A selection deep in a long line costs a render what one at its start does: 5 MB in, /screen goes from 14.7 s to 5 ms

Every render measured a selection's and the cursor's columns from the
start of their line (lineDisplayOffset walked the whole prefix twice),
so a selection near the end of a 5 MB line stalled each frame, 3 s at
1 MB in and 14.7 s at 5 MB. The cost grew with the offset, with Wrap on
or off. Three changes make it independent of where the selection is:
- display width adds (a tab is tab_width wherever it stands), so the
  offset between two columns is the width of the text between them,
  never the prefix;
- the selection's rows are clamped to what is shown: a row wholly
  before the selection is skipped, a start before the row's first
  column starts there, and an end past its last column ends there;
- a head or cursor whose column lies past its visible row (the last
  visible row of a line owns every column after its start) is not
  measured, since it is not drawn.
Measured on a Debug build, 5 MB line: offset 10, 1 MB and 5 MB now take
11, 6 and 5 ms per /screen. A new perf gate case, deep-sel, renders with
the selection 2 MB into a line: 83 us on Debug. The baselines were
re-recorded for the new harness.

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

6 files changed, 72 insertions, 12 deletions

diff --git a/src/File.zig b/src/File.zig
index 78c84287..a89db613 100644
--- a/src/File.zig
+++ b/src/File.zig
@@ -352,11 +352,18 @@ pub fn byteAtDisplayFrom(line_text: []const u8, from_raw: usize, display_col: us
     return from +| rawAtDisplay(line_text[from..], display_col);
 }
 
+/// The display columns from `from_raw` to `to_raw` on a line. Widths add
+/// (a tab is `tab_width` wherever it stands), so only the text between
+/// the two is measured, never the line from its start: a selection a
+/// million bytes into a line draws as fast as one at its start.
 pub fn lineDisplayOffset(line_text: []const u8, from_raw: usize, to_raw: usize) i32 {
-    const from_display = rawDisplayCol(line_text, from_raw);
-    const to_display = rawDisplayCol(line_text, to_raw);
-    if (to_display >= from_display) return @intCast(to_display - from_display);
-    return -@as(i32, @intCast(from_display - to_display));
+    const lo = @min(from_raw, to_raw);
+    const hi = @max(from_raw, to_raw);
+    const a = modal.graphemeStart(line_text, @min(lo, line_text.len));
+    const b = modal.graphemeStart(line_text, @min(hi, line_text.len));
+    const past = (hi -| line_text.len) - (lo -| line_text.len);
+    const width: usize = displayWidth(line_text[a..b]) +| past;
+    return if (to_raw >= from_raw) @intCast(width) else -@as(i32, @intCast(width));
 }
 
 pub fn lineDisplayEndOffset(line_text: []const u8, from_raw: usize, at_raw: usize) i32 {
diff --git a/src/body_layer.zig b/src/body_layer.zig
index 8e7cd030..914694e7 100644
--- a/src/body_layer.zig
+++ b/src/body_layer.zig
@@ -83,6 +83,17 @@ fn paintTerminalSelection(p: *Pardes, s: *Surface, pane: *Pane, r: Rect, rows: [
     }
 }
 
