refactor(painter): delete dead fragment.X fallbacks from resolved-item reads (SD-2957)

The painter coalesced ~14 resolved-item field reads with the legacy fragment
back-pointer (resolvedItem?.X ?? fragment.X). The resolve producer
(resolveLayout) already copies these fields onto the resolved item whenever
the source fragment has them, so the fragment fallback was mathematically
equivalent to just resolvedItem?.X — dead code preserved from the SD-2836
transition.

Sweep covers:
* paragraph: continuesFromPrev, continuesOnNext, markerWidth (truthy use)
* list-item content: continuesFromPrev, continuesOnNext, markerWidth (used as
  Math.max input — defaults to 0 when absent rather than reading fragment)
* list-item wrapper frame: markerWidth (used as Math.max input — defaults to 0)
* drop cap / paragraph / list marker / image: sourceAnchor
* image: pmStart, pmEnd, metadata
* fragment z-index: zIndex

Test fixture updated: the list-item-wrapper geometry test was relying on
the dead fallback (its resolved item omitted markerWidth). Populate
markerWidth on both initial and updated resolved items so the test reflects
the contract.

Out of scope (different semantics, not the same dead-fallback shape):
* block.width ?? fragment.width (image-block natural width vs fragment
  layout width — separate concepts).
* fragment.lines ?? measure.lines.slice(...) — flagged as stretch.
* fragment.scale ?? 1 — literal default with no resolved-stage equivalent.

Author: tupizz

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

@@ -5326,6 +5326,7 @@ describe('DomPainter', () => {
               fragment: initialLayout.pages[0].fragments[0],
               blockId: 'list-1',
               fragmentIndex: 0,
+              markerWidth: 30,
               block: listBlock as import('@superdoc/contracts').ListBlock,
               measure: listMeasure as import('@superdoc/contracts').ListMeasure,
             },
@@ -5358,6 +5359,7 @@ describe('DomPainter', () => {
               fragment: updatedLayout.pages[0].fragments[0],
               blockId: 'list-1',
               fragmentIndex: 0,
+              markerWidth: 30,
               block: listBlock as import('@superdoc/contracts').ListBlock,
               measure: listMeasure as import('@superdoc/contracts').ListMeasure,
             },

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

@@ -3019,9 +3019,9 @@ export class DomPainter {
       const content = resolvedItem?.content;
 
       // Prefer resolved item metadata over legacy fragment reads
-      const paraContinuesFromPrev = resolvedItem?.continuesFromPrev ?? fragment.continuesFromPrev;
-      const paraContinuesOnNext = resolvedItem?.continuesOnNext ?? fragment.continuesOnNext;
-      const paraMarkerWidth = resolvedItem?.markerWidth ?? fragment.markerWidth;
+      const paraContinuesFromPrev = resolvedItem?.continuesFromPrev;
+      const paraContinuesOnNext = resolvedItem?.continuesOnNext;
+      const paraMarkerWidth = resolvedItem?.markerWidth;
 
       const fragmentEl = this.doc.createElement('div');
       fragmentEl.classList.add(CLASS_NAMES.fragment);
@@ -3181,10 +3181,7 @@ export class DomPainter {
               const markerEl = this.doc!.createElement('span');
               markerEl.classList.add('superdoc-paragraph-marker');
               markerEl.textContent = resolvedMarker.text;
-              applySourceAnchorDataset(
-                markerEl,
-                resolvedMarker.sourceAnchor ?? resolvedItem?.sourceAnchor ?? fragment.sourceAnchor,
-              );
+              applySourceAnchorDataset(markerEl, resolvedMarker.sourceAnchor ?? resolvedItem?.sourceAnchor);
               markerEl.style.pointerEvents = 'none';
 
               markerContainer.style.position = 'relative';
@@ -3232,7 +3229,7 @@ export class DomPainter {
           this.capturePaintSnapshotLine(lineEl, context, {
             inTableFragment: false,
             inTableParagraph: false,
-            sourceAnchor: resolvedItem?.sourceAnchor ?? fragment.sourceAnchor,
+            sourceAnchor: resolvedItem?.sourceAnchor,
           });
           fragmentEl.appendChild(lineEl);
         });
@@ -3399,10 +3396,7 @@ export class DomPainter {
               const markerEl = this.doc!.createElement('span');
               markerEl.classList.add('superdoc-paragraph-marker');
               markerEl.textContent = marker.markerText ?? '';
-              applySourceAnchorDataset(
-                markerEl,
-                block.sourceAnchor ?? resolvedItem?.sourceAnchor ?? fragment.sourceAnchor,
-              );
+              applySourceAnchorDataset(markerEl, block.sourceAnchor ?? resolvedItem?.sourceAnchor);
               markerEl.style.pointerEvents = 'none';
 
               const markerJustification = marker.justification ?? 'left';
@@ -3451,7 +3445,7 @@ export class DomPainter {
           this.capturePaintSnapshotLine(lineEl, context, {
             inTableFragment: false,
             inTableParagraph: false,
-            sourceAnchor: resolvedItem?.sourceAnchor ?? fragment.sourceAnchor,
+            sourceAnchor: resolvedItem?.sourceAnchor,
           });
           fragmentEl.appendChild(lineEl);
         });
@@ -3577,9 +3571,10 @@ export class DomPainter {
       }
 
