A pane tag wraps onto rows and can collapse to one, as acme's does

acme's frame wraps a tag at its right edge and the window grows to show
every row (wind.c wintaglines); Tagup/Tagdown shrink it to one row and back.
Pane tags used to be one row, scrolled sideways to the caret. Now a tag's
lines wrap at its width (one cell kept for the caret past a full row) and it
starts expanded; insert-mode Up on the first row collapses it, Down on the
last row expands it, and Alt-Up/Alt-Down do so in either mode. A word the
wrap breaks across rows is still one word to a click and a selection.
Column and workspace tags keep scrolling sideways.

Tests read body rows relative to the body's first row; the 41 snapshot
goldens that moved were re-recorded by name after a programmatic check that
each differs only by body rows shifting under the taller tags, and twelve
scripts whose clicks targeted fixed rows now click the same text.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

1 files changed, 136 insertions, 71 deletions

diff --git a/test/panes.zig b/test/panes.zig
index a6a95124..836323a0 100644
--- a/test/panes.zig
+++ b/test/panes.zig
@@ -165,6 +165,23 @@ const TagLayerTests = struct {
     }
 };
 
+
+// Rows relative to where the pane's body and tag are, whatever height its
+// tag has (a tag wraps onto more rows when it is long).
+fn paneAt(p: *Pardes, r: anytype) *pardes.Pane {
+    for (p.panes, 0..) |slot, id| if (slot) |pane| if (std.meta.eql(p.rects[id], r)) return pane;
+    unreachable;
+}
+fn bodyY(p: *Pardes, r: anytype) u16 {
+    return p.bodyTop(paneAt(p, r), r);
+}
+fn bodyH(p: *Pardes, r: anytype) u16 {
+    return r.h -| paneAt(p, r).tag_rows;
+}
+fn tagY(p: *Pardes, r: anytype) u16 {
+    return p.tagTop(paneAt(p, r), r);
+}
+
 test "a tag with a newline in it is as tall as its lines, and each line is typed into and pointed at" {
     for ([_]bool{ false, true }) |bottom| {
         const p = try Pardes.init(std.testing.allocator, .{ .tty_only = true, .cols = 80, .rows = 14 });
@@ -407,7 +424,7 @@ const TagNavigationTests = struct {
         defer frame.deinit();
         _ = try p.render(frame.allocator());
         const rect = p.rects[0];
-        const y = if (p.settings.tag_bottom) rect.y + rect.h - pardes.BOX_H else rect.y;
+        const y = tagY(p, rect);
         const prefix: u16 = @intCast(panes.File.displayWidth(try pardes.tagline.tagPrefix(p, first)));
         ClickCursorTests.click(p, .left, rect.x + pardes.TAG_TEXT_INSET + prefix + 6, y);
         try std.testing.expectEqual(@as(usize, 0), p.active);
@@ -774,6 +791,8 @@ const TreeContextTests = struct {
         const p = try Pardes.init(std.testing.allocator, .{ .tty_only = true, .cols = 48, .rows = 14 });
         defer p.deinit();
         const pane = try setZigFile(p, "pub fn @\"界name\"(\n\tvalue: usize,\n) void {\n" ++ "    _ = value;\n" ** 12 ++ "}\n");
+        pane.tag_expanded = false; // a one-row tag keeps this small screen's rows
+        p.sync();
         p.settings.wrap = false;
         p.settings.colors = false;
         try std.testing.expect(p.executeBuiltinLine(0, "TreeContext"));
@@ -811,6 +830,8 @@ const TreeContextTests = struct {
         defer p.deinit();
         const body = "    // 012345678901234567890123456789界tail";
         const pane = try setZigFile(p, "pub fn aLongDeclarationNameThatCannotFit() void {\n    // before\n" ++ body ++ "\n}\n");
+        pane.tag_expanded = false; // a one-row tag keeps this small screen's rows
+        p.sync();
         p.settings.wrap = true;
         try std.testing.expect(p.executeBuiltinLine(0, "TreeContext"));
         pane.scrollBy(2);
@@ -953,14 +974,14 @@ const TtySelectionTests = struct {
                 _ = try p.render(frame.allocator());
                 const source = p.rects[0];
                 const sx = source.x + config.GUTTER;
-                const sy = if (p.settings.tag_bottom) source.y else source.y + pardes.BOX_H;
+                const sy = bodyY(p, source);
                 JumpSelectionTests.drag(p, sx + 1, sy, sx + 3, sy + 1);
                 try std.testing.expectEqualStrings("lpha\nbrav", p.registers.text(p.gpa, '"') orelse return error.MissingAutomaticTtyYank);
                 try noChildInput(p);
 
