fix(render): map author spans to landedText coords (INV-49/50 coloring alignment) (#64)

renderReview diffs against landedText (current minus pending proposals), so block
offsets are landedText-relative while authorSpans arrive in currentText coords. A
colored block after a length-changing pending proposal was mis-colored. Map the
spans through toLanded so authorship coloring stays aligned.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/trackChangesModel.ts

@@ -828,6 +828,17 @@ export function renderReview(
     return curOff + delta;
   };
 
+  // F12/#64 (INV-49/50): blocks are split from `landedText`, so `blk.start` is a
+  // landedText offset — but `authorSpans` arrive in `currentText` coordinates. A
+  // colored block sitting AFTER a length-changing pending proposal would otherwise
+  // be mis-colored (the offsets diverge by the revert delta). Map the spans into
+  // landedText coordinates once so authorship coloring stays aligned.
+  const landedSpans: AuthorSpan[] = authorSpans.map((s) => ({
+    ...s,
+    start: toLanded(s.start),
+    end: toLanded(s.end),
+  }));
+
   // Associate each resolved proposal with the landedText block index whose range
   // it anchors into: the largest block with start <= anchorStart (the containing
   // block, or the nearest preceding block when the anchor sits in a gap). A
@@ -857,7 +868,7 @@ export function renderReview(
     const blockIndex = op.kind === "removed" ? -1 : ci;
     const blk = op.kind === "removed" ? undefined : ranges[ci++];
     const colored = (raw: string): string =>
-      blk && !clean ? colorByAuthor(raw, blk.start, authorSpans, render) : render(raw);
+      blk && !clean ? colorByAuthor(raw, blk.start, landedSpans, render) : render(raw);
     bodyParts.push(renderReviewOp(op, render, colored, srcAttr(blk)));
     const here = blockIndex >= 0 ? byBlock.get(blockIndex) : undefined;
     if (here) for (const p of here) bodyParts.push(proposalBlockHtml(p, render));