Resolve pins to the closest branch

A pin on a pushed feature branch showed as diverged from origin/main
because the .gitmodules branch won before any distance was compared.

Now the branch containing the pin with the fewest commits after it wins;
the .gitmodules branch, the upstream and the remote default branch only
break ties and are always compared. An unpushed pin compares just those
preferred refs by commits on either side.

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

docs/architecture.md

@@ -31,7 +31,7 @@ internal/tui/                 Bubble Tea application
   tree/                       tree component: rows, navigation, mouse, view
   detail/                     detail pane; changes.go: change preview
   header/                     header line
-  footer/                     help and flash messages
+  footer/                     key bar (navigation left, global right) and flash messages
 ```
 
 ### Layering rules
@@ -64,6 +64,12 @@ type Watcher interface {
 }
 ```
 
+```go
+type Locator interface {
+    Dir(path string) string                    // absolute directory, "" if unknown
+}
+```
+
 - `Tree` returns the superproject and all submodules with `Parent` and
   `Children` linked. `Status` fields are nil.
 - `Status` is called once per submodule, concurrently. It must be safe to

docs/decisions.md

@@ -7,7 +7,8 @@ Each entry: context, decision, consequences. Newest last.
 **Context.** Hashes don't tell users whether a pin is current.
 **Decision.** Resolve each pin to a ref and show the distance (`origin/main ↓1`).
 The resolution order is fixed and the applied rule is shown in the detail pane
-(see [state-model.md](state-model.md#resolving-a-pin-to-a-ref)).
+(see [state-model.md](state-model.md#resolving-a-pin-to-a-ref); amended:
+the closest branch wins, see "Pin resolves to the closest branch").
 **Consequences.** Resolution is a heuristic; showing the rule keeps it
 transparent.
 
@@ -200,3 +201,33 @@ package so versions stay clean.
 corrupt or partial downloads, not a compromised registry (no signatures).
 The update check is a deliberate, outside-the-provider network use: only
 on `update` and a once-a-day background check that can be disabled.
+
+## Copy path with `c` via OSC 52
+
+`c` copies the selected submodule's absolute directory (optional
+`submodule.Locator`; the relative path as fallback). The absolute path is
+what a shell needs (`cd <paste>`). OSC 52 instead of a clipboard tool
+(`xclip`, `pbcopy`): no external dependency and it works over SSH. The cost:
+terminals that block OSC 52 copy nothing silently; the footer still says
+`copied`, since the application can't know.
+
+## Key groups: global, navigation, submodule
+
+Keys that act on the selected submodule (copy path, later checkout, bump) are
+shown in a palette in the detail pane, next to what they act on; global keys
+(`?`, `q`) sit right in the footer. Where the pane can't show the palette
+(hidden below 90 columns, or under 12 lines) the footer shows these keys
+instead, so small terminals need no extra UI (no overlay or action menu).
+Keys never depend on what is visible.
+
+## Pin resolves to the closest branch
+
+A pin on a pushed feature branch showed as diverged from `origin/main`,
+because `branch = main` in `.gitmodules` won before any distance was looked
+at. Now the closest branch containing the pin wins; the `.gitmodules`
+branch, the upstream and the remote default branch only break ties (and are
+always compared, even past the 16-branch cap). An unpushed pin compares only
+those preferred refs, by commits on either side: scanning every branch's
+merge base would be too slow. Cost: a pin on main far behind its tip shows a
+younger branch that contains it if that branch's tip is closer, so "n behind
+main" is no longer visible there; `via <rule>` still tells which ref it is.

docs/state-model.md

@@ -104,17 +104,30 @@ A descendant whose load failed (`error`) counts as one danger.
 ## Resolving a pin to a ref
 
 The pin is displayed as a ref, not a hash. A commit can be on several
-branches, on none, or deep in the history, so the git provider resolves it by
+branches, on none, or deep in the history. The git provider shows the
-this order and records which rule applied in `PinInfo.Source`:
+**closest** branch and records which rule proposed it in `PinInfo.Source`.
+
+Preferred refs, in this order (each only if it exists):
+
+| Preference | Ref | `RefSource` |
+|---|---|---|
+| a | `branch = …` in `.gitmodules` | `RefFromGitmodules` |
+| b | Upstream of the branch checked out in the submodule | `RefFromCurrentBranch` |
+| c | Remote default branch (`<remote>/HEAD`) | `RefFromDefaultBranch` |
+
+Resolution:
 
