Multiple fixes

README.md

@@ -12,6 +12,8 @@ Repository: https://github.com/andydixon/nexus
   - author name, email, and date/time
   - committer name, email, and date/time
   - full commit message
+- Keyboard-driven calendar and time picker for author and committer timestamps
+- Opt-in bulk removal of `Co-authored-by:` trailer lines across commit messages
 - Search commits by hash, message, author name, or email
 - Track edited commits and reset the selected commit
 - Apply all staged metadata changes in one action
@@ -27,20 +29,24 @@ Repository: https://github.com/andydixon/nexus
 - `r`: reload history
 - `x`: reset the selected commit
 - `a`: apply changes
+- `c`: toggle bulk removal of `Co-authored-by:` lines
 - `f`: toggle force push
 - `t`: toggle tag push
 - `?`: show help
 - `q` or `Ctrl+C`: quit
 
+When an author or committer date field is focused, press `Enter` to open the date/time picker. Arrow keys adjust the day and hour, `PgUp`/`PgDn` adjust the month, `+`/`-` adjust by five minutes, and `H`/`L` adjust the year. Use `t` for now, `z` for local time, `u` for UTC, `Enter` to save, or `Esc` to cancel. `Ctrl+T` remains a quick shortcut for setting the focused date to now.
+
 ## Apply Workflow
 
 When you apply changes, Nexus:
 
 1. Checks that the selected repository is clean.
 2. Creates a backup tag (`nexus-backup-<timestamp>`).
-3. Rewrites history with `git filter-branch` across all refs.
+3. Applies timestamp, metadata, message, and optional co-author trailer changes.
-4. Removes temporary rewrite references and runs repository cleanup.
+4. Rewrites history with `git filter-branch` across all refs.
-5. Optionally force pushes branches and tags using `--force-with-lease`.
+5. Removes temporary rewrite references and runs repository cleanup.
+6. Optionally force pushes branches and tags using `--force-with-lease`.
 
 Force push requires an explicit `FORCE` confirmation in the terminal.
 
@@ -67,4 +73,3 @@ History rewriting changes commit hashes and can disrupt shared branches. Coordin
 ## Licence
 
 This project is proprietary software. It is **not** released under the MIT licence.
-

app.go

@@ -7,6 +7,7 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"regexp"
 	"sort"
 	"strings"
 	"sync"
@@ -50,10 +51,12 @@ type ApplyRequest struct {
 	Commits         []CommitRecord `json:"commits"`
 	ForcePush       bool           `json:"forcePush"`
 	PushTags        bool           `json:"pushTags"`
+	RemoveCoAuthors bool           `json:"removeCoAuthors"`
 }
 
 type ApplyResult struct {
 	RewrittenCommits int      `json:"rewrittenCommits"`
+	RemovedCoAuthors int      `json:"removedCoAuthors"`
 	ForcePushed      bool     `json:"forcePushed"`
 	BackupReference  string   `json:"backupReference"`
 	Warnings         []string `json:"warnings"`
@@ -156,18 +159,19 @@ func (a *App) ApplyChanges(req ApplyRequest) (ApplyResult, error) {
 		return ApplyResult{}, err
 	}
 
-	currentByHash := make(map[string]CommitRecord, len(currentHistory))
+	incomingByHash := make(map[string]CommitRecord, len(req.Commits))
-	for _, commit := range currentHistory {
+	for _, incoming := range req.Commits {
-		currentByHash[commit.Hash] = commit
+		incomingByHash[incoming.Hash] = incoming
 	}
 
 	updatedByHash := make(map[string]CommitRecord)
 	messageOverride := make(map[string]bool)
+	removedCoAuthors := 0
 
-	for _, incoming := range req.Commits {
+	for _, current := range currentHistory {
-		current, exists := currentByHash[incoming.Hash]
+		incoming, exists := incomingByHash[current.Hash]
 		if !exists {
-			continue
+			incoming = current
 		}
 
 		normalized, err := normalizeIncomingCommit(incoming, current)
@@ -175,6 +179,13 @@ func (a *App) ApplyChanges(req ApplyRequest) (ApplyResult, error) {
 			return ApplyResult{}, fmt.Errorf("commit %s is invalid: %w", incoming.ShortHash, err)
 		}
 
