fix(edit): reach the styled rewrite's rows at the step they are written

The styled path writes rows `line_spacing` (1.5 by default) times the
size apart when a size or spacing is set, but its Reach assumed 1.2, so
an image over only the lower rows of a larger rewrite was missed. The
pitch now comes from the row writer's own step (row_step, shared by
both), at the largest size among the paragraph's lines and ranges.

The landing test gains a six-row rewrite at twice the size over an image
covering only its last row; it fails with the 1.2 step.
A case with only line_spacing set covers the other branch.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SqmHYx8FiWM5PcsoiErgp9

crates/edit/src/tests.rs

@@ -4577,6 +4577,8 @@ fn revealed_text_moves_on_top_only_when_painted_over() {
 fn an_ocr_rewrite_goes_on_top_of_paint_over_where_it_lands() {
     let scan = "q 200 0 0 100 100 100 cm /Im0 Do Q";
     let moved = text::BlockStyle { offset: Some([-290.0, -450.0]), ..Default::default() };
+    let sized = text::BlockStyle { size: Some(24.0), ..Default::default() };
+    let spaced = text::BlockStyle { line_spacing: Some(3.0), ..Default::default() };
     let cases = [
         ("BT /F1 12 Tf 3 Tr 400 600 Td (Away) Tj ET", "Moved", &moved),
         ("BT /F1 12 Tf 3 Tr 400 600 Td (Away) Tj ET", "Moved\nTwice", &moved),
@@ -4584,7 +4586,12 @@ fn an_ocr_rewrite_goes_on_top_of_paint_over_where_it_lands() {
         ("BT /F1 12 Tf 3 Tr 40 150 Td (Hi) Tj ET", "Hello there,\nthis line now runs well past the scan's left edge", &text::BlockStyle::default()),
         ("BT /F1 12 Tf 3 Tr 110 230 Td (Above) Tj ET", "One\nTwo\nThree\nFour\nFive\nSix", &text::BlockStyle::default()),
     ];
-    for (content, edit, style) in cases {
+    let low = "q 200 0 0 30 100 300 cm /Im0 Do Q";
+    let cases = cases.into_iter().map(|(c, e, s)| (c, e, s, scan)).chain([
+        ("BT /F1 12 Tf 3 Tr 110 500 Td (Above) Tj ET", "One\nTwo\nThree\nFour\nFive\nSix", &sized, low),
+        ("BT /F1 12 Tf 3 Tr 110 500 Td (Above) Tj ET", "One\nTwo\nThree\nFour\nFive\nSix", &spaced, low),
+    ]);
+    for (content, edit, style, scan) in cases {
         let mut doc = image_page_with(&format!("{content} {scan}"));
         let before = text::text_blocks(&doc, 0).unwrap().remove(0);
         let ops = pdfcraft_content::parse(&page_content_bytes(&doc, 0)).ops;

crates/edit/src/text_regions/styled.rs

@@ -402,6 +402,16 @@ fn paragraph_geometry(doc: &Document, page: &pdfcraft_model::Page, block: &TextB
     Ok((dx, dy, style.width.unwrap_or(natural).clamp(1.0, 14_400.0)))
 }
 
+/// How far below a row of `size` the next one is written: the source's leading unless a size
+/// or line spacing is chosen.
+fn row_step(style: &BlockStyle, size: f64, source_leading: f64) -> f64 {
+    if style.line_spacing.is_none() && style.size.is_none() {
+        source_leading
+    } else {
+        style.line_spacing.unwrap_or(1.5).clamp(0.5, 5.0) * style.size.unwrap_or(size)
+    }
+}
+
 fn wrap_styled_rows(
     chars: &[StyledChar],
     width: f64,
@@ -812,8 +822,9 @@ pub(crate) fn rewrite_styled_block(
         .unwrap_or(first.size * 1.5);
     // Revealed OCR text that something is painted over goes on top of the page, where it starts
     // from the initial state.
-    let largest = style.ranges.iter().filter_map(|r| r.size).chain(style.size).fold(first.size, f64::max);
-    let pitch = source_leading.max(largest * style.line_spacing.unwrap_or(1.2));
+    let largest =
+        block.lines.iter().filter_map(|i| lines.get(*i)).map(|l| l.size).chain(style.ranges.iter().filter_map(|r| r.size)).fold(first.size, f64::max);
+    let pitch = source_leading.max(row_step(style, largest, source_leading));
     let widest = measured.iter().copied().fold(width, f64::max);
     // This path lays rows out along user-space baselines, so the paragraph is upright here.
     let reach = crate::Reach { rect: block.rect, offset: [dx, dy], width: widest, rows: rows.len(), pitch, upright: true };
@@ -972,11 +983,7 @@ pub(crate) fn rewrite_styled_block(
             x += segment_width;
             pos = end;
         }
-        baseline -= if style.line_spacing.is_none() && style.size.is_none() {
-            source_leading
-        } else {
-            style.line_spacing.unwrap_or(1.5).clamp(0.5, 5.0) * style.size.unwrap_or(anchor.size)
-        };
+        baseline -= row_step(style, anchor.size, source_leading);
     }
     block_ops.push(Op::new("Q", vec![]));
     let on_top = crate::lift_on_top(over, &mut block_ops);