a builtin to put the pane taglines at the bottom

1 files changed, 144 insertions, 55 deletions

diff --git a/src/pardes.zig b/src/pardes.zig
index aa753277..ba80ee22 100644
--- a/src/pardes.zig
+++ b/src/pardes.zig
@@ -3943,9 +3943,15 @@ fn clampBorderCol(lx: u16, lw: u16, rw: u16, mcol: u16) u16 {
 /// Where a horizontal border drag settles: `mrow` clamped so either pane may
 /// shrink to just its tag row (BOX_H) but no further. `ay`/`ah` are the upper
 /// pane's y and height, `bh` the lower pane's.
-fn clampBorderRow(ay: u16, ah: u16, bh: u16, mrow: u16) u16 {
-    const lo = ay + BOX_H - 1;
-    const hi = ay +| ah +| bh -| (BOX_H + 1);
+///
+/// The handle is the seam row that is a BODY row, which is the upper pane's
+/// LAST row normally and — with Tagbottom, where that row is the upper pane's
+/// tag — the lower pane's FIRST. That is the same seam one row further down,
+/// so both walls simply move with it.
+fn clampBorderRow(ay: u16, ah: u16, bh: u16, mrow: u16, tag_bottom: bool) u16 {
+    const d: u16 = if (tag_bottom) 1 else 0;
+    const lo = ay + BOX_H - 1 + d;
+    const hi = (ay +| ah +| bh -| (BOX_H + 1)) +| d;
     return if (lo <= hi) std.math.clamp(mrow, lo, hi) else mrow;
 }
 
@@ -3967,25 +3973,32 @@ test "a corner drag's two axes clamp independently" {
     // each axis alone, at both walls
     try std.testing.expectEqual(@as(u16, config.MINW), clampBorderCol(lx, lw, rw, 0));
     try std.testing.expectEqual(@as(u16, 100 - config.MINW), clampBorderCol(lx, lw, rw, 999));
-    try std.testing.expectEqual(row_lo, clampBorderRow(ay, ah, bh, 0));
-    try std.testing.expectEqual(row_hi, clampBorderRow(ay, ah, bh, 999));
+    try std.testing.expectEqual(row_lo, clampBorderRow(ay, ah, bh, 0, false));
+    try std.testing.expectEqual(row_hi, clampBorderRow(ay, ah, bh, 999, false));
 
     // THE corner property: drag off the right edge while staying mid-height —
     // x sits at its wall, y still tracks the mouse row exactly
     try std.testing.expectEqual(@as(u16, 100 - config.MINW), clampBorderCol(lx, lw, rw, 999));
-    try std.testing.expectEqual(@as(u16, 12), clampBorderRow(ay, ah, bh, 12));
+    try std.testing.expectEqual(@as(u16, 12), clampBorderRow(ay, ah, bh, 12, false));
     // and the mirror: pinned at the bottom, x still free
-    try std.testing.expectEqual(row_hi, clampBorderRow(ay, ah, bh, 999));
+    try std.testing.expectEqual(row_hi, clampBorderRow(ay, ah, bh, 999, false));
     try std.testing.expectEqual(@as(u16, 40), clampBorderCol(lx, lw, rw, 40));
     // both pinned at once is just both walls, not a stuck gesture
     try std.testing.expectEqual(@as(u16, config.MINW), clampBorderCol(lx, lw, rw, 0));
-    try std.testing.expectEqual(row_hi, clampBorderRow(ay, ah, bh, 999));
+    try std.testing.expectEqual(row_hi, clampBorderRow(ay, ah, bh, 999, false));
+
+    // Tagbottom moves the handle to the LOWER pane's first row, one further
+    // down, and both walls travel with it — either pane still bottoms out at
+    // its bare tag row and neither can be squeezed away
+    try std.testing.expectEqual(row_lo + 1, clampBorderRow(ay, ah, bh, 0, true));
+    try std.testing.expectEqual(row_hi + 1, clampBorderRow(ay, ah, bh, 999, true));
+    try std.testing.expectEqual(@as(u16, 12), clampBorderRow(ay, ah, bh, 12, true));
 
     // degenerate pairs pass through untouched, each on its own terms: a pane
     // pair with no room stays draggable even when the column pair has room
     try std.testing.expectEqual(@as(u16, 7), clampBorderCol(0, 5, 5, 7));
     try std.testing.expectEqual(@as(u16, 40), clampBorderCol(lx, lw, rw, 40));
-    try std.testing.expectEqual(@as(u16, 9), clampBorderRow(TOPBAR_H, 1, 0, 9));
+    try std.testing.expectEqual(@as(u16, 9), clampBorderRow(TOPBAR_H, 1, 0, 9, false));
 }
 
 pub const Rect = struct { x: u16, y: u16, w: u16, h: u16 };
@@ -4104,6 +4117,12 @@ pub const Pardes = struct {
     /// something. Turned off, every row math in here is the one-row-per-line
     /// arithmetic it always was and hscroll comes back.
