diff --git a/ATTRIBUTION.toml b/ATTRIBUTION.toml
index 20866740c..9ddd3c04d 100644
--- a/ATTRIBUTION.toml
+++ b/ATTRIBUTION.toml
@@ -19,7 +19,7 @@ licence = "MIT OR Apache-2.0"
 licence_file = "LICENSE-MIT"
 kind = "translation"
 usage = "Simplified Chinese UI strings, compiled in by crates/ui-egui/src/i18n/mod.rs"
-sha256 = "5e6493d38917e6900f126d0a4fc9819b1b9a57e2d883207d03606d1c3e0c6d94"
+sha256 = "25a6a7ccbc113f8a64092b8962c9c0bfe64bfb6dc2000e2a6164881b492e8684"
 
 [[asset]]
 path = "crates/ui-egui/src/i18n/zh-hant.tsv"
@@ -30,7 +30,7 @@ licence = "MIT OR Apache-2.0"
 licence_file = "LICENSE-MIT"
 kind = "translation"
 usage = "Traditional Chinese UI strings, compiled in by crates/ui-egui/src/i18n/mod.rs"
-sha256 = "e049f7df877d07137465cbe7ead240c9cd60daaaeb298f4877eb58974c728004"
+sha256 = "957b2ca722eb3ebb6c6303ff5e25245b850b3a3e6ddba094516174e804aa96c1"
 
 [[asset]]
 path = "crates/ui-egui/src/i18n/cs.tsv"
@@ -63,7 +63,7 @@ licence = "MIT OR Apache-2.0"
 licence_file = "LICENSE-MIT"
 kind = "translation"
 usage = "Spanish UI strings, compiled in by crates/ui-egui/src/i18n/mod.rs"
-sha256 = "f47c19dcf7272068dc8b46a37eb692948f5571737f6c1c82e8282f1b7d64458d"
+sha256 = "4d139791454c1c3a00e2726e495b1170eb1f5be95f6cd5e12e7311c85aca0259"
 
 [[asset]]
 path = "crates/ui-egui/src/i18n/fr.tsv"
@@ -74,7 +74,7 @@ licence = "MIT OR Apache-2.0"
 licence_file = "LICENSE-MIT"
 kind = "translation"
 usage = "French UI strings, compiled in by crates/ui-egui/src/i18n/mod.rs"
-sha256 = "e735d7f40fa5d34627209287d82a4ce2651d7a04a31bc1bbae1b8be0ffbed972"
+sha256 = "716fb1f47bc69c355a688f116715b819a03c59d99ba9e03d65db2dd79bbe11b9"
 
 [[asset]]
 path = "crates/ui-egui/src/i18n/de.tsv"
@@ -85,7 +85,7 @@ licence = "MIT OR Apache-2.0"
 licence_file = "LICENSE-MIT"
 kind = "translation"
 usage = "German UI strings, compiled in by crates/ui-egui/src/i18n/mod.rs"
-sha256 = "97c6d0ef61a16419b8eb8807ad91a6544a5d7d9d3e20dfd35f33c39c105107a0"
+sha256 = "f78e4175753553fcb27d61697e64ab092cede8433a8ae68ca1f553879b4217dc"
 
 [[asset]]
 path = "crates/ui-egui/src/i18n/te.tsv"
@@ -96,7 +96,7 @@ licence = "MIT OR Apache-2.0"
 licence_file = "LICENSE-MIT"
 kind = "translation"
 usage = "Telugu UI strings, compiled in by crates/ui-egui/src/i18n/mod.rs"
-sha256 = "d3630f989e9725c22444dc27765142674b66f72436502ca969b2851fc38d703d"
+sha256 = "329b95966eca05438ea23deb2a48f61d9af9e984017d14942af06b3bb0799e4b"
 
 [[asset]]
 path = "crates/ui-egui/src/i18n/ru.tsv"
@@ -107,7 +107,7 @@ licence = "MIT OR Apache-2.0"
 licence_file = "LICENSE-MIT"
 kind = "translation"
 usage = "Russian UI strings, compiled in by crates/ui-egui/src/i18n/mod.rs"
-sha256 = "fb9e2120dab378f35110897e7d0ebc53fce331cc918df393946a1f96ad2335e3"
+sha256 = "50390d434fbebc5d6ed1a259db96d73d76be5678f4c87a8b04ddd1c38a4901f7"
 
 [[asset]]
 path = "crates/ui-egui/src/i18n/hu.tsv"
@@ -118,7 +118,7 @@ licence = "MIT OR Apache-2.0"
 licence_file = "LICENSE-MIT"
 kind = "translation"
 usage = "Hungarian UI strings, compiled in by crates/ui-egui/src/i18n/mod.rs"
-sha256 = "fd4281afd9a33a0e73bab937b9d05cb92200967eb1847d8f43709ca9cdabf080"
+sha256 = "4b7618b83b5b4479e5b8e4022a302689d8acf194a10368d7ef34302f8e19e299"
 
 [[asset]]
 path = "crates/ui-egui/src/i18n/bg.tsv"
@@ -129,7 +129,7 @@ licence = "MIT OR Apache-2.0"
 licence_file = "LICENSE-MIT"
 kind = "translation"
 usage = "Bulgarian UI strings, compiled in by crates/ui-egui/src/i18n/mod.rs"
-sha256 = "4de7b3bae615f5b8bc29e56cd69d932735ee82ed5b7bbdb713c8b5c0c47cea84"
+sha256 = "78053df6ec3de2d0b6a10338b57618302deb4ec8cfb794be5a4a4d2bdc2f950b"
 
 [[asset]]
 path = "crates/ui-egui/src/i18n/ja.tsv"
@@ -140,7 +140,7 @@ licence = "MIT OR Apache-2.0"
 licence_file = "LICENSE-MIT"
 kind = "translation"
 usage = "Japanese UI strings, compiled in by crates/ui-egui/src/i18n/mod.rs"
-sha256 = "cba0c2ca8989a28aa41056b98eb1c8019e3a13e882ead246ea1d69f82c44e087"
+sha256 = "285d3d9c8fff269ceb032e6be67a1c33d596f2ed80c9d8677f5655fb014f43b5"
 
 [[asset]]
 path = "crates/ui-egui/src/i18n/uk.tsv"
@@ -151,7 +151,7 @@ licence = "MIT OR Apache-2.0"
 licence_file = "LICENSE-MIT"
 kind = "translation"
 usage = "Ukrainian UI strings, compiled in by crates/ui-egui/src/i18n/mod.rs"
-sha256 = "ca16d314028a95bd3b7eb73e9ea6c9d388a844f841e8c8811e340eb5a4161227"
+sha256 = "06e8584e6f16528598e311e1b0dbd167701967c6786e14701886285babb38c9f"
 
 [[asset]]
 path = "assets/icons/accessibility.svg"
diff --git a/ROADMAP.md b/ROADMAP.md
index 4c8e3dcfe..dba0e114b 100644
--- a/ROADMAP.md
+++ b/ROADMAP.md
@@ -135,6 +135,7 @@ M0 → M1 → M2 → M3 → M4 must happen in order. After M4, M5–M12 can run
 
 - **2026-10-09 (M14, #577):** The desktop GPU setup enables the selected adapter's supported 2D texture extent instead of egui-wgpu's fixed 8192-pixel extent. This removes the artificial surface ceiling behind a mixed-DPI Windows startup crash when opening Outlook PDF attachments. Synthetic regressions cover the observed 8600 × 3423 surface, downlevel adapters and preservation of other device limits. Hardware resolution limits still apply; milestone and overall effort estimates are unchanged.
 
+- **2026-10-09 (M5, Fill & Sign flatten on save):** Preferences and `doc_save` can bake Fill & Sign text, marks and signatures into the page when saving. The option defaults off. Other comments and form fields stay, a second flatten does not reuse an XObject name already on the page, and a document that cannot be changed is left unwritten. Overall estimate unchanged (about 30–35%).
 - **2026-10-09 (M5, Fill & Sign flatten on save):** Preferences and `doc_save` can bake Fill & Sign text, marks and signatures into the page when saving. The option defaults off. Other comments and form fields stay, a second flatten does not reuse an XObject name already on the page, and a document that cannot be changed is left unwritten. Overall estimate unchanged (about 30–35%).
 - **2026-10-09 (M5.7, #434 partial):** Natural-size image stamps placed at a click or through `stamp_custom` remain upright on rotated pages, with a displayed-space-sized rectangle and a counterrotated standard appearance matrix. Move, resize, restyle and undo/redo preserve that orientation. Native and external Poppler save/reopen rendering cover all four quarter-turns; UI tests verify the displayed bounds. Explicit rectangle placement, image signatures, PDF-page stamps and image-file orientation metadata remain outside this repair. #434 stays open; milestone table and effort estimates remain unchanged.
 - **2026-10-09 (M1, raw-stream decoding limits):** COS checks unfiltered decoded data against the caller and per-stream limits before copying it, including empty filter arrays and streams whose Crypt filter was applied on load. Strict decoding uses the same raw-data guard. Tiny synthetic regressions cover exceeded, exact and zero-byte limits while retaining the filtered decoder behavior. Milestone and overall effort estimates unchanged (about 30–35%).
@@ -145,6 +146,8 @@ M0 → M1 → M2 → M3 → M4 must happen in order. After M4, M5–M12 can run
 
 - **2026-10-09 (M4, page grid zoom):** The Organize page grid zooms from 50% to 300%: toolbar buttons with a percentage that resets, trackpad pinch or Ctrl/⌘ + wheel about the page under the pointer, and ⌘+ / ⌘− / ⌘0. Pages drawn larger than their thumbnails are rendered at the size drawn while in view, so text stays sharp in documents of any length. Not yet: a slider, remembering the size, a size control for the Pages panel. Overall estimate unchanged (about 30–35%).
 
