49903c96

Widen readbackOffscreen assert to usize

a73x   2026-04-17 16:38

Prevents silent u32 overflow on width*height*4 for large targets.
Not reachable at current 80x24 call sites, but matches the usize
semantics of the slice length it compares against.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

---

diff --git a/src/renderer.zig b/src/renderer.zig
index 0d67a9b..ce9008e 100644
--- a/src/renderer.zig
+++ b/src/renderer.zig
@@ -1922,7 +1922,7 @@ pub const Context = struct {
        out_rgba: []u8,
    ) !void {
        std.debug.assert(target.format == .b8g8r8a8_unorm); // swizzle below assumes BGRA8
        std.debug.assert(out_rgba.len == target.width * target.height * 4);
        std.debug.assert(out_rgba.len == @as(usize, target.width) * @as(usize, target.height) * 4);
        if (out_rgba.len < target.readback_size) return error.BufferTooSmall;

        const mapped = try self.vkd.mapMemory(