feat(commit): generate commit messages from a configured command

docs-master/Config.md

@@ -378,6 +378,12 @@ git:
     # If true, pass '--signoff' flag when committing
     signOff: false
 
+    # Command that generates a commit message. Lazygit runs the command from the
+    # current git project root and uses stdout as the editable commit message. If
+    # the command fails, stderr is shown to the user. See
+    # https://github.com/jesseduffield/lazygit/blob/master/docs/Generated_Commit_Messages.md.
+    messageGeneratorCommand: ""
+
     # Automatic WYSIWYG wrapping of the commit message as you type
     autoWrapCommitMessage: true
 

docs-master/Generated_Commit_Messages.md

@@ -0,0 +1,175 @@
+# Generated Commit Messages
+
+Lazygit can run an external command to generate the text for a new commit message. This is useful if you want a local script, an LLM tool, or another formatter to inspect the staged diff and suggest a message.
+
+Configure the command under `git.commit.messageGeneratorCommand`:
+
+```yaml
+git:
+  commit:
+    messageGeneratorCommand: ~/bin/generate-staged-commit-message.sh
+```
+
+When this option is set, the commit menu shows `Generate Commit Message`. Selecting it runs the configured command and puts the command's stdout into the commit message fields. Lazygit does not commit immediately, so you can review and edit the generated message before submitting.
+
+## Command Contract
+
+Lazygit runs the configured command from the Git project root. For example, if your config contains:
+
+```yaml
+git:
+  commit:
+    messageGeneratorCommand: ~/bin/generate-staged-commit-message.sh --style conventional
+```
+
+Lazygit runs it like this:
+
+```sh
+(cd /path/to/repo && ~/bin/generate-staged-commit-message.sh --style conventional)
+```
+
+The command should write only the commit message to stdout. If stdout contains a blank line, Lazygit treats the first paragraph as the commit summary and the rest as the commit description.
+
+If the command exits with a non-zero status, Lazygit shows a notification with stderr. The current commit message is left unchanged.
+
+## Simple Script
+
+This example uses the staged file summary to build a basic message:
+
+```sh
+#!/usr/bin/env sh
+set -eu
+
+if git diff --cached --quiet --exit-code; then
+  echo "no staged changes" >&2
+  exit 1
+fi
+
+files=$(git diff --cached --name-only | sed -n '1,3p' | paste -sd ', ' -)
+count=$(git diff --cached --name-only | wc -l | tr -d ' ')
+
+if [ "$count" -eq 1 ]; then
+  printf 'update %s\n' "$files"
+else
+  printf 'update %s files\n\n%s\n' "$count" "$files"
+fi
+```
+
+Save it somewhere on your `PATH`, make it executable, and point Lazygit at it:
+
+```sh
+chmod +x ~/bin/generate-staged-commit-message.sh
+```
+
+```yaml
+git:
+  commit:
+    messageGeneratorCommand: ~/bin/generate-staged-commit-message.sh
+```
+
+## Codex Example
+
+This example asks `codex exec` to inspect the staged diff and output only a commit message. It checks that staged changes exist in the current Git repository and lets you override the model or add extra `codex exec` arguments with environment variables.
+
+```sh
+#!/usr/bin/env bash
+set -euo pipefail
+
+usage() {
+  cat >&2 <<'USAGE'
+Usage: generate-staged-commit-message.sh
+
+Calls Codex to generate a commit message for the currently staged changes in
+the current Git repository.
+
+Environment:
+  CODEX_MODEL       Optional model name passed to `codex exec -m`.
+  CODEX_EXTRA_ARGS  Optional additional arguments appended to `codex exec`.
+USAGE
+}
+
+die() {
+  printf 'error: %s\n' "$*" >&2
+  exit 1
+}
+
+if [[ "${1:-}" == "-h" || "${1:-}" == "--help" ]]; then
+  usage
+  exit 0
+fi
+
+[[ $# -eq 0 ]] || {
+  usage
+  exit 2
+}
+
+command -v git >/dev/null 2>&1 || die "git is not installed or not on PATH"
+command -v codex >/dev/null 2>&1 || die "codex is not installed or not on PATH"
+
+repo_root=$(git rev-parse --show-toplevel 2>/dev/null) ||
+  die "not a Git repository: $PWD"
+
+if git -C "$repo_root" diff --cached --quiet --exit-code; then
+  die "no staged changes found in $repo_root"
+fi
+
+prompt=$(cat <<'PROMPT'
+Generate a concise, high-quality Git commit message for the currently staged changes.
+
+Inspect the staged diff with:
+
+  git diff --cached --stat
+  git diff --cached
+
+Requirements:
+- Base the message only on staged changes.
+- Prefer a single-line subject under 72 characters.
+- Add a short body if it's not trivial commit and it materially improves clarity.
+- Output only the commit message. Do not wrap it in Markdown, quotes, or commentary.
+- Use the conventional commits format:
+```
+<type>[(scope)]: <description>
+
+[optional body]
+
+Signed-off-by: Your Name <you@example.com>
+```
+PROMPT
+)
+
+codex_args=(
+  exec
+  --cd "$repo_root"
+  --sandbox read-only
+  --ephemeral
+  --color never
+)
+
+if [[ -n "${CODEX_MODEL:-}" ]]; then
+  codex_args+=(-m "$CODEX_MODEL")
+fi
+
+if [[ -n "${CODEX_EXTRA_ARGS:-}" ]]; then
+  # shellcheck disable=SC2206
+  extra_args=(${CODEX_EXTRA_ARGS})
+  codex_args+=("${extra_args[@]}")
+fi
+
+exec codex "${codex_args[@]}" "$prompt"
+```
+
+Then configure Lazygit:
+
+```yaml
+git:
+  commit:
+    messageGeneratorCommand: ~/bin/generate-staged-commit-message.sh
+```
+
+## Tips
+
+Keep the command non-interactive because Lazygit captures stdout and stderr. If the command needs authentication or confirmation, handle that outside Lazygit first.
+
+Make the command fail when it cannot produce a useful message. Lazygit will show stderr and leave the current message intact.
+
+Quote paths inside scripts. Repository paths can contain spaces.