+/// Whether `col` lies past the last column its visible row shows: the last
+/// visible row of a line owns every column after its start (wrapRow), so a
+/// head millions of bytes along a long line is on that row, off the view.
+fn pastView(pane: *Pane, body: []const u8, line: i32, row: i32, at: i32, col: i32, tw: u16) bool {
+    const text = if (pane.file != null) panes.File.sourceLine(pane, line) else modal.lineSlice(body, @intCast(@max(0, row)));
+    const from: usize = @intCast(@max(0, at));
+    const to: usize = @intCast(@max(0, col));
+    if (from >= text.len) return to >= from +| tw;
+    return to >= from + panes.File.byteAtDisplay(text[from..], tw) and to < text.len;
+}
+
 fn paintSourceSelection(p: *Pardes, s: *Surface, pane: *Pane, r: Rect, rows: []const Pane.PointerRow, bg: [3]u8, fg: ?[3]u8) void {
     if (pane.isTerminal()) return paintTerminalSelection(p, s, pane, r, rows, bg, fg);
     const terminal_lines = if (pane.file == null) panes.terminal.cursorLines(p, pane) catch return else &.{};
@@ -371,14 +382,26 @@ pub fn renderBody(p: *Pardes, s: *Surface, arena: std.mem.Allocator, pane: *Pane
                 const w = pane.wrapAt(vr);
                 if (w.line < bnd.lo_row or w.line > bnd.hi_row) continue;
                 const visible_line = modal.lineSlice(body, @intCast(vr));
-                const cstart: i32 = if (w.line == bnd.lo_row)
+                // Only the visible columns are measured: a selection that
+                // starts before this row's first column starts at it, and
+                // one that ends past its last ends there.
+                const row_text = if (pane.file != null) panes.File.sourceLine(pane, w.line) else visible_line;
+                const row_at: usize = @intCast(@max(0, w.at));
+                // The byte past the row's last column, walked from its first:
+                // bounded by the view, not the line.
+                // A line that ends inside the view has no column past it.
+                const shown_to = if (row_at >= row_text.len) row_text.len else row_at + panes.File.byteAtDisplay(row_text[row_at..], tw);
+                const past_view = if (shown_to >= row_text.len) std.math.maxInt(usize) else shown_to;
+                // A row that ends before the selection starts has none of it.
+                if (w.line == bnd.lo_row and @as(usize, @intCast(@max(0, bnd.lo_col))) >= past_view) continue;
+                const cstart: i32 = if (w.line == bnd.lo_row and bnd.lo_col > w.at)
                     (if (pane.file != null)
                         panes.File.displayOffset(pane, w.line, w.at, bnd.lo_col)
                     else
                         panes.File.lineDisplayOffset(visible_line, @intCast(@max(0, w.at)), @intCast(@max(0, bnd.lo_col)))) + vpfx
                 else
                     vpfx;
-                const cend: i32 = if (w.line == bnd.hi_row)
+                const cend: i32 = if (w.line == bnd.hi_row and @as(usize, @intCast(@max(0, bnd.hi_col))) < past_view)
                     (if (pane.file != null)
                         panes.File.displayEndOffset(pane, w.line, w.at, bnd.hi_col)
                     else
@@ -396,6 +419,10 @@ pub fn renderBody(p: *Pardes, s: *Surface, arena: std.mem.Allocator, pane: *Pane
             if (primary and !preview and !hover_only) continue; // the hardware cursor IS the primary's
             if (hover_only) continue; // quiet preview preserves the source ink
             const cw = pane.wrapRow(sr.row, sr.col);
+            // A head off the view is measured not at all: its row is not
+            // drawn, and its column may be millions of bytes along.
+            if (cw.row < 0 or cw.row + @as(i32, pane.tag_rows) >= @as(i32, body_bottom)) continue;
+            if (pastView(pane, body, sr.row, cw.row, cw.at, sr.col, tw)) continue;
             const crow = cw.row + @as(i32, pane.tag_rows);
             const ccol = (if (pane.file != null)
                 panes.File.displayOffset(pane, sr.row, cw.at, sr.col)
@@ -447,6 +474,9 @@ pub fn renderBody(p: *Pardes, s: *Surface, arena: std.mem.Allocator, pane: *Pane
             const ccol = if (pane.body.cur_pinned) pane.body.cur_col else @as(i32, @intCast(cur.x));
             const cwp = pane.wrapRow(crow, ccol);
             const prow = cwp.row + @as(i32, pane.tag_rows);
+            // Off the view, the cursor is not measured (its column may be
+            // millions of bytes along a line whose start is shown).
+            if (cwp.row >= 0 and prow < body_bottom and !pastView(pane, body, crow, cwp.row, cwp.at, ccol, tw)) {
             // Files store source-byte columns; the Surface stores display
             // cells, so account for every expanded tab before the cursor.
             const cx = if (pane.file != null)
@@ -461,6 +491,7 @@ pub fn renderBody(p: *Pardes, s: *Surface, arena: std.mem.Allocator, pane: *Pane
                 ccol;
             if (prow >= pane.tag_rows and cx >= 0 and prow < body_bottom and cx < tw)
                 s.cursor = .{ .x = tx + @as(u16, @intCast(cx)), .y = body_y + @as(u16, @intCast(prow - pane.tag_rows)), .bar = pane.body.mode == .insert };
+            }
         } else if (panes.terminal.visibleCursor(pane)) |cur| {
             if (cur.y + pane.tag_rows < body_bottom and cur.x < tw)
                 s.cursor = .{ .x = tx + cur.x, .y = body_y + cur.y };