 | # | Rule | `RefSource` |
 |---|---|---|
-| 1 | `branch = …` in `.gitmodules` | `RefFromGitmodules` |
+| 1 | Pin pushed: the branch containing the pin with the fewest commits after it. Candidates are the preferred refs that contain the pin plus any remote branch containing it (`for-each-ref --contains`); a tie goes to the preferred ref | preferred ref's, else `RefFromContains` |
-| 2 | Branch currently checked out in the submodule | `RefFromCurrentBranch` |
+| 2 | Pin unpushed: the preferred ref with the fewest commits on either side (`↑n↓m`), ties by preference | preferred ref's |
-| 3 | Remote default branch, if it contains the pin | `RefFromDefaultBranch` |
+| 3 | A tag (`git describe`) | `RefFromTag` |
-| 4 | Any remote branch containing the pin, preferring the closest tip (`git branch -r --contains`) | `RefFromContains` |
+| 4 | Short SHA | `RefFromSHA` |
-| 5 | A tag (`git describe`) | `RefFromTag` |
+
-| 6 | Short SHA | `RefFromSHA` |
+So a `.gitmodules` branch is shown when it is as close as any other branch,
+but a pin that sits on a feature branch shows that branch rather than
+"diverged from main". The trade-off: a pin on main that a younger branch
+also contains shows the younger branch if its tip is fewer commits away.
 
 Distances: `git rev-list --left-right --count <pin>...<ref>` gives
 `Ahead` (left) and `Behind` (right).
@@ -143,12 +156,13 @@ are local; `<pin>` is the index gitlink.
 
 Details:
 
-- Rule 1: `branch = .` means the superproject's current branch. The rule
+- Preference a: `branch = .` means the superproject's current branch. The
-  applies only if `<remote>/<branch>` exists locally.
+  ref counts only if `<remote>/<branch>` exists locally.
-- Rule 2 uses the checked-out branch's upstream (`<branch>@{upstream}`).
+- Preference b uses the checked-out branch's upstream (`<branch>@{upstream}`).
-- Rule 4 compares at most 16 containing branches (oldest tip first) and
+- Rule 1 counts `rev-list --count <pin>..<ref>`. Besides the preferred refs
-  picks the one with the fewest commits after the pin.
+  it compares at most 16 containing branches (oldest tip first).
-- Rule 6 shows the short SHA; there is no tip and no distance.
+- Rule 2 counts `rev-list --count <pin>...<ref>`.
+- Rule 4 shows the short SHA; there is no tip and no distance.
 - `--ignore-submodules=dirty`: changes inside a nested submodule do not make
   its parent `changed` (D7), but a moved nested pin does.
 - Renames are detected only for staged moves (`git mv`); an unstaged move

docs/ux-guide.md

@@ -36,6 +36,21 @@
 | Detail pane | 40% of the width, at least 36 columns; hidden below 90 columns |
 | Footer | 1 line (more with full help) |
 