     wrap_on: bool = true,
+    /// every pane's tagline on its LAST row instead of its first (the
+    /// Tagbottom builtin). Render and hit-testing derive two locals from it —
+    /// the tag row and the first body row — and nothing else in here knows;
+    /// the Sel coordinate space is untouched, so row 0 is still the tag and
+    /// the body still starts at BOX_H whichever end they are drawn at.
+    tag_bottom: bool = false,
     show_debug: bool = false,
     /// the Crt builtin's CRT post-process, rendered by the gui shell only
     /// (the tty and web shells never read it)
@@ -8994,13 +9013,23 @@ pub const Pardes = struct {
                     // pair's h-handle, and the box must stay grabbable to move
                     if (hovered) |mid| {
                         const mr = p.rects[mid];
-                        if (mcol < mr.x + config.GUTTER and mrow < mr.y + BOX_H) {
+                        const mtag = if (p.tag_bottom) mr.y + mr.h -| BOX_H else mr.y;
+                        if (mcol < mr.x + config.GUTTER and mrow >= mtag and mrow < mtag + BOX_H) {
                             p.drag = .{ .move = .{ .id = mid, .cur_x = mcol, .cur_y = mrow } };
                             return;
                         }
                     }
                     // resize handles next: a pane's own trailing edge (v: the
-                    // left column's last col; h: the upper pane's last row).
+                    // left column's last col; h: the seam row between a stacked
+                    // pair that is a BODY row — the upper pane's last, or with
+                    // Tagbottom, where that one is the upper pane's tag, the
+                    // lower pane's first).
+                    // Either way the handle EATS one body row of one of the two
+                    // panes — a press there resizes instead of placing a cursor
+                    // — and it always has. Tagbottom does not change how many
+                    // rows that costs, only WHICH pane pays: the lower pane's
+                    // first row rather than the upper pane's last. A no-drag
+                    // click on it is a no-op in both orientations.
                     // The v test still wins outright, but it now also asks
                     // whether this same cell is one of ITS OWN column's h
                     // handles — that cell is the corner where the two lines
@@ -9011,7 +9040,8 @@ pub const Pardes = struct {
                             var corner: ?usize = null;
                             for (0..p.col_n[c] -| 1) |k| {
                                 const r = p.rects[p.col_terms[c][k]];
-                                if (mrow == r.y + r.h -| 1) {
+                                const seam = if (p.tag_bottom) r.y +| r.h else r.y + r.h -| 1;
+                                if (mrow == seam) {
                                     corner = k;
                                     break;
                                 }
@@ -9024,7 +9054,8 @@ pub const Pardes = struct {
                         if (mcol < p.col_x[cc] or mcol >= p.col_x[cc] + p.col_w[cc]) continue;
                         for (0..p.col_n[cc] -| 1) |k| {
                             const r = p.rects[p.col_terms[cc][k]];
-                            if (mrow == r.y + r.h -| 1) {
+                            const seam = if (p.tag_bottom) r.y +| r.h else r.y + r.h -| 1;
+                            if (mrow == seam) {
                                 p.drag = .{ .border_h = .{ .col = cc, .top_idx = k, .cur_y = mrow } };
                                 return;
                             }
@@ -9033,11 +9064,18 @@ pub const Pardes = struct {
                     const id = hovered orelse return;
                     const r = p.rects[id];
                     const pane = p.panes[id] orelse return;
+                    // the same two rows renderPane painted through (see there):
+                    // the tag's, and the body's first. A Sel row is still 0 for
+                    // the tag and BOX_H upward for the body whichever end they
+                    // are at, so the mapping happens HERE and everything
+                    // downstream of a Sel is untouched.
