diff --git a/src/trackChangesModel.ts b/src/trackChangesModel.ts
index 84dbfa8..57668e9 100644
--- a/src/trackChangesModel.ts
+++ b/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));
diff --git a/test/trackChangesModel.test.ts b/test/trackChangesModel.test.ts
index 800c590..85efc0d 100644
--- a/test/trackChangesModel.test.ts
+++ b/test/trackChangesModel.test.ts
@@ -392,6 +392,26 @@ describe("renderReview", () => {
     // the applied paragraph is NOT also emitted as a word-merged changed block
     expect(html).not.toContain("<del>brown</del>"); // no double-render of the change as a baseline diff
   });
+
+  test("renderReview keeps author coloring aligned on a block AFTER a length-changing pending proposal (INV-49/50)", () => {
+    // block 1 has a pending proposal whose applied text is MUCH LONGER than its
+    // original; block 2 carries a Claude authorship span (in currentText coords).
+    const baseline = "one short.\n\ntwo stable here.\n";
+    const current = "one MUCH LONGER REPLACED TEXT.\n\ntwo stable here.\n";
+    const proposals: ProposalView[] = [{
+      id: "pr_1",
+      anchorStart: current.indexOf("one MUCH LONGER REPLACED TEXT."),
+      anchorEnd: current.indexOf("one MUCH LONGER REPLACED TEXT.") + "one MUCH LONGER REPLACED TEXT.".length,
+      replaced: "one short.",
+      replacement: "one MUCH LONGER REPLACED TEXT.",
+      original: "one short.",
+    }];
+    const sStart = current.indexOf("stable");
+    const authorSpans = [{ start: sStart, end: sStart + "stable".length, author: "claude" as const }];
+    const html = renderReview(baseline, current, authorSpans, proposals);
+    // the Claude coloring wraps "stable" exactly — not shifted by the proposal's length delta.
+    expect(html).toMatch(/<span class="cw-by-claude">stable<\/span>/);
+  });
 });
 
 import { renderTrackChanges as rtc2 } from "../src/trackChangesModel";