+### Key bar and palette
+
+Keys come in three groups (`keyMap.Navigation`, `.Submodule`, `.Global`):
+
+- **Navigation** (move, fold, toggle): left in the footer.
+- **Global** (`?`, `q`): right-aligned in the footer, always kept.
+- **Submodule** (act on the selected one, e.g. `c`): a palette on the last
+  line of the detail pane. It is left out if the pane is shorter than 12
+  lines. Whenever the palette isn't shown (pane hidden or too short), these
+  keys move into the footer after the navigation keys.
+
+If the footer is too narrow, keys are dropped from the left group's end
+(submodule keys first); the global keys stay. Full help (`?`) lists all keys
+in columns, whatever the size. Keys work whether or not they are shown.
+
 ### Tree row
 
 ```
@@ -191,6 +206,7 @@ colors in components.
 | `q`, `ctrl+c` | Quit |
 | `f` | Fetch all repositories (does nothing while a fetch runs) |
 | `r` | Reload everything (e.g. after editing files) |
+| `c` | Copy the absolute directory of the selected submodule to the clipboard (OSC 52, so it also works over SSH; needs terminal support, in tmux `set -g set-clipboard on`). The footer confirms with `copied <path>`. Without a local provider (mock) the path relative to the superproject is copied |
 | `u`, `b`, `/`, `!` | Planned actions (see requirements) |
 
 "First child" always means the first child **as displayed** (children are
@@ -200,6 +216,32 @@ Collapsing an ancestor of the selection moves the selection to that ancestor.
 The view scrolls so the selection is always visible; when the first submodule
 is selected, headers above it are shown too.
 
+### Key reference
+
+Every key in the UI, where it is shown, and whether it works. Update this
+table when a key is added, moved or implemented. "Bar" is the short footer
+bar, "Palette" the detail pane's palette (the footer takes its keys over
+where the palette can't be shown, see [Key bar and palette](#key-bar-and-palette)),
+"Help" the full help (`?`).
+
+| Key | Action | Group | Shown in | Implemented |
+|---|---|---|---|---|
+| `↑` / `k`, `↓` / `j` | Move selection | Navigation | Bar, Help | yes |
+| `←` / `h`, `→` / `l` | Fold / unfold, parent / first child | Navigation | Bar, Help | yes |
+| `H` / `⇧←`, `L` / `⇧→` | Collapse / expand all | Navigation | Bar, Help | yes |
+| `space` | Toggle expand/collapse | Navigation | Bar, Help | yes |
+| `home` / `g`, `end` / `G` | First / last submodule | Navigation | Help | yes |
+| `pgup`, `pgdn` | Move by one screen | Navigation | Help | yes |
+| `c` | Copy path | Submodule | Palette, Help | yes |
+| `u` | Checkout pin | Submodule | Help | no (flashes "not implemented") |
+| `b` | Bump pin to tip | Submodule | Help | no (flashes "not implemented") |
+| `f` | Fetch all repositories | Global | Help | yes |
+| `r` | Reload everything | Global | Help | yes |
+| `/` | Filter | Global | Help | no (flashes "not implemented") |
+| `!` | Problems only | Global | Help | no (flashes "not implemented") |
+| `?` | Toggle full help | Global | Bar, Help | yes |
+| `q`, `ctrl+c` | Quit | Global | Bar, Help | yes |
+
 ### Mouse
 
 - Click a row: select it.

go.mod

@@ -3,6 +3,7 @@ module submarine
 go 1.27.3
 
 require (
+	github.com/aymanbagabas/go-osc52/v2 v2.0.1
 	github.com/charmbracelet/bubbles v1.0.0
 	github.com/charmbracelet/bubbletea v1.3.10
 	github.com/charmbracelet/lipgloss v1.1.0
@@ -11,7 +12,6 @@ require (
 )
 
 require (
-	github.com/aymanbagabas/go-osc52/v2 v2.0.1 // indirect
 	github.com/charmbracelet/colorprofile v0.4.1 // indirect
 	github.com/charmbracelet/x/cellbuf v0.0.15 // indirect
 	github.com/charmbracelet/x/term v0.2.2 // indirect

internal/submodule/git/fetch.go

@@ -36,6 +36,17 @@ func (p *Provider) Fetchable(path string) bool {
 	return ok
 }
 
+// Dir returns the absolute directory of path ("" is the superproject),
+// whether or not it is initialized.
