fix(extractor): tighten small-caps gate to cross-band junctions only

Three findings from cubic on #371, all valid.

1. Space suppression was too broad. `is_small_caps_continuation` accepted size
   ratios up to 0.92, which is *inside* the 20% band that merge_text_items
   already treats as the same size. Two similarly-sized uppercase words with a
   small real word gap therefore had their space suppressed even though the
   normal path would have merged them correctly with a space ("SEE" + "ALSO" ->
   "SEEALSO"). The helper now requires the junction to *cross* the band, since
   rescuing junctions the band would break is its only purpose; within-band
   pairs keep the normal word-spacing logic. The band is now a shared
   MERGE_FONT_SIZE_BAND constant so the helper and its caller cannot drift.

2. A trailing digit was skipped. The backward search for "the capital we are
   continuing" skipped non-alphabetic characters, so text ending in a footnote
   marker ("ANGELA M. MAZZARELLI1") found the earlier uppercase letter and
   accepted the join. It now checks the actual trailing character.

   Rejecting every trailing digit outright turned out to cost real quality, so
   this keeps one narrow exception. In meetings_in_mass_july_2023 the source
   reads "TUESDAY, JULY 4TH" with the ordinal suffix set as a smaller run; a
   blanket digit rejection reverted that to "TUESDAY, JULY 4" plus a stray "TH"
   leaking onto the next line, which is what main produces and what pdftotext
   shows is wrong. Only the four English ordinal suffixes (TH/ST/ND/RD) may
   follow a digit; anything else after one is treated as a footnote marker and
   rejected, so the case cubic raised stays blocked.

3. A test's name did not match its data. `small_caps_merge_does_not_swallow_a_
   second_column` claimed to exercise the 72pt column gap but contained only
   the second column's items, so it just re-tested the happy-path merge. It now
   holds the full nine-item row and asserts exactly two merged results,
   "ROLANDO T. ACOSTA, P.J." and "ANIL C. SINGH", which genuinely exercises the
   gap.

Both new guards were verified to be load-bearing: removing either one makes its
test fail.

The document that motivated the change is unaffected — small caps there run at
a 0.675 ratio, far outside the band — and 199AD3d.pdf p.5 still produces the
correct two-column justices table.

900 unit tests pass (10 covering small caps), fmt and clippy clean.

src/extractor/mod.rs

@@ -889,6 +889,92 @@ fn tracked_run_space_floor(group: &[&TextItem], start: usize) -> Option<(usize,
     Some((end, floor * fs))
 }
 