+                    const tag_y = if (p.tag_bottom) r.y + r.h -| BOX_H else r.y;
+                    const body_y = if (p.tag_bottom) r.y else r.y + BOX_H;
                     if (mcol < r.x + config.GUTTER) {
                         // gutter scrollbar: a left click scrolls UP to that row
                         p.active = id;
-                        pane.scrollBy(-(@as(i32, mrow) - @as(i32, r.y + BOX_H)));
-                    } else if (mrow < r.y + BOX_H) {
+                        pane.scrollBy(-(@as(i32, mrow) - @as(i32, body_y)));
+                    } else if (mrow >= tag_y and mrow < tag_y + BOX_H) {
                         // left press on the tag row: focus the tag AT that
                         // column (a rendered-tag column — the mouse and the tag
                         // agree, no clamp into the tail) and anchor a sweep, so
@@ -9050,7 +9088,7 @@ pub const Pardes = struct {
                         p.active = id;
                         exitTagEdit(pane); // clicking the body leaves tag editing
                         const sc: i32 = @as(i32, mcol) - @as(i32, r.x + config.GUTTER);
-                        const v: i32 = @as(i32, mrow) - @as(i32, r.y);
+                        const v: i32 = @as(i32, mrow) - @as(i32, body_y) + @as(i32, BOX_H);
                         pane.sel[sel_slot] = .{ .state = .dragging, .c0 = sc, .c1 = sc, .r0 = v, .r1 = v };
                         const pdf_native = if (comptime pdf_enabled) p.pdfNativeReady(pane) else false;
                         if (pdf_native) _ = p.beginPdfDrag(pane, mcol, mrow, false);
@@ -9111,17 +9149,27 @@ pub const Pardes = struct {
                     const id = hovered orelse return;
                     const r = p.rects[id];
                     const pane = p.panes[id] orelse return;
-                    if (mcol < r.x + config.GUTTER and mrow >= r.y + BOX_H) {
+                    // the tag row and the body's first, exactly as the select
+                    // arm above derives them
+                    const tag_y = if (p.tag_bottom) r.y + r.h -| BOX_H else r.y;
+                    const body_y = if (p.tag_bottom) r.y else r.y + BOX_H;
+                    const on_tag = mrow >= tag_y and mrow < tag_y + BOX_H;
+                    if (mcol < r.x + config.GUTTER and !on_tag) {
                         // gutter: right scrolls DOWN to here, mirroring left's up;
                         // middle matches left. Right focuses (look lands you
                         // there); middle does not.
-                        const local = @as(i32, mrow) - @as(i32, r.y + BOX_H);
+                        const local = @as(i32, mrow) - @as(i32, body_y);
                         if (m.button == config.look_button) p.active = id;
                         pane.scrollBy(if (m.button == config.look_button) local else -local);
                     } else if (mcol >= r.x + config.GUTTER) {
                         if (m.button == config.look_button) p.active = id;
                         const c: i32 = @as(i32, mcol) - @as(i32, r.x + config.GUTTER);
-                        const v: i32 = @as(i32, mrow) - @as(i32, r.y);
+                        // unlike the select button, execute and look sweep the
+                        // TAG through this same Sel — that is how middle-clicking
+                        // Del on a tagline runs it — so the tag row is row 0 and
+                        // everything else counts from BOX_H, wherever the tag is
+                        // physically drawn.
+                        const v: i32 = if (on_tag) 0 else @as(i32, mrow) - @as(i32, body_y) + @as(i32, BOX_H);
                         pane.sel[@intFromEnum(m.button)] = .{ .state = .dragging, .c0 = c, .c1 = c, .r0 = v, .r1 = v };
                         // Once a body gesture starts over a native PDF, keep
                         // it native even when the point misses a letterbox or
@@ -9129,7 +9177,7 @@ pub const Pardes = struct {
                         // inert instead of executing hidden projected text.
                         // Tag clicks remain ordinary text/builtin gestures.