+func (p *Provider) Dir(path string) string {
+	if path == "" {
+		return p.root
+	}
+	p.mu.RLock()
+	defer p.mu.RUnlock()
+	return p.mods[path].dir
+}
+
 // repoDir returns the worktree of path if it is initialized.
 func (p *Provider) repoDir(path string) (string, bool) {
 	if path == "" {

internal/submodule/git/provider.go

@@ -20,7 +20,7 @@ import (
 )
 
 // maxContainsCandidates limits how many remote branches containing the pin
-// are compared when resolving the pin by RefFromContains.
+// are compared besides the preferred refs when resolving a pushed pin.
 const maxContainsCandidates = 16
 
 // maxBetween limits the commits listed between pin and tip.
@@ -269,80 +269,130 @@ func status(ctx context.Context, in info) (*submodule.Status, error) {
 }
 
 // resolve finds the ref that describes the pin, following the order in
-// docs/state-model.md. containing lists the remote branches containing the
+// docs/state-model.md: the closest branch wins, the preferred refs (see
-// pin, oldest tip first.
+// preferredRefs) break ties. containing lists the remote branches containing
+// the pin, oldest tip first.
 func resolve(ctx context.Context, in info, pin, branch string, containing []string) (string, submodule.RefSource, error) {
-	remote, err := remoteName(ctx, in.dir)
+	preferred, err := preferredRefs(ctx, in, branch)
 	if err != nil {
 		return "", 0, err
 	}
 
-	// 1. branch from .gitmodules
+	// 1. pushed: the branch containing the pin with the fewest commits after it
-	if b := in.branch; b != "" && remote != "" {
+	if len(containing) > 0 {
-		if b == "." {
+		var cands []candidate
-			b, _, err = try(ctx, in.superDir, "symbolic-ref", "--short", "-q", "HEAD")
+		for _, c := range preferred {
-			if err != nil {
+			if _, ok, err := try(ctx, in.dir, "merge-base", "--is-ancestor", pin, c.ref); err != nil {
-				return "", 0, err
-			}
-		}
-		if b != "" {
-			if _, ok, err := try(ctx, in.dir, "rev-parse", "--verify", "-q", "refs/remotes/"+remote+"/"+b); err != nil {
 				return "", 0, err
 			} else if ok {
-				return remote + "/" + b, submodule.RefFromGitmodules, nil
+				cands = append(cands, c)
 			}
 		}
-	}
-
-	// 2. upstream of the checked-out branch
-	if branch != "" {
-		if up, ok, err := try(ctx, in.dir, "rev-parse", "--abbrev-ref", "--symbolic-full-name", branch+"@{upstream}"); err != nil {
-			return "", 0, err
-		} else if ok && up != "" {
-			return up, submodule.RefFromCurrentBranch, nil
-		}
-	}
-
-	// 3. remote default branch, if it contains the pin
-	if remote != "" {
-		if def, ok, err := try(ctx, in.dir, "symbolic-ref", "--short", "-q", "refs/remotes/"+remote+"/HEAD"); err != nil {
-			return "", 0, err
-		} else if ok {
-			if _, ok, err := try(ctx, in.dir, "merge-base", "--is-ancestor", pin, def); err != nil {
-				return "", 0, err
-			} else if ok {
-				return def, submodule.RefFromDefaultBranch, nil
-			}
-		}
-	}
-
-	// 4. remote branch containing the pin with the closest tip
-	best, bestN := "", -1
 		for _, r := range containing[:min(len(containing), maxContainsCandidates)] {
-		out, err := run(ctx, in.dir, "rev-list", "--count", pin+".."+r)
+			if !slices.ContainsFunc(cands, func(c candidate) bool { return c.ref == r }) {
-		if err != nil {
+				cands = append(cands, candidate{r, submodule.RefFromContains})
+			}
+		}
+		if c, ok, err := closest(ctx, in.dir, pin+"..", cands); err != nil {
 			return "", 0, err
+		} else if ok {
+			return c.ref, c.source, nil
 		}
-		var n int
-		if _, err := fmt.Sscan(out, &n); err == nil && (bestN < 0 || n < bestN) {
-			best, bestN = r, n
-		}
-	}
-	if best != "" {
-		return best, submodule.RefFromContains, nil
 	}
 
-	// 5. nearest tag
+	// 2. unpushed: the preferred ref with the fewest commits on either side
+	if c, ok, err := closest(ctx, in.dir, pin+"...", preferred); err != nil {
+		return "", 0, err
+	} else if ok {
+		return c.ref, c.source, nil
+	}
+