                 const target = p.rects[1];
                 const tx = target.x + config.GUTTER + 2;
-                const ty = if (p.settings.tag_bottom) target.y else target.y + pardes.BOX_H;
+                const ty = bodyY(p, target);
                 p.update(.{ .mouse = .{ .button = .left, .kind = .press, .col = tx, .row = ty } });
                 p.update(.{ .mouse = .{ .button = .right, .kind = .press, .col = tx, .row = ty } });
                 p.update(.{ .mouse = .{ .button = .right, .kind = .release, .col = tx, .row = ty } });
@@ -1180,7 +1201,7 @@ const ClickCursorTests = struct {
                     _ = try p.render(frame.allocator());
                     const rect = p.rects[0];
                     const x = rect.x + config.GUTTER + panes.File.gutterWidth(pane);
-                    const y = if (bottom_tag) rect.y else rect.y + pardes.BOX_H;
+                    const y = bodyY(p, rect);
                     click(p, .left, x + 15, y + case.click_row);
                     try std.testing.expectEqual(case.row, pane.body.cur_row);
                     try std.testing.expectEqual(case.col, pane.body.cur_col);
@@ -1249,7 +1270,7 @@ const ClickCursorTests = struct {
         _ = try p.render(frame.allocator());
         const rect = p.rects[0];
         const x = rect.x + config.GUTTER + panes.File.gutterWidth(pane);
-        const y = if (p.settings.tag_bottom) rect.y else rect.y + pardes.BOX_H;
+        const y = bodyY(p, rect);
         JumpSelectionTests.drag(p, x + 1, y + 4, x + 3, y + 4);
         try std.testing.expectEqualStrings("lph", pardes.test_api.heldSelection(p, 0).?);
         for (0..2) |_| p.update(.{ .mouse = .{ .button = .wheel_down, .kind = .press, .col = x + 2, .row = y + 4 } });
@@ -1458,22 +1479,29 @@ const TagNameTintTests = struct {
         var arena = std.heap.ArenaAllocator.init(p.gpa);
         defer arena.deinit();
         const surface = try p.render(arena.allocator());
-        const text = try pardes.tagline.tagText(p, arena.allocator(), pane);
+        // The tag as shown: its rows wrapped, each offset mapped back to the
+        // tag's own to say whether it is in the name.
+        const shown = try pardes.tagline.shownTag(p, arena.allocator(), pane);
         const base = std.mem.lastIndexOfScalar(u8, name, '/') orelse return error.MissingDirectory;
         const rect = p.rects[id];
-        const y = if (p.settings.tag_bottom) rect.y + rect.h - pardes.BOX_H else rect.y;
         const left = rect.x + pardes.TAG_TEXT_INSET;
         var visible_name: usize = 0;
-        var at: usize = 0;
-        while (at < text.len) : (at = modal.nextGrapheme(text, at)) {
-            const start: i32 = @as(i32, @intCast(panes.File.rawDisplayCol(text, at))) - pane.tag_scroll;
-            const end = start + @as(i32, @intCast(panes.File.displayWidth(text[at..modal.nextGrapheme(text, at)])));
-            var col = @max(0, start);
-            while (col < end and col < rect.w - pardes.TAG_TEXT_INSET) : (col += 1) {
-                const in_name = at > base and at < name.len;
-                const fg = if (in_name) name_fg else tag_fg;
-                try std.testing.expectEqual(pardes.Color{ .rgb = fg }, surface.at(left + @as(u16, @intCast(col)), y).style.fg);
-                if (in_name) visible_name += 1;
+        for (0..pane.tag_rows) |row| {
+            const line_start = modal.lineStartOffset(shown.text, row + pane.tag_top);
+            const line = modal.lineSlice(shown.text, row + pane.tag_top);
+            const y = tagY(p, rect) + @as(u16, @intCast(row));
+            var at: usize = 0;
+            while (at < line.len) : (at = modal.nextGrapheme(line, at)) {
+                const real = shown.toReal(line_start + at);
+                const start: i32 = @intCast(panes.File.rawDisplayCol(line, at));
+                const end = start + @as(i32, @intCast(panes.File.displayWidth(line[at..modal.nextGrapheme(line, at)])));
+                var col = start;
+                while (col < end and col < rect.w - pardes.TAG_TEXT_INSET) : (col += 1) {
+                    const in_name = real > base and real < name.len;
+                    const fg = if (in_name) name_fg else tag_fg;
+                    try std.testing.expectEqual(pardes.Color{ .rgb = fg }, surface.at(left + @as(u16, @intCast(col)), y).style.fg);
+                    if (in_name) visible_name += 1;
+                }
             }
         }
         return visible_name;
@@ -1499,7 +1527,7 @@ const TagNameTintTests = struct {
         }
     }
 
