Ask each context whether it has content to select

Whether a view draws a selection is about to be derived in one place from
the context stack, which needs to ask any context — list or not — whether
there is something for a selection to sit on. Name the existing flag after
that question, and let a list context answer it from its length.

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

pkg/gui/context/base_context.go

@@ -28,7 +28,7 @@ type BaseContext struct {
 	hasControlledBounds         bool
 	needsRerenderOnWidthChange  types.NeedsRerenderOnWidthChangeLevel
 	needsRerenderOnHeightChange bool
-	highlightOnFocus            bool
+	hasSelectableContent        bool
 
 	*ParentContextMgr
 }
@@ -49,7 +49,7 @@ type NewBaseContextOpts struct {
 	Focusable                   bool
 	Transient                   bool
 	HasUncontrolledBounds       bool // negating for the sake of making false the default
-	HighlightOnFocus            bool
+	HasSelectableContent        bool
 	NeedsRerenderOnWidthChange  types.NeedsRerenderOnWidthChangeLevel
 	NeedsRerenderOnHeightChange bool
 
@@ -70,7 +70,7 @@ func NewBaseContext(opts NewBaseContextOpts) *BaseContext {
 		focusable:                   opts.Focusable,
 		transient:                   opts.Transient,
 		hasControlledBounds:         hasControlledBounds,
-		highlightOnFocus:            opts.HighlightOnFocus,
+		hasSelectableContent:        opts.HasSelectableContent,
 		needsRerenderOnWidthChange:  opts.NeedsRerenderOnWidthChange,
 		needsRerenderOnHeightChange: opts.NeedsRerenderOnHeightChange,
 		ParentContextMgr:            &ParentContextMgr{},
@@ -118,6 +118,10 @@ func (self *BaseContext) GetKind() types.ContextKind {
 	return self.kind
 }
 
+func (self *BaseContext) HasSelectableContent() bool {
+	return self.hasSelectableContent
+}
+
 func (self *BaseContext) GetKey() types.ContextKey {
 	return self.key
 }

pkg/gui/context/list_context_trait.go

@@ -37,6 +37,10 @@ type ListContextTrait struct {
 
 func (self *ListContextTrait) IsListContext() {}
 
+func (self *ListContextTrait) HasSelectableContent() bool {
+	return self.list.Len() > 0
+}
+
 func (self *ListContextTrait) FocusLine(scrollIntoView bool) {
 	self.Context.FocusLine(scrollIntoView)
 
@@ -102,7 +106,7 @@ func formatListFooter(selectedLineIdx int, length int) string {
 func (self *ListContextTrait) HandleFocus(opts types.OnFocusOpts) {
 	self.FocusLine(!opts.KeepScrollPosition)
 
-	self.GetViewTrait().SetHighlight(self.list.Len() > 0)
+	self.GetViewTrait().SetHighlight(self.HasSelectableContent())
 
 	self.Context.HandleFocus(opts)
 }

pkg/gui/context/main_context.go

@@ -21,12 +21,12 @@ func NewMainContext(
 	ctx := &MainContext{
 		SimpleContext: NewSimpleContext(
 			NewBaseContext(NewBaseContextOpts{
-				Kind:             types.MAIN_CONTEXT,
-				View:             view,
-				WindowName:       windowName,
-				Key:              key,
-				Focusable:        true,
-				HighlightOnFocus: false,
+				Kind:                 types.MAIN_CONTEXT,
+				View:                 view,
+				WindowName:           windowName,
+				Key:                  key,
+				Focusable:            true,
+				HasSelectableContent: false,
 			})),
 		SearchTrait: NewSearchTrait(c),
 	}

pkg/gui/context/merge_conflicts_context.go

@@ -35,12 +35,12 @@ func NewMergeConflictsContext(
 		viewModel: viewModel,
 		Context: NewSimpleContext(
 			NewBaseContext(NewBaseContextOpts{
-				Kind:             types.MAIN_CONTEXT,
-				View:             c.Views().MergeConflicts,
-				WindowName:       "main",
-				Key:              MERGE_CONFLICTS_CONTEXT_KEY,
-				Focusable:        true,
-				HighlightOnFocus: true,
+				Kind:                 types.MAIN_CONTEXT,
+				View:                 c.Views().MergeConflicts,
+				WindowName:           "main",
+				Key:                  MERGE_CONFLICTS_CONTEXT_KEY,
+				Focusable:            true,
+				HasSelectableContent: true,
 			}),
 		),
 		c: c,

pkg/gui/context/patch_explorer_context.go

@@ -47,7 +47,7 @@ func NewPatchExplorerContext(
 			Key:                        key,
 			Kind:                       types.MAIN_CONTEXT,
 			Focusable:                  true,
-			HighlightOnFocus:           true,
+			HasSelectableContent:       true,
 			NeedsRerenderOnWidthChange: types.NEEDS_RERENDER_ON_WIDTH_CHANGE_WHEN_WIDTH_CHANGES,
 		})),
 		SearchTrait: NewSearchTrait(c),

pkg/gui/context/simple_context.go

@@ -33,7 +33,7 @@ func NewDisplayContext(key types.ContextKey, view *gocui.View, windowName string
 }
 
 func (self *SimpleContext) HandleFocus(opts types.OnFocusOpts) {
-	if self.highlightOnFocus {
+	if self.hasSelectableContent {
 		self.GetViewTrait().SetHighlight(true)
 	}
 

pkg/gui/types/context.go

@@ -75,6 +75,10 @@ type IBaseContext interface {
 	// determined independently.
 	HasControlledBounds() bool
 
+	// true if the context holds something for a selection to sit on. Contexts that
+	// don't show a selection at all say false, and so do lists with nothing in them.
+	HasSelectableContent() bool
+
 	// the total height of the content that the view is currently showing
 	TotalContentHeight() int