Show the pin, tip and checkout as a spine in the detail pane

Replace the Pinned/Checkout/Tip rows and the list of commits between pin
and tip with one line of history, newest on top: a node per commit with
its roles (pin, tip, you, staged, HEAD) and the number of commits between
two nodes. A staged pin shows the committed pin as its own node and notes
when it moves back. All three on one commit read "in sync".

Add Status.Drift, Committed and CommittedDrift and Status.Spine(); drop
Status.Between and Repo.FetchedAt. The fetch age moves from the header to
the detail pane (right-aligned in the name's line). The header summary is
right-aligned, ordered by importance and cut with an ellipsis if too narrow.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

internal/tui/header/header.go

@@ -3,9 +3,10 @@ package header
 
 import (
 	"fmt"
-	"time"
+	"strings"
 
 	"github.com/charmbracelet/lipgloss"
+	"github.com/charmbracelet/x/ansi"
 
 	"submarine/internal/submodule"
 	"submarine/internal/tui/theme"
@@ -14,10 +15,9 @@ import (
 // Fetch is the progress of the application's own background fetch.
 type Fetch struct {
 	Running bool
-	Done    int       // repositories fetched (or failed)
-	Total   int       // repositories to fetch
-	Failed  int       // failed fetches of the last run
-	At      time.Time // when the last run finished
+	Done    int // repositories fetched (or failed)
+	Total   int // repositories to fetch
+	Failed  int // failed fetches of the last run
 }
 
 // View renders repo info, state counts and fetch state on one line. spinner
@@ -65,47 +65,44 @@ func View(t theme.Theme, repo *submodule.Repo, fetch Fetch, spinner string, widt
 		}
 	})
 
+	// most important first: errors, issues by severity, staged pins, then the
+	// total
 	sep := seg(t.Muted, " · ")
-	mid := seg(t.Muted, fmt.Sprintf("%d submodules", total))
+	var parts []string
 	if errored > 0 {
-		mid += sep + t.LevelStyle(submodule.LevelDanger, bar).Render(fmt.Sprintf("%d error", errored))
+		parts = append(parts, t.LevelStyle(submodule.LevelDanger, bar).Render(fmt.Sprintf("%d error", errored)))
 	}
 	for _, k := range []submodule.IssueKind{
 		submodule.IssueUnpushed, submodule.IssueConflict, submodule.IssueMissing,
 		submodule.IssueOffPin, submodule.IssueChanged,
 	} {
 		if n := perKind[k]; n > 0 {
-			mid += sep + t.LevelStyle(level[k], bar).Render(fmt.Sprintf("%d %s", n, theme.IssueWord(k)))
+			parts = append(parts, t.LevelStyle(level[k], bar).Render(fmt.Sprintf("%d %s", n, theme.IssueWord(k))))
 		}
 	}
 	if staged > 0 {
-		mid += sep + seg(t.Info, fmt.Sprintf("%d pin staged", staged))
+		parts = append(parts, seg(t.Info, fmt.Sprintf("%d pin staged", staged)))
 	}
 	if loading > 0 {
-		mid += sep + seg(t.Muted, fmt.Sprintf("%d loading", loading))
+		parts = append(parts, seg(t.Muted, fmt.Sprintf("%d loading", loading)))
 	}
+	parts = append(parts, seg(t.Muted, fmt.Sprintf("%d submodules", total)))
+	mid := strings.Join(parts, sep)
 
-	var right string
+	// the summary and the fetch state form one group at the right edge
+	right := mid
 	switch {
 	case fetch.Running:
-		right = seg(t.Primary, spinner) + seg(t.Muted, fmt.Sprintf(" fetching %d/%d ", fetch.Done, fetch.Total))
-	default:
-		// our own fetch may have finished before the watcher saw FETCH_HEAD
-		at := repo.FetchedAt
-		if fetch.At.After(at) {
-			at = fetch.At
-		}
-		right = seg(t.Muted, "fetched "+theme.Ago(at))
-		if fetch.Failed > 0 {
-			right += seg(t.Muted, " · ") + seg(t.Warn, fmt.Sprintf("%d failed", fetch.Failed))
-		}
-		right += seg(t.Muted, " ")
+		right += sep + seg(t.Primary, spinner) + seg(t.Muted, fmt.Sprintf(" fetching %d/%d", fetch.Done, fetch.Total))
+	case fetch.Failed > 0:
+		right += sep + seg(t.Warn, fmt.Sprintf("%d failed", fetch.Failed))
 	}
+	right += seg(t.Muted, " ")
 
-	gap := width - lipgloss.Width(left) - lipgloss.Width(mid) - lipgloss.Width(right)
+	gap := width - lipgloss.Width(left) - lipgloss.Width(right)
 	if gap < 4 {
-		return bar.Width(width).MaxWidth(width).Render(left + seg(t.Text, "   ") + mid)
+		// too narrow: the least important part, on the right, is cut
+		return bar.Width(width).Render(ansi.Truncate(left+seg(t.Text, "   ")+mid, width, "…"))
 	}
-	sp := func(n int) string { return bar.Render(fmt.Sprintf("%*s", n, "")) }
-	return left + sp(gap/2) + mid + sp(gap-gap/2) + right
+	return left + bar.Render(fmt.Sprintf("%*s", gap, "")) + right
 }