                         const pdf_native = if (comptime pdf_enabled)
-                            mrow >= r.y + BOX_H and p.pdfNativeReady(pane)
+                            !on_tag and p.pdfNativeReady(pane)
                         else
                             false;
                         if (pdf_native) _ = p.beginPdfDrag(pane, mcol, mrow, true);
@@ -9163,7 +9211,7 @@ pub const Pardes = struct {
                 if (d.corner_idx) |k| if (k + 1 < p.col_n[c]) {
                     const a = p.rects[p.col_terms[c][k]];
                     const b = p.rects[p.col_terms[c][k + 1]];
-                    d.cur_y = clampBorderRow(a.y, a.h, b.h, mrow);
+                    d.cur_y = clampBorderRow(a.y, a.h, b.h, mrow, p.tag_bottom);
                 } else {
                     d.cur_y = mrow;
                 };
@@ -9174,7 +9222,7 @@ pub const Pardes = struct {
                 if (k + 1 < p.col_n[cc]) {
                     const a = p.rects[p.col_terms[cc][k]];
                     const b = p.rects[p.col_terms[cc][k + 1]];
-                    d.cur_y = clampBorderRow(a.y, a.h, b.h, mrow);
+                    d.cur_y = clampBorderRow(a.y, a.h, b.h, mrow, p.tag_bottom);
                 } else d.cur_y = mrow;
             },
             .move => |*d| {
@@ -9186,7 +9234,29 @@ pub const Pardes = struct {
                     const r = p.rects[s.id];
                     const b = @intFromEnum(s.button);
                     pane.sel[b].c1 = @as(i32, mcol) - @as(i32, r.x + config.GUTTER);
-                    pane.sel[b].r1 = @as(i32, mrow) - @as(i32, r.y);
+                    // A Tagbottom drag STAYS IN THE REGION ITS ANCHOR STARTED
+                    // IN, which is the one place the two coordinate spaces
+                    // genuinely disagree: Sel row 0 is the tag and the body
+                    // counts up from BOX_H, but on screen the tag is now BELOW
+                    // the body. Sweeping down past the last line onto the
+                    // tagline — the ordinary "select to the end" gesture — would
+                    // therefore drive r1 to the TOP of Sel space and invert the
+                    // selection: the highlight jumps above the anchor, and a 1-2
+                    // Cut on it deletes lines nobody swept. So a body-anchored
+                    // drag is clamped to the body rows and a tag-anchored one
+                    // (execute/look only; the left button's tag sweep is its own
+                    // .tag drag) stays on the tag, which is one line anyway.
+                    // The cost is that a body sweep can no longer be extended
+                    // onto the bottom tagline to pick up the tag text.
+                    // With the tag on TOP, Sel order IS screen order and the
+                    // gesture is contiguous and correct, so nothing is clamped.
+                    if (p.tag_bottom) {
+                        const body_h = r.h -| BOX_H;
+                        pane.sel[b].r1 = if (pane.sel[b].r0 < BOX_H or body_h == 0)
+                            0
+                        else
+                            @as(i32, @min(@max(mrow, r.y), r.y + body_h - 1)) - @as(i32, r.y) + @as(i32, BOX_H);
+                    } else pane.sel[b].r1 = @as(i32, mrow) - @as(i32, r.y);
                     if (comptime pdf_enabled) {
                         if (s.pdf.native) {
                             if (p.updatePdfSelection(pane, mcol, mrow, false))
@@ -9406,7 +9476,11 @@ pub const Pardes = struct {
         const ra = p.rects[p.col_terms[cc][k]];
         const rb = p.rects[p.col_terms[cc][k + 1]];
         const combined: f32 = @floatFromInt(ra.h + rb.h);
-        var nt: f32 = @floatFromInt((cur_y + 1) -| ra.y);
+        // the handle is the upper pane's LAST row (inclusive, hence the +1), or
+        // with Tagbottom the lower pane's FIRST — which is that row's height
+        // already, with nothing to add. Either way a no-drag click hands back
+        // exactly ra.h and nothing moves.