+		if req.RemoveCoAuthors {
+			var removed int
+			normalized.Message, removed = removeCoAuthorLines(normalized.Message)
+			normalized.Subject = firstLine(normalized.Message)
+			removedCoAuthors += removed
+		}
+
 		if editableFieldsChanged(current, normalized) {
 			updatedByHash[incoming.Hash] = normalized
 			messageOverride[incoming.Hash] = normalizeMessage(current.Message) != normalizeMessage(normalized.Message)
@@ -183,6 +194,7 @@ func (a *App) ApplyChanges(req ApplyRequest) (ApplyResult, error) {
 
 	result := ApplyResult{
 		RewrittenCommits: len(updatedByHash),
+		RemovedCoAuthors: removedCoAuthors,
 		Warnings:         []string{},
 	}
 
@@ -468,17 +480,29 @@ func normalizeIncomingCommit(incoming CommitRecord, current CommitRecord) (Commi
 }
 
 func normalizeGitDate(input string) (string, error) {
+	parsed, err := parseGitDate(input)
+	if err != nil {
+		return "", err
+	}
+	return formatGitDate(parsed), nil
+}
+
+func parseGitDate(input string) (time.Time, error) {
 	date := strings.TrimSpace(input)
 	if date == "" {
-		return "", errors.New("date cannot be empty")
+		return time.Time{}, errors.New("date cannot be empty")
 	}
 
 	layouts := []string{
 		time.RFC3339Nano,
 		time.RFC3339,
+		"2006-01-02 15:04:05 -0700",
+		time.RFC1123Z,
+		time.RFC822Z,
 		"2006-01-02T15:04:05",
 		"2006-01-02T15:04",
 		"2006-01-02 15:04:05",
+		"2006-01-02 15:04",
 	}
 
 	for _, layout := range layouts {
@@ -487,29 +511,58 @@ func normalizeGitDate(input string) (string, error) {
 			err error
 		)
 
-		if layout == time.RFC3339 || layout == time.RFC3339Nano {
+		if strings.Contains(layout, "Z07") || strings.Contains(layout, "-0700") || layout == time.RFC1123Z || layout == time.RFC822Z {
 			t, err = time.Parse(layout, date)
 		} else {
 			t, err = time.ParseInLocation(layout, date, time.Local)
 		}
 		if err == nil {
-			return t.Format("2006-01-02T15:04:05-07:00"), nil
+			return t, nil
 		}
 	}
 
-	return "", errors.New("date must be RFC3339 or YYYY-MM-DDTHH:MM[:SS]")
+	return time.Time{}, errors.New("date must be ISO 8601, a standard Git date, or YYYY-MM-DD HH:MM[:SS]")
+}
+
+func formatGitDate(value time.Time) string {
+	return value.Format("2006-01-02T15:04:05-07:00")
+}
+
+var coAuthorLinePattern = regexp.MustCompile(`(?i)^\s*co-authored(?:-|\s+)by\s*:`)
+
+func removeCoAuthorLines(message string) (string, int) {
+	lines := strings.Split(strings.ReplaceAll(message, "\r\n", "\n"), "\n")
+	kept := make([]string, 0, len(lines))
+	removed := 0
+	for _, line := range lines {
+		if coAuthorLinePattern.MatchString(line) {
+			removed++
+			continue
+		}
+		kept = append(kept, line)
+	}
+	return normalizeMessage(strings.Join(kept, "\n")), removed
 }
 
 func editableFieldsChanged(current CommitRecord, incoming CommitRecord) bool {
 	return current.AuthorName != incoming.AuthorName ||
 		current.AuthorEmail != incoming.AuthorEmail ||
-		current.AuthorDate != incoming.AuthorDate ||
+		!gitDatesEqual(current.AuthorDate, incoming.AuthorDate) ||
 		current.CommitterName != incoming.CommitterName ||
 		current.CommitterEmail != incoming.CommitterEmail ||
-		current.CommitterDate != incoming.CommitterDate ||
+		!gitDatesEqual(current.CommitterDate, incoming.CommitterDate) ||
 		normalizeMessage(current.Message) != normalizeMessage(incoming.Message)
 }
 
