cli: the cursor clears the header, and the band stops at the corner

THE HEADER COVERS ROWS. The sticky question stands ON the first rows of
the viewport rather than pushing them down, but the scroll floor was the
offset, so a selection scrolled "into view" landed underneath it: ^P up a
delta list moved the cursor and showed nothing, twice in a row, which is
indistinguishable from a cursor that has stopped. The floor is the offset
plus the header's height now. One pass, not a fixed point: scrolling up
can retire the header, and the row is only ever further from it for that.

AND A CORNER IS STILL A RULE. The band that carries the selection wash
stops at the rule closing a box, tested by the glyph in the first painted
cell -- but the adornment's snake closes into `╰`, so the band walked
straight past it and washed the `< figaro` header of the answer below. A
row is a rule when the line runs from its first cell or its second.

Author: gluck

internal/cli/adornment_test.go

@@ -606,3 +606,84 @@ func TestSelectedBlockKeepsItsGutterMarker(t *testing.T) {
 	}
 	t.Fatal("fixture: no short row to wash")
 }
+
+// stickyAdorned is the fixture for what the header hides: three turns, the
+// last one's question adorned and open, and the sticky header on.
+func stickyAdorned(t testing.TB) (*transcript, nodeRef) {
+	t.Helper()
+	tr := adornFixtureH(t, 8, 3)
+	tr.view.(*ariaView).settings.sticky = true
+	inq := nodeRef{turn: 3, index: inquiryNode}
+	tr.adorned[inq] = true
+	tr.dropTurnsRows(map[int]struct{}{3: {}})
+	tr.buildIndex()
+	return tr, inq
+}
+
+// THE HEADER COVERS ROWS, SO THE CURSOR MUST CLEAR IT. Walking a delta list
+// upward with ^P used to park the focused row underneath the pinned question,
+// where it cannot be seen: the scroll floor was the offset, and the offset is
+// not where the conversation starts on screen.
+func TestSelectedRowClearsTheStickyHeader(t *testing.T) {
+	tr, inq := stickyAdorned(t)
+	tr.selectRef(deltaRefOf(inq, 2), false)
+
+	// Park the selection under the header on purpose, then ask for it back.
+	span, ok := tr.nodeSpanOf(tr.selection.focus.nodeRef)
+	if !ok {
+		t.Fatal("fixture: the delta row has no span")
+	}
+	tr.offset = span.first
+	tr.render()
+	if tr.headRows() == 0 {
+		t.Fatal("fixture: the header is not pinned, so nothing is covered")
+	}
+	tr.ensureSelectionVisible()
+	if head := tr.headRows(); span.first < tr.offset+head {
+		t.Fatalf("the focused row is under the header: row %d, offset %d, header %d",
+			span.first, tr.offset, head)
+	}
+
+	// And every step up the list stays clear of it.
+	for range 2 {
+		tr.key(0x10) // ^P
+		span, ok := tr.nodeSpanOf(tr.selection.focus.nodeRef)
+		if !ok {
+			t.Fatal("the focus lost its span")
+		}
+		if head := tr.headRows(); span.first < tr.offset+head {
+			t.Fatalf("^P parked %+v under the header: row %d, offset %d, header %d",
+				tr.selection.focus.nodeRef, span.first, tr.offset, head)
+		}
+	}
+}
+
+// THE BAND STOPS AT THE CORNER THE SNAKE CLOSES INTO. That row is a rule
+// wearing a corner glyph, so a band that only knew `─` ran straight past it
+// and washed the voice header of the answer below.
+func TestWashStopsAtTheAdornmentsCorner(t *testing.T) {
+	defer term.SetColorMode(term.ColorAlways)()
+	tr, inq := stickyAdorned(t)
+	tr.selectRef(deltaRefOf(inq, 2), false)
+	tr.ensureSelectionVisible()
+
+	rows := tr.window(tr.offset, tr.offset+8, nil)
+	corner, voice := -1, -1
+	for i, r := range rows {
+		switch plain := strings.TrimSpace(stripANSI(r)); {
+		case strings.HasPrefix(plain, "╰─"):
+			corner = i
+		case plain == "< figaro":
+			voice = i
+		}
+	}
+	if corner < 0 || voice < 0 {
+		t.Fatalf("fixture: want a corner and a voice header:\n%s", strings.Join(stripANSIAll(rows), "\n"))
+	}
+	if !washed(rows[corner]) {
+		t.Errorf("the corner closes the box and belongs to the band: %q", stripANSI(rows[corner]))
+	}
+	if washed(rows[voice]) {
+		t.Errorf("the wash ran past the corner onto %q", stripANSI(rows[voice]))
+	}
+}

