Edit the selected hunk from the focused main view

The staging view can hand the hunk you are on to an editor and apply what
comes back, which is how you stage something the diff cannot express: half
of a changed line, or a change written differently from either side. The
focused main view has to be able to do the same before that view can go.

The hunk is git's own, context and all, rather than lazygit's block of
adjacent changes: an editable patch is one that still applies, and the
context lines are what let git place it. What the editor leaves behind is
applied whole rather than matched against the file's diff again, the point
being that it says something the diff didn't.

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

docs-master/keybindings/Keybindings_en.md

@@ -228,6 +228,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
 | `` e `` | Edit file | Open file in external editor. |
 | `` <space> `` | Stage | Toggle selection staged / unstaged. |
 | `` d `` | Discard | When unstaged change is selected, discard the change using `git reset`. When staged change is selected, unstage the change. |
+| `` E `` | Edit hunk | Edit selected hunk in external editor. |
 | `` <ctrl+o> `` | Copy selected text to clipboard |  |
 | `` <left>, h `` | Go to previous hunk |  |
 | `` <right>, l `` | Go to next hunk |  |
@@ -347,6 +348,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
 | `` e `` | Edit file | Open file in external editor. |
 | `` <space> `` | Stage | Toggle selection staged / unstaged. |
 | `` d `` | Discard | When unstaged change is selected, discard the change using `git reset`. When staged change is selected, unstage the change. |
+| `` E `` | Edit hunk | Edit selected hunk in external editor. |
 | `` <ctrl+o> `` | Copy selected text to clipboard |  |
 | `` <left>, h `` | Go to previous hunk |  |
 | `` <right>, l `` | Go to next hunk |  |

docs-master/keybindings/Keybindings_ja.md

@@ -197,6 +197,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
 | `` e `` | ファイルを編集 | 外部エディタでファイルを開きます。 |
 | `` <space> `` | ステージ | 選択された部分のステージ / アンステージを切り替えます。 |
 | `` d `` | 破棄 | ステージされていない変更が選択されている場合、`git reset`を使用して変更を破棄します。ステージされた変更が選択されている場合、変更をアンステージします。 |
+| `` E `` | ハンクを編集 | 選択したハンクを外部エディタで編集します。 |
 | `` <ctrl+o> `` | 選択したテキストをクリップボードにコピー |  |
 | `` <left>, h `` | 前のハンクに移動 |  |
 | `` <right>, l `` | 次のハンクに移動 |  |
@@ -324,6 +325,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
 | `` e `` | ファイルを編集 | 外部エディタでファイルを開きます。 |
 | `` <space> `` | ステージ | 選択された部分のステージ / アンステージを切り替えます。 |
 | `` d `` | 破棄 | ステージされていない変更が選択されている場合、`git reset`を使用して変更を破棄します。ステージされた変更が選択されている場合、変更をアンステージします。 |
+| `` E `` | ハンクを編集 | 選択したハンクを外部エディタで編集します。 |
 | `` <ctrl+o> `` | 選択したテキストをクリップボードにコピー |  |
 | `` <left>, h `` | 前のハンクに移動 |  |
 | `` <right>, l `` | 次のハンクに移動 |  |

docs-master/keybindings/Keybindings_ko.md

@@ -89,6 +89,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
 | `` e `` | 파일 편집 | Open file in external editor. |
 | `` <space> `` | Staged 전환 | 선택한 행을 staged / unstaged |
 | `` d `` | 변경을 삭제 (git reset) | When unstaged change is selected, discard the change using `git reset`. When staged change is selected, unstage the change. |
+| `` E `` | Edit hunk | Edit selected hunk in external editor. |
 | `` <ctrl+o> `` | 선택한 텍스트를 클립보드에 복사 |  |
 | `` <left>, h `` | 이전 hunk를 선택 |  |
 | `` <right>, l `` | 다음 hunk를 선택 |  |
@@ -181,6 +182,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
 | `` e `` | 파일 편집 | Open file in external editor. |
 | `` <space> `` | Staged 전환 | 선택한 행을 staged / unstaged |
 | `` d `` | 변경을 삭제 (git reset) | When unstaged change is selected, discard the change using `git reset`. When staged change is selected, unstage the change. |
+| `` E `` | Edit hunk | Edit selected hunk in external editor. |
 | `` <ctrl+o> `` | 선택한 텍스트를 클립보드에 복사 |  |
 | `` <left>, h `` | 이전 hunk를 선택 |  |
 | `` <right>, l `` | 다음 hunk를 선택 |  |