+- **2026-10-09 (M4, page grid zoom):** The Organize page grid zooms from 50% to 300%: toolbar buttons with a percentage that resets, trackpad pinch or Ctrl/⌘ + wheel about the page under the pointer, and ⌘+ / ⌘− / ⌘0. Pages drawn larger than their thumbnails are rendered at the size drawn while in view, so text stays sharp in documents of any length. Not yet: a slider, remembering the size, a size control for the Pages panel. Overall estimate unchanged (about 30–35%).
+
 - **2026-10-08 (M5.7, signature resize proportions):** Image signature corner handles preserve the embedded image's original aspect ratio and anchor the opposite corner; edge midpoint handles stretch width or height independently. The live preview and committed edit share the constrained geometry, including page/view rotation and reopened PDFs whose rectangles were stretched previously. Synthetic UI tests cover all corners, edge resizing, undo and redo. Milestone and effort estimates unchanged.
 - **2026-10-08 (M5.7, live signature adjustment):** Embedded image signatures resize and move with every pointer frame. Movement hides the frame and handles, which return on release; Escape cancels without committing. A cached background preserves the page beneath the image, and only the completed gesture enters undo history. The read-only engine preview and `comment_image_preview` tool share bounded image decoding and render layers. Synthetic pixel tests cover live geometry, alpha, coloured page content, rotation, cancellation and encrypted save/reopen. Milestone and effort estimates unchanged.
 - **2026-10-08 (M10/M4, create from multiple files):** Create a PDF ▸ Multiple files is live. The picked PDFs, images and `.txt` files open as one unsaved document in the Organize page grid, where pages are removed and reordered and Save pages writes what is shown. The grid gained a "+" at every gap that inserts files right there, and on desktop files dropped on the grid go to the gap under the pointer; Insert from file now takes several files in order, converts images and text, and selects what it inserted. File-type detection moved from the shell into `pdfcraft-create` (`source_kind`), with one engine entry point (`Session::convert_to_pdf`) shared by Open, Insert, Create and the new `doc_create_multiple` tool (which can also write one PDF per file). Not yet: Office/HTML/Markdown inputs, PDF Portfolios, progress for big batches, dropping onto the grid in the web build. Overall estimate unchanged (about 30–35%).
@@ -168,6 +171,8 @@ Newest first. One line per session: the date, what moved, and the new overall pe
 
 - **2026-10-09 (community, M14, #503):** Ukrainian (Українська, `uk`) adds 2,047 original catalog entries covering commands, tools, dialogs, panels, notices, history and contributor controls. Auto resolves `uk`/`uk_UA`; the manual preference persists. Integer plurals distinguish one/few/many, including 11–14 and large counts; fixed-count templates use count-neutral wording. Calendar dates use genitive month names; Home cards fit wrapped text and the search hint keeps clear of its shortcut. Coverage checks scan UI literals, and font checks use bundled Inter and JetBrains Mono, including ґ/є/і/ї. Control tests check translated Preferences, command search, error framing and language switching with unsaved documents. Overall estimate unchanged (about 30–35%).
 
+- **2026-10-09 (community, M5, #158):** Fill & Sign date format. Preferences ▸ Date format sets the pattern Fill & Sign dates use: 12 presets or any pattern in Acrobat date letters (with `\` escapes), checked and previewed as typed, remembered, and settable through `fill_sign_date_format`, `fill_sign_add` `format`/`language` and `ui set date-format`/`date-language`. Month and weekday names come in the interface languages (Czech in the genitive after a day), following the interface language unless one is picked. Fill & Sign text is still Helvetica/WinAnsi, so a date with other letters (Czech ř, Japanese, Chinese) is refused with a warning rather than saved as "?". This goes past Acrobat, whose Fill & Sign has no format setting. Overall estimate unchanged (about 30–35%).
+
 - **2026-10-09 (community, Home pinned folders):** Home gets a Folders section: File ▸ Pin folder to Home… (or "Pin a folder…" on Home) pins up to 8 folders, and each lists its newest PDFs (name, how long ago, size; 8 at first, up to 100 with Show more), one click to open, Unpin to remove. Folders are read on a worker thread and listed again every few seconds while Home shows, so new scans appear without reopening anything; a folder that can't be read (moved, offline synced drive) stays pinned and says so. Each folder is described by where it is ("iCloud Drive", "OneDrive · Contoso", "Documents › Work") rather than its full path, so two folders called "Scans" can be told apart. Cloud drives work through their local synced folder; nothing is read through a provider's API. Settings keep only absolute paths, without duplicates. Command label translated in every catalog; Home strings in French, Spanish, Japanese and both Chinese catalogs. Not yet: subfolders, search inside a pinned folder, the web build. Overall estimate unchanged (about 30–35%).
 
 - **2026-10-09 (community, M14, Telugu):** Telugu (తెలుగు, `te`) as a complete catalog of 1,984 entries covering every command, All tools entry, dialog, panel and notice; `te` and `te_IN` locales follow it. Telugu text is drawn with a craft-fonts `Telu` face (Noto Sans Telugu, storytold/craft-fonts#10), kept in the web build too, after the CJK and Arabic faces; egui shapes its conjuncts. Commands use the plain imperative and sentences the polite form. The craft-fonts revision pinned for releases has no Telugu face yet, so release builds show Telugu as replacement boxes until the pin moves. Overall estimate unchanged (about 30–35%).
diff --git a/crates/automation/src/comments.rs b/crates/automation/src/comments.rs
index ebeab2625..b7f83c2f1 100644
--- a/crates/automation/src/comments.rs
+++ b/crates/automation/src/comments.rs
@@ -419,6 +419,35 @@ impl Automation {
         Ok(out)
     }
 
+    /// Preferences ▸ Date format: set it with `format` and its names' `language` (`auto`
+    /// follows the app's interface language, so English here), or read them.
+    pub(crate) fn fill_sign_date_format(&mut self, a: &Args) -> Result<Value> {
+        use pdfcraft_engine::dates;
+        let format = a.opt_str("format")?;
+        let language = a.opt_str("language")?.map(|l| Some(l).filter(|l| !l.trim().eq_ignore_ascii_case("auto")));
+        // Check the format before changing anything, so a bad one leaves both settings alone.
+        if let Some(f) = format {
+            dates::check_date_format(f).map_err(ToolError::InvalidArgs)?;
+        }
+        if let Some(l) = language {
+            self.session.set_date_language(l).map_err(ToolError::InvalidArgs)?;
+        }
+        if let Some(f) = format {
+            self.session.set_date_format(f).map_err(ToolError::InvalidArgs)?;
+        }
+        let today = self.session.today_text(None, None).map_err(ToolError::Failed)?;
+        let languages: Vec<Value> = dates::DATE_LANGUAGES.iter().map(|l| json!({ "code": l.code, "name": l.name })).collect();
+        Ok(json!({
+            "format": self.session.date_format(),
+            "language": self.session.date_language().unwrap_or("auto"),
+            // Characters Fill & Sign can't write into a PDF yet; dates with them are refused.
+            "unwritable": dates::unwritable(&today),
+            "today": today,
+            "presets": dates::DATE_FORMATS,
+            "languages": languages,
+        }))
+    }
+
     pub(crate) fn fill_sign_add(&mut self, a: &Args) -> Result<Value> {
         use pdfcraft_engine::FillMark;
         let page = self.page(a)?;
@@ -449,8 +478,11 @@ impl Automation {
                 (text_at(&t), t)
             }
             "date" => {
-                let (yy, m, d) = self.session.today();
-                let t = format!("{m}/{d}/{yy}");
+                let lang = a.opt_str("language")?;
+                if let Some(l) = lang.filter(|l| pdfcraft_engine::dates::date_language(l).is_none()) {
+                    return Err(ToolError::InvalidArgs(format!("unknown date language {l:?} (see fill_sign_date_format)")));
+                }
+                let t = self.session.today_text_for_pdf(a.opt_str("format")?, lang).map_err(ToolError::InvalidArgs)?;
                 (text_at(&t), t)
             }
             // A typed signature or initials in the script font, left edge at `at`, upright as displayed.
diff --git a/crates/automation/src/lib.rs b/crates/automation/src/lib.rs
index 0315f58c2..b3999c078 100644
--- a/crates/automation/src/lib.rs
+++ b/crates/automation/src/lib.rs
@@ -530,6 +530,7 @@ impl Automation {
             "doc_print" => self.doc_print(&a)?,
             "doc_remove_hidden" => self.doc_remove_hidden(&a)?,
             "fill_sign_add" => self.fill_sign_add(&a)?,
+            "fill_sign_date_format" => self.fill_sign_date_format(&a)?,
             "measure_distance" => self.measurement_add(&a, pdfcraft_engine::measure::Kind::Distance)?,
             "measure_perimeter" => self.measurement_add(&a, pdfcraft_engine::measure::Kind::Perimeter)?,
             "measure_area" => self.measurement_add(&a, pdfcraft_engine::measure::Kind::Area)?,
diff --git a/crates/automation/src/tools.rs b/crates/automation/src/tools.rs
index 92f42e72f..74eb2bbb6 100644
--- a/crates/automation/src/tools.rs
+++ b/crates/automation/src/tools.rs
@@ -915,7 +915,7 @@ pub fn tools() -> Vec<ToolDef> {
         t(
             "fill_sign_add",
             "Fill & Sign: type text or place a mark",
-            "Fill in a form that has no fields, as Acrobat's Fill & Sign does: type text (`text`, 10 pt), place a check, cross, dot or line, today's date, or a signature or initials (either `text` drawn in a script font, or `path` to a local PNG/JPEG image up to 4 MiB and 4 megapixels, preserving transparency). `at` [x, y] is in points from the top-left of the page: text's top-left, mark's centre, signature's left edge centred vertically. Image signatures fit within 150 pt wide and 32 pt tall (24 pt for initials). Creates movable, undoable annotations.",
+            "Fill in a form that has no fields, as Acrobat's Fill & Sign does: type text (`text`, 10 pt), place a check, cross, dot or line, today's date (in Preferences ▸ Date format, see fill_sign_date_format, or `format`), or a signature or initials (either `text` drawn in a script font, or `path` to a local PNG/JPEG image up to 4 MiB and 4 megapixels, preserving transparency). `at` [x, y] is in points from the top-left of the page: text's top-left, mark's centre, signature's left edge centred vertically. Image signatures fit within 150 pt wide and 32 pt tall (24 pt for initials). Creates movable, undoable annotations.",
         )
         .cmd("sign.fill.text")
         .with(schema(
@@ -926,10 +926,14 @@ pub fn tools() -> Vec<ToolDef> {
                 "at": point(),
                 "text": { "type": "string", "minLength": 1 },
                 "path": { "type": "string", "description": "PNG or JPEG for signature/initials; pass either path or text." },
+                "format": { "type": "string", "description": "For type date: this pattern instead of the date-format preference, e.g. \"dd.mm.yyyy\"." },
+                "language": { "type": "string", "description": "For type date: month and weekday names in this language code (see fill_sign_date_format) instead of the preference." },
                 "author": { "type": "string" },
             }),
             &["doc", "page", "type", "at"],
         )),
+        t("fill_sign_date_format", "Date format for Fill & Sign", "Preferences ▸ Date format: the pattern Fill & Sign dates use (default m/d/yyyy). Set it with `format` (Acrobat date codes yyyy yy mmmm mmm mm m dddd ddd dd d, other runs of y, m or d are refused; H h M s t are time letters and need \\ before them; \\ shows the next character as is), or read it. `language` sets the language of month and weekday names (a code from `languages`, or `auto` to follow the app's interface language; English headless). Returns the format, the language, today in them, `unwritable` (characters of today's date that Fill & Sign can't write into a PDF yet, Western European only; fill_sign_add refuses such a date), the ready-made presets and the languages.")
+            .with(schema(json!({ "format": { "type": "string", "minLength": 1, "maxLength": 64 }, "language": { "type": "string" } }), &[])),
         t(
             "doc_create",
             "Create a PDF",
diff --git a/crates/automation/tests/automation.rs b/crates/automation/tests/automation.rs
index f42cbb6fd..a3ba9976b 100644
--- a/crates/automation/tests/automation.rs
+++ b/crates/automation/tests/automation.rs
@@ -1375,8 +1375,44 @@ fn fill_and_sign_through_tools() {
     ));
     let texts = page_text(&mut a, doc);
     assert!(texts[0].contains("Ada Lovelace") && texts[0].contains("11/14/2023"), "{texts:?}");
+    // Preferences ▸ Date format, and a one-off pattern.
+    let f = ok(&mut a, "fill_sign_date_format", json!({}));
+    assert_eq!((f["format"].as_str(), f["today"].as_str()), (Some("m/d/yyyy"), Some("11/14/2023")), "{f}");
+    assert_eq!(ok(&mut a, "fill_sign_date_format", json!({ "format": "yyyy.mm.dd." }))["today"], "2023.11.14.");
+    ok(&mut a, "fill_sign_add", json!({ "doc": doc, "page": 1, "type": "date", "at": [20, 220] }));
+    ok(&mut a, "fill_sign_add", json!({ "doc": doc, "page": 1, "type": "date", "at": [20, 240], "format": "d \\de mmmm" }));
+    let texts = page_text(&mut a, doc);
+    assert!(texts[0].contains("2023.11.14.") && texts[0].contains("14 de November"), "{texts:?}");
+    assert!(matches!(a.call("fill_sign_date_format", &json!({ "format": "HH:MM" })), Err(ToolError::InvalidArgs(_))));
+    assert_eq!(ok(&mut a, "fill_sign_date_format", json!({}))["format"], "yyyy.mm.dd.", "a rejected format keeps the previous one");
+    // Month and weekday names in a chosen language, for the preference or one date.
+    let f = ok(&mut a, "fill_sign_date_format", json!({ "format": "d. mmmm yyyy", "language": "cs" }));
+    assert_eq!((f["language"].as_str(), f["today"].as_str()), (Some("cs"), Some("14. listopadu 2023")), "{f}");
+    assert_eq!(f["languages"].as_array().unwrap().len(), pdfcraft_engine::dates::DATE_LANGUAGES.len(), "every date language");
+    ok(&mut a, "fill_sign_add", json!({ "doc": doc, "page": 1, "type": "date", "at": [20, 280], "format": "d \\de mmmm", "language": "es" }));
+    assert!(page_text(&mut a, doc)[0].contains("14 de noviembre"));
+    assert!(matches!(a.call("fill_sign_date_format", &json!({ "format": "yyy" })), Err(ToolError::InvalidArgs(_))));
+    // A date the PDF's text font can't hold is refused, not saved as "?".
+    match a.call("fill_sign_add", &json!({ "doc": doc, "page": 1, "type": "date", "at": [20, 300], "format": "dddd", "language": "ja" })) {
+        Err(ToolError::InvalidArgs(e)) => assert!(e.contains("火曜日") && e.contains("can't be written into the PDF yet"), "{e}"),
+        other => panic!("expected a refusal, got {other:?}"),
+    }
+    let f = ok(&mut a, "fill_sign_date_format", json!({ "format": "dddd", "language": "ja" }));
+    assert_eq!((f["today"].as_str(), f["unwritable"].as_str()), (Some("火曜日"), Some("火曜日")));
+    ok(&mut a, "fill_sign_date_format", json!({ "format": "d. mmmm yyyy", "language": "cs" }));
+    assert!(matches!(a.call("fill_sign_date_format", &json!({ "format": "dd", "language": "xx" })), Err(ToolError::InvalidArgs(_))));
+    assert!(matches!(
+        a.call("fill_sign_add", &json!({ "doc": doc, "page": 1, "type": "date", "at": [20, 300], "language": "xx" })),
+        Err(ToolError::InvalidArgs(_))
+    ));
+    let f = ok(&mut a, "fill_sign_date_format", json!({ "language": "auto" }));
+    assert_eq!((f["format"].as_str(), f["language"].as_str(), f["today"].as_str()), (Some("d. mmmm yyyy"), Some("auto"), Some("14. November 2023")));
+    assert!(matches!(
+        a.call("fill_sign_add", &json!({ "doc": doc, "page": 1, "type": "date", "at": [20, 260], "format": "Year" })),
+        Err(ToolError::InvalidArgs(_))
+    ));
     let list = ok(&mut a, "comment_list", json!({ "doc": doc }));
-    assert_eq!(list["count"], 4);
+    assert_eq!(list["count"], 7);
     assert!(matches!(a.call("fill_sign_add", &json!({ "doc": doc, "page": 1, "type": "text", "at": [1, 1] })), Err(ToolError::InvalidArgs(_))));
 }
 