internal/cli/transcript_index.go

@@ -2,6 +2,7 @@ package cli
 
 import (
 	"strings"
+	"unicode/utf8"
 
 	"github.com/jack-work/figaro/internal/livelog/aria"
 	ldrender "github.com/jack-work/figaro/internal/livelog/render"
@@ -342,11 +343,17 @@ func (t *transcript) bandEdge(from, step int) int {
 	return edge
 }
 
-// isRuleRow reports whether a row is one of the box's horizontal rules: the
-// only rows whose first painted cell is the rule glyph.
+// isRuleRow reports whether a row is one of the box's horizontal rules, which
+// is where a band stops. A rule may open on a corner (the adornment's snake
+// closes into one) so the glyph at column zero is not the test: the row is a
+// rule when the line runs from its first cell or its second.
 func isRuleRow(row string) bool {
 	rest, _ := firstVisible(row)
-	return strings.HasPrefix(rest, "─")
+	if strings.HasPrefix(rest, "─") {
+		return true
+	}
+	_, n := utf8.DecodeRuneInString(rest)
+	return n > 0 && strings.HasPrefix(rest[n:], "─")
 }
 
 // washVisual paints the visual highlight over a finished row. It is applied

internal/cli/transcript_selection.go

@@ -804,6 +804,12 @@ func (t *transcript) repairSelection() {
 
 // ensureSelectionVisible scrolls the focused node into the body, if it is not
 // already there.
+//
+// THE HEADER COVERS ROWS, so "in the body" is not "past the offset". The
+// sticky question stands ON the first rows of the viewport rather than pushing
+// them down, and a selection scrolled to the offset landed UNDER it: walking
+// a delta list upward with ^P looked like a cursor that stopped moving. The
+// floor is the offset plus whatever the header hides.
 func (t *transcript) ensureSelectionVisible() {
 	if !t.selection.active {
 		return
@@ -814,8 +820,11 @@ func (t *transcript) ensureSelectionVisible() {
 		return
 	}
 	body, _ := t.layout(len(t.footLines()))
-	if span.first < t.offset {
-		t.offset = span.first
+	if head := t.headRows(); span.first < t.offset+head {
+		// One pass, not a fixed point: scrolling up may retire the header
+		// (the question's own rows reach the top), and the row is only ever
+		// further from the chrome for it.
+		t.offset = max(span.first-head, 0)
 	} else if span.last >= t.offset+body {
 		t.offset = span.last - body + 1
 	}

skills/figaro/reference/ui-stream.md

@@ -612,7 +612,15 @@ owns, its chrome rows included, so the band a reader sees IS the block.
 The wash also closes over the chrome BETWEEN washed rows and over the rule that
 fences the box beneath them: select a question and the heading, the text and
 the seam under it lift together. It stops at the first row of a block that is
-not selected, so the answer's voice header stays the answer's.
+not selected, and at the rule that closes the box, corner glyph and all (the
+adornment's snake closes into a `╰`, and a band that only knew `─` washed the
+answer's voice header on the way past).
+
+**A selected row is never under the header.** The pinned question COVERS the
+first rows of the viewport rather than pushing them down, so the floor a
+selection scrolls against is the offset plus the header's height. Walking a
+delta list upward with `^P` pushes the conversation down a row at a time
+instead of parking the cursor somewhere the reader cannot see it.
 
 Colour is the only channel here. A terminal with colour off shows no selection
 cue at all, which is the deliberate end of a cue that used to be drawn twice.