refactor(direction): centralize last paragraph isRtl reads on helper (SD-2778)

packages/layout-engine/layout-bridge/src/position-hit.ts

@@ -23,7 +23,12 @@ import type {
   ParagraphBlock,
   ParagraphMeasure,
 } from '@superdoc/contracts';
-import { adjustAvailableWidthForTextIndent, computeLinePmRange, getFirstLineIndentOffset } from '@superdoc/contracts';
+import {
+  adjustAvailableWidthForTextIndent,
+  computeLinePmRange,
+  getFirstLineIndentOffset,
+  getParagraphInlineDirection,
+} from '@superdoc/contracts';
 import { charOffsetToPm, findCharacterAtX } from './text-measurement.js';
 import type { PageGeometryHelper } from './page-geometry-helper.js';
 
@@ -120,26 +125,9 @@ export const getAtomicPmRange = (fragment: AtomicFragment, block: FlowBlock): {
 
 export const isRtlBlock = (block: FlowBlock): boolean => {
   if (block.kind !== 'paragraph') return false;
-  const attrs = block.attrs as Record<string, unknown> | undefined;
-  if (!attrs) return false;
-  // AIDEV-NOTE: The typed directionContext.inlineDirection (SD-2776) is the source of
-  // truth for paragraph inline direction. Check the value, not the key — `inlineDirection`
-  // can be `undefined` per the resolver contract (no explicit w:bidi anywhere in the
-  // cascade), and we should fall through to the legacy field in that case.
   // Do NOT consult attrs.textDirection here: that's writing-mode (ECMA §17.18.93,
   // values lrTb/tbRl/btLr/lrTbV/tbRlV/tbLrV) which is a separate axis from inline RTL.
-  const directionContext = attrs.directionContext as { inlineDirection?: string } | undefined;
-  if (directionContext?.inlineDirection != null) {
-    return directionContext.inlineDirection === 'rtl';
-  }
-  // AIDEV-NOTE: compat-fallback — `attrs.direction` / `attrs.dir` are the legacy scalar
-  // duplicates of `directionContext.inlineDirection`. Retire once SD-2778 collapses
-  // them on `ParagraphAttrs`.
-  const directionAttr = attrs.direction ?? attrs.dir;
-  if (typeof directionAttr === 'string' && directionAttr.toLowerCase() === 'rtl') {
-    return true;
-  }
-  return false;
+  return getParagraphInlineDirection(block.attrs) === 'rtl';
 };
 
 export const determineColumn = (layout: Layout, fragmentX: number): number => {

packages/layout-engine/layout-bridge/test/position-hit.test.ts

@@ -61,4 +61,13 @@ describe('isRtlBlock', () => {
       ),
     ).toBe(true);
   });
+
+  // SD-2778: switching to getParagraphInlineDirection is strictly broader on
+  // fallback than the prior inline read. Specifically, the helper picks up
+  // paragraphProperties.rightToLeft when neither directionContext nor the legacy
+  // scalar field is present. Pin that case so the broader fallback is intentional.
+  it('falls back to paragraphProperties.rightToLeft when no other direction signal is present', () => {
+    expect(isRtlBlock(paragraph({ paragraphProperties: { rightToLeft: true } }))).toBe(true);
+    expect(isRtlBlock(paragraph({ paragraphProperties: { rightToLeft: false } }))).toBe(false);
+  });
 });

packages/layout-engine/layout-resolved/src/resolveLayout.test.ts

@@ -1777,7 +1777,12 @@ describe('resolveLayout', () => {
         id,
         runs: [{ kind: 'text', text: 'RTL list item' }],
         attrs: {
-          direction: 'rtl',
+          // SD-2778: use directionContext so this test only passes through the
+          // new helper-driven typed path. The pre-migration code read
+          // attrs.direction directly, so the prior `direction: 'rtl'` fixture
+          // would have passed against the old implementation too and didn't
+          // actually prove the migration.
+          directionContext: { inlineDirection: 'rtl', writingMode: 'horizontal-tb' },
           indent: { right, hanging: -24 },
           wordLayout: {
             marker: {

packages/layout-engine/layout-resolved/src/resolveParagraph.ts

@@ -9,7 +9,7 @@ import type {
   ResolvedDropCapItem,
   ResolvedListMarkerItem,
 } from '@superdoc/contracts';
-import { adjustAvailableWidthForTextIndent } from '@superdoc/contracts';
+import { adjustAvailableWidthForTextIndent, getParagraphInlineDirection } from '@superdoc/contracts';
 import {
   isMinimalWordLayout,
   resolveListMarkerGeometry,
@@ -93,7 +93,7 @@ export function resolveParagraphContent(
   const paraIndent = (block.attrs as ParagraphAttrs | undefined)?.indent;
   const paraIndentLeft = paraIndent?.left ?? 0;
   const paraIndentRight = paraIndent?.right ?? 0;
-  const isRtl = (block.attrs as ParagraphAttrs | undefined)?.direction === 'rtl';
+  const isRtl = getParagraphInlineDirection(block.attrs) === 'rtl';
   const {
     anchorIndentPx: paraMarkerAnchorIndent,
     firstLinePx: markerFirstLine,