diff --git a/crates/engine/src/dates.rs b/crates/engine/src/dates.rs
new file mode 100644
index 000000000..fab1b5dbb
--- /dev/null
+++ b/crates/engine/src/dates.rs
@@ -0,0 +1,550 @@
+//! The date format Fill & Sign stamps (Preferences ▸ Date format), kept on the [`Session`] so
+//! the app and the automation tools write the same text. Acrobat's Fill & Sign has no such
+//! setting (only Acrobat Sign's account settings do); this one is per user and takes any
+//! pattern in Acrobat's date letters, not just a fixed list, with month and weekday names in
+//! any of [`DATE_LANGUAGES`].
+//!
+//! Patterns use `util.printd`'s date letters: `yyyy` `yy`, `mmmm` `mmm` `mm` `m`, `dddd` `ddd`
+//! `dd` `d`. `\` shows the next character as is (`d \de mmmm` → `8 de October`).
+
+use crate::Session;
+
+/// The format until the user picks one (Acrobat's: US month/day/year).
+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] = [
+    "m/d/yyyy",
+    "mm/dd/yyyy",
+    "d/m/yyyy",
+    "dd/mm/yyyy",
+    "dd.mm.yyyy",
+    "yyyy-mm-dd",
+    "yyyy.mm.dd.",
+    "d mmm yyyy",
+    "d mmmm yyyy",
+    "mmm d, yyyy",
+    "mmmm d, yyyy",
+    "dddd, mmmm d, yyyy",
+];
+
+/// The longest pattern kept (settings and tool arguments are untrusted).
+pub const MAX_DATE_FORMAT_CHARS: usize = 64;
+
+/// Month and weekday names in one language. Weekdays start on Sunday.
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct DateLanguage {
+    /// The interface-language code where there is one (`en`, `cs`, `pt-br`, `zh-hans`, …).
+    pub code: &'static str,
+    /// Its name in itself, for pickers.
+    pub name: &'static str,
+    pub months: [&'static str; 12],
+    /// The month after a day number (`mmmm` when the pattern also shows `d` or `dd`), where
+    /// the language changes it: Czech `8. října`, Russian `8 октября`.
+    pub months_with_day: Option<[&'static str; 12]>,
+    pub months_short: [&'static str; 12],
+    pub days: [&'static str; 7],
+    pub days_short: [&'static str; 7],
+}
+
+const CJK_MONTHS: [&str; 12] = ["1月", "2月", "3月", "4月", "5月", "6月", "7月", "8月", "9月", "10月", "11月", "12月"];
+const ZH_MONTHS: [&str; 12] = ["一月", "二月", "三月", "四月", "五月", "六月", "七月", "八月", "九月", "十月", "十一月", "十二月"];
+const ZH_DAYS: [&str; 7] = ["星期日", "星期一", "星期二", "星期三", "星期四", "星期五", "星期六"];
+
+/// The languages month and weekday names can be written in (Preferences ▸ Date format ▸ Language):
+/// the interface languages, in the same order and with the same names.
+pub const DATE_LANGUAGES: [DateLanguage; 14] = [
+    DateLanguage {
+        code: "en",
+        name: "English",
+        months: ["January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"],
+        months_with_day: None,
+        months_short: ["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"],
+        days: ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"],
+        days_short: ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"],
+    },
+    DateLanguage {
+        code: "ja",
+        name: "日本語",
+        months: CJK_MONTHS,
+        months_with_day: None,
+        months_short: CJK_MONTHS,
+        days: ["日曜日", "月曜日", "火曜日", "水曜日", "木曜日", "金曜日", "土曜日"],
+        days_short: ["日", "月", "火", "水", "木", "金", "土"],
+    },
+    DateLanguage {
+        code: "zh-hans",
+        name: "简体中文",
+        months: ZH_MONTHS,
+        months_with_day: None,
+        months_short: CJK_MONTHS,
+        days: ZH_DAYS,
+        days_short: ["周日", "周一", "周二", "周三", "周四", "周五", "周六"],
+    },
+    DateLanguage {
+        code: "zh-hant",
+        name: "繁體中文",
+        months: ZH_MONTHS,
+        months_with_day: None,
+        months_short: CJK_MONTHS,
+        days: ZH_DAYS,
+        days_short: ["週日", "週一", "週二", "週三", "週四", "週五", "週六"],
+    },
+    DateLanguage {
+        code: "cs",
+        name: "Čeština",
+        months: ["leden", "únor", "březen", "duben", "květen", "červen", "červenec", "srpen", "září", "říjen", "listopad", "prosinec"],
+        months_with_day: Some([
+            "ledna",
+            "února",
+            "března",
+            "dubna",
+            "května",
+            "června",
+            "července",
+            "srpna",
+            "září",
+            "října",
+            "listopadu",
+            "prosince",
+        ]),
+        months_short: ["led", "úno", "bře", "dub", "kvě", "čvn", "čvc", "srp", "zář", "říj", "lis", "pro"],
+        days: ["neděle", "pondělí", "úterý", "středa", "čtvrtek", "pátek", "sobota"],
+        days_short: ["ne", "po", "út", "st", "čt", "pá", "so"],
+    },
+    DateLanguage {
+        code: "pt-br",
+        name: "Português (Brasil)",
+        months: ["janeiro", "fevereiro", "março", "abril", "maio", "junho", "julho", "agosto", "setembro", "outubro", "novembro", "dezembro"],
+        months_with_day: None,
+        months_short: ["jan", "fev", "mar", "abr", "mai", "jun", "jul", "ago", "set", "out", "nov", "dez"],
+        days: ["domingo", "segunda-feira", "terça-feira", "quarta-feira", "quinta-feira", "sexta-feira", "sábado"],
+        days_short: ["dom", "seg", "ter", "qua", "qui", "sex", "sáb"],
+    },
+    DateLanguage {
+        code: "de",
+        name: "Deutsch",
+        months: ["Januar", "Februar", "März", "April", "Mai", "Juni", "Juli", "August", "September", "Oktober", "November", "Dezember"],
+        months_with_day: None,
+        months_short: ["Jan.", "Feb.", "März", "Apr.", "Mai", "Juni", "Juli", "Aug.", "Sept.", "Okt.", "Nov.", "Dez."],
+        days: ["Sonntag", "Montag", "Dienstag", "Mittwoch", "Donnerstag", "Freitag", "Samstag"],
+        days_short: ["So.", "Mo.", "Di.", "Mi.", "Do.", "Fr.", "Sa."],
+    },
+    DateLanguage {
+        code: "es",
+        name: "Español",
+        months: ["enero", "febrero", "marzo", "abril", "mayo", "junio", "julio", "agosto", "septiembre", "octubre", "noviembre", "diciembre"],
+        months_with_day: None,
+        months_short: ["ene", "feb", "mar", "abr", "may", "jun", "jul", "ago", "sept", "oct", "nov", "dic"],
+        days: ["domingo", "lunes", "martes", "miércoles", "jueves", "viernes", "sábado"],
+        days_short: ["dom", "lun", "mar", "mié", "jue", "vie", "sáb"],
+    },
+    DateLanguage {
+        code: "fr",
+        name: "Français",
+        months: ["janvier", "février", "mars", "avril", "mai", "juin", "juillet", "août", "septembre", "octobre", "novembre", "décembre"],
+        months_with_day: None,
+        months_short: ["janv.", "févr.", "mars", "avr.", "mai", "juin", "juil.", "août", "sept.", "oct.", "nov.", "déc."],
+        days: ["dimanche", "lundi", "mardi", "mercredi", "jeudi", "vendredi", "samedi"],
+        days_short: ["dim.", "lun.", "mar.", "mer.", "jeu.", "ven.", "sam."],
+    },
+    DateLanguage {
+        code: "ru",
+        name: "Русский",
+        months: ["январь", "февраль", "март", "апрель", "май", "июнь", "июль", "август", "сентябрь", "октябрь", "ноябрь", "декабрь"],
+        months_with_day: Some(["января", "февраля", "марта", "апреля", "мая", "июня", "июля", "августа", "сентября", "октября", "ноября", "декабря"]),
+        months_short: ["янв.", "февр.", "март", "апр.", "май", "июнь", "июль", "авг.", "сент.", "окт.", "нояб.", "дек."],
+        days: ["воскресенье", "понедельник", "вторник", "среда", "четверг", "пятница", "суббота"],
+        days_short: ["вс", "пн", "вт", "ср", "чт", "пт", "сб"],
+    },
+    DateLanguage {
+        code: "bg",
+        name: "Български",
+        months: ["януари", "февруари", "март", "април", "май", "юни", "юли", "август", "септември", "октомври", "ноември", "декември"],
+        months_with_day: None,
+        months_short: ["яну", "фев", "март", "апр", "май", "юни", "юли", "авг", "сеп", "окт", "ное", "дек"],
+        days: ["неделя", "понеделник", "вторник", "сряда", "четвъртък", "петък", "събота"],
+        days_short: ["нд", "пн", "вт", "ср", "чт", "пт", "сб"],
+    },
+    DateLanguage {
+        code: "te",
+        name: "తెలుగు",
+        months: ["జనవరి", "ఫిబ్రవరి", "మార్చి", "ఏప్రిల్", "మే", "జూన్", "జులై", "ఆగస్టు", "సెప్టెంబర్", "అక్టోబర్", "నవంబర్", "డిసెంబర్"],
+        months_with_day: None,
+        months_short: ["జన", "ఫిబ్ర", "మార్చి", "ఏప్రి", "మే", "జూన్", "జులై", "ఆగ", "సెప్టెం", "అక్టో", "నవం", "డిసెం"],
+        days: ["ఆదివారం", "సోమవారం", "మంగళవారం", "బుధవారం", "గురువారం", "శుక్రవారం", "శనివారం"],
+        days_short: ["ఆది", "సోమ", "మంగళ", "బుధ", "గురు", "శుక్ర", "శని"],
+    },
+    DateLanguage {
+        code: "hu",
+        name: "Magyar",
+        months: [
+            "január",
+            "február",
+            "március",
+            "április",
+            "május",
+            "június",
+            "július",
+            "augusztus",
+            "szeptember",
+            "október",
+            "november",
+            "december",
+        ],
+        months_with_day: None,
+        months_short: ["jan.", "febr.", "márc.", "ápr.", "máj.", "jún.", "júl.", "aug.", "szept.", "okt.", "nov.", "dec."],
+        days: ["vasárnap", "hétfő", "kedd", "szerda", "csütörtök", "péntek", "szombat"],
+        days_short: ["V", "H", "K", "Sze", "Cs", "P", "Szo"],
+    },
+    DateLanguage {
+        code: "uk",
+        name: "Українська",
+        months: ["січень", "лютий", "березень", "квітень", "травень", "червень", "липень", "серпень", "вересень", "жовтень", "листопад", "грудень"],
+        months_with_day: Some([
+            "січня",
+            "лютого",
+            "березня",
+            "квітня",
+            "травня",
+            "червня",
+            "липня",
+            "серпня",
+            "вересня",
+            "жовтня",
+            "листопада",
+            "грудня",
+        ]),
+        months_short: ["січ.", "лют.", "бер.", "квіт.", "трав.", "черв.", "лип.", "серп.", "вер.", "жовт.", "лист.", "груд."],
+        days: ["неділя", "понеділок", "вівторок", "середа", "четвер", "пʼятниця", "субота"],
+        days_short: ["нд", "пн", "вт", "ср", "чт", "пт", "сб"],
+    },
+];
+
+/// The date language for `code` (any case), or `None` when there's none.
+pub fn date_language(code: &str) -> Option<&'static DateLanguage> {
+    DATE_LANGUAGES.iter().find(|l| l.code.eq_ignore_ascii_case(code.trim()))
+}
+
+/// The characters of `text` that Fill & Sign can't write into a PDF yet, each once. Its text is
+/// drawn in Helvetica with WinAnsi encoding (Western European letters), so anything else (`ř`,
+/// Japanese, Chinese) would become `?` in the file.
+pub fn unwritable(text: &str) -> String {
+    let mut out = String::new();
+    for c in text.chars() {
+        let mut buf = [0u8; 4];
+        if c != '?' && pdfcraft_fonts::win_ansi(c.encode_utf8(&mut buf)) == b"?" && !out.contains(c) {
+            out.push(c);
+        }
+    }
+    out
+}
+
+/// `fmt` trimmed, when it's a usable date pattern: not too long, showing at least a year,
+/// month or day, and no time letters (`H h M s t`) unless escaped with `\`.
+pub fn check_date_format(fmt: &str) -> Result<&str, String> {
+    let fmt = fmt.trim();
+    if fmt.is_empty() {
+        return Err("the date format is empty".into());
+    }
+    if fmt.chars().count() > MAX_DATE_FORMAT_CHARS {
+        return Err(format!("the date format is longer than {MAX_DATE_FORMAT_CHARS} characters"));
+    }
+    let letters: String = unescaped(fmt).filter_map(|(c, escaped)| (!escaped).then_some(c)).collect();
+    if let Some(c) = letters.chars().find(|c| matches!(c, 'H' | 'h' | 'M' | 's' | 't')) {
+        return Err(format!("`{c}` is a time letter (H h M s t); put \\ before it to show it as is"));
+    }
+    if !letters.chars().any(|c| matches!(c, 'y' | 'm' | 'd')) {
+        return Err("the date format shows no year (y), month (m) or day (d)".into());
+    }
+    // Only whole codes: `yyy` or `mmmmm` would silently show something else.
+    for (c, n, _) in runs(fmt).into_iter().filter(|r| !r.2) {
+        let fits = match c {
+            'y' => n == 2 || n == 4,
+            'm' | 'd' => (1..=4).contains(&n),
+            _ => true,
+        };
+        if !fits {
+            let code: String = std::iter::repeat_n(c, n).collect();
+            let use_ = match c {
+                'y' => "yy or yyyy",
+                'm' => "m, mm, mmm or mmmm",
+                _ => "d, dd, ddd or dddd",
+            };
+            return Err(format!("`{code}` is not a date code; use {use_}"));
+        }
+    }
+    Ok(fmt)
+}
+
+/// `fmt` as runs of the same character with whether it's escaped: `dd.\mm` → (`d`, 2, no),
+/// (`.`, 1, no), (`m`, 1, yes), (`m`, 1, no). Escaped characters are never grouped.
+fn runs(fmt: &str) -> Vec<(char, usize, bool)> {
+    let mut runs: Vec<(char, usize, bool)> = Vec::new();
+    for (c, escaped) in unescaped(fmt) {
+        match runs.last_mut() {
+            Some((last, n, false)) if !escaped && *last == c => *n += 1,
+            _ => runs.push((c, 1, escaped)),
+        }
+    }
+    runs
+}
+
+/// The day `(year, month, day)` written in `fmt` with `lang`'s names. Anything but the date