-    test "tag filename tint follows scrolled Unicode drafted names and yields to selection" {
+    test "tag filename tint follows wrapped Unicode drafted names and yields to selection" {
         const p = try Pardes.init(std.testing.allocator, .{ .tty_only = true, .cols = 38, .rows = 14 });
         defer p.deinit();
         const pane = try p.setTestFile("body\n");
@@ -1509,17 +1537,20 @@ const TagNameTintTests = struct {
         pardes.tagline.draftName(p, pane, 0);
         redraft(pane, name);
         pane.input.cur_col = @intCast(std.mem.indexOf(u8, name, "界").?);
+        p.sync(); // the drafted name's rows
         try std.testing.expect((try check(p, 0, name)) > 0);
-        try std.testing.expect(pane.tag_scroll > 0);
-        // A sweep over the wide glyph wears the selection over the tint.
-        const col: i32 = @intCast(panes.File.rawDisplayCol(name, @intCast(pane.input.cur_col)));
-        pane.sel[0] = .{ .state = .done, .c0 = col, .c1 = col + 1, .r0 = 0, .r1 = 0 };
-        pane.tag_scroll += 4; // bring both cells of the selected wide glyph into view
+        try std.testing.expect(pane.tag_rows > 1); // the long name wraps
+        // A sweep over the wide glyph, on the row it wrapped to, wears the
+        // selection over the tint.
         var arena = std.heap.ArenaAllocator.init(p.gpa);
         defer arena.deinit();
+        const shown = try pardes.tagline.shownTag(p, arena.allocator(), pane);
+        const pos = modal.positionAt(shown.text, shown.fromReal(@intCast(pane.input.cur_col)));
+        const col: i32 = @intCast(panes.File.rawDisplayCol(modal.lineSlice(shown.text, pos.row), pos.col));
+        pane.sel[0] = .{ .state = .done, .c0 = col, .c1 = col + 1, .r0 = @intCast(pos.row), .r1 = @intCast(pos.row) };
         const surface = try p.render(arena.allocator());
-        const x = p.rects[0].x + pardes.TAG_TEXT_INSET + @as(u16, @intCast(col - pane.tag_scroll));
-        const y = if (p.settings.tag_bottom) p.rects[0].y + p.rects[0].h - pardes.BOX_H else p.rects[0].y;
+        const x = p.rects[0].x + pardes.TAG_TEXT_INSET + @as(u16, @intCast(col));
+        const y = tagY(p, p.rects[0]) + @as(u16, @intCast(pos.row));
         try std.testing.expectEqual(pardes.Color{ .rgb = p.theme().sel_fg }, surface.at(x, y).style.fg);
         try std.testing.expectEqual(pardes.Color{ .rgb = p.theme().sel_fg }, surface.at(x + 1, y).style.fg);
     }
@@ -1542,7 +1573,7 @@ const TagNameTintTests = struct {
             p.settings.focus_tint = active;
             const surface = try p.render(arena.allocator());
             const x = p.rects[0].x + pardes.TAG_TEXT_INSET;
-            const y = if (p.settings.tag_bottom) p.rects[0].y + p.rects[0].h - pardes.BOX_H else p.rects[0].y;
+            const y = tagY(p, p.rects[0]);
             const fg = if (active) active_fg else tag_fg;
             try std.testing.expectEqual(pardes.Color{ .rgb = fg }, surface.at(x + 1, y).style.fg);
             try std.testing.expectEqual(pardes.Color{ .rgb = fg }, surface.at(x + 5, y).style.fg);
@@ -1561,7 +1592,7 @@ fn redraft(pane: *Pane, name: []const u8) void {
 /// Click the tagline at the end of the path: a name draft, caret there.
 fn clickPathEnd(p: *Pardes, pane: *Pane) void {
     const rect = p.rects[p.active];
-    const y = if (p.settings.tag_bottom) rect.y + rect.h - pardes.BOX_H else rect.y;
+    const y = tagY(p, rect);
     const x = rect.x + pardes.TAG_TEXT_INSET + @as(u16, @intCast(panes.File.displayWidth(pane.file.?.path) - 1));
     ClickCursorTests.click(p, .left, x, y);
     std.debug.assert(pane.prompt == .name);
@@ -1703,7 +1734,7 @@ test "paste into pane commands and prompts never inserts into the body" {
     try std.testing.expect(std.mem.indexOf(u8, pardes.tagline.curTail(pane), " Custom\nCommand") != null);
 }
 