+        var nt: f32 = @floatFromInt(if (p.tag_bottom) cur_y -| ra.y else (cur_y + 1) -| ra.y);
         nt = std.math.clamp(nt, @as(f32, BOX_H), @max(@as(f32, BOX_H), combined - BOX_H));
         const pair = a.vweight + b.vweight;
         a.vweight = pair * (nt / combined);
@@ -10494,9 +10568,10 @@ pub const Pardes = struct {
         const r = for (p.panes, 0..) |slot, i| {
             if (slot == pane) break p.rects[i];
         } else return null;
-        if (mrow < r.y + BOX_H or mrow >= r.y + r.h) return null;
+        const body_y = if (p.tag_bottom) r.y else r.y + BOX_H;
+        if (mrow < body_y or mrow >= body_y + (r.h -| BOX_H)) return null;
         const local_y = @as(f64, @floatFromInt(
-            @as(u32, mrow - (r.y + BOX_H)) * p.cell_pixels.h + p.cell_pixels.h / 2,
+            @as(u32, mrow - body_y) * p.cell_pixels.h + p.cell_pixels.h / 2,
         ));
         const page = pdfPageAtOffset(&pv, pv.document_scroll_y + local_y);
         const document_y = pv.document_scroll_y + local_y;
@@ -10528,7 +10603,7 @@ pub const Pardes = struct {
             if (slot == pane) break p.rects[i];
         } else return null;
         const body_x = @as(i64, r.x + config.GUTTER);
-        const body_y = @as(i64, r.y + BOX_H);
+        const body_y = @as(i64, if (p.tag_bottom) r.y else r.y + BOX_H);
         var px = (@as(i64, mcol) - body_x) * p.cell_pixels.w + p.cell_pixels.w / 2;
         var py = (@as(i64, mrow) - body_y) * p.cell_pixels.h + p.cell_pixels.h / 2;
         if (clamp_to_page) {
@@ -12049,7 +12124,10 @@ pub const Pardes = struct {
             if (text.len == 0 and !leader_here) continue;
             const tx = r.x + config.GUTTER;
             const tw = r.w - config.GUTTER;
-            const row = r.y + r.h - 1;
+            // ...at the OTHER end from the tagline, whichever end that is:
+            // Tagbottom moved the tag onto this row, so the twin moves to the
+            // pane's first. They stay a pair with the body between them.
+            const row = if (p.tag_bottom) r.y else r.y + r.h - 1;
             // In the EDITOR's colours, not the tag bar's: this row is the one
             // place the program talks back to you about the buffer you are in,
             // and it reads as part of that buffer rather than as another strip
@@ -12153,7 +12231,9 @@ pub const Pardes = struct {
                     if (p.hover_col < p.col_x[cc] or p.hover_col >= p.col_x[cc] + p.col_w[cc]) continue;
                     for (0..p.col_n[cc] -| 1) |k| {
                         const r = p.rects[p.col_terms[cc][k]];
-                        if (p.hover_row == r.y + r.h -| 1) {
+                        // the same seam the h-handle hit test picks (see there)
+                        const seam = if (p.tag_bottom) r.y +| r.h else r.y + r.h -| 1;
+                        if (p.hover_row == seam) {
                             var col = p.col_x[cc];
                             while (col < p.col_x[cc] + p.col_w[cc]) : (col += 1) s.overlayDash(col, p.hover_row, "╌");
                         }
@@ -12227,6 +12307,12 @@ pub const Pardes = struct {
         const chrome = p.chromeTheme();
         const tx = r.x + config.GUTTER; // text area (tag + body), right of the gutter
         const tw = r.w - config.GUTTER;
+        // The pane's two anchor rows, computed once: the tagline's, and the
+        // body's first. The Tagbottom builtin swaps which end each is at and
+        // NOTHING else in here reads r.y — that is the whole of the feature on
+        // the render side. r.h == 0 returned above, so the bottom row exists.
+        const tag_y = if (p.tag_bottom) r.y + r.h - 1 else r.y;
+        const body_y = if (p.tag_bottom) r.y else r.y + BOX_H;
         // the pane's own background, for everything that has to read as "no
         // chrome here": the body text, and the blank right half of the
         // scrollbar's second column. `.default` means the host terminal's own
@@ -12272,9 +12358,9 @@ pub const Pardes = struct {
         const box_lum = (@as(u16, box_bg[0]) * 3 + @as(u16, box_bg[1]) * 6 + @as(u16, box_bg[2])) / 10;
         const box_ink: [3]u8 = if (box_lum > 140) .{ 0x00, 0x00, 0x00 } else .{ 0xff, 0xff, 0xff };
         const box_style: CellStyle = .{ .fg = .{ .rgb = box_ink }, .bg = .{ .rgb = box_bg } };
-        s.fill(r.x, r.y, config.GUTTER, BOX_H, box_style);
+        s.fill(r.x, tag_y, config.GUTTER, BOX_H, box_style);
         const box_mode = if (pane.tag_edit) pane.tag_mode else pane.mode;
-        s.set(r.x, r.y, switch (box_mode) {
+        s.set(r.x, tag_y, switch (box_mode) {
             .normal => config.tag_normal,
             .insert => config.tag_insert,
             .tty => config.tag_tty,
@@ -12282,7 +12368,7 @@ pub const Pardes = struct {
 
         // tag: live prefix (cwd/path) + editable tail, on a dim bar
         const tag_style: CellStyle = .{ .fg = .{ .rgb = chrome.tag_fg }, .bg = .{ .rgb = chrome.tag_bg } };
-        s.fill(tx, r.y, tw, BOX_H, .{ .bg = .{ .rgb = chrome.tag_bg } });
+        s.fill(tx, tag_y, tw, BOX_H, .{ .bg = .{ .rgb = chrome.tag_bg } });
         const tag = try p.tagText(arena, pane);
         // An armed input — `/`, Find, Grep, Rename, WsSymbols, Select/Split,
         // `|` — is still TYPED INTO the tag tail: same buffer, same offsets,
@@ -12301,7 +12387,7 @@ pub const Pardes = struct {
             @min(tag.len, tag.len - @min(tag.len, pane.tag_tail.items.len) + at)
         else
             tag.len;
-        _ = s.print(tx, r.y, tw, tag[0..tag_cut], tag_style);
+        _ = s.print(tx, tag_y, tw, tag[0..tag_cut], tag_style);
         // tag char selection highlight (helix v/x, or a tagline sweep),
         // inclusive [lo, hi] — rendered-tag columns, so no conversion.