docs-master/keybindings/Keybindings_nl.md

@@ -236,6 +236,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
 | `` e `` | Verander bestand | Open bestand in externe editor. |
 | `` <space> `` | Toggle staged | Toggle lijnen staged / unstaged |
 | `` d `` | Verwijdert change (git reset) | When unstaged change is selected, discard the change using `git reset`. When staged change is selected, unstage the change. |
+| `` E `` | Edit hunk | Edit selected hunk in external editor. |
 | `` <ctrl+o> `` | Copy selected text to clipboard |  |
 | `` <left>, h `` | Selecteer de vorige hunk |  |
 | `` <right>, l `` | Selecteer de volgende hunk |  |
@@ -325,6 +326,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
 | `` e `` | Verander bestand | Open bestand in externe editor. |
 | `` <space> `` | Toggle staged | Toggle lijnen staged / unstaged |
 | `` d `` | Verwijdert change (git reset) | When unstaged change is selected, discard the change using `git reset`. When staged change is selected, unstage the change. |
+| `` E `` | Edit hunk | Edit selected hunk in external editor. |
 | `` <ctrl+o> `` | Copy selected text to clipboard |  |
 | `` <left>, h `` | Selecteer de vorige hunk |  |
 | `` <right>, l `` | Selecteer de volgende hunk |  |

docs-master/keybindings/Keybindings_pl.md

@@ -104,6 +104,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
 | `` e `` | Edytuj plik | Otwórz plik w zewnętrznym edytorze. |
 | `` <space> `` | Zatwierdź | Przełącz zaznaczenie zatwierdzone/niezatwierdzone. |
 | `` d `` | Odrzuć | Gdy zaznaczona jest niezatwierdzona zmiana, odrzuć ją używając `git reset`. Gdy zaznaczona jest zatwierdzona zmiana, cofnij zatwierdzenie. |
+| `` E `` | Edytuj fragment | Edytuj wybrany fragment w zewnętrznym edytorze. |
 | `` <ctrl+o> `` | Kopiuj zaznaczony tekst do schowka |  |
 | `` <left>, h `` | Idź do poprzedniego fragmentu |  |
 | `` <right>, l `` | Idź do następnego fragmentu |  |
@@ -220,6 +221,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
 | `` e `` | Edytuj plik | Otwórz plik w zewnętrznym edytorze. |
 | `` <space> `` | Zatwierdź | Przełącz zaznaczenie zatwierdzone/niezatwierdzone. |
 | `` d `` | Odrzuć | Gdy zaznaczona jest niezatwierdzona zmiana, odrzuć ją używając `git reset`. Gdy zaznaczona jest zatwierdzona zmiana, cofnij zatwierdzenie. |
+| `` E `` | Edytuj fragment | Edytuj wybrany fragment w zewnętrznym edytorze. |
 | `` <ctrl+o> `` | Kopiuj zaznaczony tekst do schowka |  |
 | `` <left>, h `` | Idź do poprzedniego fragmentu |  |
 | `` <right>, l `` | Idź do następnego fragmentu |  |

docs-master/keybindings/Keybindings_pt.md

@@ -240,6 +240,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
 | `` e `` | Editar arquivo | Abrir arquivo no editor externo. |
 | `` <space> `` | Etapa | Ativar/desativar seleção em staged/unstaged |
 | `` d `` | Descartar | Quando a mudança não desejada for selecionada, descarte a mudança usando `git reset`. Quando a mudança em fase é selecionada, despare a mudança. |
+| `` E `` | Editar hunk | Editar o local selecionado no editor externo. |
 | `` <ctrl+o> `` | Copiar texto selecionado para área de transferência |  |
 | `` <left>, h `` | Ir para o local anterior |  |
 | `` <right>, l `` | Ir para o próximo trecho |  |
@@ -356,6 +357,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
 | `` e `` | Editar arquivo | Abrir arquivo no editor externo. |
 | `` <space> `` | Etapa | Ativar/desativar seleção em staged/unstaged |
 | `` d `` | Descartar | Quando a mudança não desejada for selecionada, descarte a mudança usando `git reset`. Quando a mudança em fase é selecionada, despare a mudança. |
+| `` E `` | Editar hunk | Editar o local selecionado no editor externo. |
 | `` <ctrl+o> `` | Copiar texto selecionado para área de transferência |  |
 | `` <left>, h `` | Ir para o local anterior |  |
 | `` <right>, l `` | Ir para o próximo trecho |  |