+func gitDatesEqual(left string, right string) bool {
+	leftDate, leftErr := normalizeGitDate(left)
+	rightDate, rightErr := normalizeGitDate(right)
+	if leftErr != nil || rightErr != nil {
+		return strings.TrimSpace(left) == strings.TrimSpace(right)
+	}
+	return leftDate == rightDate
+}
+
 func firstLine(message string) string {
 	parts := strings.SplitN(message, "\n", 2)
 	return strings.TrimSpace(parts[0])
@@ -539,7 +592,7 @@ func shellQuote(value string) string {
 
 func runGit(repo string, args ...string) (string, error) {
 	cmd := exec.Command("git", append([]string{"-C", repo}, args...)...)
-	cmd.Env = os.Environ()
+	cmd.Env = append(os.Environ(), "FILTER_BRANCH_SQUELCH_WARNING=1")
 
 	var stdout bytes.Buffer
 	var stderr bytes.Buffer

app_apply_test.go

@@ -124,3 +124,70 @@ func TestRewriteHistoryFailsWhenNoRefsAreRewritten(t *testing.T) {
 		t.Fatalf("unexpected error: %v", err)
 	}
 }
+
+func TestApplyChangesUpdatesDatesAndRemovesCoAuthorTrailers(t *testing.T) {
+	repo := t.TempDir()
+	run := func(args ...string) string {
+		t.Helper()
+		cmd := exec.Command("git", append([]string{"-C", repo}, args...)...)
+		out, err := cmd.CombinedOutput()
+		if err != nil {
+			t.Fatalf("git %v failed: %v\n%s", args, err, string(out))
+		}
+		return string(out)
+	}
+
+	run("init")
+	run("config", "user.name", "Original User")
+	run("config", "user.email", "original@example.com")
+	if err := os.WriteFile(filepath.Join(repo, "a.txt"), []byte("one\n"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	run("add", "a.txt")
+	run("commit", "-m", "subject", "-m", "Context: Co-authored-by: stays because it is prose.\n\nCo-authored-by: One <one@example.com>\nco-authored by: Two <two@example.com>")
+
+	app := NewApp()
+	if _, err := app.SetRepository(repo); err != nil {
+		t.Fatal(err)
+	}
+	history, err := app.LoadHistory()
+	if err != nil {
+		t.Fatal(err)
+	}
+	history[0].AuthorDate = "2020-06-15 09:30:45 +0530"
+	history[0].CommitterDate = "Mon, 15 Jun 2020 04:00:45 +0000"
+
+	result, err := app.ApplyChanges(ApplyRequest{Commits: history, RemoveCoAuthors: true})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if result.RemovedCoAuthors != 2 {
+		t.Fatalf("expected two removed co-author lines, got %d", result.RemovedCoAuthors)
+	}
+
+	log := run("log", "-1", "--pretty=format:%aI%x1f%cI%x1f%B")
+	fields := strings.SplitN(log, "\x1f", 3)
+	if len(fields) != 3 || !gitDatesEqual(fields[0], "2020-06-15T09:30:45+05:30") || !gitDatesEqual(fields[1], "2020-06-15T04:00:45Z") {
+		t.Fatalf("expected exact rewritten dates, got: %s", log)
+	}
+	if strings.Contains(strings.ToLower(log), "co-authored-by: one") || strings.Contains(strings.ToLower(log), "co-authored by: two") {
+		t.Fatalf("expected trailer lines to be removed, got: %s", log)
+	}
+	if !strings.Contains(log, "Context: Co-authored-by: stays because it is prose.") {
+		t.Fatalf("expected non-trailer prose to remain, got: %s", log)
+	}
+}
+
+func TestRemoveCoAuthorLinesOnlyMatchesWholeTrailerLines(t *testing.T) {
+	message := "subject\r\n\r\nCo-authored-by: Ada <ada@example.com>\r\n  CO-AUTHORED BY: Grace <grace@example.com>\r\nNote: Co-authored-by: this is prose"
+	cleaned, removed := removeCoAuthorLines(message)
+	if removed != 2 {
+		t.Fatalf("expected two removed lines, got %d", removed)
+	}
+	if strings.Contains(cleaned, "Ada") || strings.Contains(cleaned, "Grace") {
+		t.Fatalf("expected co-author trailers to be removed: %q", cleaned)
+	}
+	if !strings.Contains(cleaned, "Note: Co-authored-by: this is prose") {
+		t.Fatalf("expected ordinary prose to remain: %q", cleaned)
+	}
+}

tui.go

@@ -40,6 +40,7 @@ const (
 	overlayConfirmApply
 	overlayConfirmForce
 	overlayHelp
+	overlayDatePicker
 )
 
 type statusKind string
@@ -145,9 +146,12 @@ type tuiModel struct {
 	searchInput      textinput.Model
 	pathInput        textinput.Model
 	confirmInput     textinput.Model
+	datePickerTime   time.Time
+	datePickerTarget int
 
 	forcePush       bool
 	pushTags        bool
+	removeCoAuthors bool
 	busy            bool
 