+	// 3. nearest tag
 	if tag, ok, err := try(ctx, in.dir, "describe", "--tags", "--abbrev=0", pin); err != nil {
 		return "", 0, err
 	} else if ok && tag != "" {
 		return tag, submodule.RefFromTag, nil
 	}
 
-	// 6. the commit itself
+	// 4. the commit itself
 	return "", submodule.RefFromSHA, nil
 }
 
+// candidate is a ref the pin may resolve to and the rule that proposed it.
+type candidate struct {
+	ref    string
+	source submodule.RefSource
+}
+
+// preferredRefs returns the refs the user most likely means, in order of
+// preference and without duplicates: the .gitmodules branch, the upstream of
+// the checked-out branch, the remote default branch. Each must exist.
+func preferredRefs(ctx context.Context, in info, branch string) ([]candidate, error) {
+	remote, err := remoteName(ctx, in.dir)
+	if err != nil {
+		return nil, err
+	}
+	var refs []candidate
+	add := func(ref string, source submodule.RefSource) {
+		if ref != "" && !slices.ContainsFunc(refs, func(c candidate) bool { return c.ref == ref }) {
+			refs = append(refs, candidate{ref, source})
+		}
+	}
+
+	// branch from .gitmodules
+	if b := in.branch; b != "" && remote != "" {
+		if b == "." {
+			b, _, err = try(ctx, in.superDir, "symbolic-ref", "--short", "-q", "HEAD")
+			if err != nil {
+				return nil, err
+			}
+		}
+		if b != "" {
+			if _, ok, err := try(ctx, in.dir, "rev-parse", "--verify", "-q", "refs/remotes/"+remote+"/"+b); err != nil {
+				return nil, err
+			} else if ok {
+				add(remote+"/"+b, submodule.RefFromGitmodules)
+			}
+		}
+	}
+
+	// upstream of the checked-out branch
+	if branch != "" {
+		if up, ok, err := try(ctx, in.dir, "rev-parse", "--abbrev-ref", "--symbolic-full-name", branch+"@{upstream}"); err != nil {
+			return nil, err
+		} else if ok {
+			add(up, submodule.RefFromCurrentBranch)
+		}
+	}
+
+	// remote default branch
+	if remote != "" {
+		if def, ok, err := try(ctx, in.dir, "symbolic-ref", "--short", "-q", "refs/remotes/"+remote+"/HEAD"); err != nil {
+			return nil, err
+		} else if ok {
+			add(def, submodule.RefFromDefaultBranch)
+		}
+	}
+	return refs, nil
+}
+
+// closest returns the candidate with the fewest commits in the range
+// `<from><ref>` (from is e.g. "<pin>.."); the first one wins a tie.
+func closest(ctx context.Context, dir, from string, cands []candidate) (candidate, bool, error) {
+	best, bestN := candidate{}, -1
+	for _, c := range cands {
+		out, err := run(ctx, dir, "rev-list", "--count", from+c.ref)
+		if err != nil {
+			return candidate{}, false, err
+		}
+		var n int
+		if _, err := fmt.Sscan(out, &n); err == nil && (bestN < 0 || n < bestN) {
+			best, bestN = c, n
+		}
+	}
+	return best, bestN >= 0, nil
+}
+
 // remoteName returns "origin" if it exists, else the first remote, else "".
 func remoteName(ctx context.Context, dir string) (string, error) {
 	out, err := run(ctx, dir, "remote")

internal/submodule/git/provider_test.go

@@ -75,7 +75,7 @@ func TestTree(t *testing.T) {
 	submodule.Walk(repo.Submodules, func(s *submodule.Submodule) { paths = append(paths, s.Path) })
 	want := []string{
 		"src/core", "src/ui", "src/net", "libs/store", "libs/log", "libs/log/modules/nested",
-		"libs/feature", "libs/conflict", "libs/staged", "libs/missing", "vendor", "libs/work",
+		"libs/feature", "libs/conflict", "libs/staged", "libs/missing", "vendor", "libs/work", "libs/topic",
 	}
 	if !slices.Equal(paths, want) {
 		t.Errorf("paths = %v\nwant    %v", paths, want)
@@ -106,6 +106,7 @@ func TestStatus(t *testing.T) {
 		{path: "libs/log", ref: "origin/main", source: submodule.RefFromCurrentBranch},
 		{path: "libs/log/modules/nested", issues: []submodule.IssueKind{submodule.IssueChanged}, ref: "origin/main", source: submodule.RefFromDefaultBranch, checkout: submodule.CheckoutDetached},
 		{path: "libs/feature", ref: "origin/feat/search", source: submodule.RefFromContains, behind: 1, checkout: submodule.CheckoutDetached},