docs-master/keybindings/Keybindings_ru.md

@@ -79,6 +79,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
 | `` e `` | Редактировать файл | Open file in external editor. |
 | `` <space> `` | Переключить индекс | Переключить строку в проиндексированные / непроиндексированные |
 | `` d `` | Отменить изменение (git reset) | When unstaged change is selected, discard the change using `git reset`. When staged change is selected, unstage the change. |
+| `` E `` | Изменить эту часть | Edit selected hunk in external editor. |
 | `` <ctrl+o> `` | Скопировать выделенный текст в буфер обмена |  |
 | `` <left>, h `` | Выбрать предыдущую часть |  |
 | `` <right>, l `` | Выбрать следующую часть |  |
@@ -125,6 +126,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
 | `` e `` | Редактировать файл | Open file in external editor. |
 | `` <space> `` | Переключить индекс | Переключить строку в проиндексированные / непроиндексированные |
 | `` d `` | Отменить изменение (git reset) | When unstaged change is selected, discard the change using `git reset`. When staged change is selected, unstage the change. |
+| `` E `` | Изменить эту часть | Edit selected hunk in external editor. |
 | `` <ctrl+o> `` | Скопировать выделенный текст в буфер обмена |  |
 | `` <left>, h `` | Выбрать предыдущую часть |  |
 | `` <right>, l `` | Выбрать следующую часть |  |

docs-master/keybindings/Keybindings_zh-CN.md

@@ -291,6 +291,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
 | `` e `` | 编辑文件 | 使用外部编辑器打开文件 |
 | `` <space> `` | 切换暂存状态 | 切换行暂存状态 |
 | `` d `` | 取消变更(git reset) | 当选择未暂存的变更时，使用git reset丢弃该变更。当选择已暂存的变更时，取消暂存该变更 |
+| `` E `` | 编辑代码块 | 在外部编辑器中编辑选中的代码块 |
 | `` <ctrl+o> `` | 复制选中文本到剪贴板 |  |
 | `` <left>, h `` | 选择上一个区块 |  |
 | `` <right>, l `` | 选择下一个区块 |  |
@@ -353,6 +354,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
 | `` e `` | 编辑文件 | 使用外部编辑器打开文件 |
 | `` <space> `` | 切换暂存状态 | 切换行暂存状态 |
 | `` d `` | 取消变更(git reset) | 当选择未暂存的变更时，使用git reset丢弃该变更。当选择已暂存的变更时，取消暂存该变更 |
+| `` E `` | 编辑代码块 | 在外部编辑器中编辑选中的代码块 |
 | `` <ctrl+o> `` | 复制选中文本到剪贴板 |  |
 | `` <left>, h `` | 选择上一个区块 |  |
 | `` <right>, l `` | 选择下一个区块 |  |

docs-master/keybindings/Keybindings_zh-TW.md

@@ -80,6 +80,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
 | `` e `` | 編輯檔案 | 使用外部編輯器開啟 |
 | `` <space> `` | 切換預存 | 切換現有行的狀態 (已預存/未預存) |
 | `` d `` | 刪除變更 (git reset) | 選取未暫存的變更時，使用 `git reset` 捨棄變更。選取已暫存的變更時，取消暫存變更。 |
+| `` E `` | 編輯程式碼塊 | 在外部編輯器中編輯選中的程式碼塊。 |
 | `` <ctrl+o> `` | 複製所選文本至剪貼簿 |  |
 | `` <left>, h `` | 選擇上一段 |  |
 | `` <right>, l `` | 選擇下一段 |  |
@@ -375,6 +376,7 @@ _This file is auto-generated. To update, make the changes in the pkg/i18n direct
 | `` e `` | 編輯檔案 | 使用外部編輯器開啟 |
 | `` <space> `` | 切換預存 | 切換現有行的狀態 (已預存/未預存) |
 | `` d `` | 刪除變更 (git reset) | 選取未暫存的變更時，使用 `git reset` 捨棄變更。選取已暫存的變更時，取消暫存變更。 |
+| `` E `` | 編輯程式碼塊 | 在外部編輯器中編輯選中的程式碼塊。 |
 | `` <ctrl+o> `` | 複製所選文本至剪貼簿 |  |
 | `` <left>, h `` | 選擇上一段 |  |
 | `` <right>, l `` | 選擇下一段 |  |