+/// Fractional font-size band within which `merge_text_items` treats two runs as
+/// the same size. Shared with `is_small_caps_continuation`, which exists only to
+/// rescue junctions this band would otherwise break.
+const MERGE_FONT_SIZE_BAND: f32 = 0.20;
+
+/// Detect a small-caps continuation: typesetters render small caps as a
+/// full-size capital immediately followed by shrunken capitals in the same
+/// font (`(R) Tj` at 9.98pt, then `(OLANDO) Tj` at 6.74pt). Those runs are one
+/// word, but the font-size band in `merge_text_items` would split them,
+/// leaving "R" and "OLANDO" as separate items — which then read as separate
+/// table columns, since column boundaries cluster on item start positions.
+///
+/// Gated tightly so it cannot absorb the other reasons a smaller run follows a
+/// larger one:
+///   - runs the size band already accepts — excluded by requiring the junction
+///     to *cross* the band, so within-band pairs keep the normal word-spacing
+///     logic instead of having their space suppressed
+///   - superscripts / footnote markers — excluded by requiring an uppercase
+///     *letter* on both sides, so digits never qualify
+///   - drop caps — excluded because the body text that follows is mixed case
+///   - adjacent table cells or separate words — excluded by requiring the runs
+///     to be visually contiguous (essentially no gap)
+fn is_small_caps_continuation(
+    text_so_far: &str,
+    first: &TextItem,
+    next: &TextItem,
+    gap: f32,
+) -> bool {
+    // Must shrink. Real small caps sit near 0.7-0.8 of the full cap height;
+    // anything smaller is a superscript or a different run entirely.
+    if first.font_size <= 0.0 || next.font_size >= first.font_size {
+        return false;
+    }
+    // Only rescue junctions the size band would have broken. Within-band pairs
+    // merge on their own, and suppressing their space would swallow real word
+    // gaps between two similarly-sized uppercase words.
+    if (next.font_size - first.font_size).abs() <= first.font_size * MERGE_FONT_SIZE_BAND {
+        return false;
+    }
+    if next.font_size / first.font_size < 0.55 {
+        return false;
+    }
+    // Visually contiguous: the capital and its small caps touch. A real word
+    // space or a column gap disqualifies.
+    if !(-first.font_size * 0.2..=first.font_size * 0.15).contains(&gap) {
+        return false;
+    }
+    // The continuation must be all-uppercase letters (digits and lowercase
+    // both disqualify), and must contain at least one letter.
+    let mut saw_letter = false;
+    for ch in next.text.chars() {
+        if ch.is_alphabetic() {
+            saw_letter = true;
+            if !ch.is_uppercase() {
+                return false;
+            }
+        } else if ch.is_numeric() {
+            return false;
+        }
+    }
+    if !saw_letter {
+        return false;
+    }
+    // What we are continuing must itself end in a capital. Check the actual
+    // trailing character rather than skipping back to the nearest letter: after
+    // "ANGELA M. MAZZARELLI1" the run to continue is the footnote marker, not
+    // the "I" before it.
+    let trimmed = text_so_far.trim_end();
+    if trimmed.chars().last().is_some_and(|c| c.is_numeric()) {
+        // One legitimate exception: an ordinal suffix set as a smaller run,
+        // e.g. "JULY 4" + "TH". Only the four English suffixes qualify —
+        // anything else after a digit is a footnote marker or numeric suffix.
+        return matches!(trimmed_suffix(next), "TH" | "ST" | "ND" | "RD");
+    }
+    trimmed
+        .chars()
+        .rev()
+        .find(|c| c.is_alphabetic())
+        .is_some_and(|c| c.is_uppercase())
+}
+
+/// The continuation run's text, trimmed — used to spot ordinal suffixes.
+fn trimmed_suffix(next: &TextItem) -> &str {
+    next.text.trim()
+}
+
 pub(crate) fn merge_text_items(items: Vec<TextItem>) -> Vec<TextItem> {
     if items.is_empty() {
         return items;
@@ -947,8 +1033,16 @@ pub(crate) fn merge_text_items(items: Vec<TextItem>) -> Vec<TextItem> {
             let mut j = i + 1;
             while j < group.len() {
                 let next = group[j];
-                // Must be similar font size (within 20%)
-                if (next.font_size - first.font_size).abs() > first.font_size * 0.20 {
+                // A small-caps junction is mid-word: it both survives the
+                // font-size band below and must never take a space.
+                let small_caps_join =
+                    is_small_caps_continuation(&text, first, next, next.x - end_x);
+                // Must be similar font size, except for genuine small-caps
+                // runs, where the shrunken capitals are the same word as the
+                // full-size initial (see helper).
+                if (next.font_size - first.font_size).abs() > first.font_size * MERGE_FONT_SIZE_BAND
+                    && !small_caps_join
+                {
                     break;
                 }
                 // Never merge across style boundaries: the merged item
@@ -1002,7 +1096,7 @@ pub(crate) fn merge_text_items(items: Vec<TextItem>) -> Vec<TextItem> {
                     Some((run_end, floor)) if j <= run_end => floor,
                     _ => threshold,
                 };
-                if needs_bullet_space || gap > effective_threshold {
+                if !small_caps_join && (needs_bullet_space || gap > effective_threshold) {
                     text.push(' ');
                 }
                 text.push_str(&next.text);
@@ -3006,6 +3100,145 @@ mod tests {
         }
     }
 
