Accept compact SVG arc flags in svg_path size check (#2299)

Found while testing crates/geom/src/lib.rs:57-87 (number_past, called from svg_path at :49)

Co-authored-by: Claude Haiku 5.5 <noreply@anthropic.com>

crates/geom/src/lib.rs

@@ -63,7 +63,15 @@ fn number_past(d: &str, max: f64) -> bool {
         big
     }
     let (mut cur, mut dot, mut exp) = (String::new(), false, false);
+    // Whether the command is an arc, and how many numbers it has had: the 4th and 5th of each
+    // seven are flags, single `0`/`1` characters that may run into the next number unseparated.
+    let (mut arc, mut idx) = (false, 0usize);
     for c in d.chars() {
+        if cur.is_empty() && arc && matches!(idx % 7, 3 | 4) && matches!(c, '0' | '1') {
+            idx += 1;
+            (dot, exp) = (false, false);
+            continue;
+        }
         let continues = match c {
             '0'..='9' => true,
             '.' => !dot && !exp,
@@ -77,9 +85,13 @@ fn number_past(d: &str, max: f64) -> bool {
             cur.push(c);
             continue;
         }
+        idx += cur.chars().any(|c| c.is_ascii_digit()) as usize;
         if big(&mut cur, max) {
             return true;
         }
+        if c.is_ascii_alphabetic() {
+            (arc, idx) = (matches!(c, 'A' | 'a'), 0);
+        }
         (dot, exp) = (c == '.', false);
         if matches!(c, '+' | '-' | '.') {
             cur.push(c);

crates/geom/tests/svg_arc_flags.rs

@@ -0,0 +1,14 @@
+use figcraft_geom::svg_path;
+
+#[test]
+fn compact_arc_flags_are_not_part_of_the_next_number() {
+    let compact = svg_path("M0 0A5 5 0 11999999999 0").expect("compact flags parse");
+    let spaced = svg_path("M0 0A5 5 0 1 1 999999999 0").expect("spaced flags parse");
+    assert_eq!(compact, spaced);
+}
+
+#[test]
+fn a_real_oversized_arc_coordinate_is_still_refused() {
+    assert!(svg_path("M0 0A5 5 0 112000000000 0").is_err());
+    assert!(svg_path("M0 0A5 5 0 1 1 2000000000 0").is_err());
+}