-test "long pane tags reveal commands and map visible clicks to whole tag addresses" {
+test "a long pane tag wraps onto rows, and a click on a wrapped row maps to the whole tag's address" {
     const p = try Pardes.init(std.testing.allocator, .{ .tty_only = true, .cols = 50, .rows = 12 });
     defer p.deinit();
     const pane = try p.setTestFile("body\n");
@@ -1715,13 +1746,15 @@ test "long pane tags reveal commands and map visible clicks to whole tag address
     var arena = std.heap.ArenaAllocator.init(p.gpa);
     defer arena.deinit();
     const surface = try p.render(arena.allocator());
-    try std.testing.expect(pane.tag_scroll > 0);
+    try std.testing.expect(pane.tag_rows > 1);
     try std.testing.expect(surface.cursor.?.x < p.rects[0].x + p.rects[0].w);
     const text = try pardes.tagline.tagText(p, p.gpa, pane);
     defer p.gpa.free(text);
-    const offset = std.mem.indexOf(u8, text, "SyntaxBold").?;
-    const x: u16 = @intCast(p.rects[0].x + pardes.TAG_TEXT_INSET + panes.File.rawDisplayCol(text, offset) - pane.tag_scroll);
-    const y = p.rects[0].y;
+    const shown = try pardes.tagline.shownTag(p, arena.allocator(), pane);
+    const at = shown.fromReal(std.mem.indexOf(u8, text, "SyntaxBold").?);
+    const pos = modal.positionAt(shown.text, at);
+    const x: u16 = @intCast(p.rects[0].x + pardes.TAG_TEXT_INSET + panes.File.rawDisplayCol(modal.lineSlice(shown.text, pos.row), pos.col));
+    const y = p.tagTop(pane, p.rects[0]) + @as(u16, @intCast(pos.row));
     const before = p.settings.syntax_bold;
     p.update(.{ .mouse = .{ .col = x, .row = y, .button = config.exec_button, .kind = .press } });
     p.update(.{ .mouse = .{ .col = x, .row = y, .button = config.exec_button, .kind = .release } });
@@ -1729,6 +1762,32 @@ test "long pane tags reveal commands and map visible clicks to whole tag address
     try std.testing.expectEqualStrings(text, try pardes.tagline.tagText(p, p.scratch.allocator(), pane));
 }
 
