[READ-ONLY] Mirror of https://github.com/bombshell-dev/tty. Platform independent 2D layout engine for terminal applications based on Clay
✨ feat(term): resolve caret cell on empty text content
Substitute a single-space slice for empty text nodes carrying a caret
declaration so the layout engine emits one cell of geometry at the text
element's origin. Replaces the v1-limitation test with one asserting
the spec's outcome (CUP to row 1, col 1 + DECTCEM-show).
Charles Lowell
(Jul 8, 2026, 2:16 PM +0300)
8d47badc
895565d4
+14
-8
+10
src/clayterm.c
+10
src/clayterm.c
···
776
776
char *str_chars = (char *)&buf[i];
777
777
i += str_words;
778
778
779
+
/* A caret on empty content is a rendering commitment the layout
780
+
* engine cannot satisfy on its own — zero cells give locate_caret
781
+
* nothing to attach the cursor to. Substitute a single space so
782
+
* the caret lands at the text element's origin, per the spec's
783
+
* "as if the content were a single space" outcome. */
784
+
if (caret != 0xFFFFFFFF && str_len == 0) {
785
+
str_chars = (char *)" ";
786
+
str_len = 1;
787
+
}
788
+
779
789
/* Record the FIRST caret declaration per frame for the
780
790
* single-hardware-cursor contract; later declarations are
781
791
* intentionally ignored (multi-cursor is unspecified). */
+4
-8
test/term.test.ts
+4
-8
test/term.test.ts
···
434
434
});
435
435
436
436
it("shows the cursor at the text origin when content is empty and caret is 0", () => {
437
-
// v1 known limitation: Clay does not emit a text render command for an
438
-
// empty string, so locate_caret never finds a matching slice and suppresses
439
-
// cursor visibility. The proper fix requires looking up the element's
440
-
// bounding box separately (e.g. via get_element_bounds) rather than
441
-
// scanning text render commands. Until that is implemented, no cursor
442
-
// appears when the caret-bearing text node is empty.
437
+
// Declaring a `caret` on empty content is a rendering commitment: the
438
+
// renderer places the cursor at the cell the caret would occupy if the
439
+
// content were a single space. Origin of the text element is (row 1, col 1).
443
440
let ansi = decode(
444
441
term.render([
445
442
open("root", {
···
449
446
close(),
450
447
]).output,
451
448
);
452
-
expect(ansi).not.toContain("\x1b[?25h");
453
-
expect(ansi).not.toContain("\x1b[?25l");
449
+
expect(ansi).toMatch(/\x1b\[1;1H\x1b\[\?25h$/);
454
450
});
455
451
456
452
it("hides the cursor when transitioning from caret-present to caret-absent", () => {