pkg/gui/controllers/main_view_controller.go

@@ -97,6 +97,14 @@ func (self *MainViewController) GetKeybindings(opts types.KeybindingsOpts) []*ty
 			Tooltip:           self.c.Tr.DiscardSelectionTooltip,
 			DisplayOnScreen:   true,
 		},
+		{
+			Keys:              opts.GetKeys(opts.Config.Main.EditSelectHunk),
+			Handler:           self.editHunk,
+			Description:       self.c.Tr.EditHunk,
+			DescriptionFunc:   self.workingTreeActionDescription(self.c.Tr.EditHunk),
+			GetDisabledReason: self.diffSelectionDisabledReason,
+			Tooltip:           self.c.Tr.EditHunkTooltip,
+		},
 		{
 			Keys:              opts.GetKeys(opts.Config.Universal.CopyToClipboard),
 			Handler:           self.copySelection,
@@ -396,6 +404,21 @@ func (self *MainViewController) discardSelection() error {
 	return actions.DiscardSelection(self.context, first, last)
 }
 
+// editHunk hands the hunk around the selection to an editor, and is only offered over
+// the working tree's diff: what comes back is applied to the index, which is not
+// something a commit's diff has any use for.
+func (self *MainViewController) editHunk() error {
+	actions, ok := self.diffSource().(*WorkingTreeDiffActions)
+	if !ok {
+		return nil
+	}
+	first, last, ok := self.context.GetView().SelectedBufferLineRange()
+	if !ok {
+		return nil
+	}
+	return actions.EditHunk(self.context, first, last)
+}
+
 // workingTreeAction wraps a command that acts on the working tree — committing, finding
 // the commit to fix up — so that it only runs while the focused main view is showing the
 // working tree's diff. Over a commit's diff the key does nothing, so that browsing

pkg/gui/controllers/working_tree_diff_actions.go

@@ -3,6 +3,7 @@ package controllers
 import (
 	"fmt"
 	"path/filepath"
+	"strings"
 
 	"github.com/jesseduffield/generics/set"
 	"github.com/jesseduffield/lazygit/pkg/commands/git_commands"
@@ -99,6 +100,87 @@ func (self *WorkingTreeDiffActions) DiscardSelection(pane types.DiffPaneContext,
 		})
 }
 
+// EditHunk opens the git hunk holding the selection in an editor, as a patch against
+// the index, and applies whatever comes back. It is how you stage something the diff
+// can't express — half of a changed line, or a change written differently from either
+// side — since what the editor hands back is applied rather than matched against the
+// file's own diff.
+//
+// The hunk is the git one, context and all, rather than lazygit's block of adjacent
+// changes: an editable patch is one that still applies, and the context lines are what
+// let git place it.
+func (self *WorkingTreeDiffActions) EditHunk(
+	pane types.DiffPaneContext, firstBufferLine int, lastBufferLine int,
+) error {
+	infos, onStagedSide, ok := self.diffLineSelection(pane, firstBufferLine, lastBufferLine)
+	if !ok {
+		return nil
+	}
+	file := self.fileForDiffLinePath(infos[0].Path)
+	if file == nil {
+		return nil
+	}
+
+	parsedPatch := patch.Parse(self.c.Git().WorkingTree.WorktreeFileDiff(file, git_commands.DiffModePlain, onStagedSide))
+	lineIndices := changeLineIndices(parsedPatch, infos[:1])
+	if len(lineIndices) == 0 {
+		return nil
+	}
+
+	hunkIdx := parsedPatch.HunkContainingLine(lineIndices[0])
+	hunkStartIdx := parsedPatch.HunkStartIdx(hunkIdx)
+	patchText := parsedPatch.
+		Transform(patch.TransformOpts{
+			Reverse:             onStagedSide,
+			IncludedLineIndices: patch.ExpandRange(hunkStartIdx, parsedPatch.HunkEndIdx(hunkIdx)),
+			FileNameOverride:    file.GetPath(),
+		}).
+		FormatPlain()
+
+	patchFilepath, err := self.c.Git().Patch.SaveTemporaryPatch(patchText)
+	if err != nil {
+		return err
+	}
+
+	// The patch is written with a two-line header before its hunk, so the line the
+	// user was on sits that much further down the file they are about to edit.
+	const headerLineCount = 2
+	if err := self.c.Helpers().Files.EditFileAtLineAndWait(patchFilepath,
+		lineIndices[0]-hunkStartIdx+headerLineCount+1); err != nil {
+		return err
+	}
+
+	editedPatchText, err := self.c.Git().File.Cat(patchFilepath)
+	if err != nil {
+		return err
+	}
+
+	self.c.LogAction(self.c.Tr.Actions.ApplyPatch)
+
+	// Everything the editor left behind is taken, this being a patch the user wrote
+	// rather than a selection out of one of ours.
+	lineCount := strings.Count(editedPatchText, "\n") + 1
+	newPatchText := patch.
+		Parse(editedPatchText).
+		Transform(patch.TransformOpts{
+			IncludedLineIndices: patch.ExpandRange(0, lineCount),
+			FileNameOverride:    file.GetPath(),
+		}).
+		FormatPlain()
+
+	if err := self.c.Git().Patch.ApplyPatch(newPatchText, git_commands.ApplyPatchOpts{
+		Reverse: onStagedSide,
+		Cached:  true,
+	}); err != nil {
+		return err
+	}
+
+	// Block input until the refresh has landed, as the staging commands do: the diff is
+	// about to be rebuilt from a file that no longer looks the way it did.
+	self.c.RefreshBlockingInput(types.RefreshOptions{Scope: []types.RefreshableView{types.FILES}})
+	return nil
+}
+
 // diffLineSelection resolves what the user has selected in a pane of the focused main
 // view to the change lines to act on, and reports whether they are the staged side of
 // the diff — which is a question about the pane, so it is the same for every file of a