+test "a word the tag's wrapping breaks across rows is still one word to a click" {
+    const p = try Pardes.init(std.testing.allocator, .{ .tty_only = true, .cols = 50, .rows = 12 });
+    defer p.deinit();
+    const pane = try p.setTestFile("body\n");
+    try pane.appendTag(" SyntaxBold");
+    var arena = std.heap.ArenaAllocator.init(p.gpa);
+    defer arena.deinit();
+    // Lengthen the path until the wrap splits the word after "Synt".
+    var pad: usize = 1;
+    const shown = while (pad < 80) : (pad += 1) {
+        p.gpa.free(pane.file.?.path);
+        const path = try std.fmt.allocPrint(arena.allocator(), "/{s}/f.zig", .{("a" ** 80)[0..pad]});
+        pane.file.?.path = try p.gpa.dupe(u8, path);
+        p.sync();
+        const s = try pardes.tagline.shownTag(p, arena.allocator(), pane);
+        if (std.mem.indexOf(u8, s.text, "Synt\n") != null) break s;
+    } else return error.NoSplit;
+    const pos = modal.positionAt(shown.text, std.mem.indexOf(u8, shown.text, "Synt").?);
+    const x: u16 = @intCast(p.rects[0].x + pardes.TAG_TEXT_INSET + pos.col + 1);
+    const y = p.tagTop(pane, p.rects[0]) + @as(u16, @intCast(pos.row));
+    const before = p.settings.syntax_bold;
+    p.update(.{ .mouse = .{ .col = x, .row = y, .button = config.exec_button, .kind = .press } });
+    p.update(.{ .mouse = .{ .col = x, .row = y, .button = config.exec_button, .kind = .release } });
+    try std.testing.expectEqual(!before, p.settings.syntax_bold);
+}
+
 test "terminal overlay recoloring never materializes unrelated history" {
     const testing = std.testing;
     const p = try Pardes.init(testing.allocator, .{ .tty_only = true, .cols = 32, .rows = 8 });
@@ -1751,7 +1810,7 @@ test "terminal overlay recoloring never materializes unrelated history" {
     const surface = try p.render(frame.allocator());
     try testing.expect(p.shell_rows.pane == null);
     const rect = p.rects[0];
-    const body_y = if (p.settings.tag_bottom) rect.y else rect.y + pardes.BOX_H;
+    const body_y = bodyY(p, rect);
     const cell = surface.at(rect.x + config.GUTTER, body_y);
     try testing.expectEqualStrings("c", cell.grapheme());
     try testing.expectEqual(pardes.Color{ .rgb = p.theme().palette.?[2] }, cell.style.fg);
@@ -1799,7 +1858,7 @@ test "terminal output keeps following new rows after scrollback eviction" {
         const surface = try p.render(frame.allocator());
         const rect = p.rects[0];
         const x = rect.x + config.GUTTER;
-        const y = (if (p.settings.tag_bottom) rect.y else rect.y + pardes.BOX_H) + pane.rows - 2;
+        const y = (bodyY(p, rect)) + pane.rows - 2;
         for (last, 0..) |byte, col| {
             const cell = surface.at(x + @as(u16, @intCast(col)), y);
             try std.testing.expectEqualStrings(&.{byte}, cell.grapheme());
@@ -2452,7 +2511,7 @@ test "unplaced terminal panes keep their allocated grid until placement" {
     p.update(.tick);
     try std.testing.expect(p.rects[id].w > 0 and p.rects[id].h > pardes.BOX_H);
     try std.testing.expectEqual(p.rects[id].w - config.GUTTER, pane.cols);
-    try std.testing.expectEqual(p.rects[id].h - pardes.BOX_H, pane.rows);
+    try std.testing.expectEqual(bodyH(p, p.rects[id]), pane.rows);
 }
 
 test "document panes ignore terminal output without allocating terminal state" {
@@ -2805,7 +2864,7 @@ const OutputTests = struct {
         layout.compute(p);
         const surface = try p.render(frame.allocator());
         const rect = p.rects[pane.search_pane.?];
-        const body_y = if (p.settings.tag_bottom) rect.y else rect.y + pardes.BOX_H;
+        const body_y = bodyY(p, rect);
         for (file.location_rows, 0..) |row, index| {
             if (!row.declaration) continue;
             const line = modal.lineSlice(file.content, index);
@@ -2853,7 +2912,7 @@ const OutputTests = struct {
         _ = try p.render(frame.allocator());
         const rect = p.rects[id];
         const x = rect.x + config.GUTTER + panes.File.gutterWidth(help) + @as(u16, @intCast(at - line_start + 2));
-        const y = (if (p.settings.tag_bottom) rect.y else rect.y + pardes.BOX_H) + @as(u16, @intCast(row));
+        const y = (bodyY(p, rect)) + @as(u16, @intCast(row));
         p.update(.{ .mouse = .{ .button = config.exec_button, .kind = .press, .col = x, .row = y } });
         p.update(.{ .mouse = .{ .button = config.exec_button, .kind = .release, .col = x, .row = y } });
         try std.testing.expect(p.active != id);
@@ -2923,7 +2982,7 @@ const OutputTests = struct {
         p.acknowledgePanelPresentation(&.{});
         const rect = p.rects[id];
         const x = rect.x + config.GUTTER + panes.File.gutterWidth(result);
-        const y = if (p.settings.tag_bottom) rect.y else rect.y + pardes.BOX_H;
+        const y = bodyY(p, rect);
         p.update(.{ .mouse = .{ .button = config.select_button, .kind = .press, .col = x, .row = y } });
         p.update(.{ .mouse = .{ .button = config.select_button, .kind = .drag, .col = x + 2, .row = y + 1 } });
         try std.testing.expect(p.drag == .select);
@@ -3238,8 +3297,8 @@ const TerminalTests = struct {
         defer frame.deinit();
         const r = p.rects[0];
         const tx = r.x + config.GUTTER;
-        const body_y = if (p.settings.tag_bottom) r.y else r.y + pardes.BOX_H;
-        const rows: usize = r.h - pardes.BOX_H;
+        const body_y = bodyY(p, r);
+        const rows: usize = bodyH(p, r);
         const cols: usize = r.w -| config.GUTTER;
 