 	status     string
@@ -283,6 +287,7 @@ func (m *tuiModel) handleApplyFinished(msg applyFinishedMsg) {
 		m.repoLoaded = true
 	}
 	if msg.commits != nil {
+		m.removeCoAuthors = false
 		m.commits = newestFirst(msg.commits)
 		m.originalByHash = mapByHash(m.commits)
 		m.draftByHash = cloneMapByHash(m.commits)
@@ -315,6 +320,8 @@ func (m tuiModel) handleKey(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
 		return m.updatePathEntry(msg)
 	case overlayConfirmApply, overlayConfirmForce:
 		return m.updateConfirmation(msg)
+	case overlayDatePicker:
+		return m.updateDatePicker(msg)
 	}
 
 	if m.focus == focusForm {
@@ -347,6 +354,10 @@ func (m tuiModel) handleKey(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
 	case "t":
 		m.pushTags = !m.pushTags
 		m.setStatus(fmt.Sprintf("Push tags %s", onOff(m.pushTags)), statusInfo)
+	case "c":
+		m.removeCoAuthors = !m.removeCoAuthors
+		count, lines := coAuthorCleanupImpact(m.commits, m.draftByHash)
+		m.setStatus(fmt.Sprintf("Co-author cleanup %s: %d line%s across %d commit%s", onOff(m.removeCoAuthors), lines, plural(lines), count, plural(count)), statusInfo)
 	case "a":
 		return m.beginApply()
 	case "x":
@@ -451,12 +462,35 @@ func (m tuiModel) updateConfirmation(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
 func (m tuiModel) updateForm(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
 	key := msg.String()
 	switch key {
+	case "enter":
+		if m.formFocus == formAuthorDate || m.formFocus == formCommitterDate {
+			selected, err := parseGitDate(m.inputs[m.formFocus].Value())
+			if err != nil {
+				m.setStatus(fmt.Sprintf("Cannot open date picker: %v", err), statusError)
+				return m, nil
+			}
+			m.datePickerTime = selected
+			m.datePickerTarget = m.formFocus
+			m.overlay = overlayDatePicker
+			m.blurForm()
+			m.setStatus("Date/time picker opened.", statusInfo)
+			return m, nil
+		}
+	case "ctrl+t":
+		if m.formFocus == formAuthorDate || m.formFocus == formCommitterDate {
+			m.inputs[m.formFocus].SetValue(time.Now().Format("2006-01-02T15:04:05-07:00"))
+			m.syncFormToDraft()
+			m.setStatus("Updated the focused date/time to now.", statusInfo)
+		}
+		return m, nil
 	case "esc":
+		m.normalizeFocusedDateInput()
 		m.syncFormToDraft()
 		m.focus = focusList
 		m.blurForm()
 		return m, nil
 	case "tab", "shift+tab":
+		m.normalizeFocusedDateInput()
 		m.syncFormToDraft()
 		next, returnToList := nextFormFocus(m.formFocus, key == "shift+tab")
 		if returnToList {
@@ -478,6 +512,50 @@ func (m tuiModel) updateForm(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
 	return m, cmd
 }
 
+func (m tuiModel) updateDatePicker(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
+	switch msg.String() {
+	case "esc":
+		m.overlay = overlayNone
+		m.focusFormField(m.datePickerTarget)
+		m.setStatus("Date/time change cancelled.", statusInfo)
+	case "enter":
+		m.inputs[m.datePickerTarget].SetValue(formatGitDate(m.datePickerTime))
+		m.overlay = overlayNone
+		m.focusFormField(m.datePickerTarget)
+		m.syncFormToDraft()
+		m.setStatus("Date/time updated.", statusInfo)
+	case "left", "h":
+		m.datePickerTime = m.datePickerTime.AddDate(0, 0, -1)
+	case "right", "l":
+		m.datePickerTime = m.datePickerTime.AddDate(0, 0, 1)
+	case "up", "k":
+		m.datePickerTime = m.datePickerTime.Add(time.Hour)
+	case "down", "j":
+		m.datePickerTime = m.datePickerTime.Add(-time.Hour)
+	case "pgup", "[":
+		m.datePickerTime = shiftCalendarMonth(m.datePickerTime, -1)
+	case "pgdown", "]":
+		m.datePickerTime = shiftCalendarMonth(m.datePickerTime, 1)
+	case "shift+left", "H":
+		m.datePickerTime = shiftCalendarYear(m.datePickerTime, -1)
+	case "shift+right", "L":
+		m.datePickerTime = shiftCalendarYear(m.datePickerTime, 1)
+	case "-", "_":
+		m.datePickerTime = m.datePickerTime.Add(-5 * time.Minute)
+	case "+", "=":
+		m.datePickerTime = m.datePickerTime.Add(5 * time.Minute)
+	case "t":
+		m.datePickerTime = time.Now()
+	case "u":
+		m.datePickerTime = sameWallClockIn(m.datePickerTime, time.UTC)
+	case "z":
+		m.datePickerTime = sameWallClockIn(m.datePickerTime, time.Local)
+	case "0":
+		m.datePickerTime = m.datePickerTime.Add(-time.Duration(m.datePickerTime.Second()) * time.Second)
+	}
+	return m, nil
+}
+
 func (m tuiModel) beginApply() (tea.Model, tea.Cmd) {
 	if !m.repoLoaded {
 		m.setStatus("Load a repository before applying changes.", statusError)
@@ -485,9 +563,13 @@ func (m tuiModel) beginApply() (tea.Model, tea.Cmd) {
 	}
 
