fix(painter-dom): custom hover wins on locked SDTs under chrome:'none' (SD-3322)

The custom hover background was overridden for LOCKED controls under chrome:'none'.
The base lock-hover rules (a built-in tint on inline, transparent on block) have
equal specificity to the plain custom hover rules but come later in source order,
so they won; the chrome-none lock-hover reset only reset z-index, not background.

Re-assert the custom hover background in that reset block - it carries the extra
.superdoc-cc-chrome-none class, so it outranks the base lock-hover rules. A locked
control now follows --sd-content-controls-custom-*-hover-bg. With no custom var
set the default is empty, so the built-in lock-hover tint no longer leaks under
chrome:'none' for locked controls (consistently empty). Only the contract-templates
demo has locked chrome-none controls, and it wants the custom hover, not the tint.

Add a regression test asserting the custom hover vars are re-asserted after the
base lock-hover rules (source order = it wins). painter-dom 1179/1179 green.

Author: caio-pizzol

packages/layout-engine/painters/dom/src/styles.test.ts

@@ -352,6 +352,30 @@ describe('ensureSdtContainerStyles', () => {
       'border-left: var(--sd-content-controls-custom-block-border-left, var(--sd-content-controls-custom-block-border, 0 solid transparent));',
     );
   });
+
+  it('locked-hover under chrome-none follows the custom hover background, not the built-in lock-hover (SD-3322)', () => {
+    ensureSdtContainerStyles(document);
+    const styleEl = document.querySelector('[data-superdoc-sdt-container-styles="true"]');
+    const cssText = styleEl?.textContent ?? '';
+
+    // The base lock-hover rules (built-in tint on inline, transparent on block)
+    // come first and have equal specificity to the plain custom hover rules, so
+    // they would otherwise win for locked controls.
+    const baseInlineLockHover = cssText.indexOf('background-color: var(--sd-content-controls-lock-hover-bg');
+    const baseBlockLockHover = cssText.indexOf(
+      '.superdoc-structured-content-block[data-lock-mode].sdt-group-hover:not(.ProseMirror-selectednode) {',
+    );
+    expect(baseInlineLockHover).toBeGreaterThan(-1);
+    expect(baseBlockLockHover).toBeGreaterThan(-1);
+
+    // The chrome-none lock-hover reset re-asserts the custom hover background
+    // AFTER them (extra .superdoc-cc-chrome-none class + later source order wins),
+    // so a locked control under chrome:'none' uses the custom variable.
+    const customInlineHoverReassert = cssText.lastIndexOf('--sd-content-controls-custom-inline-hover-bg');
+    const customBlockHoverReassert = cssText.lastIndexOf('--sd-content-controls-custom-block-hover-bg');
+    expect(customInlineHoverReassert).toBeGreaterThan(baseInlineLockHover);
+    expect(customBlockHoverReassert).toBeGreaterThan(baseBlockLockHover);
+  });
 });
 
 describe('ensureTrackChangeStyles', () => {

packages/layout-engine/painters/dom/src/styles.ts

@@ -885,11 +885,20 @@ const SDT_CONTAINER_STYLES = `
   border: none;
 }
 
-/* Reset the lock-hover z-index boost so a suppressed SDT does not stack
- * above host-attached custom UI. Mirrors the base lock-hover selectors with
- * the chrome-none prefix so specificity stays above the boost rule. */
-.superdoc-cc-chrome-none .superdoc-structured-content-block[data-lock-mode].sdt-group-hover:not(.ProseMirror-selectednode),
+/* Chrome opt-out for the lock-hover affordance. The base lock-hover rules above
+ * paint a built-in tint and boost z-index on hovered locked controls; under
+ * chrome:'none' that would override the custom hover background and stack above
+ * host-attached UI. Re-assert the custom hover background (so a locked control
+ * follows --sd-content-controls-custom-*-hover-bg, defaulting to empty - no tint
+ * leaks) and reset the z-index. Mirrors the base lock-hover selectors with the
+ * chrome-none prefix, so the extra class wins over the base rules. Split inline
+ * vs block because each reads its own hover variable. */
 .superdoc-cc-chrome-none .superdoc-structured-content-inline[data-lock-mode]:hover:not(.ProseMirror-selectednode, [data-appearance='hidden']) {
+  background: var(--sd-content-controls-custom-inline-hover-bg, var(--sd-content-controls-custom-inline-bg, none));
+  z-index: auto;
+}
+.superdoc-cc-chrome-none .superdoc-structured-content-block[data-lock-mode].sdt-group-hover:not(.ProseMirror-selectednode) {
+  background: var(--sd-content-controls-custom-block-hover-bg, var(--sd-content-controls-custom-block-bg, none));
   z-index: auto;
 }