         const Snap = struct { text: [][7]u8, len: []u8, style: []pardes.CellStyle };
@@ -3479,7 +3538,7 @@ const TerminalTests = struct {
         defer frame.deinit();
         const r = p.rects[0];
         const tx = r.x + config.GUTTER;
-        const body_y = if (p.settings.tag_bottom) r.y else r.y + pardes.BOX_H;
+        const body_y = bodyY(p, r);
         const red: pardes.Color = .{ .index = 1 };
         const green: pardes.Color = .{ .index = 2 };
         const blue: pardes.Color = .{ .index = 4 };
@@ -3534,7 +3593,7 @@ const TerminalTests = struct {
         defer frame.deinit();
         const r = p.rects[0];
         const tx = r.x + config.GUTTER;
-        const body_y = if (p.settings.tag_bottom) r.y else r.y + pardes.BOX_H;
+        const body_y = bodyY(p, r);
 
         p.shell_rows.stale = true;
         const s = try p.render(frame.allocator());
@@ -3582,8 +3641,8 @@ const TerminalTests = struct {
         defer frame.deinit();
         const r = p.rects[0];
         const tx = r.x + config.GUTTER;
-        const body_y = if (p.settings.tag_bottom) r.y else r.y + pardes.BOX_H;
-        const body_h = r.h - pardes.BOX_H;
+        const body_y = bodyY(p, r);
+        const body_h = bodyH(p, r);
 
         p.shell_rows.stale = true;
         const s = try p.render(frame.allocator());
@@ -3621,7 +3680,7 @@ const TerminalTests = struct {
         defer frame.deinit();
         const r = p.rects[0];
         const tx = r.x + config.GUTTER;
-        const body_y = if (p.settings.tag_bottom) r.y else r.y + pardes.BOX_H;
+        const body_y = bodyY(p, r);
         const red: pardes.Color = .{ .index = 1 };
         const green: pardes.Color = .{ .index = 2 };
         const blue: pardes.Color = .{ .index = 4 };
@@ -3658,7 +3717,7 @@ const TerminalTests = struct {
         defer frame.deinit();
         const r = p.rects[0];
         const tx = r.x + config.GUTTER;
-        const body_y = if (p.settings.tag_bottom) r.y else r.y + pardes.BOX_H;
+        const body_y = bodyY(p, r);
         const red: pardes.Color = .{ .index = 1 };
 
         // Covers far more rows than the grid was ever dumped for, so the anchor
@@ -3740,7 +3799,7 @@ const TerminalTests = struct {
                 defer frame.deinit();
                 const r = p.rects[0];
                 const tx = r.x + config.GUTTER;
-                const body_y = if (p.settings.tag_bottom) r.y else r.y + pardes.BOX_H;
+                const body_y = bodyY(p, r);
                 p.shell_rows.stale = true;
                 const s = try p.render(frame.allocator());
 
@@ -3818,8 +3877,8 @@ const TerminalTests = struct {
         defer frame.deinit();
         const r = p.rects[0];
         const tx = r.x + config.GUTTER;
-        const body_y = if (p.settings.tag_bottom) r.y else r.y + pardes.BOX_H;
-        const rows: usize = r.h - pardes.BOX_H;
+        const body_y = bodyY(p, r);
+        const rows: usize = bodyH(p, r);
         const cols: usize = r.w -| config.GUTTER;
 
         // What tty mode shows with nothing left behind: the reference.
@@ -3870,6 +3929,8 @@ const TerminalTests = struct {
                 defer p.deinit();
                 while (p.nextEffect()) |_| {}
                 const pane = p.panes[0].?;
+                pane.tag_expanded = false; // a one-row tag keeps this small screen's rows
+                p.sync();
                 pane.tty_filter = filter;
                 pane.body.mode = mode;
                 p.update(.{ .output = .{ .pane = 0, .bytes = "\x1b[32m\u{754C}\x1b[41m\x1b[K\x1b[7G\x1b[44m\x1b[K\r\n" } });
@@ -3878,7 +3939,7 @@ const TerminalTests = struct {
                 defer frame.deinit();
                 const r = p.rects[0];
                 const tx = r.x + config.GUTTER;
-                const body_y = if (p.settings.tag_bottom) r.y else r.y + pardes.BOX_H;
+                const body_y = bodyY(p, r);
                 p.shell_rows.stale = true;
                 const s = try p.render(frame.allocator());
 
@@ -3914,7 +3975,7 @@ const TerminalTests = struct {
             defer frame.deinit();
             const r = p.rects[0];
             const tx = r.x + config.GUTTER;
-            const body_y = if (p.settings.tag_bottom) r.y else r.y + pardes.BOX_H;
+            const body_y = bodyY(p, r);
             p.shell_rows.stale = true;
             const s = try p.render(frame.allocator());
 