 	m.syncFormToDraft()
-	count := dirtyCommitCount(m.commits, m.originalByHash, m.draftByHash)
+	if err := validateDraftDates(m.commits, m.draftByHash); err != nil {
+		m.setStatus(err.Error(), statusError)
+		return m, nil
+	}
+	count := plannedRewriteCount(m.commits, m.originalByHash, m.draftByHash, m.removeCoAuthors)
 	if count == 0 && !m.forcePush {
-		m.setStatus("No history edits to apply.", statusInfo)
+		m.setStatus("No history edits or co-author lines to apply.", statusInfo)
 		return m, nil
 	}
 
@@ -561,7 +643,7 @@ func (m tuiModel) renderTopBar(width int) string {
 		repoText = fmt.Sprintf("%s  %s  %s", filepath.Base(m.repository.Path), branch, clean)
 	}
 
-	flags := fmt.Sprintf("force:%s tags:%s edits:%d", onOff(m.forcePush), onOff(m.pushTags), dirtyCommitCount(m.commits, m.originalByHash, m.draftByHash))
+	flags := fmt.Sprintf("force:%s tags:%s coauthors:%s edits:%d", onOff(m.forcePush), onOff(m.pushTags), onOff(m.removeCoAuthors), plannedRewriteCount(m.commits, m.originalByHash, m.draftByHash, m.removeCoAuthors))
 	if m.busy {
 		flags = "working..."
 	}
@@ -599,9 +681,9 @@ func (m tuiModel) renderBottomBar(width int) string {
 	}
 
 	status := lipgloss.NewStyle().Foreground(statusColor).Render(truncateText(m.status, contentWidth))
-	help := "Tab form/list  / search  p path  r reload  x reset  a apply  f force  t tags  ? help  q quit"
+	help := "Tab form/list  / search  p path  r reload  x reset  a apply  c co-authors  f force  t tags  ? help  q quit"
 	if m.focus == focusForm {
-		help = "Tab next field  Shift+Tab previous  Esc list  Enter newline in message  Ctrl+C quit"
+		help = "Tab next field  Shift+Tab previous  Ctrl+T set focused date to now  Esc list  Ctrl+C quit"
 	}
 	if m.overlay == overlayPath {
 		help = "Enter load repository  Esc close"
@@ -612,6 +694,9 @@ func (m tuiModel) renderBottomBar(width int) string {
 	if m.overlay == overlayConfirmForce {
 		help = "Type FORCE then Enter to rewrite and force push, Esc to cancel"
 	}
+	if m.overlay == overlayDatePicker {
+		help = "←/→ day  ↑/↓ hour  PgUp/PgDn month  +/- 5 min  H/L year  t now  z local  u UTC  Enter save  Esc cancel"
+	}
 
 	return barStyle.Render(status + "\n" + dimStyle.Render(truncateText(help, contentWidth)))
 }
@@ -706,6 +791,8 @@ func (m tuiModel) renderDetailPane(width int, height int) string {
 		content = m.renderConfirmPane(innerWidth, innerHeight)
 	case overlayHelp:
 		content = m.renderHelpPane(innerWidth, innerHeight)
+	case overlayDatePicker:
+		content = m.renderDatePickerPane(innerWidth, innerHeight)
 	default:
 		content = m.renderFormPane(innerWidth, innerHeight)
 	}
@@ -713,6 +800,38 @@ func (m tuiModel) renderDetailPane(width int, height int) string {
 	return renderBox(style, width, height, content)
 }
 