+/// letters is copied as is; a month or day out of range shows as its number.
+pub fn format_day(fmt: &str, (y, m, d): (i64, u32, u32), lang: &DateLanguage) -> String {
+    let runs = runs(fmt);
+    let with_day = runs.iter().any(|&(c, n, escaped)| !escaped && c == 'd' && n <= 2);
+    let month = (m as usize).checked_sub(1);
+    let weekday = weekday(y, m, d);
+    let mut out = String::new();
+    for (c, n, escaped) in runs {
+        match (c, n) {
+            _ if escaped => out.push(c),
+            ('y', 4..) => out.push_str(&format!("{:04}", y.clamp(0, 9999))),
+            ('y', _) => out.push_str(&format!("{:02}", y.rem_euclid(100))),
+            ('m', 3..) => {
+                let names = if n >= 4 { lang.months_with_day.filter(|_| with_day).unwrap_or(lang.months) } else { lang.months_short };
+                match month.and_then(|i| names.get(i)) {
+                    Some(name) => out.push_str(name),
+                    None => out.push_str(&m.to_string()),
+                }
+            }
+            ('m', 2) => out.push_str(&format!("{m:02}")),
+            ('m', _) => out.push_str(&m.to_string()),
+            ('d', 3..) => {
+                let names = if n >= 4 { lang.days } else { lang.days_short };
+                match weekday.and_then(|w| names.get(w)) {
+                    Some(name) => out.push_str(name),
+                    None => out.push_str(&d.to_string()),
+                }
+            }
+            ('d', 2) => out.push_str(&format!("{d:02}")),
+            ('d', _) => out.push_str(&d.to_string()),
+            _ => out.extend(std::iter::repeat_n(c, n)),
+        }
+    }
+    out
+}
+
+/// The weekday (0 = Sunday) of a Gregorian date in years 1–9999, or `None` for an invalid one.
+fn weekday(y: i64, m: u32, d: u32) -> Option<usize> {
+    const T: [i64; 12] = [0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4];
+    if !(1..=9999).contains(&y) || !(1..=31).contains(&d) {
+        return None;
+    }
+    let t = *T.get((m as usize).checked_sub(1)?)?;
+    let y = y - i64::from(m < 3);
+    Some((y + y / 4 - y / 100 + y / 400 + t + i64::from(d)).rem_euclid(7) as usize)
+}
+
+/// The characters of `fmt`, each with whether a `\` before it makes it literal.
+fn unescaped(fmt: &str) -> impl Iterator<Item = (char, bool)> + '_ {
+    let mut chars = fmt.chars();
+    std::iter::from_fn(move || match chars.next()? {
+        '\\' => Some(chars.next().map_or(('\\', true), |c| (c, true))),
+        c => Some((c, false)),
+    })
+}
+
+impl Session {
+    /// Preferences ▸ Date format: the pattern Fill & Sign dates use. Rejects unusable patterns
+    /// (see [`check_date_format`]) and keeps the previous one.
+    pub fn set_date_format(&mut self, fmt: &str) -> Result<(), String> {
+        let fmt = check_date_format(fmt)?;
+        self.date_format = (fmt != DEFAULT_DATE_FORMAT).then(|| fmt.to_string());
+        Ok(())
+    }
+
+    pub fn date_format(&self) -> &str {
+        self.date_format.as_deref().unwrap_or(DEFAULT_DATE_FORMAT)
+    }
+
+    /// Preferences ▸ Date format ▸ Language: the language of month and weekday names, or
+    /// `None` to follow the interface language. Rejects codes not in [`DATE_LANGUAGES`].
+    pub fn set_date_language(&mut self, code: Option<&str>) -> Result<(), String> {
+        self.date_language = match code {
+            None => None,
+            Some(c) => Some(date_language(c).map(|l| l.code.to_string()).ok_or_else(|| {
+                let codes: Vec<&str> = DATE_LANGUAGES.iter().map(|l| l.code).collect();
+                format!("unknown date language {c:?} (use one of {})", codes.join(", "))
+            })?),
+        };
+        Ok(())
+    }
+
+    pub fn date_language(&self) -> Option<&str> {
+        self.date_language.as_deref()
+    }
+
+    /// Today's local date in `fmt` (or the session's date format) with the names of `lang`
+    /// (or the session's date language; English when neither is set or known).
+    pub fn today_text(&self, fmt: Option<&str>, lang: Option<&str>) -> Result<String, String> {
+        let fmt = match fmt {
+            Some(f) => check_date_format(f)?,
+            None => self.date_format(),
+        };
+        let lang = lang.or(self.date_language()).and_then(date_language).unwrap_or(&DATE_LANGUAGES[0]);
+        Ok(format_day(fmt, self.today(), lang))
+    }
+
+    /// [`Session::today_text`] for writing into a PDF: refused when the date has characters
+    /// Fill & Sign can't write yet (see [`unwritable`]), rather than saving them as `?`.
+    pub fn today_text_for_pdf(&self, fmt: Option<&str>, lang: Option<&str>) -> Result<String, String> {
+        let text = self.today_text(fmt, lang)?;
+        match unwritable(&text) {
+            bad if bad.is_empty() => Ok(text),
+            bad => Err(format!(
+                "\"{text}\" can't be written into the PDF yet: Fill & Sign text is Western European only ({bad}); pick a numeric format such as dd.mm.yyyy"
+            )),
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const DAY: (i64, u32, u32) = (2026, 3, 7);
+    const EN: &DateLanguage = &DATE_LANGUAGES[0];
+
+    fn in_lang(fmt: &str, code: &str) -> String {
+        format_day(fmt, DAY, date_language(code).unwrap())
+    }
+
+    #[test]
+    fn presets_write_the_day_in_their_own_order() {
+        let shown: Vec<String> = DATE_FORMATS.iter().map(|f| format_day(f, DAY, EN)).collect();
+        assert_eq!(
+            shown,
+            [
+                "3/7/2026",
+                "03/07/2026",
+                "7/3/2026",
+                "07/03/2026",
+                "07.03.2026",
+                "2026-03-07",
+                "2026.03.07.",
+                "7 Mar 2026",
+                "7 March 2026",
+                "Mar 7, 2026",
+                "March 7, 2026",
+                "Saturday, March 7, 2026",
+            ]
+        );
+        assert!(DATE_FORMATS.iter().all(|f| check_date_format(f).is_ok()));
+        assert_eq!(DATE_FORMATS[0], DEFAULT_DATE_FORMAT);
+    }
+
+    #[test]
+    fn escaped_letters_are_shown_as_is() {
+        assert_eq!(format_day("d \\de mmmm \\de yyyy", DAY, EN), "7 de March de 2026");
+        assert_eq!(format_day("yyyy\\", DAY, EN), "2026\\");
+        assert_eq!(check_date_format("d \\de mmmm"), Ok("d \\de mmmm"));
+    }
+
+    #[test]
+    fn unusable_patterns_are_rejected() {
+        assert!(check_date_format("   ").is_err());
+        assert!(check_date_format("Date: dd/mm").unwrap_err().contains("`t`"));
+        assert!(check_date_format("mm/dd HH:MM").is_err());
+        assert!(check_date_format("Year").is_err(), "no date letters");
+        assert!(check_date_format(&"d".repeat(MAX_DATE_FORMAT_CHARS + 1)).is_err());
+        assert_eq!(check_date_format("  yyyy-mm-dd "), Ok("yyyy-mm-dd"));
+    }
+
+    #[test]
+    fn only_whole_date_codes_are_accepted() {
+        for (fmt, code) in [("yyyyyyyy", "`yyyyyyyy`"), ("yyy", "`yyy`"), ("d/m/y", "`y`"), ("mmmmm d", "`mmmmm`"), ("ddddd", "`ddddd`")] {
+            let e = check_date_format(fmt).unwrap_err();
+            assert!(e.contains(code) && e.contains("is not a date code"), "{fmt}: {e}");
+        }
+        for fmt in ["yy", "yyyy", "m", "mm", "mmm", "mmmm", "d", "dd", "ddd", "dddd", r"\y\y\y yyyy"] {
+            assert!(check_date_format(fmt).is_ok(), "{fmt}");
+        }
+    }
+
+    #[test]
+    fn hostile_days_and_patterns_do_not_panic() {
+        for fmt in ["mmmm", "mmm", "dddd", "ddd", "\\", "yyyyyyyyy", "é d ü", "d. mmmm"] {
+            for day in [(i64::MAX, u32::MAX, u32::MAX), (i64::MIN, 0, 0), (2026, 13, 40), (0, 2, 29)] {
+                for lang in &DATE_LANGUAGES {
+                    let _ = format_day(fmt, day, lang);
+                }
+            }
+        }
+        assert_eq!(format_day("mmmm dddd", (2026, 13, 40), EN), "13 40", "out of range shows numbers");
+    }
+
+    #[test]
+    fn the_session_stamps_today_in_its_format() {
+        // 2023-11-14 (UTC) on the injected clock.
+        let mut s = Session::new().with_clock(|| 1_700_000_000);
+        assert_eq!(s.date_format(), DEFAULT_DATE_FORMAT);
+        assert_eq!(s.today_text(None, None).as_deref(), Ok("11/14/2023"));
+        s.set_date_format("dd.mm.yyyy").unwrap();
+        assert_eq!(s.today_text(None, None).as_deref(), Ok("14.11.2023"));
+        assert_eq!(s.today_text(Some("yyyy-mm-dd"), None).as_deref(), Ok("2023-11-14"));
+        assert!(s.today_text(Some("HH"), None).is_err());
+        assert!(s.set_date_format("nothing").is_err());
+        assert_eq!(s.date_format(), "dd.mm.yyyy", "a rejected pattern keeps the previous one");
+    }
+
+    #[test]
+    fn names_follow_the_date_language() {
+        assert_eq!(in_lang("dddd, d \\de mmmm \\de yyyy", "es"), "sábado, 7 de marzo de 2026");
+        assert_eq!(in_lang("ddd d mmm", "pt-br"), "sáb 7 mar");
+        assert_eq!(in_lang("dddd d mmmm yyyy", "fr"), "samedi 7 mars 2026");
+        assert_eq!(in_lang("dddd, d mmmm", "te"), "శనివారం, 7 మార్చి");
+        assert_eq!(in_lang("yyyy\\年mmmmd\\日 dddd", "ja"), "2026年3月7日 土曜日");
+        assert_eq!(in_lang("yyyy\\年mmmmd\\日 dddd", "zh-hans"), "2026年三月7日 星期六");
+        assert_eq!(in_lang("ddd", "zh-hant"), "週六");
+        assert_eq!(date_language("PT-BR").map(|l| l.code), Some("pt-br"));
+        assert!(date_language("xx").is_none());
+        for l in &DATE_LANGUAGES {
+            assert!(l.months.iter().chain(&l.months_short).chain(&l.days).chain(&l.days_short).all(|n| !n.is_empty()), "{}", l.code);
+        }
+    }
+
+    #[test]
+    fn czech_and_russian_months_change_after_a_day() {
+        assert_eq!(in_lang("d. mmmm yyyy", "cs"), "7. března 2026");
+        assert_eq!(in_lang("mmmm yyyy", "cs"), "březen 2026");
+        assert_eq!(in_lang("d mmmm yyyy", "ru"), "7 марта 2026");
+        assert_eq!(in_lang("mmmm yyyy", "ru"), "март 2026");
+        // A weekday (dddd) is not a day number.
+        assert_eq!(in_lang("dddd, mmmm", "cs"), "sobota, březen");
+    }
+
+    #[test]
+    fn the_session_writes_names_in_its_date_language() {
+        let mut s = Session::new().with_clock(|| 1_700_000_000);
+        s.set_date_format("dddd d mmmm").unwrap();
+        assert_eq!(s.today_text(None, None).as_deref(), Ok("Tuesday 14 November"), "English by default");
+        assert_eq!(s.today_text(None, Some("es")).as_deref(), Ok("martes 14 noviembre"), "a caller's language");
+        s.set_date_language(Some("PT-BR")).unwrap();
+        assert_eq!(s.date_language(), Some("pt-br"));
+        assert_eq!(s.today_text(None, None).as_deref(), Ok("terça-feira 14 novembro"));
+        assert_eq!(s.today_text(Some("d mmmm"), Some("uk")).as_deref(), Ok("14 листопада"), "Ukrainian months after a day");
+        assert_eq!(s.today_text(Some("dddd d mmmm"), Some("de")).as_deref(), Ok("Dienstag 14 November"));
+        assert!(s.set_date_language(Some("it")).unwrap_err().contains("zh-hant"), "only the interface languages");
+        assert_eq!(s.date_language(), Some("pt-br"), "an unknown language keeps the previous one");
+        s.set_date_language(None).unwrap();
+        assert_eq!(s.date_language(), None);
+    }
+
+    #[test]
+    fn dates_the_pdf_cannot_hold_are_refused_not_damaged() {
+        assert_eq!(unwritable("8. října 2026"), "ř");
+        assert_eq!(unwritable("2026年10月8日"), "年月日");
+        assert_eq!(unwritable("sábado, 7 de março – 2026?"), "", "Western European, dashes and ? are fine");
+        let mut s = Session::new().with_clock(|| 1_700_000_000);
+        s.set_date_format("d. mmmm yyyy").unwrap();
+        assert_eq!(s.today_text_for_pdf(None, Some("es")).as_deref(), Ok("14. noviembre 2023"));
+        assert_eq!(s.today_text_for_pdf(None, Some("cs")).as_deref(), Ok("14. listopadu 2023"), "no letter outside WinAnsi");
+        let e = s.today_text_for_pdf(Some("dddd"), Some("ja")).unwrap_err();
+        assert!(e.contains("火曜日") && e.contains("can't be written into the PDF yet"), "{e}");
+        assert!(s.today_text_for_pdf(Some("dd.mm.yyyy"), Some("ja")).is_ok(), "numbers are fine in any language");
+        assert!(s.today_text_for_pdf(Some("yyyy\\年mm\\月"), Some("ja")).unwrap_err().contains("年月"));
+    }
+}
diff --git a/crates/engine/src/lib.rs b/crates/engine/src/lib.rs
index fbd92be35..cbffb07ae 100644
--- a/crates/engine/src/lib.rs
+++ b/crates/engine/src/lib.rs
@@ -16,6 +16,7 @@ pub mod actions;
 pub mod catalog;
 pub mod commands;
 pub mod compare;
+pub mod dates;
 pub mod export;
 pub mod js;
 pub mod links;
@@ -1898,6 +1899,10 @@ pub struct Session {
     trust: Arc<TrustStore>,
     /// Preferences ▸ JavaScript ▸ Enable Acrobat JavaScript, inverted (on by default).
     js_off: bool,
+    /// Preferences ▸ Date format, when not the default (see [`dates`]).
+    date_format: Option<String>,
+    /// Preferences ▸ Date format ▸ Language, when not following the interface language.
+    date_language: Option<String>,
 }
 