pkg/integration/tests/main_view/edit_hunk_in_focused_diff.go

@@ -0,0 +1,59 @@
+package main_view
+
+import (
+	"github.com/jesseduffield/lazygit/pkg/config"
+	. "github.com/jesseduffield/lazygit/pkg/integration/components"
+)
+
+var EditHunkInFocusedDiff = NewIntegrationTest(NewIntegrationTestArgs{
+	Description:  "Edit the hunk around the selection in an editor, and stage what comes back",
+	ExtraCmdArgs: []string{},
+	Skip:         false,
+	SetupConfig: func(cfg *config.AppConfig) {
+		cfg.GetUserConfig().Gui.UseHunkModeInStagingView = false
+		// Stand in for the editor: record the line it was pointed at, outside the
+		// repo so that the files panel keeps saying what the test is about, then
+		// write a patch that stages something neither side of the diff says. That
+		// is the point of editing a hunk.
+		cfg.GetUserConfig().OS.EditAtLineAndWait = "echo {{line}} > ../edit-line && " +
+			"printf '%s\\n' '--- a/file1' '+++ b/file1' '@@ -1,3 +1,3 @@' " +
+			"' one' '-two' '+TWO_EDITED' ' three' > {{filename}}"
+	},
+	SetupRepo: func(shell *Shell) {
+		shell.CreateFileAndAdd("file1", "one\ntwo\nthree\n")
+		shell.Commit("one")
+
+		shell.UpdateFile("file1", "one\nTWO\nthree\n")
+	},
+	Run: func(t *TestDriver, keys config.KeybindingConfig) {
+		t.Views().Files().
+			IsFocused().
+			Lines(
+				Contains("file1").IsSelected(),
+			).
+			Press(keys.Universal.FocusMainView)
+
+		t.Views().Main().
+			IsFocused().
+			SelectedLines(Contains("-two")).
+			Press(keys.Main.EditSelectHunk)
+
+		// The patch is written with a two-line header, so the deletion the cursor was
+		// on is its fifth line.
+		t.FileSystem().FileContent("../edit-line", Equals("5\n"))
+
+		// What the editor wrote went into the index, leaving the working tree as it
+		// was: the file is changed on both sides now, differently.
+		t.Views().Files().Lines(
+			Contains("MM").Contains("file1"),
+		)
+		t.Views().Secondary().ContainsLines(
+			Contains("-two"),
+			Contains("+TWO_EDITED"),
+		)
+		t.Views().Main().ContainsLines(
+			Contains("-TWO_EDITED"),
+			Contains("+TWO"),
+		)
+	},
+})

pkg/integration/tests/test_list.go

@@ -375,6 +375,7 @@ var tests = []*components.IntegrationTest{
 	main_view.DiscardDiffLines,
 	main_view.DragRangeWithAutoscroll,
 	main_view.DragSelectsDiffLineRange,
+	main_view.EditHunkInFocusedDiff,
 	main_view.EditSelectedDiffLine,
 	main_view.EscapeDismissesSelection,
 	main_view.FileNavigationScrollsToTheTop,