@@ -3947,10 +4008,10 @@ const TerminalTests = struct {
         const s = try p.render(frame.allocator());
         const r = p.rects[0];
         const tx = r.x + config.GUTTER;
-        const body_y = if (p.settings.tag_bottom) r.y else r.y + pardes.BOX_H;
+        const body_y = bodyY(p, r);
 
         var bad: usize = 0;
-        for (0..r.h -| pardes.BOX_H) |vr| {
+        for (0..bodyH(p, r)) |vr| {
             var buf: [16]u8 = undefined;
             var n: usize = 0;
             for (0..10) |c| {
@@ -3990,7 +4051,7 @@ const TerminalTests = struct {
             defer frame.deinit();
             const r = p.rects[0];
             const tx = r.x + config.GUTTER;
-            const body_y = if (p.settings.tag_bottom) r.y else r.y + pardes.BOX_H;
+            const body_y = bodyY(p, r);
 
             p.update(.{ .output = .{ .pane = 0, .bytes = "plain text\r\n" } });
             p.shell_rows.stale = true;
@@ -4028,7 +4089,7 @@ const TerminalTests = struct {
         defer frame.deinit();
         const r = p.rects[0];
         const tx = r.x + config.GUTTER;
-        const body_y = if (p.settings.tag_bottom) r.y else r.y + pardes.BOX_H;
+        const body_y = bodyY(p, r);
 
         // The state two ordinary edits reach: one at the bottom, one that split a
         // line further up. The buffer now spans rows 2..6 and diverges at BOTH
@@ -4066,7 +4127,7 @@ const TerminalTests = struct {
         defer frame.deinit();
         const r = p.rects[0];
         const tx = r.x + config.GUTTER;
-        const body_y = if (p.settings.tag_bottom) r.y else r.y + pardes.BOX_H;
+        const body_y = bodyY(p, r);
 
         // The state three keystrokes reach on any blank shell row: type a character
         // and delete it, and the buffer holds NO text while still standing in for
@@ -4091,6 +4152,8 @@ const TerminalTests = struct {
         defer p.deinit();
         while (p.nextEffect()) |_| {}
         const pane = p.panes[0].?;
+        pane.tag_expanded = false; // a one-row tag keeps this small screen's rows
+        p.sync();
         pane.tty_filter = false;
         pane.body.mode = .tty;
 
@@ -4100,7 +4163,7 @@ const TerminalTests = struct {
         defer frame.deinit();
         const r = p.rects[0];
         const tx = r.x + config.GUTTER;
-        const body_y = if (p.settings.tag_bottom) r.y else r.y + pardes.BOX_H;
+        const body_y = bodyY(p, r);
         const blue: pardes.Color = .{ .index = 4 };
 
         p.shell_rows.stale = true;
@@ -4143,12 +4206,12 @@ const TerminalTests = struct {
         defer frame.deinit();
         const r = p.rects[0];
         const tx = r.x + config.GUTTER;
-        const body_y = if (p.settings.tag_bottom) r.y else r.y + pardes.BOX_H;
+        const body_y = bodyY(p, r);
 
         const s = try p.render(frame.allocator());
         const want = pardes.Color{ .index = 33 };
         var seen = false;
-        for (0..@as(usize, r.h -| pardes.BOX_H)) |vr| {
+        for (0..@as(usize, bodyH(p, r))) |vr| {
             var buf: [15]u8 = undefined;
             for (0..15) |c| {
                 const g = s.at(tx + @as(u16, @intCast(c)), body_y + @as(u16, @intCast(vr))).grapheme();
@@ -4196,11 +4259,11 @@ const TerminalTests = struct {
         defer frame.deinit();
         const r = p.rects[0];
         const tx = r.x + config.GUTTER;
-        const body_y = if (p.settings.tag_bottom) r.y else r.y + pardes.BOX_H;
+        const body_y = bodyY(p, r);
 
         const s = try p.render(frame.allocator());
         var seen = false;
-        for (0..@as(usize, r.h -| pardes.BOX_H)) |vr| {
+        for (0..@as(usize, bodyH(p, r))) |vr| {
             var buf: [12]u8 = undefined;
             for (0..12) |c| {
                 const g = s.at(tx + @as(u16, @intCast(c)), body_y + @as(u16, @intCast(vr))).grapheme();
@@ -4250,8 +4313,8 @@ const TerminalTests = struct {
             defer frame.deinit();
             const r = p.rects[0];
             const tx = r.x + config.GUTTER;
-            const body_y = if (p.settings.tag_bottom) r.y else r.y + pardes.BOX_H;
-            const body_h = r.h -| pardes.BOX_H;
+            const body_y = bodyY(p, r);
+            const body_h = bodyH(p, r);
 