 /// Lay a dynamic XFA form out (pages and fields) and give its widgets appearances.
diff --git a/crates/ui-egui/src/canvas.rs b/crates/ui-egui/src/canvas.rs
index d0f6e9536..504a613a6 100644
--- a/crates/ui-egui/src/canvas.rs
+++ b/crates/ui-egui/src/canvas.rs
@@ -1535,6 +1535,9 @@ pub fn document_area(app: &mut PdfCraftApp, index: usize, ui: &mut egui::Ui) {
     let mut open_initials = false;
     let author = app.comment_prefs.author.clone();
     let today = app.session.today();
+    // In Preferences ▸ Date format, or why it can't be stamped into the PDF.
+    let date_text = crate::date_text_for_pdf(&app.session);
+    let mut refused: Option<String> = None;
     let by_line = app.session.stamp_by_line(&author);
     let mut stamp_placed = false;
     let mut image_action: Option<crate::edit_text_ui::ImageAction> = None;
@@ -1811,7 +1814,7 @@ pub fn document_area(app: &mut PdfCraftApp, index: usize, ui: &mut egui::Ui) {
                     initials.as_ref(),
                     &mut app.signature_preview,
                     &author,
-                    today,
+                    &date_text,
                 ) {
                     Some(crate::fill_sign::FillAction::Edit(e)) => view.pending_edit = Some(*e),
                     Some(crate::fill_sign::FillAction::Signature(e)) => {
@@ -1820,6 +1823,7 @@ pub fn document_area(app: &mut PdfCraftApp, index: usize, ui: &mut egui::Ui) {
                     }
                     Some(crate::fill_sign::FillAction::CreateSignature) => open_signature = true,
                     Some(crate::fill_sign::FillAction::CreateInitials) => open_initials = true,
+                    Some(crate::fill_sign::FillAction::Refused(why)) => refused = Some(why),
                     None => {}
                 }
             }
@@ -2345,6 +2349,9 @@ pub fn document_area(app: &mut PdfCraftApp, index: usize, ui: &mut egui::Ui) {
         Some(crate::edit_text_ui::ImageAction::Save(page, index)) => app.save_page_image(page, index),
         None => {}
     }
+    if let Some(why) = refused {
+        app.notify_error(why);
+    }
     if open_signature || open_initials {
         app.signature_draft = crate::fill_sign::SigDraft::new(open_initials, &app.comment_prefs.author);
         app.dialog = Some(crate::Dialog::Signature);
diff --git a/crates/ui-egui/src/fill_sign.rs b/crates/ui-egui/src/fill_sign.rs
index 825b95745..152fde4a1 100644
--- a/crates/ui-egui/src/fill_sign.rs
+++ b/crates/ui-egui/src/fill_sign.rs
@@ -1,7 +1,7 @@
 //! Fill & Sign (Acrobat's Fill & Sign tool, execution plan M5.7): type text onto the page, place
-//! ✓ ✕ ● ─ marks and today's date, and sign with a drawn signature. Everything is an annotation
-//! (typewriter text, PdfCraft-drawn stamps, ink), so it can be moved, deleted and undone like
-//! any comment.
+//! ✓ ✕ ● ─ marks and today's date (in Preferences ▸ Date format), and sign with a drawn
+//! signature. Everything is an annotation (typewriter text, PdfCraft-drawn stamps, ink), so it
+//! can be moved, deleted and undone like any comment.
 