+		{path: "libs/topic", ref: "origin/feat/search", source: submodule.RefFromContains, checkout: submodule.CheckoutDetached},
 		{path: "libs/conflict", issues: []submodule.IssueKind{submodule.IssueConflict}, ref: "origin/main", source: submodule.RefFromCurrentBranch, staged: true},
 		{path: "libs/staged", ref: "origin/main", source: submodule.RefFromCurrentBranch, staged: true},
 		{path: "libs/missing", issues: []submodule.IssueKind{submodule.IssueMissing}},

internal/submodule/provider.go

@@ -26,6 +26,13 @@ type Watcher interface {
 	Watch(ctx context.Context) <-chan Change
 }
 
+// Locator is implemented by providers whose submodules live on the local
+// disk. Dir returns the absolute directory of path ("" is the superproject),
+// or "" if it is unknown.
+type Locator interface {
+	Dir(path string) string
+}
+
 // Change reports that the git metadata of a repository changed.
 type Change struct {
 	Path      string // "" is the superproject

internal/tui/app.go

@@ -73,7 +73,7 @@ func New(ctx context.Context, p submodule.Provider, opts Options) Model {
 		loads:    newReloader(),
 		ticking:  true, // Init schedules the first tick
 		tree:     tree.New(t),
-		detail:   detail.New(t),
+		detail:   detail.New(t, k.Submodule()),
 		footer:   footer.New(t, k),
 		spinner:  sp,
 	}
@@ -353,6 +353,8 @@ func (m Model) handleKey(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
 		return m, m.startFetch()
 	case key.Matches(msg, k.Reload):
 		return m, m.reloadTree(true)
+	case key.Matches(msg, k.Copy):
+		return m.copyPath()
 	case key.Matches(msg, k.Update, k.Bump, k.Filter, k.Issues):
 		cmd := m.footer.Flash("“" + msg.String() + "” is not implemented in the prototype")
 		m.layout()
@@ -361,6 +363,24 @@ func (m Model) handleKey(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
 	return m, nil
 }
 
+// copyPath copies the absolute directory of the selected submodule to the
+// clipboard, or its path in the superproject if the provider can't tell.
+func (m Model) copyPath() (tea.Model, tea.Cmd) {
+	s := m.tree.Selected()
+	if s == nil {
+		return m, nil
+	}
+	path := s.Path
+	if l, ok := m.provider.(submodule.Locator); ok {
+		if dir := l.Dir(s.Path); dir != "" {
+			path = dir
+		}
+	}
+	cmd := tea.Batch(copyToClipboard(path), m.footer.Flash("copied "+path))
+	m.layout()
+	return m, cmd
+}
+
 // layout distributes the terminal size among the components.
 func (m *Model) layout() {
 	m.footer.SetWidth(m.width)
@@ -373,6 +393,7 @@ func (m *Model) layout() {
 		treeWidth = m.width - detailWidth
 		m.detail.SetSize(detailWidth-2, bodyHeight) // border + padding
 	}
+	m.footer.SetActions(!m.showDetail || !m.detail.PaletteVisible())
 	m.tree.SetSize(treeWidth, bodyHeight)
 }
 

internal/tui/clipboard.go

@@ -0,0 +1,21 @@
+package tui
+
+import (
+	"os"
+
+	"github.com/aymanbagabas/go-osc52/v2"
+	tea "github.com/charmbracelet/bubbletea"
+)
+
+// copyToClipboard sets the system clipboard with the OSC 52 escape sequence,
+// which works over SSH and in terminals that allow it; others ignore it.
+func copyToClipboard(text string) tea.Cmd {
+	return func() tea.Msg {
+		seq := osc52.New(text)
+		if os.Getenv("TMUX") != "" {
+			seq = seq.Tmux()
+		}
+		_, _ = seq.WriteTo(os.Stderr)
+		return nil
+	}
+}

internal/tui/detail/detail.go

@@ -6,6 +6,8 @@ import (
 	"path"
 	"strings"
 
+	"github.com/charmbracelet/bubbles/help"
+	"github.com/charmbracelet/bubbles/key"
 	"github.com/charmbracelet/lipgloss"
 	"github.com/charmbracelet/x/ansi"
 
@@ -20,9 +22,20 @@ type Model struct {
 	width   int
 	height  int
 	spinner string
+	help    help.Model
+	actions []key.Binding
 }
 
-func New(t theme.Theme) Model { return Model{theme: t} }
+// paletteMinHeight is the pane height below which the palette is left out:
+// the information is worth more than the hints.
+const paletteMinHeight = 12
+