+    /// Small caps as typesetters emit them: a full-size capital at 9.98pt
+    /// immediately followed by shrunken capitals at 6.74pt, touching.
+    /// Modelled on `199AD3d.pdf` p.5 ("ROLANDO T. ACOSTA, P.J.").
+    #[test]
+    fn small_caps_run_merges_into_one_word() {
+        let items = vec![
+            make_item_fs("R", 144.36, 581.84, 7.20, 9.98),
+            make_item_fs("OLANDO", 151.56, 581.84, 30.56, 6.74),
+            make_item_fs("T. A", 185.45, 581.84, 17.58, 9.98),
+            make_item_fs("COSTA", 203.94, 581.84, 23.15, 6.74),
+            make_item_fs(", P.J.", 227.09, 581.84, 22.56, 9.98),
+        ];
+        let merged = merge_text_items(items);
+        assert_eq!(merged.len(), 1, "got {:?}", merged);
+        assert_eq!(merged[0].text, "ROLANDO T. ACOSTA, P.J.");
+    }
+
+    /// The full two-column row: both names must merge independently and the
+    /// 72pt column gap between them must survive as an item boundary.
+    #[test]
+    fn small_caps_merge_does_not_swallow_a_second_column() {
+        let items = vec![
+            // Column 1: "ROLANDO T. ACOSTA, P.J." ending at x=249.65
+            make_item_fs("R", 144.36, 581.84, 7.20, 9.98),
+            make_item_fs("OLANDO", 151.56, 581.84, 30.56, 6.74),
+            make_item_fs("T. A", 185.45, 581.84, 17.58, 9.98),
+            make_item_fs("COSTA", 203.94, 581.84, 23.15, 6.74),
+            make_item_fs(", P.J.", 227.09, 581.84, 22.56, 9.98),
+            // Column 2 starts at x=321.96 — a 72pt gap.
+            make_item_fs("A", 321.96, 581.84, 7.20, 9.98),
+            make_item_fs("NIL", 329.17, 581.84, 12.72, 6.74),
+            make_item_fs("C. S", 345.04, 581.84, 19.59, 9.98),
+            make_item_fs("INGH", 364.62, 581.84, 19.08, 6.74),
+        ];
+        let merged = merge_text_items(items);
+        let texts: Vec<&str> = merged.iter().map(|i| i.text.as_str()).collect();
+        assert_eq!(
+            texts,
+            vec!["ROLANDO T. ACOSTA, P.J.", "ANIL C. SINGH"],
+            "column gap should keep the two names apart"
+        );
+    }
+
+    #[test]
+    fn small_caps_merge_keeps_word_space_between_same_size_capitals() {
+        // Two uppercase words at sizes the merge band already accepts (9.98 and
+        // 9.0, a 10% drop) separated by a real word gap. The small-caps path
+        // must not claim this junction and swallow the space.
+        let items = vec![
+            make_item_fs("SEE", 100.0, 500.0, 18.0, 9.98),
+            make_item_fs("ALSO", 119.2, 500.0, 24.0, 9.0),
+        ];
+        let merged = merge_text_items(items);
+        assert_eq!(merged.len(), 1, "got {:?}", merged);
+        assert_eq!(merged[0].text, "SEE ALSO");
+    }
+
+    #[test]
+    fn trailing_digit_is_not_a_capital_awaiting_small_caps() {
+        // "...MAZZARELLI1" ends in a footnote marker; the backward search for an
+        // uppercase letter must not skip the digit and glue the next run.
+        assert!(!is_small_caps_continuation(
+            "ANGELA M. MAZZARELLI1",
+            &make_item_fs("ANGELA", 100.0, 500.0, 40.0, 9.98),
+            &make_item_fs("SHULMAN", 140.0, 500.0, 30.0, 6.74),
+            0.0,
+        ));
+    }
+
+    #[test]
+    fn ordinal_suffix_after_a_digit_still_merges() {
+        // "TUESDAY, JULY 4" + "TH" is one word in the source; the digit guard
+        // must not block the four English ordinal suffixes.
+        for suffix in ["TH", "ST", "ND", "RD"] {
+            assert!(
+                is_small_caps_continuation(
+                    "TUESDAY, JULY 4",
+                    &make_item_fs("JULY", 100.0, 500.0, 30.0, 12.0),
+                    &make_item_fs(suffix, 130.0, 500.0, 8.0, 8.0),
+                    0.0,
+                ),
+                "{suffix} should merge after a digit"
+            );
+        }
+    }
+
+    #[test]
+    fn superscript_footnote_marker_is_not_a_small_caps_continuation() {
+        // A digit must never qualify — otherwise footnote markers get glued on
+        // without the superscript handling.
+        assert!(!is_small_caps_continuation(
+            "MAZZARELLI",
+            &make_item_fs("MAZZARELLI", 100.0, 500.0, 50.0, 9.98),
+            &make_item_fs("1", 150.0, 503.0, 3.0, 6.74),
+            0.0,
+        ));
+    }
+
+    #[test]
+    fn drop_cap_is_not_a_small_caps_continuation() {
+        // Mixed-case body text after a large initial is a drop cap, not small
+        // caps.
+        assert!(!is_small_caps_continuation(
+            "T",
+            &make_item_fs("T", 100.0, 500.0, 20.0, 30.0),
+            &make_item_fs("he court held", 120.0, 500.0, 60.0, 10.0),
+            0.0,
+        ));
+    }
+
+    #[test]
+    fn separate_word_is_not_a_small_caps_continuation() {
+        // A real word space disqualifies even when both runs are uppercase.
+        let first = make_item_fs("SEE", 100.0, 500.0, 20.0, 9.98);
+        let next = make_item_fs("ALSO", 128.0, 500.0, 25.0, 6.74);
+        assert!(!is_small_caps_continuation("SEE", &first, &next, 8.0));
+    }
+
+    #[test]
+    fn lowercase_continuation_is_not_small_caps() {
+        assert!(!is_small_caps_continuation(
+            "SMALL",
+            &make_item_fs("SMALL", 100.0, 500.0, 30.0, 9.98),
+            &make_item_fs("caps", 130.0, 500.0, 20.0, 6.74),
+            0.0,
+        ));
+    }
+
+    #[test]
+    fn too_small_a_ratio_is_not_small_caps() {
+        // 0.4 ratio is a superscript/sub-run, outside the small-caps band.
+        assert!(!is_small_caps_continuation(
+            "A",
+            &make_item_fs("A", 100.0, 500.0, 7.0, 10.0),
+            &make_item_fs("BC", 107.0, 500.0, 8.0, 4.0),
+            0.0,
+        ));
+    }
+
     #[test]
     fn test_merge_subscript_items_chemical_formula() {
         // NH₃: "NH" at fs=8 followed by subscript "3" at fs=4.7