+func (m tuiModel) renderDatePickerPane(width int, height int) string {
+	target := "Author date"
+	if m.datePickerTarget == formCommitterDate {
+		target = "Committer date"
+	}
+	zoneName, offset := m.datePickerTime.Zone()
+	if zoneName == "" {
+		zoneName = formatZoneOffset(offset)
+	} else {
+		zoneName = fmt.Sprintf("%s (%s)", zoneName, formatZoneOffset(offset))
+	}
+
+	lines := []string{
+		headerStyle.Render("Date & Time Picker"),
+		mutedStyle.Render(target),
+		"",
+		lipgloss.NewStyle().Bold(true).Foreground(colorGreen).Render(m.datePickerTime.Format("Monday, 02 January 2006")),
+		lipgloss.NewStyle().Bold(true).Foreground(colorCyan).Render(m.datePickerTime.Format("15:04:05") + "  " + zoneName),
+		"",
+	}
+	lines = append(lines, renderMonthCalendar(m.datePickerTime)...)
+	lines = append(lines,
+		"",
+		"←/→ or h/l  day        ↑/↓ or k/j  hour",
+		"PgUp/PgDn or [/]  month   H/L  year   +/-  five minutes",
+		"t  now    z  local timezone    u  UTC    0  clear seconds",
+		"",
+		dimStyle.Render("Enter saves the selection. Esc keeps the original timestamp."),
+	)
+	return fitLines(lines, height, width)
+}
+
 func (m tuiModel) renderPathPane(width int, height int) string {
 	lines := []string{
 		headerStyle.Render("Open Repository"),
@@ -727,12 +846,16 @@ func (m tuiModel) renderPathPane(width int, height int) string {
 }
 
 func (m tuiModel) renderConfirmPane(width int, height int) string {
-	count := dirtyCommitCount(m.commits, m.originalByHash, m.draftByHash)
+	count := plannedRewriteCount(m.commits, m.originalByHash, m.draftByHash, m.removeCoAuthors)
+	coAuthorCommits, coAuthorLines := coAuthorCleanupImpact(m.commits, m.draftByHash)
 	lines := []string{
 		headerStyle.Render("Confirm Rewrite"),
 		"",
 		fmt.Sprintf("This will rewrite Git history for %d edited commit%s. A backup tag will be created first.", count, plural(count)),
 	}
+	if m.removeCoAuthors {
+		lines = append(lines, "", fmt.Sprintf("Co-author cleanup will remove %d matching line%s from %d commit%s.", coAuthorLines, plural(coAuthorLines), coAuthorCommits, plural(coAuthorCommits)))
+	}
 
 	if m.forcePush {
 		lines = append(lines,
@@ -757,7 +880,8 @@ func (m tuiModel) renderHelpPane(width int, height int) string {
 		"Tab moves from the list into the commit form.",
 		"Form: Tab and Shift+Tab move through every editable value. Esc returns to the list.",
 		"/ searches commits. p opens a repository path prompt. r reloads history.",
-		"x resets the selected commit. a applies edits. f toggles force push. t toggles tag push.",
+		"x resets the selected commit. a applies edits. c toggles bulk Co-authored-by cleanup.",
+		"f toggles force push. t toggles tag push. Ctrl+T stamps the focused date field with the current local time.",
 		"",
 		headerStyle.Render("Safety"),
 		"",
@@ -1004,6 +1128,15 @@ func (m *tuiModel) syncFormToDraft() {
 	m.draftByHash[m.selectedHash] = draft
 }
 
+func (m *tuiModel) normalizeFocusedDateInput() {
+	if m.formFocus != formAuthorDate && m.formFocus != formCommitterDate {
+		return
+	}
+	if normalized, err := normalizeGitDate(m.inputs[m.formFocus].Value()); err == nil {
+		m.inputs[m.formFocus].SetValue(normalized)
+	}
+}
+
 func (m *tuiModel) resetSelectedCommit() {
 	if m.selectedHash == "" {
 		return
@@ -1030,6 +1163,7 @@ func (m tuiModel) applyRequest() ApplyRequest {
 		Commits:         commits,
 		ForcePush:       m.forcePush,
 		PushTags:        m.pushTags,
+		RemoveCoAuthors: m.removeCoAuthors,
 	}
 }
 
@@ -1146,6 +1280,46 @@ func dirtyCommitCount(commits []CommitRecord, originalByHash map[string]CommitRe
 	return count
 }
 
