keys are configurable via
+                 |neogit_setup_mappings| for the commit view).
+  • `Y`          Yank the current commit hash to the clipboard.
+  • `za` / `<tab>` Toggle folding for the current section.
+  • Popup shortcuts honour |neogit_setup_mappings|, default keys:
+      - `A` Cherry-pick, `b` Branch, `B` Bisect, `c` Commit, `d` Diff,
+        `f` Fetch, `i` Ignore, `l` Log, `m` Merge, `p` Pull, `P` Push,
+        `r` Rebase, `t` Tag, `v` Revert, `w` Worktree, `X` Reset, `Z` Stash.
 
 ==============================================================================
 Refs Buffer                                                 *neogit_refs_buffer*

lua/neogit/buffers/commit_view/init.lua

@@ -4,8 +4,10 @@ local ui = require("neogit.buffers.commit_view.ui")
 local git = require("neogit.lib.git")
 local config = require("neogit.config")
 local popups = require("neogit.popups")
+local commit_view_maps = require("neogit.config").get_reversed_commit_view_maps()
 local status_maps = require("neogit.config").get_reversed_status_maps()
 local notification = require("neogit.lib.notification")
+local jump = require("neogit.lib.jump")
 
 local api = vim.api
 
@@ -151,6 +153,71 @@ function M:update(commit_id, filter)
   self.buffer:win_call(vim.cmd, "normal! gg")
 end
 
+---Generate a callback to re-open CommitViewBuffer in the current commit
+---@param self CommitViewBuffer
+---@return fun()
+local function get_reopen_cb(self)
+  local original_cursor = api.nvim_win_get_cursor(0)
+  local back_commit = self.commit_info.oid
+  return function()
+    M.new(back_commit):open()
+    api.nvim_win_set_cursor(0, original_cursor)
+  end
+end
+
+---@param self CommitViewBuffer
+---@param location LocationInHunk
+---@return string|nil, integer[]
+local function location_to_commit_cursor(self, location)
+  if string.sub(location.line, 1, 1) == "-" then
+    return git.log.parent(self.commit_info.oid), { location.old, 0 }
+  else
+    return self.commit_info.oid, { location.new, 0 }
+  end
+end
+
+---Visit the file at the location specified by the provided hunk component
+---@param self CommitViewBuffer
+---@param component Component A component that evaluates is_jumpable_hunk_line_component() to true
+---@param worktree boolean if true, try to jump to the file in the current worktree. Otherwise jump to the file in the referenced commit
+local function diff_visit_file(self, component, worktree)
+  local hunk_component = component.parent.parent
+  local hunk = hunk_component.options.hunk
+  local path = vim.trim(hunk.file)
+  if path == "" then
+    notification.warn("Unable to determine file path for diff line")
+    return
+  end
+
+  local line = self.buffer:cursor_line()
+  local offset = line - hunk_component.position.row_start
+  local location = jump.translate_hunk_location(hunk, offset)
+  if not location then
+    -- Cursor outside the hunk, shouldn't happen. Don't warn in that case
+    return
+  end
+
+  if worktree then
+    local cursor = { location.new, 0 }
+    jump.goto_file_at(path, cursor)
+  else
+    local target_commit, cursor = location_to_commit_cursor(self, location)
+    if not target_commit then
+      notification.warn("Unable to retrieve parent commit")
+      return nil, cursor
+    end
+    jump.goto_file_in_commit_at(target_commit, path, cursor, get_reopen_cb(self))
+  end
+end
+
+---@param c Component
+---@return boolean
+local function is_jumpable_hunk_line_component(c)
+  return c.options.line_hl == "NeogitDiffContext"
+    or c.options.line_hl == "NeogitDiffAdd"
+    or c.options.line_hl == "NeogitDiffDelete"
+end
+
 ---Opens the CommitViewBuffer
 ---If already open will close the buffer
 ---@param kind? string
@@ -189,15 +256,29 @@ function M:open(kind)
             notification.warn("Couldn't determine commit URL to open")
           end
         end,
+        [commit_view_maps["OpenFileInWorktree"]] = function()
+          -- Abort if rebase_editor
+          local c = self.buffer.ui:get_component_under_cursor(function(c)
+            return is_jumpable_hunk_line_component(c)
+          end)
+          if c then
+            diff_visit_file(self, c, true)
+          end
+        end,
         ["<cr>"] = function()
           local c = self.buffer.ui:get_component_under_cursor(function(c)
-            return c.options.highlight == "NeogitFilePath"
+            return c.options.highlight == "NeogitFilePath" or is_jumpable_hunk_line_component(c)
           end)
 
           if not c then
             return
           end
 
+          if is_jumpable_hunk_line_component(c) then
+            diff_visit_file(self, c, false)
+            return
+          end
+
           -- Some paths are padded for formatting purposes. We need to trim them
           -- in order to use them as match patterns.
           local selected_path = vim.fn.trim(c.value)

lua/neogit/buffers/status/actions.lua

@@ -8,6 +8,7 @@ local input = require("neogit.lib.input")
 local notification = require("neogit.lib.notification")
 local util = require("neogit.lib.util")
 local config = require("neogit.config")
+local jump = require("neogit.lib.jump")
 
 local FuzzyFinderBuffer = require("neogit.buffers.fuzzy_finder")
 
@@ -53,41 +54,25 @@ end
 
 ---@param self StatusBuffer
 ---@param item StatusItem
----@return table|nil
+---@return integer[]|nil
 local function translate_cursor_location(self, item)
   if rawget(item, "diff") then
     local line = self.buffer:cursor_line()
 
     for _, hunk in ipairs(item.diff.hunks) do
       if line >= hunk.first and line <= hunk.last then
         local offset = line - hunk.first
-        local row = hunk.disk_from + offset - 1
-
-        for i = 1, offset do
-          -- If the line is a deletion, we need to adjust the row
-          if string.sub(hunk.lines[i], 1, 1) == "-" then
-            row = row - 1
-          end
+        local location = jump.translate_hunk_location(hunk, offset)
+        if location then
+          return { location.new, 0 }
         end
-
-        return { row, 0 }
       end
     end
   end
 end
 
 local function open(type, path, cursor)
-  local command = ("silent! %s %s | %s"):format(type, fn.fnameescape(path), cursor and cursor[1] or "1")
-
-  logger.debug("[Status - Open] '" .. command .. "'")
-
-  vim.cmd(command)
-
-  command = "redraw! | norm! zz"
-
-  logger.debug("[Status - Open] '" .. command .. "'")
-
-  vim.cmd(command)
+  jump.open(type, path, cursor, "[Status - Open]")
 end
 
 local M = {}

lua/neogit/config.lua

@@ -62,6 +62,11 @@ function M.get_reversed_commit_editor_maps_I()
   return get_reversed_maps("commit_editor_I")
 end
 
+---@return table<string, string[]>
+function M.get_reversed_commit_view_maps()
+  return get_reversed_maps("commit_view")
+end
+
 ---@return table<string, string[]>
 function M.get_reversed_refs_view_maps()
   return get_reversed_maps("refs_view")
@@ -590,6 +595,9 @@ function M.get_default_values()
     },
     ignored_settings = {},
     mappings = {
+      commit_view = {
+        ["a"] = "OpenFileInWorktree",
+      },
       commit_editor = {
         ["q"] = "Close",
         ["<c-c><c-c>"] = "Submit",