fix(linter): prevent useConsistentCurlyBraces from suggesting invalid JSX text conversion

.changeset/fix-curly-braces-opening-brace.md

@@ -0,0 +1,5 @@
+---
+"@biomejs/biome": patch
+---
+
+Fixed [#8011](https://github.com/biomejs/biome/issues/8011): [`useConsistentCurlyBraces`](https://biomejs.dev/linter/rules/use-consistent-curly-braces/) no longer suggests removing curly braces from JSX expression children containing characters that would cause parsing issues or semantic changes when converted to plain JSX text (`{`, `}`, `<`, `>`, `&`).

crates/biome_js_analyze/src/lint/style/use_consistent_curly_braces.rs

@@ -410,7 +410,17 @@ fn contains_only_spaces(literal: &JsStringLiteralExpression) -> bool {
         .is_ok_and(|text| text.bytes().all(|b| b == b' '))
 }
 
-const FORBIDDEN_CHARS: [char; 4] = ['>', '"', '\'', '}'];
+/// Characters that would cause parsing issues or semantic changes if a JSX expression
+/// child is converted to plain JSX text. When a string literal contains any of these,
+/// we must NOT suggest removing the curly braces.
+///
+/// - `{` `}` - would be parsed as expression delimiters
+/// - `<` `>` - would be parsed as tag delimiters
+/// - `&` - would be parsed as HTML entity start
+/// - `"` `'` - included for consistency, though mainly relevant in attribute contexts
+///
+/// See: https://github.com/biomejs/biome/issues/8011
+const FORBIDDEN_CHARS: [char; 7] = ['{', '}', '<', '>', '&', '"', '\''];
 
 fn contains_forbidden_chars(str_literal: &JsStringLiteralExpression) -> bool {
     str_literal.inner_string_text().is_ok_and(|text| {

crates/biome_js_analyze/tests/specs/style/useConsistentCurlyBraces/valid.jsx

@@ -28,6 +28,22 @@ let baz = 4;
 
 <Foo>{'Invalid closing tag }'}</Foo>
 
+<Foo>Invalid opening tag {'{'}</Foo>
+
+<Foo>{'Invalid opening tag {'}</Foo>
+
+<Foo>{'start {{'}</Foo>
+
+<Foo>{'}} end'}</Foo>
+
+<Foo>{'<script>'}</Foo>
+
+<Foo>{'a < b'}</Foo>
+
+<Foo>{'&amp;'}</Foo>
+
+<Foo>{'Tom & Jerry'}</Foo>
+
 <Foo>Jupiter {">"} Venus</Foo>
 
 <Foo>Jupiter {'>'} Venus</Foo>

crates/biome_js_analyze/tests/specs/style/useConsistentCurlyBraces/valid.jsx.snap

@@ -34,6 +34,22 @@ let baz = 4;
 
 <Foo>{'Invalid closing tag }'}</Foo>
 
+<Foo>Invalid opening tag {'{'}</Foo>
+
+<Foo>{'Invalid opening tag {'}</Foo>
+
+<Foo>{'start {{'}</Foo>
+
+<Foo>{'}} end'}</Foo>
+
+<Foo>{'<script>'}</Foo>
+
+<Foo>{'a < b'}</Foo>
+
+<Foo>{'&amp;'}</Foo>
+
+<Foo>{'Tom & Jerry'}</Foo>
+
 <Foo>Jupiter {">"} Venus</Foo>
 
 <Foo>Jupiter {'>'} Venus</Foo>