docs-master/README.md

@@ -2,6 +2,7 @@
 
 * [Configuration](./Config.md).
 * [Custom Commands](./Custom_Command_Keybindings.md)
+* [Generated Commit Messages](./Generated_Commit_Messages.md)
 * [Custom Pagers](./Custom_Pagers.md)
 * [Dev docs](./dev)
 * [Keybindings](./keybindings)

pkg/config/user_config.go

@@ -370,6 +370,8 @@ type PagingConfig struct {
 type CommitConfig struct {
 	// If true, pass '--signoff' flag when committing
 	SignOff bool `yaml:"signOff"`
+	// Command that generates a commit message. Lazygit runs the command from the current git project root and uses stdout as the editable commit message. If the command fails, stderr is shown to the user. See https://github.com/jesseduffield/lazygit/blob/master/docs/Generated_Commit_Messages.md.
+	MessageGeneratorCommand string `yaml:"messageGeneratorCommand"`
 	// Automatic WYSIWYG wrapping of the commit message as you type
 	AutoWrapCommitMessage bool `yaml:"autoWrapCommitMessage"`
 	// If autoWrapCommitMessage is true, the width to wrap to
@@ -902,9 +904,10 @@ func GetDefaultConfigForPlatform(platform string) *UserConfig {
 		},
 		Git: GitConfig{
 			Commit: CommitConfig{
-				SignOff:               false,
-				AutoWrapCommitMessage: true,
-				AutoWrapWidth:         72,
+				SignOff:                 false,
+				MessageGeneratorCommand: "",
+				AutoWrapCommitMessage:   true,
+				AutoWrapWidth:           72,
 			},
 			Merging: MergingConfig{
 				ManualCommit:       false,

pkg/gui/context/commit_message_context.go

@@ -5,7 +5,9 @@ import (
 	"path/filepath"
 	"strconv"
 	"strings"
+	"time"
 
+	"github.com/jesseduffield/lazygit/pkg/gui/presentation"
 	"github.com/jesseduffield/lazygit/pkg/gui/types"
 	"github.com/jesseduffield/lazygit/pkg/utils"
 	"github.com/spf13/afero"
@@ -41,6 +43,10 @@ type CommitMessageViewModel struct {
 	// invoked when pressing the switch-to-editor key binding
 	onSwitchToEditor func(string) error
 
+	generatingCommitMessage       bool
+	cancelingCommitMessage        bool
+	cancelGenerateCommitMessageFn func()
+
 	// the following two fields are used for the display of the "hooks disabled" subtitle
 	forceSkipHooks  bool
 	skipHooksPrefix string
@@ -164,13 +170,70 @@ func (self *CommitMessageContext) SetPanelState(
 	self.GetView().Title = summaryTitle
 	self.c.Views().CommitDescription.Title = descriptionTitle
 