diff --git a/test/perf-baseline-gui-Debug.json b/test/perf-baseline-gui-Debug.json
index 8808dd55..ace9a967 100644
--- a/test/perf-baseline-gui-Debug.json
+++ b/test/perf-baseline-gui-Debug.json
@@ -1 +1 @@
-{"harness":"f420fe5db60d6e97","build":{"compiler":"0.16.0","target":"x86_64-linux.5.10...6.19-gnu.2.38","cpu":"x86_64","driver_optimize":"ReleaseFast","core_optimize":"Debug","c_optimize":"ReleaseFast","terminal_optimize":"ReleaseSafe","platform":"gui","grammars":"full","mupdf":true,"jpx":true,"tracy":false,"quic":false,"theme_animation":true,"terminal_simd":true,"prebuilt_shaders":false},"cols":120,"rows":40,"reps":10,"only":"medium","fixtures":[{"name":"small","lines":1000,"cols":60,"bytes":62694},{"name":"medium","lines":50000,"cols":60,"bytes":3201944},{"name":"large","lines":300000,"cols":60,"bytes":19464444},{"name":"longline","lines":400,"cols":8000,"bytes":3200400},{"name":"esp32p4","lines":12,"cols":240,"bytes":2892}],"cells":[{"op":"open","fixture":"medium","min_us":1740,"med_us":2009,"p90_us":2077,"max_us":2079},{"op":"render","fixture":"medium","min_us":76,"med_us":80,"p90_us":90,"max_us":101},{"op":"key-down","fixture":"medium","min_us":77,"med_us":81,"p90_us":94,"max_us":95},{"op":"key-right","fixture":"medium","min_us":77,"med_us":82,"p90_us":86,"max_us":89},{"op":"page-down","fixture":"medium","min_us":77,"med_us":78,"p90_us":86,"max_us":99},{"op":"wheel","fixture":"medium","min_us":76,"med_us":76,"p90_us":80,"max_us":89},{"op":"edit-char","fixture":"medium","min_us":924,"med_us":1330,"p90_us":1522,"max_us":1566},{"op":"body-2m","fixture":"medium","min_us":4888,"med_us":8435,"p90_us":10635,"max_us":11460},{"op":"body-appends","fixture":"medium","min_us":119102,"med_us":187377,"p90_us":230392,"max_us":245721}]}
+{"harness":"e63a8b27a0bcb261","build":{"compiler":"0.16.0","target":"x86_64-linux.5.10...6.19-gnu.2.38","cpu":"x86_64","driver_optimize":"ReleaseFast","core_optimize":"Debug","c_optimize":"ReleaseFast","terminal_optimize":"ReleaseSafe","platform":"gui","grammars":"full","mupdf":true,"jpx":true,"tracy":false,"quic":false,"theme_animation":true,"terminal_simd":true,"prebuilt_shaders":false},"cols":120,"rows":40,"reps":10,"only":"medium","fixtures":[{"name":"small","lines":1000,"cols":60,"bytes":62694},{"name":"medium","lines":50000,"cols":60,"bytes":3201944},{"name":"large","lines":300000,"cols":60,"bytes":19464444},{"name":"longline","lines":400,"cols":8000,"bytes":3200400},{"name":"esp32p4","lines":12,"cols":240,"bytes":2892}],"cells":[{"op":"open","fixture":"medium","min_us":2100,"med_us":2437,"p90_us":2875,"max_us":3207},{"op":"render","fixture":"medium","min_us":82,"med_us":84,"p90_us":88,"max_us":89},{"op":"key-down","fixture":"medium","min_us":88,"med_us":95,"p90_us":102,"max_us":114},{"op":"key-right","fixture":"medium","min_us":84,"med_us":88,"p90_us":94,"max_us":105},{"op":"page-down","fixture":"medium","min_us":83,"med_us":86,"p90_us":88,"max_us":89},{"op":"wheel","fixture":"medium","min_us":82,"med_us":85,"p90_us":90,"max_us":99},{"op":"edit-char","fixture":"medium","min_us":1276,"med_us":1769,"p90_us":2239,"max_us":2754},{"op":"body-2m","fixture":"medium","min_us":5333,"med_us":9734,"p90_us":12257,"max_us":14666},{"op":"body-appends","fixture":"medium","min_us":135052,"med_us":262059,"p90_us":295829,"max_us":304576},{"op":"deep-sel","fixture":"medium","min_us":77,"med_us":79,"p90_us":83,"max_us":118}]}
diff --git a/test/perf-baseline-tty-Debug.json b/test/perf-baseline-tty-Debug.json
index ef42f0ad..6b5c0bd5 100644
--- a/test/perf-baseline-tty-Debug.json
+++ b/test/perf-baseline-tty-Debug.json
@@ -1 +1 @@
-{"harness":"f420fe5db60d6e97","build":{"compiler":"0.16.0","target":"x86_64-linux.5.10...6.19-gnu.2.38","cpu":"x86_64","driver_optimize":"ReleaseFast","core_optimize":"Debug","c_optimize":"ReleaseFast","terminal_optimize":"ReleaseSafe","platform":"tty","grammars":"full","mupdf":true,"jpx":true,"tracy":false,"quic":false,"theme_animation":true,"terminal_simd":true,"prebuilt_shaders":false},"cols":120,"rows":40,"reps":10,"only":"medium","fixtures":[{"name":"small","lines":1000,"cols":60,"bytes":62694},{"name":"medium","lines":50000,"cols":60,"bytes":3201944},{"name":"large","lines":300000,"cols":60,"bytes":19464444},{"name":"longline","lines":400,"cols":8000,"bytes":3200400},{"name":"esp32p4","lines":12,"cols":240,"bytes":2892}],"cells":[{"op":"open","fixture":"medium","min_us":1743,"med_us":2011,"p90_us":2152,"max_us":2217},{"op":"render","fixture":"medium","min_us":76,"med_us":79,"p90_us":80,"max_us":84},{"op":"key-down","fixture":"medium","min_us":77,"med_us":78,"p90_us":85,"max_us":89},{"op":"key-right","fixture":"medium","min_us":77,"med_us":80,"p90_us":83,"max_us":95},{"op":"page-down","fixture":"medium","min_us":78,"med_us":78,"p90_us":87,"max_us":95},{"op":"wheel","fixture":"medium","min_us":76,"med_us":80,"p90_us":88,"max_us":90},{"op":"edit-char","fixture":"medium","min_us":1122,"med_us":1501,"p90_us":1812,"max_us":2440},{"op":"body-2m","fixture":"medium","min_us":4949,"med_us":8504,"p90_us":10909,"max_us":11452},{"op":"body-appends","fixture":"medium","min_us":115605,"med_us":190785,"p90_us":226244,"max_us":245258}]}