 use egui::{Color32, CornerRadius, Pos2, Sense, Stroke, pos2, vec2};
 use pdfcraft_engine::{Edit, FillMark, NewAnnotation, Shape, SignatureImage, Style};
@@ -379,7 +379,7 @@ pub(crate) fn page_input(
     initials: Option<&SavedSig>,
     preview: &mut Option<(SavedSig, egui::TextureHandle)>,
     author: &str,
-    today: (i64, u32, u32),
+    date_text: &Result<String, String>,
 ) -> Option<FillAction> {
     let pointer = ui.input(|i| i.pointer.hover_pos())?;
     if !resp.contains_pointer() || !xf.rect.contains(pointer) {
@@ -409,10 +409,10 @@ pub(crate) fn page_input(
             view.fill_text = Some(TypeBox { page, at: [at[0], at[1] + TEXT_SIZE * 0.6], text: String::new(), focus: true });
             None
         }
-        FillTool::Date => {
-            let (y, m, d) = today;
-            Some(FillAction::Edit(Box::new(typed(page, [at[0], at[1] + TEXT_SIZE * 0.6], &format!("{m}/{d}/{y}"), author))))
-        }
+        FillTool::Date => Some(match date_text {
+            Ok(text) => FillAction::Edit(Box::new(typed(page, [at[0], at[1] + TEXT_SIZE * 0.6], text, author))),
+            Err(why) => FillAction::Refused(why.clone()),
+        }),
         FillTool::Signature => match signature {
             Some(s) => place(page, p, at, s, false, author).map(|e| FillAction::Signature(Box::new(e))),
             None => Some(FillAction::CreateSignature),
@@ -440,6 +440,8 @@ pub enum FillAction {
     CreateSignature,
     /// No initials yet.
     CreateInitials,
+    /// Nothing placed, and why (today's date can't be written into the PDF yet).
+    Refused(String),
 }
 