         //
@@ -12315,7 +12401,7 @@ pub const Pardes = struct {
             var col: usize = b.lo;
             const end: usize = b.hi;
             while (col <= end and col < tw) : (col += 1) {
-                const cell = s.at(tx + @as(u16, @intCast(col)), r.y);
+                const cell = s.at(tx + @as(u16, @intCast(col)), tag_y);
                 cell.default = false;
                 cell.style.bg = .{ .rgb = th.sel_bg };
                 cell.style.fg = .{ .rgb = th.sel_fg };
@@ -12324,7 +12410,7 @@ pub const Pardes = struct {
         // cursor while editing the tag: a rendered-tag column, verbatim
         if (active and pane.tag_edit) {
             // bar while typing, block for `:` normal mode (same rule as a body)
-            if (pane.tag_col < tw) s.cursor = .{ .x = tx + pane.tag_col, .y = r.y, .bar = pane.mode == .insert };
+            if (pane.tag_col < tw) s.cursor = .{ .x = tx + pane.tag_col, .y = tag_y, .bar = pane.mode == .insert };
         }
 
         // A native PDF page uses the same backend-neutral pixel attachment as
@@ -12332,8 +12418,8 @@ pub const Pardes = struct {
         // extracted text projection becomes an ordinary readable body.
         if (comptime pdf_enabled) {
             if (hasPdf(pane) and p.native_images and p.drawPdf(pane, r, tx, tw)) {
-                s.fill(r.x, r.y + BOX_H, 1, r.h -| BOX_H, .{ .bg = .{ .rgb = chrome.scroll_track } });
-                s.fill(r.x + 1, r.y + BOX_H, 1, r.h -| BOX_H, .{ .bg = pane_bg });
+                s.fill(r.x, body_y, 1, r.h -| BOX_H, .{ .bg = .{ .rgb = chrome.scroll_track } });
+                s.fill(r.x + 1, body_y, 1, r.h -| BOX_H, .{ .bg = pane_bg });
                 if (r.h > BOX_H) {
                     const pv = &pane.pdf.?;
                     const track_h: usize = r.h - BOX_H;
@@ -12353,7 +12439,7 @@ pub const Pardes = struct {
                     ));
                     var sy = pos;
                     while (sy < track_h and sy < pos + len) : (sy += 1)
-                        s.fill(r.x, r.y + BOX_H + @as(u16, @intCast(sy)), 1, 1, .{ .bg = .{ .rgb = chrome.scroll_thumb } });
+                        s.fill(r.x, body_y + @as(u16, @intCast(sy)), 1, 1, .{ .bg = .{ .rgb = chrome.scroll_thumb } });
                 }
                 return;
             }
@@ -12366,8 +12452,8 @@ pub const Pardes = struct {
             p.drawImage(pane, r, tx, tw);
             // thumbless, but the same one column as the real scrollbar below —
             // that is the whole point of drawing it
-            s.fill(r.x, r.y + BOX_H, 1, r.h -| BOX_H, .{ .bg = .{ .rgb = chrome.scroll_track } });
-            s.fill(r.x + 1, r.y + BOX_H, 1, r.h -| BOX_H, .{ .bg = pane_bg });
+            s.fill(r.x, body_y, 1, r.h -| BOX_H, .{ .bg = .{ .rgb = chrome.scroll_track } });
+            s.fill(r.x + 1, body_y, 1, r.h -| BOX_H, .{ .bg = pane_bg });
             return;
         }
 
@@ -12384,7 +12470,7 @@ pub const Pardes = struct {
         var i: u16 = 0;
         while (it.next()) |line| : (i += 1) {
             if (i >= body_h) break;
-            _ = s.print(tx, r.y + BOX_H + i, tw, line, body_style);
+            _ = s.print(tx, body_y + i, tw, line, body_style);
         }
 
         // the two file-only passes and the terminal-only one: each is the
@@ -12409,7 +12495,7 @@ pub const Pardes = struct {
                 var wr: u16 = 0;
                 while (wr + 1 < pane.wrap_n and wr + 1 < body_h) : (wr += 1) {
