[Rush]

@let small = count < 10; was cut at the <, which the HTML lexer took for the start of a tag, and reported as an incomplete @let declaration, so the component was left uncompiled.

Angular's _consumeLetDeclarationValue ends the value only at a ; outside quotes (or EOF), so a < is part of the expression. The lexer now does the same; the quote handling it already had is unchanged.

Tests: two lexer cases next to the existing @let ones (html_lexer_test.rs), and tests/let_value_less_than_test.rs, which compiles

@let small = count < 10; @let both = a < b && b < c;
<span>{{ small }} {{ both }}</span>

to const small_r1 = (ctx.count < 10); and const both_r2 = ((ctx.a < ctx.b) && (ctx.b < ctx.c));, as @angular/compiler-cli 21.0.1 does (without the parentheses). The lexer tests fail without the change.