+func plannedRewriteCount(commits []CommitRecord, originalByHash map[string]CommitRecord, draftByHash map[string]CommitRecord, removeCoAuthors bool) int {
+	count := 0
+	for _, commit := range commits {
+		dirty := commitDirty(commit.Hash, originalByHash, draftByHash)
+		draft := draftByHash[commit.Hash]
+		_, coAuthorLines := removeCoAuthorLines(draft.Message)
+		if dirty || (removeCoAuthors && coAuthorLines > 0) {
+			count++
+		}
+	}
+	return count
+}
+
+func coAuthorCleanupImpact(commits []CommitRecord, draftByHash map[string]CommitRecord) (int, int) {
+	commitCount := 0
+	lineCount := 0
+	for _, commit := range commits {
+		draft := draftByHash[commit.Hash]
+		_, removed := removeCoAuthorLines(draft.Message)
+		if removed > 0 {
+			commitCount++
+			lineCount += removed
+		}
+	}
+	return commitCount, lineCount
+}
+
+func validateDraftDates(commits []CommitRecord, draftByHash map[string]CommitRecord) error {
+	for _, commit := range commits {
+		draft := draftByHash[commit.Hash]
+		if _, err := normalizeGitDate(draft.AuthorDate); err != nil {
+			return fmt.Errorf("commit %s has an invalid author date: %v", draft.ShortHash, err)
+		}
+		if _, err := normalizeGitDate(draft.CommitterDate); err != nil {
+			return fmt.Errorf("commit %s has an invalid committer date: %v", draft.ShortHash, err)
+		}
+	}
+	return nil
+}
+
 func commitDirty(hash string, originalByHash map[string]CommitRecord, draftByHash map[string]CommitRecord) bool {
 	original, hasOriginal := originalByHash[hash]
 	draft, hasDraft := draftByHash[hash]
@@ -1273,6 +1447,61 @@ func formatCommitTime(value string) string {
 	return parsed.Local().Format("2006-01-02 15:04")
 }
 
+func sameWallClockIn(value time.Time, location *time.Location) time.Time {
+	return time.Date(value.Year(), value.Month(), value.Day(), value.Hour(), value.Minute(), value.Second(), value.Nanosecond(), location)
+}
+
+func shiftCalendarMonth(value time.Time, months int) time.Time {
+	targetMonth := time.Date(value.Year(), value.Month()+time.Month(months), 1, value.Hour(), value.Minute(), value.Second(), value.Nanosecond(), value.Location())
+	day := minInt(value.Day(), targetMonth.AddDate(0, 1, -1).Day())
+	return time.Date(targetMonth.Year(), targetMonth.Month(), day, value.Hour(), value.Minute(), value.Second(), value.Nanosecond(), value.Location())
+}
+
+func shiftCalendarYear(value time.Time, years int) time.Time {
+	targetYear := value.Year() + years
+	lastDay := time.Date(targetYear, value.Month()+1, 0, value.Hour(), value.Minute(), value.Second(), value.Nanosecond(), value.Location()).Day()
+	return time.Date(targetYear, value.Month(), minInt(value.Day(), lastDay), value.Hour(), value.Minute(), value.Second(), value.Nanosecond(), value.Location())
+}
+
+func formatZoneOffset(offsetSeconds int) string {
+	sign := "+"
+	if offsetSeconds < 0 {
+		sign = "-"
+		offsetSeconds = -offsetSeconds
+	}
+	return fmt.Sprintf("%s%02d:%02d", sign, offsetSeconds/3600, (offsetSeconds%3600)/60)
+}
+
+func renderMonthCalendar(selected time.Time) []string {
+	first := time.Date(selected.Year(), selected.Month(), 1, 0, 0, 0, 0, selected.Location())
+	leading := (int(first.Weekday()) + 6) % 7
+	daysInMonth := first.AddDate(0, 1, -1).Day()
+
+	lines := []string{
+		lipgloss.NewStyle().Bold(true).Foreground(colorMagenta).Render(selected.Format("January 2006")),
+		dimStyle.Render("Mo Tu We Th Fr Sa Su"),
+	}
+	week := make([]string, 7)
+	for day := 1; day <= daysInMonth; day++ {
+		position := leading + day - 1
+		cell := fmt.Sprintf("%2d", day)
+		if day == selected.Day() {
+			cell = lipgloss.NewStyle().Bold(true).Foreground(colorPanel).Background(colorCyan).Render(cell)
+		}
+		week[position%7] = cell
+		if position%7 == 6 || day == daysInMonth {
+			for index := range week {
+				if week[index] == "" {
+					week[index] = "  "
+				}
+			}
+			lines = append(lines, strings.Join(week, " "))
+			week = make([]string, 7)
+		}
+	}
+	return lines
+}
+
 func applyResultSummary(result ApplyResult) string {
 	parts := []string{}
 	if result.RewrittenCommits == 0 {
@@ -1283,6 +1512,9 @@ func applyResultSummary(result ApplyResult) string {
 	if result.BackupReference != "" {
 		parts = append(parts, "Backup "+result.BackupReference+".")
 	}
+	if result.RemovedCoAuthors > 0 {
+		parts = append(parts, fmt.Sprintf("Removed %d co-author line%s.", result.RemovedCoAuthors, plural(result.RemovedCoAuthors)))
+	}
 	if result.ForcePushed {
 		parts = append(parts, "Force push completed.")
 	}

