Add terminal E2E matrix runner

src/tui.zig

@@ -2373,26 +2373,36 @@ fn appendEditorCells(
     is_cursor_line: bool,
     cursor_col: usize,
 ) !void {
-    _ = cursor_col;
-    var remaining = max_cells;
-    if (is_cursor_line and remaining > 0) {
+    var i: usize = 0;
+    var source_col: usize = 0;
+    var visual_col: usize = 0;
+    var drew_cursor = false;
+    while (i < bytes.len and visual_col < max_cells) {
+        if (is_cursor_line and !drew_cursor and source_col >= cursor_col) {
+            try out.appendSlice(allocator, ansi_cursor);
+            try out.appendSlice(allocator, "▌");
+            try out.appendSlice(allocator, ansi_reset);
+            try out.appendSlice(allocator, ansi_current_line);
+            try out.appendSlice(allocator, ansi_text);
+            visual_col += 1;
+            drew_cursor = true;
+            if (visual_col >= max_cells) break;
+        }
+        const len = std.unicode.utf8ByteSequenceLength(bytes[i]) catch 1;
+        const end = @min(bytes.len, i + len);
+        const width = @max(@as(usize, 1), session_mod.cellWidth(bytes[i..end]));
+        if (visual_col + width > max_cells) break;
+        try out.appendSlice(allocator, bytes[i..end]);
+        source_col += width;
+        visual_col += width;
+        i = end;
+    }
+    if (is_cursor_line and !drew_cursor and visual_col < max_cells) {
         try out.appendSlice(allocator, ansi_cursor);
         try out.appendSlice(allocator, "▌");
         try out.appendSlice(allocator, ansi_reset);
         try out.appendSlice(allocator, ansi_current_line);
         try out.appendSlice(allocator, ansi_text);
-        remaining -= 1;
-    }
-    var i: usize = 0;
-    var col: usize = 0;
-    while (i < bytes.len and col < remaining) {
-        const len = std.unicode.utf8ByteSequenceLength(bytes[i]) catch 1;
-        const end = @min(bytes.len, i + len);
-        const width = @max(@as(usize, 1), session_mod.cellWidth(bytes[i..end]));
-        if (col + width > remaining) break;
-        try out.appendSlice(allocator, bytes[i..end]);
-        col += width;
-        i = end;
     }
 }
 
@@ -2560,7 +2570,8 @@ test "regular: scripted narrow terminal trace edits saves exits and replays save
     const result = try runTrace(std.testing.allocator, .{ .width = 12, .height = 4 }, trace);
     defer result.deinit(std.testing.allocator);
     try std.testing.expect(result.quit);
-    try std.testing.expect(std.mem.indexOf(u8, result.frame, "aébc") != null);
+    try std.testing.expect(std.mem.indexOf(u8, result.frame, "aé") != null);
+    try std.testing.expect(std.mem.indexOf(u8, result.frame, "bc") != null);
     try assertLinesFit(result.frame, 12);
     try std.testing.expectEqualStrings("aébc", result.saved_bytes.?);
 
@@ -4901,3 +4912,18 @@ test "regular: normal mode Space leader still works after insert escape" {
     try client.handleInput("w");
     try std.testing.expectEqualStrings("abc", try client.saved());
 }
+
+test "regular: cursor marker follows cursor column after typed text" {
+    var client = try Client.init(std.testing.allocator, .{ .width = 48, .height = 6 });
+    defer client.deinit();
+    try client.handleTraceLine("open ");
+    client.enterInsertMode();
+    for ("what") |byte| {
+        const key_bytes = [_]u8{byte};
+        try client.handleInput(&key_bytes);
+    }
+    const frame = try client.render(std.testing.allocator);
+    defer std.testing.allocator.free(frame);
+    try std.testing.expect(std.mem.indexOf(u8, frame, "what") != null);
+    try std.testing.expect(std.mem.indexOf(u8, frame, "▌what") == null);
+}