 /// The in-place editor for typed text. Returns the edit once committed.
diff --git a/crates/ui-egui/src/i18n/bg.tsv b/crates/ui-egui/src/i18n/bg.tsv
index 518f34ca3..4f86638a7 100644
--- a/crates/ui-egui/src/i18n/bg.tsv
+++ b/crates/ui-egui/src/i18n/bg.tsv
@@ -2054,3 +2054,10 @@ action wizard	Start	Старт
 	Larger pages	По-големи страници
 	Smaller pages	По-малки страници
 	Reset page size	Възстанови размера на страниците
+	Date format	Формат на датата
+	Fill & Sign dates	Дати при попълване и подписване
+	Pattern	Шаблон
+	Today: {date}	Днес: {date}
+	yyyy or yy year · m or mm month · mmm or mmmm month name · d or dd day · ddd or dddd weekday. H, h, M, s and t are time letters and can't be used on their own: put {escape} before a letter to show it as is.	yyyy или yy година · m или mm месец · mmm или mmmm име на месеца · d или dd ден · ddd или dddd ден от седмицата. H, h, M, s и t са букви за час и не могат да се използват самостоятелно: поставете {escape} пред буква, за да се покаже както е.
+	Same as interface ({language})	Като интерфейса ({language})
+	{chars} can't be written into the PDF yet: Fill & Sign text is Western European only. Pick a numeric format such as dd.mm.yyyy.	{chars} все още не може да се запише в PDF: текстът при попълване и подписване поддържа само западноевропейски знаци. Изберете числов формат, например dd.mm.yyyy.
diff --git a/crates/ui-egui/src/i18n/de.tsv b/crates/ui-egui/src/i18n/de.tsv
index 0b6cb3911..8bb47e799 100644
--- a/crates/ui-egui/src/i18n/de.tsv
+++ b/crates/ui-egui/src/i18n/de.tsv
@@ -2092,3 +2092,10 @@ action wizard	Start	Starten
 	Larger pages	Größere Seiten
 	Smaller pages	Kleinere Seiten
 	Reset page size	Seitengröße zurücksetzen
+	Date format	Datumsformat
+	Fill & Sign dates	Datumsangaben beim Ausfüllen und Unterschreiben
+	Pattern	Muster
+	Today: {date}	Heute: {date}
+	yyyy or yy year · m or mm month · mmm or mmmm month name · d or dd day · ddd or dddd weekday. H, h, M, s and t are time letters and can't be used on their own: put {escape} before a letter to show it as is.	yyyy oder yy Jahr · m oder mm Monat · mmm oder mmmm Monatsname · d oder dd Tag · ddd oder dddd Wochentag. H, h, M, s und t sind Zeitbuchstaben und können nicht allein verwendet werden: Setze {escape} vor einen Buchstaben, um ihn unverändert anzuzeigen.
+	Same as interface ({language})	Wie die Oberfläche ({language})
+	{chars} can't be written into the PDF yet: Fill & Sign text is Western European only. Pick a numeric format such as dd.mm.yyyy.	{chars} kann noch nicht in das PDF geschrieben werden: Text beim Ausfüllen und Unterschreiben ist auf westeuropäische Zeichen beschränkt. Wähle ein numerisches Format wie dd.mm.yyyy.
diff --git a/crates/ui-egui/src/i18n/es.tsv b/crates/ui-egui/src/i18n/es.tsv
index 4973979b9..5e8177891 100644
--- a/crates/ui-egui/src/i18n/es.tsv
+++ b/crates/ui-egui/src/i18n/es.tsv
@@ -2008,3 +2008,10 @@
 	Larger pages	Páginas más grandes
 	Smaller pages	Páginas más pequeñas
 	Reset page size	Restablecer el tamaño de las páginas
+	Date format	Formato de fecha
+	Fill & Sign dates	Fechas de Rellenar y firmar
+	Pattern	Patrón
+	Today: {date}	Hoy: {date}
+	yyyy or yy year · m or mm month · mmm or mmmm month name · d or dd day · ddd or dddd weekday. H, h, M, s and t are time letters and can't be used on their own: put {escape} before a letter to show it as is.	yyyy o yy año · m o mm mes · mmm o mmmm nombre del mes · d o dd día · ddd o dddd día de la semana. H, h, M, s y t son letras de hora y no pueden usarse solas: pon {escape} delante de una letra para mostrarla tal cual.
+	Same as interface ({language})	Igual que la interfaz ({language})
+	{chars} can't be written into the PDF yet: Fill & Sign text is Western European only. Pick a numeric format such as dd.mm.yyyy.	{chars} todavía no se puede escribir en el PDF: el texto de Rellenar y firmar solo admite caracteres de Europa occidental. Elige un formato numérico como dd.mm.yyyy.
diff --git a/crates/ui-egui/src/i18n/fr.tsv b/crates/ui-egui/src/i18n/fr.tsv
index a6b5c08da..f4c971706 100644
--- a/crates/ui-egui/src/i18n/fr.tsv
+++ b/crates/ui-egui/src/i18n/fr.tsv
@@ -2045,3 +2045,10 @@
 	Larger pages	Pages plus grandes
 	Smaller pages	Pages plus petites
 	Reset page size	Rétablir la taille des pages
+	Date format	Format de date
+	Fill & Sign dates	Dates de Remplir et signer
+	Pattern	Modèle
+	Today: {date}	Aujourd'hui : {date}
+	yyyy or yy year · m or mm month · mmm or mmmm month name · d or dd day · ddd or dddd weekday. H, h, M, s and t are time letters and can't be used on their own: put {escape} before a letter to show it as is.	yyyy ou yy année · m ou mm mois · mmm ou mmmm nom du mois · d ou dd jour · ddd ou dddd jour de la semaine. H, h, M, s et t sont des lettres d'heure et ne peuvent pas être utilisées seules : placez {escape} devant une lettre pour l'afficher telle quelle.
+	Same as interface ({language})	Comme l'interface ({language})
+	{chars} can't be written into the PDF yet: Fill & Sign text is Western European only. Pick a numeric format such as dd.mm.yyyy.	{chars} ne peut pas encore être écrit dans le PDF : le texte de Remplir et signer est limité aux caractères d'Europe occidentale. Choisissez un format numérique comme dd.mm.yyyy.
diff --git a/crates/ui-egui/src/i18n/hu.tsv b/crates/ui-egui/src/i18n/hu.tsv
index ef0a7306f..1d395e26b 100644
--- a/crates/ui-egui/src/i18n/hu.tsv
+++ b/crates/ui-egui/src/i18n/hu.tsv
@@ -2088,8 +2088,12 @@ action wizard	Start	Indítás
 	Larger pages	Nagyobb oldalak
 	Smaller pages	Kisebb oldalak
 	Reset page size	Oldalméret visszaállítása
-	Larger pages	Nagyobb oldalak
-	Smaller pages	Kisebb oldalak
-	Reset page size	Oldalméret visszaállítása
 	Flatten Fill & Sign when saving	Kitöltés és aláírás beégetése mentéskor
 	Text, marks and signatures become part of the page. Other comments stay editable.	A szöveg, a jelek és az aláírások az oldal részévé válnak. A többi megjegyzés szerkeszthető marad.
+	Date format	Dátumformátum
+	Fill & Sign dates	Kitöltés és aláírás dátumai
+	Pattern	Minta
+	Today: {date}	Ma: {date}
+	yyyy or yy year · m or mm month · mmm or mmmm month name · d or dd day · ddd or dddd weekday. H, h, M, s and t are time letters and can't be used on their own: put {escape} before a letter to show it as is.	yyyy vagy yy év · m vagy mm hónap · mmm vagy mmmm a hónap neve · d vagy dd nap · ddd vagy dddd a hét napja. A H, h, M, s és t időbetűk, önmagukban nem használhatók: tegyél {escape} jelet a betű elé, hogy változatlanul jelenjen meg.
+	Same as interface ({language})	Mint a felület ({language})
+	{chars} can't be written into the PDF yet: Fill & Sign text is Western European only. Pick a numeric format such as dd.mm.yyyy.	{chars} még nem írható a PDF-be: a kitöltés és aláírás szövege csak nyugat-európai karaktereket támogat. Válassz számokból álló formátumot, például dd.mm.yyyy.
diff --git a/crates/ui-egui/src/i18n/ja.tsv b/crates/ui-egui/src/i18n/ja.tsv
index 341515b63..a34233e51 100644
--- a/crates/ui-egui/src/i18n/ja.tsv
+++ b/crates/ui-egui/src/i18n/ja.tsv
@@ -1984,3 +1984,10 @@
 	Larger pages	ページを大きく表示
 	Smaller pages	ページを小さく表示
 	Reset page size	ページサイズをリセット
+	Date format	日付の形式
+	Fill & Sign dates	入力と署名の日付
+	Pattern	パターン
+	Today: {date}	今日: {date}
+	yyyy or yy year · m or mm month · mmm or mmmm month name · d or dd day · ddd or dddd weekday. H, h, M, s and t are time letters and can't be used on their own: put {escape} before a letter to show it as is.	yyyy または yy 年 · m または mm 月 · mmm または mmmm 月名 · d または dd 日 · ddd または dddd 曜日。H、h、M、s、t は時刻の文字なので単独では使えません。文字をそのまま表示するには前に {escape} を付けます。
+	Same as interface ({language})	表示言語と同じ（{language}）
+	{chars} can't be written into the PDF yet: Fill & Sign text is Western European only. Pick a numeric format such as dd.mm.yyyy.	{chars} はまだ PDF に書き込めません。入力と署名のテキストは西ヨーロッパの文字のみに対応しています。dd.mm.yyyy などの数字の形式を選んでください。
diff --git a/crates/ui-egui/src/i18n/mod.rs b/crates/ui-egui/src/i18n/mod.rs
index e1939349b..d9c8c4195 100644
--- a/crates/ui-egui/src/i18n/mod.rs
+++ b/crates/ui-egui/src/i18n/mod.rs
@@ -1820,4 +1820,12 @@ mod tests {
             }
         }
     }
+
+    /// Preferences ▸ Date format ▸ Language offers exactly the interface languages, in order.
+    #[test]
+    fn date_languages_are_the_interface_languages() {
+        let interface: Vec<(&str, &str)> = Lang::all().map(|l| (l.code(), l.name())).collect();
+        let dates: Vec<(&str, &str)> = pdfcraft_engine::dates::DATE_LANGUAGES.iter().map(|l| (l.code, l.name)).collect();
+        assert_eq!(dates, interface);
+    }
 }
diff --git a/crates/ui-egui/src/i18n/ru.tsv b/crates/ui-egui/src/i18n/ru.tsv
index c7888b4f6..6641c93c4 100644
--- a/crates/ui-egui/src/i18n/ru.tsv
+++ b/crates/ui-egui/src/i18n/ru.tsv
@@ -2006,3 +2006,10 @@
 	Larger pages	Крупнее страницы
 	Smaller pages	Мельче страницы
 	Reset page size	Сбросить размер страниц
+	Date format	Формат даты
+	Fill & Sign dates	Даты для «Заполнить и подписать»
+	Pattern	Шаблон
+	Today: {date}	Сегодня: {date}
+	yyyy or yy year · m or mm month · mmm or mmmm month name · d or dd day · ddd or dddd weekday. H, h, M, s and t are time letters and can't be used on their own: put {escape} before a letter to show it as is.	yyyy или yy — год · m или mm — месяц · mmm или mmmm — название месяца · d или dd — день · ddd или dddd — день недели. H, h, M, s и t — буквы времени, их нельзя использовать отдельно: поставьте {escape} перед буквой, чтобы показать её как есть.
+	Same as interface ({language})	Как в интерфейсе ({language})
+	{chars} can't be written into the PDF yet: Fill & Sign text is Western European only. Pick a numeric format such as dd.mm.yyyy.	{chars} пока нельзя записать в PDF: текст «Заполнить и подписать» поддерживает только западноевропейские символы. Выберите числовой формат, например dd.mm.yyyy.
diff --git a/crates/ui-egui/src/i18n/te.tsv b/crates/ui-egui/src/i18n/te.tsv
index 301d49a82..47db38dc7 100644
--- a/crates/ui-egui/src/i18n/te.tsv
+++ b/crates/ui-egui/src/i18n/te.tsv
@@ -2024,3 +2024,10 @@ action wizard	Start	ప్రారంభించు
 	Pin folder to Home…	ఫోల్డర్‌ను హోమ్‌కు పిన్ చేయి…
 	No recent files	ఇటీవలి ఫైళ్లు లేవు
 	Go to page…	పేజీకి వెళ్లు…
+	Date format	తేదీ ఫార్మాట్
+	Fill & Sign dates	నింపడం & సంతకం తేదీలు
+	Pattern	నమూనా
+	Today: {date}	ఈరోజు: {date}