tui_test.go

@@ -5,7 +5,9 @@ import (
 	"path/filepath"
 	"strings"
 	"testing"
+	"time"
 
+	tea "github.com/charmbracelet/bubbletea"
 	"github.com/charmbracelet/lipgloss"
 )
 
@@ -147,6 +149,58 @@ func TestViewFitsTerminalDimensions(t *testing.T) {
 	}
 }
 
+func TestDatePickerOpensAndSavesFromDateField(t *testing.T) {
+	model := newTUIModel(NewApp(), "/tmp/repo")
+	commit := CommitRecord{
+		Hash: "one", ShortHash: "one", AuthorName: "A", AuthorEmail: "a@example.com",
+		AuthorDate: "2024-01-02T10:00:00+00:00", CommitterName: "A", CommitterEmail: "a@example.com",
+		CommitterDate: "2024-01-02T10:00:00+00:00", Message: "subject",
+	}
+	model.handleRepoLoaded(repoLoadedMsg{repo: RepositoryState{Path: "/tmp/repo"}, commits: []CommitRecord{commit}})
+	model.focus = focusForm
+	model.focusFormField(formAuthorDate)
+
+	updated, _ := model.updateForm(tea.KeyMsg{Type: tea.KeyEnter})
+	model = updated.(tuiModel)
+	if model.overlay != overlayDatePicker {
+		t.Fatalf("expected date picker overlay, got %v", model.overlay)
+	}
+
+	model.datePickerTime = time.Date(2025, time.March, 4, 12, 35, 45, 0, time.FixedZone("test", 90*60))
+	updated, _ = model.updateDatePicker(tea.KeyMsg{Type: tea.KeyEnter})
+	model = updated.(tuiModel)
+	if got := model.draftByHash["one"].AuthorDate; got != "2025-03-04T12:35:45+01:30" {
+		t.Fatalf("expected selected date to be saved, got %q", got)
+	}
+}
+
+func TestPlannedRewriteCountIncludesCoAuthorCleanup(t *testing.T) {
+	commits := []CommitRecord{
+		{Hash: "one", Message: "subject\n\nCo-authored-by: A <a@example.com>"},
+		{Hash: "two", Message: "another subject"},
+	}
+	original := mapByHash(commits)
+	drafts := cloneMapByHash(commits)
+
+	if got := plannedRewriteCount(commits, original, drafts, false); got != 0 {
+		t.Fatalf("expected no planned rewrites with cleanup disabled, got %d", got)
+	}
+	if got := plannedRewriteCount(commits, original, drafts, true); got != 1 {
+		t.Fatalf("expected one planned cleanup rewrite, got %d", got)
+	}
+}
+
+func TestCalendarShiftsClampToValidDays(t *testing.T) {
+	jan31 := time.Date(2024, time.January, 31, 9, 15, 30, 0, time.UTC)
+	if got := shiftCalendarMonth(jan31, 1); got != time.Date(2024, time.February, 29, 9, 15, 30, 0, time.UTC) {
+		t.Fatalf("expected leap-year February to clamp to the 29th, got %s", got)
+	}
+	leapDay := time.Date(2024, time.February, 29, 9, 15, 30, 0, time.UTC)
+	if got := shiftCalendarYear(leapDay, 1); got != time.Date(2025, time.February, 28, 9, 15, 30, 0, time.UTC) {
+		t.Fatalf("expected non-leap year to clamp to 28 February, got %s", got)
+	}
+}
+
 func maxRenderedLineWidth(value string) int {
 	width := 0
 	for _, line := range strings.Split(value, "\n") {