+{"harness":"e63a8b27a0bcb261","build":{"compiler":"0.16.0","target":"x86_64-linux.5.10...6.19-gnu.2.38","cpu":"x86_64","driver_optimize":"ReleaseFast","core_optimize":"Debug","c_optimize":"ReleaseFast","terminal_optimize":"ReleaseSafe","platform":"tty","grammars":"full","mupdf":true,"jpx":true,"tracy":false,"quic":false,"theme_animation":true,"terminal_simd":true,"prebuilt_shaders":false},"cols":120,"rows":40,"reps":10,"only":"medium","fixtures":[{"name":"small","lines":1000,"cols":60,"bytes":62694},{"name":"medium","lines":50000,"cols":60,"bytes":3201944},{"name":"large","lines":300000,"cols":60,"bytes":19464444},{"name":"longline","lines":400,"cols":8000,"bytes":3200400},{"name":"esp32p4","lines":12,"cols":240,"bytes":2892}],"cells":[{"op":"open","fixture":"medium","min_us":1830,"med_us":2222,"p90_us":2264,"max_us":2287},{"op":"render","fixture":"medium","min_us":78,"med_us":83,"p90_us":86,"max_us":94},{"op":"key-down","fixture":"medium","min_us":80,"med_us":84,"p90_us":89,"max_us":98},{"op":"key-right","fixture":"medium","min_us":78,"med_us":81,"p90_us":88,"max_us":96},{"op":"page-down","fixture":"medium","min_us":78,"med_us":82,"p90_us":89,"max_us":95},{"op":"wheel","fixture":"medium","min_us":77,"med_us":85,"p90_us":96,"max_us":109},{"op":"edit-char","fixture":"medium","min_us":1125,"med_us":1307,"p90_us":1558,"max_us":1584},{"op":"body-2m","fixture":"medium","min_us":5189,"med_us":9224,"p90_us":10859,"max_us":14741},{"op":"body-appends","fixture":"medium","min_us":108477,"med_us":198709,"p90_us":227756,"max_us":252672},{"op":"deep-sel","fixture":"medium","min_us":73,"med_us":77,"p90_us":80,"max_us":91}]}
diff --git a/test/perf-baseline-tty-ReleaseFast.json b/test/perf-baseline-tty-ReleaseFast.json
index 66421ba3..87a31754 100644
--- a/test/perf-baseline-tty-ReleaseFast.json
+++ b/test/perf-baseline-tty-ReleaseFast.json
@@ -1 +1 @@
-{"harness":"f420fe5db60d6e97","build":{"compiler":"0.16.0","target":"x86_64-linux.5.10...6.19-gnu.2.38","cpu":"x86_64","driver_optimize":"ReleaseFast","core_optimize":"ReleaseFast","c_optimize":"ReleaseFast","terminal_optimize":"ReleaseFast","platform":"tty","grammars":"full","mupdf":true,"jpx":true,"tracy":false,"quic":false,"theme_animation":true,"terminal_simd":true,"prebuilt_shaders":false},"cols":120,"rows":40,"reps":10,"only":"medium","fixtures":[{"name":"small","lines":1000,"cols":60,"bytes":62694},{"name":"medium","lines":50000,"cols":60,"bytes":3201944},{"name":"large","lines":300000,"cols":60,"bytes":19464444},{"name":"longline","lines":400,"cols":8000,"bytes":3200400},{"name":"esp32p4","lines":12,"cols":240,"bytes":2892}],"cells":[{"op":"open","fixture":"medium","min_us":1751,"med_us":2134,"p90_us":2183,"max_us":2415},{"op":"render","fixture":"medium","min_us":76,"med_us":77,"p90_us":91,"max_us":92},{"op":"key-down","fixture":"medium","min_us":77,"med_us":78,"p90_us":82,"max_us":83},{"op":"key-right","fixture":"medium","min_us":79,"med_us":85,"p90_us":100,"max_us":102},{"op":"page-down","fixture":"medium","min_us":78,"med_us":82,"p90_us":86,"max_us":95},{"op":"wheel","fixture":"medium","min_us":76,"med_us":79,"p90_us":83,"max_us":87},{"op":"edit-char","fixture":"medium","min_us":1063,"med_us":1290,"p90_us":1527,"max_us":1564},{"op":"body-2m","fixture":"medium","min_us":4950,"med_us":9414,"p90_us":10945,"max_us":13152},{"op":"body-appends","fixture":"medium","min_us":117839,"med_us":189253,"p90_us":232943,"max_us":247720}]}
+{"harness":"e63a8b27a0bcb261","build":{"compiler":"0.16.0","target":"x86_64-linux.5.10...6.19-gnu.2.38","cpu":"x86_64","driver_optimize":"ReleaseFast","core_optimize":"ReleaseFast","c_optimize":"ReleaseFast","terminal_optimize":"ReleaseFast","platform":"tty","grammars":"full","mupdf":true,"jpx":true,"tracy":false,"quic":false,"theme_animation":true,"terminal_simd":true,"prebuilt_shaders":false},"cols":120,"rows":40,"reps":10,"only":"medium","fixtures":[{"name":"small","lines":1000,"cols":60,"bytes":62694},{"name":"medium","lines":50000,"cols":60,"bytes":3201944},{"name":"large","lines":300000,"cols":60,"bytes":19464444},{"name":"longline","lines":400,"cols":8000,"bytes":3200400},{"name":"esp32p4","lines":12,"cols":240,"bytes":2892}],"cells":[{"op":"open","fixture":"medium","min_us":2042,"med_us":2280,"p90_us":2451,"max_us":2478},{"op":"render","fixture":"medium","min_us":82,"med_us":84,"p90_us":87,"max_us":104},{"op":"key-down","fixture":"medium","min_us":83,"med_us":86,"p90_us":90,"max_us":93},{"op":"key-right","fixture":"medium","min_us":84,"med_us":87,"p90_us":91,"max_us":104},{"op":"page-down","fixture":"medium","min_us":84,"med_us":87,"p90_us":93,"max_us":96},{"op":"wheel","fixture":"medium","min_us":81,"med_us":85,"p90_us":89,"max_us":89},{"op":"edit-char","fixture":"medium","min_us":1309,"med_us":1613,"p90_us":1840,"max_us":2128},{"op":"body-2m","fixture":"medium","min_us":5386,"med_us":11064,"p90_us":11706,"max_us":12374},{"op":"body-appends","fixture":"medium","min_us":144772,"med_us":232307,"p90_us":273586,"max_us":281169},{"op":"deep-sel","fixture":"medium","min_us":79,"med_us":83,"p90_us":87,"max_us":130}]}
diff --git a/test/perf.zig b/test/perf.zig
index 95b55748..94076a25 100644
--- a/test/perf.zig
+++ b/test/perf.zig
@@ -53,6 +53,10 @@ const Op = enum {
     /// close, as a shell's `>>` loop makes: each costs its own bytes, not a
     /// pass over the whole body for its cursor, line index and saved hash.
     body_appends,
+    /// A render with the selection 2 MB into one line: only the columns
+    /// shown are measured, so it costs what a selection at the line's
+    /// start does (4.5 s a frame at 5 MB before).
+    deep_selection,
 
