M5: year-first slash dates (yyyy/mm/dd, yyyy/m/d) for Fill & Sign and headers

Taiwan, Japan and China write dates year first with slashes (Windows'
zh-TW short date is yyyy/M/d), and neither the Fill & Sign presets nor
the header and footer date tokens offered it. Both now have yyyy/mm/dd
and yyyy/m/d. The header and footer list gains them at its end, since
its selection is an index.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RUNQSPVXx3dDBabRZHAnjz

crates/edit/src/lib.rs

@@ -54,7 +54,7 @@ pub struct HeaderFooter {
     /// Left, centre and right header text, then left, centre and right footer text. Tokens:
     /// `<<1>>` page number, `<<n>>` page count, `<<1 of n>>`, `<<1/n>>`, `<<Page 1>>`,
     /// `<<Page 1 of n>>`, dates `<<m/d/yyyy>>`, `<<mm/dd/yyyy>>`, `<<d/m/yyyy>>`, `<<yyyy-mm-dd>>`,
-    /// `<<m/d/yy>>`, `<<mmmm d, yyyy>>`, and Bates numbers `<<Bates Number#6#1#PRE#SUF>>`
+    /// `<<yyyy/mm/dd>>`, `<<yyyy/m/d>>`, `<<m/d/yy>>`, `<<mmmm d, yyyy>>`, and Bates numbers `<<Bates Number#6#1#PRE#SUF>>`
     /// (digits, start, prefix, suffix).
     pub text: [String; 6],
     pub font_size: f64,
@@ -244,6 +244,8 @@ pub fn expand(template: &str, page_number: u32, count: usize, bates: u64, cx: &C
             "d/m/yyyy" => format!("{d}/{m}/{y}"),
             "dd/mm/yyyy" => format!("{d:02}/{m:02}/{y}"),
             "yyyy-mm-dd" => format!("{y}-{m:02}-{d:02}"),
+            "yyyy/mm/dd" => format!("{y}/{m:02}/{d:02}"),
+            "yyyy/m/d" => format!("{y}/{m}/{d}"),
             "mmmm d, yyyy" => format!("{} {d}, {y}", MONTHS[(m.clamp(1, 12) - 1) as usize]),
             t if t.starts_with("Bates Number") => {
                 // Bates Number#digits#start#prefix#suffix (start is applied by the caller).

crates/edit/src/tests.rs

@@ -60,6 +60,7 @@ fn tokens_expand() {
     assert_eq!(expand("Page <<1>> of <<n>>", 3, 10, 0, &c), "Page 3 of 10");
     assert_eq!(expand("<<1 of n>> · <<Page 1>> · <<1/n>>", 2, 5, 0, &c), "2 of 5 · Page 2 · 2/5");
     assert_eq!(expand("<<m/d/yyyy>> <<yyyy-mm-dd>> <<mmmm d, yyyy>>", 1, 1, 0, &c), "10/1/2026 2026-10-01 October 1, 2026");
+    assert_eq!(expand("<<yyyy/mm/dd>> <<yyyy/m/d>>", 1, 1, 0, &c), "2026/10/01 2026/10/1");
     assert_eq!(expand("<<Bates Number#6#100#ABC#-X>>", 1, 1, 104, &c), "ABC000104-X");
     assert_eq!(expand("keep <<unknown>> and <<unclosed", 1, 1, 0, &c), "keep <<unknown>> and <<unclosed");
     assert_eq!(bates_start("x <<Bates Number#6#100#A#B>>"), Some(100));

crates/engine/src/dates.rs

@@ -13,7 +13,7 @@ use crate::Session;
 pub const DEFAULT_DATE_FORMAT: &str = "m/d/yyyy";
 
 /// Ready-made formats for Preferences ▸ Date format. Any other valid pattern works too.
-pub const DATE_FORMATS: [&str; 12] = [
+pub const DATE_FORMATS: [&str; 14] = [
     "m/d/yyyy",
     "mm/dd/yyyy",
     "d/m/yyyy",
@@ -21,6 +21,9 @@ pub const DATE_FORMATS: [&str; 12] = [
     "dd.mm.yyyy",
     "yyyy-mm-dd",
     "yyyy.mm.dd.",
+    // Year first with slashes, as Taiwan, Japan and China write it (Windows' zh-TW short date).
+    "yyyy/mm/dd",
+    "yyyy/m/d",
     "d mmm yyyy",
     "d mmmm yyyy",
     "mmm d, yyyy",
@@ -604,6 +607,8 @@ mod tests {
                 "07.03.2026",
                 "2026-03-07",
                 "2026.03.07.",
+                "2026/03/07",
+                "2026/3/7",
                 "7 Mar 2026",
                 "7 March 2026",
                 "Mar 7, 2026",

crates/ui-egui/src/marks_ui.rs

@@ -112,7 +112,9 @@ impl Default for MarksDraft {
 }
 
 const PAGE_FORMATS: [&str; 5] = ["<<1>>", "<<1 of n>>", "<<1/n>>", "<<Page 1>>", "<<Page 1 of n>>"];
-const DATE_FORMATS: [&str; 6] = ["<<m/d/yyyy>>", "<<mm/dd/yyyy>>", "<<d/m/yyyy>>", "<<yyyy-mm-dd>>", "<<m/d/yy>>", "<<mmmm d, yyyy>>"];
+// New formats go last: `date_format` is an index into this list.
+const DATE_FORMATS: [&str; 8] =
+    ["<<m/d/yyyy>>", "<<mm/dd/yyyy>>", "<<d/m/yyyy>>", "<<yyyy-mm-dd>>", "<<m/d/yy>>", "<<mmmm d, yyyy>>", "<<yyyy/mm/dd>>", "<<yyyy/m/d>>"];
 const BOX_NAMES: [&str; 6] =
     ["Left Header Text", "Center Header Text", "Right Header Text", "Left Footer Text", "Center Footer Text", "Right Footer Text"];