+func New(t theme.Theme, actions []key.Binding) Model {
+	return Model{theme: t, help: theme.NewHelp(t), actions: actions}
+}
+
+// PaletteVisible reports whether the palette of submodule actions fits.
+func (m Model) PaletteVisible() bool { return m.height >= paletteMinHeight }
 
 func (m *Model) SetSize(w, h int)        { m.width, m.height = w, h }
 func (m *Model) SetSpinner(frame string) { m.spinner = frame }
@@ -38,10 +51,21 @@ func (m Model) View(s *submodule.Submodule) string {
 	for i, l := range lines {
 		lines[i] = ansi.Truncate(l, m.width, "…")
 	}
-	if len(lines) > m.height {
+	height := m.height
-		lines = lines[:m.height]
+	var palette string
+	if m.PaletteVisible() {
+		height-- // the palette is the last line
+		m.help.Width = 0
+		palette = ansi.Truncate(m.help.ShortHelpView(m.actions), m.width, "…")
 	}
-	return lipgloss.NewStyle().Width(m.width).Height(m.height).Render(strings.Join(lines, "\n"))
+	if len(lines) > height {
+		lines = lines[:height]
+	}
+	body := lipgloss.NewStyle().Width(m.width).Height(height).Render(strings.Join(lines, "\n"))
+	if palette == "" {
+		return body
+	}
+	return body + "\n" + palette
 }
 
 func (m Model) lines(s *submodule.Submodule) []string {

internal/tui/footer/footer.go

@@ -2,11 +2,14 @@
 package footer
 
 import (
+	"strings"
 	"time"
 
 	"github.com/charmbracelet/bubbles/help"
+	"github.com/charmbracelet/bubbles/key"
 	tea "github.com/charmbracelet/bubbletea"
 	"github.com/charmbracelet/lipgloss"
+	"github.com/charmbracelet/x/ansi"
 
 	"submarine/internal/tui/theme"
 )
@@ -15,26 +18,34 @@ const flashDuration = 2 * time.Second
 
 type clearFlashMsg struct{ id int }
 
+// Keys provides the key groups. The short bar shows Navigation (and
+// Submodule, if requested) on the left and Global on the right; full help
+// shows FullHelp.
+type Keys interface {
+	help.KeyMap
+	Navigation() []key.Binding
+	Submodule() []key.Binding
+	Global() []key.Binding
+}
+
 type Model struct {
 	theme   theme.Theme
 	help    help.Model
-	keys    help.KeyMap
+	keys    Keys
 	width   int
 	flash   string
 	flashID int
+	actions bool // show the submodule bindings in the short bar
 }
 
-func New(t theme.Theme, keys help.KeyMap) Model {
+func New(t theme.Theme, keys Keys) Model {
-	h := help.New()
+	return Model{theme: t, help: theme.NewHelp(t), keys: keys}
-	h.Styles.ShortKey = theme.Fg(t.Text).Bold(true)
-	h.Styles.ShortDesc = theme.Fg(t.Muted)
-	h.Styles.ShortSeparator = theme.Fg(t.Border)
-	h.Styles.FullKey = h.Styles.ShortKey
-	h.Styles.FullDesc = h.Styles.ShortDesc
-	h.Styles.FullSeparator = h.Styles.ShortSeparator
-	return Model{theme: t, help: h, keys: keys}
 }
 
+// SetActions shows the submodule bindings in the short bar. Set it if the
+// detail pane doesn't show them.
+func (m *Model) SetActions(on bool) { m.actions = on }
+
 func (m *Model) SetWidth(w int) {
 	m.width = w
 	m.help.Width = w - 2
@@ -62,5 +73,29 @@ func (m Model) View() string {
 	if m.flash != "" {
 		return style.Foreground(m.theme.Warn).Render(m.flash)
 	}
+	if m.help.ShowAll {
 		return style.Render(m.help.View(m.keys))
 	}
+	return style.Render(m.shortBar(m.width - 2))
+}
+
+// shortBar puts the global keys on the right and as many of the others on the
+// left as fit; the submodule keys are dropped first.
+func (m Model) shortBar(w int) string {
+	h := m.help
+	h.Width = 0
+	right := h.ShortHelpView(m.keys.Global())
+	left := m.keys.Navigation()
+	if m.actions {
+		left = append(left[:len(left):len(left)], m.keys.Submodule()...)
+	}
+	for ; ; left = left[:len(left)-1] {
+		l := h.ShortHelpView(left)
+		if gap := w - lipgloss.Width(l) - lipgloss.Width(right); gap >= 2 || len(left) == 0 {
+			if gap < 0 { // not even the global keys fit
+				return ansi.Truncate(right, w, "…")
+			}
+			return l + strings.Repeat(" ", gap) + right
+		}
+	}
+}

internal/tui/keys.go

@@ -7,7 +7,7 @@ type keyMap struct {
 	CollapseAll, ExpandAll                      key.Binding