       // Prefer resolved item metadata over legacy fragment reads
-      const listContinuesFromPrev = resolvedItem?.continuesFromPrev ?? fragment.continuesFromPrev;
-      const listContinuesOnNext = resolvedItem?.continuesOnNext ?? fragment.continuesOnNext;
-      const listMarkerWidth = resolvedItem?.markerWidth ?? fragment.markerWidth;
+      const listContinuesFromPrev = resolvedItem?.continuesFromPrev;
+      const listContinuesOnNext = resolvedItem?.continuesOnNext;
+      // Default to 0 (no marker gutter) when absent — used directly in Math.max below.
+      const listMarkerWidth = resolvedItem?.markerWidth ?? 0;
 
       const fragmentEl = this.doc.createElement('div');
       fragmentEl.classList.add(CLASS_NAMES.fragment, `${CLASS_NAMES.fragment}-list-item`);
@@ -3616,10 +3611,7 @@ export class DomPainter {
 
       const markerEl = this.doc.createElement('span');
       markerEl.classList.add('superdoc-list-marker');
-      applySourceAnchorDataset(
-        markerEl,
-        item.marker.sourceAnchor ?? item.sourceAnchor ?? resolvedItem?.sourceAnchor ?? fragment.sourceAnchor,
-      );
+      applySourceAnchorDataset(markerEl, item.marker.sourceAnchor ?? item.sourceAnchor ?? resolvedItem?.sourceAnchor);
 
       // Track B: Use marker styling from wordLayout if available
       const wordLayout: MinimalWordLayout | undefined = item.paragraph.attrs?.wordLayout as
@@ -3700,7 +3692,7 @@ export class DomPainter {
         this.capturePaintSnapshotLine(lineEl, context, {
           inTableFragment: false,
           inTableParagraph: false,
-          sourceAnchor: resolvedItem?.sourceAnchor ?? fragment.sourceAnchor,
+          sourceAnchor: resolvedItem?.sourceAnchor,
         });
         contentEl.appendChild(lineEl);
       });
@@ -3748,17 +3740,17 @@ export class DomPainter {
       }
 
       // Add PM position markers for transaction targeting
-      const imgPmStart = resolvedItem?.pmStart ?? fragment.pmStart;
+      const imgPmStart = resolvedItem?.pmStart;
       if (imgPmStart != null) {
         fragmentEl.dataset.pmStart = String(imgPmStart);
       }
-      const imgPmEnd = resolvedItem?.pmEnd ?? fragment.pmEnd;
+      const imgPmEnd = resolvedItem?.pmEnd;
       if (imgPmEnd != null) {
         fragmentEl.dataset.pmEnd = String(imgPmEnd);
       }
 
       // Add metadata for interactive image resizing (skip watermarks - they should not be interactive)
-      const imgMetadata = resolvedItem?.metadata ?? fragment.metadata;
+      const imgMetadata = resolvedItem?.metadata;
       if (imgMetadata && !block.attrs?.vmlWatermark) {
         fragmentEl.setAttribute('data-image-metadata', JSON.stringify(imgMetadata));
       }
@@ -6949,7 +6941,7 @@ export class DomPainter {
       return '';
     }
 
-    const zIndex = resolvedZIndex ?? fragment.zIndex;
+    const zIndex = resolvedZIndex;
     return zIndex != null ? String(zIndex) : '';
   }
 
@@ -6968,7 +6960,7 @@ export class DomPainter {
     el.style.width = `${item.width}px`;
     el.dataset.blockId = item.blockId;
     el.dataset.layoutEpoch = String(this.layoutEpoch);
-    applySourceAnchorDataset(el, item.sourceAnchor ?? fragment.sourceAnchor);
+    applySourceAnchorDataset(el, item.sourceAnchor);
     this.applyFragmentWrapperZIndex(el, fragment, item.zIndex);
 
     if (item.fragmentKind === 'image' || item.fragmentKind === 'drawing' || item.fragmentKind === 'table') {
@@ -6992,7 +6984,9 @@ export class DomPainter {
     section?: 'body' | 'header' | 'footer',
   ): void {
     this.applyResolvedFragmentFrame(el, item, fragment, section);
-    const mw = item.markerWidth ?? fragment.markerWidth;
+    // Default to 0 (no marker gutter expansion) when markerWidth is absent — the resolve
+    // stage populates this for list items that have a measured marker (SD-2957).
+    const mw = item.markerWidth ?? 0;
     el.style.left = `${item.x - mw}px`;
     el.style.width = `${item.width + mw}px`;
   }