                     if (pane.wrap_line[wr + 1] != pane.wrap_line[wr]) continue;
-                    s.set(tx + tw - 1, r.y + BOX_H + wr, config.wrap_marker, .{
+                    s.set(tx + tw - 1, body_y + wr, config.wrap_marker, .{
                         .fg = .{ .rgb = chrome.lineno },
                         .bg = pane_bg,
                     });
@@ -12454,9 +12540,12 @@ pub const Pardes = struct {
             var row: u16 = 0;
             while (row < r.h) : (row += 1) {
                 if (@as(i32, row) < r0 or @as(i32, row) > r1) continue;
+                // a Sel row, so 0 is the tag and BOX_H upward is the body —
+                // the one place the two coordinate spaces meet on the render side
+                const sy = if (row < BOX_H) tag_y else body_y + row - BOX_H;
                 var col: i32 = if (pane.file != null) @max(c0, @as(i32, config.PREFIX_W)) else c0;
                 while (col <= c1 and col < tw) : (col += 1) {
-                    const cell = s.at(tx + @as(u16, @intCast(col)), r.y + row);
+                    const cell = s.at(tx + @as(u16, @intCast(col)), sy);
                     cell.default = false;
                     cell.style.bg = .{ .rgb = sel_btn[b] };
                     cell.style.fg = .{ .rgb = th.sel_fg };
@@ -12476,7 +12565,7 @@ pub const Pardes = struct {
                 if (ar < lo or ar > hi) continue;
                 var col: u16 = if (pane.file != null) config.PREFIX_W else 0;
                 while (col < tw) : (col += 1) {
-                    const cell = s.at(tx + col, r.y + row);
+                    const cell = s.at(tx + col, body_y + row - BOX_H);
                     cell.default = false;
                     cell.style.bg = .{ .rgb = th.sel_bg };
                     cell.style.fg = .{ .rgb = th.sel_fg };
@@ -12531,12 +12620,11 @@ pub const Pardes = struct {
                 while (vr + @as(i32, BOX_H) < @as(i32, r.h)) : (vr += 1) {
                     const w = pane.wrapAt(vr);
                     if (w.line < bnd.lo_row or w.line > bnd.hi_row) continue;
-                    const prow = vr + @as(i32, BOX_H);
                     const cstart: i32 = if (w.line == bnd.lo_row) bnd.lo_col - w.at + vpfx else vpfx;
                     const cend: i32 = if (w.line == bnd.hi_row) bnd.hi_col - w.at + vpfx else @as(i32, tw) - 1;
                     var col: i32 = @max(cstart, vpfx);
                     while (col <= cend and col < tw) : (col += 1) {
-                        const cell = s.at(tx + @as(u16, @intCast(col)), r.y + @as(u16, @intCast(prow)));
+                        const cell = s.at(tx + @as(u16, @intCast(col)), body_y + @as(u16, @intCast(vr)));
                         cell.default = false;
                         cell.style.bg = .{ .rgb = bg };
                         cell.style.fg = .{ .rgb = th.sel_fg };
@@ -12547,7 +12635,7 @@ pub const Pardes = struct {
                 const crow = cw.row + @as(i32, BOX_H);
                 const ccol = sr.col - cw.at + vpfx;
                 if (crow >= BOX_H and crow < @as(i32, r.h) and ccol >= vpfx and ccol < tw) {
-                    const cell = s.at(tx + @as(u16, @intCast(ccol)), r.y + @as(u16, @intCast(crow)));
+                    const cell = s.at(tx + @as(u16, @intCast(ccol)), body_y + @as(u16, @intCast(crow - BOX_H)));
                     cell.default = false;
                     cell.style.bg = .{ .rgb = th.sel_fg };
                     cell.style.fg = .{ .rgb = th.sel_bg };