     fn label(o: Op) []const u8 {
         return switch (o) {
@@ -65,6 +69,7 @@ const Op = enum {
             .edit_char => "edit-char",
             .body_write => "body-2m",
             .body_appends => "body-appends",
+            .deep_selection => "deep-sel",
         };
     }
 };
@@ -83,6 +88,16 @@ fn bodyWrite(core: *pardes.Pardes, serial: u32) void {
     _ = core.serveFs(.{ .tag = 4, .op = .release, .node = body, .handle = h, .opened = true });
 }
 
+/// One line of 2 MB appended to the file, no newline in it.
+fn longLine(core: *pardes.Pardes, serial: u32) void {
+    const Node = pardes.ctlfs.Node;
+    const body = Node.of(serial, .body);
+    @memset(&body_chunk, 'z');
+    const h = core.serveFs(.{ .tag = 1, .op = .open, .node = body, .omode = 1 }).handle;
+    for (0..8) |_| _ = core.serveFs(.{ .tag = 2, .op = .write, .node = body, .handle = h, .data = &body_chunk });
+    _ = core.serveFs(.{ .tag = 4, .op = .release, .node = body, .handle = h, .opened = true });
+}
+
 const append_chunk_len = 8 * 1024;
 const append_count = 64;
 
@@ -534,9 +549,16 @@ fn measure(op: Op, fx: Fixture, path: []const u8, expected_bytes: usize, reps: u
         core.update(.{ .key = .{ .cp = 'i', .text = "i" } });
         pump(core);
     }
+    if (op == .deep_selection) {
+        longLine(core, pane.serial);
+        pump(core);
+        const len: u32 = @intCast(pane.file.?.content.len);
+        pardes.ctlfs.pane.setDot(pane, .{ .q0 = len - 10, .q1 = len - 5 });
+        pump(core);
+    }
 