             var step: usize = 0;
             while (step < 12) : (step += 1) {
@@ -4345,11 +4408,11 @@ const TerminalTests = struct {
         defer frame.deinit();
         const r = p.rects[0];
         const tx = r.x + config.GUTTER;
-        const body_y = if (p.settings.tag_bottom) r.y else r.y + pardes.BOX_H;
+        const body_y = bodyY(p, r);
 
         const s = try p.render(frame.allocator());
         var seen: usize = 0;
-        for (0..@as(usize, r.h -| pardes.BOX_H)) |vr| {
+        for (0..@as(usize, bodyH(p, r))) |vr| {
             var buf: [12]u8 = undefined;
             for (0..12) |c| {
                 const g = s.at(tx + @as(u16, @intCast(c)), body_y + @as(u16, @intCast(vr))).grapheme();
@@ -4427,7 +4490,7 @@ test "cancelled normal gestures leave no count or subprefix after mouse and focu
             switch (gesture) {
                 .body, .tag => {
                     const rect = p.rects[0];
-                    const tag_y = if (p.settings.tag_bottom) rect.y + rect.h - pardes.BOX_H else rect.y;
+                    const tag_y = tagY(p, rect);
                     const body_y = p.bodyTop(pane, rect);
                     const x = if (gesture == .tag)
                         rect.x + pardes.TAG_TEXT_INSET + @as(u16, @intCast(panes.File.displayWidth(try pardes.tagline.tagPrefix(p, pane)))) + 3
@@ -4557,9 +4620,9 @@ test "growing a file pane colors every newly visible Zig keyword" {
         _ = frame.reset(.retain_capacity);
         const surface = try p.render(frame.allocator());
         const rect = p.rects[0];
-        const body_y = if (p.settings.tag_bottom) rect.y else rect.y + pardes.BOX_H;
+        const body_y = bodyY(p, rect);
         var seen: usize = 0;
-        for (body_y..body_y + rect.h - pardes.BOX_H) |y| {
+        for (body_y..body_y + bodyH(p, rect)) |y| {
             for (rect.x + config.GUTTER..rect.x + rect.w - 1) |x| {
                 const first = surface.at(@intCast(x), @intCast(y));
                 const second = surface.at(@intCast(x + 1), @intCast(y));
@@ -4600,6 +4663,8 @@ test "Zig keywords keep every rendered byte colored across line-number widths" {
                 const p = try Pardes.init(gpa, .{ .tty_only = true, .cols = view.cols, .rows = 10 });
                 defer p.deinit();
                 const pane = try p.setTestFile(source);
+                pane.tag_expanded = false; // a one-row tag keeps this small screen's rows
+                p.sync();
                 const file = &pane.file.?;
                 gpa.free(file.path);
                 file.path = try gpa.dupe(u8, "/highlight.zig");
@@ -4616,8 +4681,8 @@ test "Zig keywords keep every rendered byte colored across line-number widths" {
                 var seen: usize = 0;
                 var if_position: ?struct { x: u16, y: u16 } = null;
                 const rect = p.rects[0];
-                const body_y = if (p.settings.tag_bottom) rect.y else rect.y + pardes.BOX_H;
-                for (body_y..body_y + rect.h - pardes.BOX_H) |y| {
+                const body_y = bodyY(p, rect);
+                for (body_y..body_y + bodyH(p, rect)) |y| {
                     for (rect.x + config.GUTTER..rect.x + rect.w - 1) |x| {
                         const first = surface.at(@intCast(x), @intCast(y));
                         const second = surface.at(@intCast(x + 1), @intCast(y));
@@ -4666,7 +4731,7 @@ test "terminal overlays preserve trailing blank styles without coloring inserted
     defer frame.deinit();
     const rect = p.rects[0];
     const x = rect.x + config.GUTTER;
-    const y = if (p.settings.tag_bottom) rect.y else rect.y + pardes.BOX_H;
+    const y = bodyY(p, rect);
     const palette = p.theme().palette.?;
     const colors = [_]pardes.Color{ .{ .rgb = palette[1] }, .{ .rgb = palette[2] }, .{ .rgb = palette[4] } };
     const original = try p.render(frame.allocator());