@@ -12574,9 +12662,9 @@ pub const Pardes = struct {
                 else
                     ccol;
                 if (prow >= BOX_H and cx >= 0 and prow < r.h and cx < tw)
-                    s.cursor = .{ .x = tx + @as(u16, @intCast(cx)), .y = r.y + @as(u16, @intCast(prow)), .bar = pane.mode == .insert };
+                    s.cursor = .{ .x = tx + @as(u16, @intCast(cx)), .y = body_y + @as(u16, @intCast(prow - BOX_H)), .bar = pane.mode == .insert };
             } else if (cur.y + BOX_H < r.h and cur.x < tw) {
-                s.cursor = .{ .x = tx + cur.x, .y = r.y + cur.y + BOX_H, .bar = pane.mode == .insert };
+                s.cursor = .{ .x = tx + cur.x, .y = body_y + cur.y, .bar = pane.mode == .insert };
             }
         }
 
@@ -12600,8 +12688,8 @@ pub const Pardes = struct {
         // config.GUTTER columns and the click handlers still scroll on any of
         // them, so the blank column is still live. Only the ink narrowed.
         if (r.h > BOX_H) {
-            s.fill(r.x, r.y + BOX_H, 1, r.h - BOX_H, .{ .bg = .{ .rgb = chrome.scroll_track } });
-            s.fill(r.x + 1, r.y + BOX_H, 1, r.h - BOX_H, .{ .bg = pane_bg });
+            s.fill(r.x, body_y, 1, r.h - BOX_H, .{ .bg = .{ .rgb = chrome.scroll_track } });
+            s.fill(r.x + 1, body_y, 1, r.h - BOX_H, .{ .bg = pane_bg });
             const sb: struct { total: usize, offset: usize, len: usize } = if (pane.file) |*f| .{
                 .total = file_pane.nlines(p.gpa, f),
                 .offset = f.scroll,
@@ -12620,7 +12708,7 @@ pub const Pardes = struct {
             const pos = (track_h * sb.offset) / total;
             var sy: usize = pos;
             while (sy < track_h and sy < pos + len) : (sy += 1) {
-                s.fill(r.x, r.y + BOX_H + @as(u16, @intCast(sy)), 1, 1, .{ .bg = .{ .rgb = chrome.scroll_thumb } });
+                s.fill(r.x, body_y + @as(u16, @intCast(sy)), 1, 1, .{ .bg = .{ .rgb = chrome.scroll_thumb } });
             }
         }
     }
@@ -12757,7 +12845,7 @@ pub const Pardes = struct {
                     .pixel_offset_y = placed.pixel_offset_y,
                 },
                 .x = tx,
-                .y = r.y + BOX_H,
+                .y = if (p.tag_bottom) r.y else r.y + BOX_H,
                 .w = tw,
                 .h = r.h - BOX_H,
                 .rgba = slot.rgba,
@@ -12787,6 +12875,7 @@ pub const Pardes = struct {
         if (iv.rgba.len == 0 or r.h <= BOX_H) return;
         const body_cols = tw;
         const body_rows = r.h - BOX_H;
+        const body_y = if (p.tag_bottom) r.y else r.y + BOX_H;
         const use_petscii = iv.petscii or !p.native_images;
         if (!use_petscii) {
             if (!p.appendImagePlace(.{
@@ -12795,7 +12884,7 @@ pub const Pardes = struct {
                 } else 0),
                 .serial = pane.serial,
                 .x = tx,
-                .y = r.y + BOX_H,
+                .y = body_y,
                 .w = body_cols,
                 .h = body_rows,
                 .rgba = iv.rgba,
@@ -12839,7 +12928,7 @@ pub const Pardes = struct {
                     .terminal => .{ .index = c.bg },
                 };
                 const sx = tx + @as(u16, @intCast(offx + cx));
-                const sy = r.y + BOX_H + @as(u16, @intCast(offy + cy));
+                const sy = body_y + @as(u16, @intCast(offy + cy));
                 if (sx < s.cols and sy < s.rows)
                     s.set(sx, sy, c.glyph[0..c.glen], .{ .fg = fg, .bg = bg });
             }