     for (0..warmup + reps) |n| {
-        seek(pane, fx, n);
+        if (op != .deep_selection) seek(pane, fx, n);
         _ = try frame(core); // settle the view at the new spot, untimed
         const before = .{ .row = pane.body.cur_row, .col = pane.body.cur_col, .scroll = pane.scroll(), .len = pane.file.?.content.len };
         const rect = core.rects[id];
@@ -545,7 +567,7 @@ fn measure(op: Op, fx: Fixture, path: []const u8, expected_bytes: usize, reps: u
         const t0 = nowNs();
         switch (op) {
             .open => unreachable,
-            .render => {},
+            .render, .deep_selection => {},
             .key_down => core.update(.{ .key = .{ .cp = 'j', .text = "j" } }),
             .key_right => core.update(.{ .key = .{ .cp = 'l', .text = "l" } }),
             .page_down => core.update(.{ .key = .{ .cp = pardes.Key.page_down } }),
@@ -561,7 +583,7 @@ fn measure(op: Op, fx: Fixture, path: []const u8, expected_bytes: usize, reps: u
             .open => unreachable,
             .body_write => if (pane.file.?.content.len != before.len + 8 * body_chunk.len) return error.BodyWriteWasNotAppended,
             .body_appends => if (pane.file.?.content.len != before.len + append_count * append_chunk_len) return error.BodyAppendsWereNotAppended,
-            .render => if (pane.body.cur_row != before.row or pane.body.cur_col != before.col or pane.file.?.content.len != before.len)
+            .render, .deep_selection => if (pane.body.cur_row != before.row or pane.body.cur_col != before.col or pane.file.?.content.len != before.len)
                 return error.RenderChangedDocument,
             .key_down => if (pane.body.cur_row != before.row + 1) return error.DownDidNotMove,
             .key_right => if (pane.body.cur_row != before.row or pane.body.cur_col != before.col + 1) return error.RightDidNotMove,