+	self.RenderCommitDescriptionSubtitle()
+
+	self.c.Views().CommitDescription.Visible = true
+}
+
+func (self *CommitMessageContext) StartGeneratingCommitMessage(cancel func()) {
+	self.viewModel.generatingCommitMessage = true
+	self.viewModel.cancelingCommitMessage = false
+	self.viewModel.cancelGenerateCommitMessageFn = cancel
+	self.c.Views().CommitMessage.Editable = false
+	self.c.Views().CommitDescription.Editable = false
+	self.RenderCommitDescriptionSubtitle()
+}
+
+func (self *CommitMessageContext) StopGeneratingCommitMessage() {
+	self.viewModel.generatingCommitMessage = false
+	self.viewModel.cancelingCommitMessage = false
+	self.viewModel.cancelGenerateCommitMessageFn = nil
+	self.c.Views().CommitMessage.Editable = true
+	self.c.Views().CommitDescription.Editable = true
+	self.RenderCommitDescriptionSubtitle()
+}
+
+func (self *CommitMessageContext) IsGeneratingCommitMessage() bool {
+	return self.viewModel.generatingCommitMessage
+}
+
+func (self *CommitMessageContext) CancelGenerateCommitMessage() bool {
+	if !self.viewModel.generatingCommitMessage {
+		return false
+	}
+
+	if !self.viewModel.cancelingCommitMessage {
+		self.viewModel.cancelingCommitMessage = true
+		if self.viewModel.cancelGenerateCommitMessageFn != nil {
+			self.viewModel.cancelGenerateCommitMessageFn()
+		}
+	}
+	self.RenderCommitDescriptionSubtitle()
+	return true
+}
+
+func (self *CommitMessageContext) RenderCommitDescriptionSubtitle() {
+	if self.viewModel.generatingCommitMessage {
+		loader := presentation.Loader(time.Now(), self.c.UserConfig().Gui.Spinner)
+		if self.viewModel.cancelingCommitMessage {
+			self.c.Views().CommitDescription.Subtitle = utils.ResolvePlaceholderString(self.c.Tr.CancelingGenerateCommitMessageSubTitle,
+				map[string]string{"spinner": loader})
+			return
+		}
+
+		self.c.Views().CommitDescription.Subtitle = utils.ResolvePlaceholderString(self.c.Tr.GenerateCommitMessageSubTitle,
+			map[string]string{
+				"spinner":   loader,
+				"cancelKey": self.c.UserConfig().Keybinding.Universal.Return.String(),
+			})
+		return
+	}
+
 	self.c.Views().CommitDescription.Subtitle = utils.ResolvePlaceholderString(self.c.Tr.CommitDescriptionSubTitle,
 		map[string]string{
 			"togglePanelKeyBinding": self.c.UserConfig().Keybinding.Universal.TogglePanel.String(),
 			"commitMenuKeybinding":  self.c.UserConfig().Keybinding.CommitMessage.CommitMenu.String(),
 		})
-
-	self.c.Views().CommitDescription.Visible = true
 }
 
 func (self *CommitMessageContext) RenderSubtitle() {

pkg/gui/context/commit_message_context_test.go

@@ -0,0 +1,68 @@
+package context
+
+import (
+	"testing"
+
+	"github.com/jesseduffield/lazygit/pkg/common"
+	"github.com/jesseduffield/lazygit/pkg/config"
+	"github.com/jesseduffield/lazygit/pkg/gocui"
+	guiTypes "github.com/jesseduffield/lazygit/pkg/gui/types"
+	"github.com/jesseduffield/lazygit/pkg/i18n"
+	"github.com/sirupsen/logrus"
+	"github.com/spf13/afero"
+	"github.com/stretchr/testify/assert"
+)
+
+type commitMessageTestGuiCommon struct {
+	guiTypes.IGuiCommon
+	views guiTypes.Views
+}
+
+func (self commitMessageTestGuiCommon) Views() guiTypes.Views {
+	return self.views
+}
+
+func TestCommitMessageGenerationSubtitle(t *testing.T) {
+	userConfig := config.GetDefaultConfig()
+	cmn := &common.Common{
+		Log: logrus.NewEntry(logrus.New()),
+		Tr:  i18n.EnglishTranslationSet(),
+		Fs:  afero.NewMemMapFs(),
+	}
+	cmn.SetUserConfig(userConfig)
+
+	commitMessageView := gocui.NewView("commitMessage", 0, 0, 80, 3, gocui.OutputNormal)
+	commitDescriptionView := gocui.NewView("commitDescription", 0, 4, 80, 10, gocui.OutputNormal)
+	commitMessageView.Editable = true
+	commitDescriptionView.Editable = true
+
+	ctx := NewCommitMessageContext(&ContextCommon{
+		Common: cmn,
+		IGuiCommon: commitMessageTestGuiCommon{views: guiTypes.Views{
+			CommitMessage:     commitMessageView,
+			CommitDescription: commitDescriptionView,
+		}},
+	})
+
+	ctx.SetPanelState(NoCommitIndex, "Commit summary", "Commit description", false, "", nil, nil, false, "")
+	assert.Contains(t, commitDescriptionView.Subtitle, "Press <tab> to toggle focus")
+
+	cancelCalled := false
+	ctx.StartGeneratingCommitMessage(func() {
+		cancelCalled = true
+	})
+
+	assert.False(t, commitMessageView.Editable)
+	assert.False(t, commitDescriptionView.Editable)
+	assert.Contains(t, commitDescriptionView.Subtitle, "Generating commit message")
+	assert.Contains(t, commitDescriptionView.Subtitle, "<esc>")
+
+	assert.True(t, ctx.CancelGenerateCommitMessage())
+	assert.True(t, cancelCalled)
+	assert.Contains(t, commitDescriptionView.Subtitle, "Canceling commit message generation")
+
+	ctx.StopGeneratingCommitMessage()
+	assert.True(t, commitMessageView.Editable)
+	assert.True(t, commitDescriptionView.Editable)
+	assert.Contains(t, commitDescriptionView.Subtitle, "Press <tab> to toggle focus")
+}