 	Home, End, PageUp, PageDown                 key.Binding
 	Update, Bump, Fetch, Reload, Filter, Issues key.Binding
-	Help, Quit                                  key.Binding
+	Copy, Help, Quit                            key.Binding
 }
 
 func defaultKeys() keyMap {
@@ -29,16 +29,29 @@ func defaultKeys() keyMap {
 		Reload:      key.NewBinding(key.WithKeys("r"), key.WithHelp("r", "reload")),
 		Filter:      key.NewBinding(key.WithKeys("/"), key.WithHelp("/", "filter")),
 		Issues:      key.NewBinding(key.WithKeys("!"), key.WithHelp("!", "problems only")),
+		Copy:        key.NewBinding(key.WithKeys("c"), key.WithHelp("c", "copy path")),
 		Help:        key.NewBinding(key.WithKeys("?"), key.WithHelp("?", "help")),
 		Quit:        key.NewBinding(key.WithKeys("q", "ctrl+c"), key.WithHelp("q", "quit")),
 	}
 }
 
-func (k keyMap) ShortHelp() []key.Binding {
+// Navigation returns the bindings that move the selection or fold the tree.
+func (k keyMap) Navigation() []key.Binding {
 	move := key.NewBinding(key.WithKeys("up"), key.WithHelp("↑↓/jk", "move"))
 	fold := key.NewBinding(key.WithKeys("left"), key.WithHelp("←→/hl", "fold"))
 	all := key.NewBinding(key.WithKeys("H"), key.WithHelp("⇧←→/HL", "fold all"))
-	return []key.Binding{move, fold, all, k.Toggle, k.Help, k.Quit}
+	return []key.Binding{move, fold, all, k.Toggle}
+}
+
+// Submodule returns the bindings that act on the selected submodule. They
+// are shown in the detail pane, or in the footer if the pane can't show them.
+func (k keyMap) Submodule() []key.Binding { return []key.Binding{k.Copy} }
+
+// Global returns the bindings that don't depend on the selection.
+func (k keyMap) Global() []key.Binding { return []key.Binding{k.Help, k.Quit} }
+
+func (k keyMap) ShortHelp() []key.Binding {
+	return append(append(k.Navigation(), k.Submodule()...), k.Global()...)
 }
 
 func (k keyMap) FullHelp() [][]key.Binding {
@@ -46,7 +59,8 @@ func (k keyMap) FullHelp() [][]key.Binding {
 		{k.Up, k.Down, k.Left, k.Right, k.Toggle},
 		{k.CollapseAll, k.ExpandAll},
 		{k.Home, k.End, k.PageUp, k.PageDown},
-		{k.Update, k.Bump, k.Fetch, k.Reload, k.Filter, k.Issues},
+		{k.Copy, k.Update, k.Bump},
+		{k.Fetch, k.Reload, k.Filter, k.Issues},
 		{k.Help, k.Quit},
 	}
 }

internal/tui/theme/help.go

@@ -0,0 +1,15 @@
+package theme
+
+import "github.com/charmbracelet/bubbles/help"
+
+// NewHelp returns a help renderer in the theme's colors.
+func NewHelp(t Theme) help.Model {
+	h := help.New()
+	h.Styles.ShortKey = Fg(t.Text).Bold(true)
+	h.Styles.ShortDesc = Fg(t.Muted)
+	h.Styles.ShortSeparator = Fg(t.Border)
+	h.Styles.FullKey = h.Styles.ShortKey
+	h.Styles.FullDesc = h.Styles.ShortDesc
+	h.Styles.FullSeparator = h.Styles.ShortSeparator
+	return h
+}

scripts/make-fixture.sh

@@ -72,6 +72,8 @@ g "$w" push origin main
 g "$root/work/log" submodule add "$root/remotes/nested.git" modules/nested
 g "$root/work/log" commit -m "Add nested"
 g "$root/work/log" push origin main
+# "archive" ties with main (same tip, sorts first) -> the preferred ref wins
+g "$root/work/log" push origin main:archive
 
 super="$root/super"
 git init -q "$super"
@@ -88,6 +90,7 @@ add ui libs/staged
 add net libs/missing
 add ui vendor
 add work libs/work
+add feature libs/topic -b main
 g "$super" submodule update --init --recursive
 g "$super" commit -m "Add submodules"
 
@@ -109,6 +112,13 @@ g "$super/libs/feature" checkout origin/feat/search~1
 g "$super" add libs/feature
 g "$super" commit -m "Pin feature search"
 
+# libs/topic: .gitmodules says main, but the pin is the tip of feat/search
+# -> the closest branch wins over the configured one
+g "$super/libs/topic" fetch
+g "$super/libs/topic" checkout origin/feat/search
+g "$super" add libs/topic
+g "$super" commit -m "Pin topic search"
+
 # src/core: checkout moved away from the pin -> off pin
 g "$super/src/core" checkout HEAD~1