+	yyyy or yy year · m or mm month · mmm or mmmm month name · d or dd day · ddd or dddd weekday. H, h, M, s and t are time letters and can't be used on their own: put {escape} before a letter to show it as is.	yyyy లేదా yy సంవత్సరం · m లేదా mm నెల · mmm లేదా mmmm నెల పేరు · d లేదా dd రోజు · ddd లేదా dddd వారం రోజు. H, h, M, s, t సమయ అక్షరాలు, వాటిని ఒంటరిగా ఉపయోగించలేరు: అక్షరాన్ని యథాతథంగా చూపడానికి దాని ముందు {escape} పెట్టండి.
+	Same as interface ({language})	ఇంటర్‌ఫేస్ లాగానే ({language})
+	{chars} can't be written into the PDF yet: Fill & Sign text is Western European only. Pick a numeric format such as dd.mm.yyyy.	{chars} ను ఇంకా PDF లో రాయలేము: నింపడం & సంతకం టెక్స్ట్ పశ్చిమ యూరోపియన్ అక్షరాలకు మాత్రమే పరిమితం. dd.mm.yyyy వంటి సంఖ్యా ఫార్మాట్‌ను ఎంచుకోండి.
diff --git a/crates/ui-egui/src/i18n/uk.tsv b/crates/ui-egui/src/i18n/uk.tsv
index 516562a5d..0cdef4e28 100644
--- a/crates/ui-egui/src/i18n/uk.tsv
+++ b/crates/ui-egui/src/i18n/uk.tsv
@@ -2110,8 +2110,12 @@ calendar date	December	грудня
 	Larger pages	Більші сторінки
 	Smaller pages	Менші сторінки
 	Reset page size	Скинути розмір сторінок
-	Larger pages	Більші сторінки
-	Smaller pages	Менші сторінки
-	Reset page size	Скинути розмір сторінок
 	Flatten Fill & Sign when saving	Звести «Заповнення й підпис» під час збереження
 	Text, marks and signatures become part of the page. Other comments stay editable.	Текст, позначки й підписи стають частиною сторінки. Інші коментарі залишаються редагованими.
+	Date format	Формат дати
+	Fill & Sign dates	Дати заповнення й підпису
+	Pattern	Шаблон
+	Today: {date}	Сьогодні: {date}
+	yyyy or yy year · m or mm month · mmm or mmmm month name · d or dd day · ddd or dddd weekday. H, h, M, s and t are time letters and can't be used on their own: put {escape} before a letter to show it as is.	yyyy або yy рік · m або mm місяць · mmm або mmmm назва місяця · d або dd день · ddd або dddd день тижня. H, h, M, s і t — літери часу, їх не можна використовувати окремо: поставте {escape} перед літерою, щоб показати її як є.
+	Same as interface ({language})	Як в інтерфейсі ({language})
+	{chars} can't be written into the PDF yet: Fill & Sign text is Western European only. Pick a numeric format such as dd.mm.yyyy.	{chars} поки не можна записати в PDF: текст заповнення й підпису підтримує лише західноєвропейські символи. Виберіть числовий формат, наприклад dd.mm.yyyy.
diff --git a/crates/ui-egui/src/i18n/zh-hans.tsv b/crates/ui-egui/src/i18n/zh-hans.tsv
index f8b5233d7..d8cdb1b50 100644
--- a/crates/ui-egui/src/i18n/zh-hans.tsv
+++ b/crates/ui-egui/src/i18n/zh-hans.tsv
@@ -2056,3 +2056,10 @@
 	Larger pages	放大页面
 	Smaller pages	缩小页面
 	Reset page size	重置页面大小
+	Date format	日期格式
+	Fill & Sign dates	填写与签名的日期
+	Pattern	模式
+	Today: {date}	今天：{date}
+	yyyy or yy year · m or mm month · mmm or mmmm month name · d or dd day · ddd or dddd weekday. H, h, M, s and t are time letters and can't be used on their own: put {escape} before a letter to show it as is.	yyyy 或 yy 年 · m 或 mm 月 · mmm 或 mmmm 月份名称 · d 或 dd 日 · ddd 或 dddd 星期。H、h、M、s 和 t 是时间字母，不能单独使用：在字母前加 {escape} 可按原样显示。
+	Same as interface ({language})	与界面相同（{language}）
+	{chars} can't be written into the PDF yet: Fill & Sign text is Western European only. Pick a numeric format such as dd.mm.yyyy.	暂时无法将 {chars} 写入 PDF：填写与签名的文字仅支持西欧字符。请选择数字格式，例如 dd.mm.yyyy。
diff --git a/crates/ui-egui/src/i18n/zh-hant.tsv b/crates/ui-egui/src/i18n/zh-hant.tsv
index c7982efa9..e2b2403f4 100644
--- a/crates/ui-egui/src/i18n/zh-hant.tsv
+++ b/crates/ui-egui/src/i18n/zh-hant.tsv
@@ -1977,3 +1977,10 @@
 	Larger pages	放大頁面
 	Smaller pages	縮小頁面
 	Reset page size	重設頁面大小
+	Date format	日期格式
+	Fill & Sign dates	填寫與簽署的日期
+	Pattern	模式
+	Today: {date}	今天：{date}
+	yyyy or yy year · m or mm month · mmm or mmmm month name · d or dd day · ddd or dddd weekday. H, h, M, s and t are time letters and can't be used on their own: put {escape} before a letter to show it as is.	yyyy 或 yy 年 · m 或 mm 月 · mmm 或 mmmm 月份名稱 · d 或 dd 日 · ddd 或 dddd 星期。H、h、M、s 和 t 是時間字母，不能單獨使用：在字母前加上 {escape} 即可照原樣顯示。
+	Same as interface ({language})	與介面相同（{language}）
+	{chars} can't be written into the PDF yet: Fill & Sign text is Western European only. Pick a numeric format such as dd.mm.yyyy.	暫時無法將 {chars} 寫入 PDF：填寫與簽署的文字僅支援西歐字元。請選擇數字格式，例如 dd.mm.yyyy。
diff --git a/crates/ui-egui/src/js_ui.rs b/crates/ui-egui/src/js_ui.rs
index f5015bed1..d285372b6 100644
--- a/crates/ui-egui/src/js_ui.rs
+++ b/crates/ui-egui/src/js_ui.rs
@@ -313,6 +313,8 @@ pub(crate) fn preferences_body(ui: &mut egui::Ui, app: &mut PdfCraftApp, t: &Tok
         egui::RichText::new(tl!("Text, marks and signatures become part of the page. Other comments stay editable.")).small().color(t.text_muted),
     );
     ui.add_space(8.0);
+    date_format(ui, app, t);
+    ui.add_space(8.0);
     ui.label(egui::RichText::new("JavaScript").font(theme::semibold(13.0)));
     egui::Frame::new().fill(t.hover).corner_radius(egui::CornerRadius::same(6)).inner_margin(egui::Margin::same(10)).show(ui, |ui| {
         ui.set_width(ui.available_width());
@@ -329,3 +331,94 @@ pub(crate) fn preferences_body(ui: &mut egui::Ui, app: &mut PdfCraftApp, t: &Tok
     ui.add_space(10.0);
     buttons(ui, tl!("OK"), &[]).is_some()
 }
+
+/// Preferences ▸ Date format: a preset, or any pattern typed in, for Fill & Sign dates, and the
+/// language of its month and weekday names. A valid pattern applies as it's typed; an invalid
+/// one stays in the box with the reason, and the last valid one stays in use.
+fn date_format(ui: &mut egui::Ui, app: &mut PdfCraftApp, t: &Tokens) {
+    use pdfcraft_engine::dates::{DATE_FORMATS, DATE_LANGUAGES, MAX_DATE_FORMAT_CHARS};
+    ui.label(egui::RichText::new(tl!("Date format")).font(theme::semibold(13.0)));
+    let sample = |app: &PdfCraftApp, f: &str| format!("{}   {f}", app.date_text(Some(f)).unwrap_or_default());
+    ui.horizontal(|ui| {
+        let label = ui.label(tl!("Fill & Sign dates"));
+        let current = app.session.date_format().to_string();
+        let selected = if DATE_FORMATS.contains(&current.as_str()) { sample(app, &current) } else { tl!("Custom").to_string() };
+        egui::ComboBox::from_id_salt("date-format")
+            .selected_text(selected)
+            .width(240.0)
+            .show_ui(ui, |ui| {
+                for f in DATE_FORMATS {
+                    if ui.selectable_label(current == f, sample(app, f)).clicked() && app.session.set_date_format(f).is_ok() {
+                        app.date_format_draft = None;
+                        ui.close();
+                    }
+                }
+            })
+            .response
+            .labelled_by(label.id);
+    });
+    ui.horizontal(|ui| {
+        let label = ui.label(tl!("Pattern"));
+        let mut text = app.date_format_draft.clone().unwrap_or_else(|| app.session.date_format().to_string());
+        let edit = ui.add(egui::TextEdit::singleline(&mut text).desired_width(160.0).char_limit(MAX_DATE_FORMAT_CHARS)).labelled_by(label.id);
+        // The box keeps the text as typed (a trailing space included) while it has focus; the
+        // setting takes the trimmed pattern whenever it's valid.
+        if edit.changed() {
+            let _ = app.session.set_date_format(&text);
+            app.date_format_draft = Some(text.clone());
+        }
+        if !edit.has_focus() && pdfcraft_engine::dates::check_date_format(&text).is_ok() {
+            app.date_format_draft = None;
+        }
+        match app.date_text(Some(&text)) {
+            Ok(today) => ui.label(egui::RichText::new(crate::i18n::fmt(tl!("Today: {date}"), &[("date", &today)])).color(t.text_muted)),
+            // The engine's reason, in English.
+            Err(e) => ui.label(egui::RichText::new(e).color(egui::Color32::from_rgb(0xD1, 0x3B, 0x3B))),
+        };
+    });
+    // Fill & Sign refuses a date it would save as "?"; say so before anyone tries.
+    let bad = app.date_text(None).map(|today| pdfcraft_engine::dates::unwritable(&today)).unwrap_or_default();
+    if !bad.is_empty() {
+        ui.label(
+            egui::RichText::new(crate::i18n::fmt(
+                tl!(
+                    "{chars} can't be written into the PDF yet: Fill & Sign text is Western European only. Pick a numeric format such as dd.mm.yyyy."
+                ),
+                &[("chars", &bad)],
+            ))
+            .color(egui::Color32::from_rgb(0xD1, 0x3B, 0x3B)),
+        );
+    }
+    ui.horizontal(|ui| {
+        let label = ui.label(tl!("Language"));
+        let interface = crate::i18n::current().name();
+        let follow = crate::i18n::fmt(tl!("Same as interface ({language})"), &[("language", interface)]);
+        let current = app.session.date_language().map(str::to_string);
+        let selected = DATE_LANGUAGES.iter().find(|l| current.as_deref() == Some(l.code)).map_or(follow.clone(), |l| l.name.to_string());
+        egui::ComboBox::from_id_salt("date-language")
+            .selected_text(selected)
+            .width(240.0)
+            .show_ui(ui, |ui| {
+                if ui.selectable_label(current.is_none(), follow).clicked() && app.session.set_date_language(None).is_ok() {
+                    ui.close();
+                }
+                for l in &DATE_LANGUAGES {
+                    if ui.selectable_label(current.as_deref() == Some(l.code), l.name).clicked()
+                        && app.session.set_date_language(Some(l.code)).is_ok()
+                    {
+                        ui.close();
+                    }
+                }
+            })
+            .response
+            .labelled_by(label.id);
+    });
+    ui.label(
+        egui::RichText::new(crate::i18n::fmt(
+            tl!("yyyy or yy year · m or mm month · mmm or mmmm month name · d or dd day · ddd or dddd weekday. H, h, M, s and t are time letters and can't be used on their own: put {escape} before a letter to show it as is."),
+            &[("escape", "\\")],
+        ))
+        .small()
+        .color(t.text_muted),
+    );
+}
diff --git a/crates/ui-egui/src/lib.rs b/crates/ui-egui/src/lib.rs
index feb39e213..5447c2cb7 100644
--- a/crates/ui-egui/src/lib.rs
+++ b/crates/ui-egui/src/lib.rs
@@ -86,6 +86,19 @@ mod redact_ui;
 pub use redact_ui::{HiddenDraft, PagesDraft as RedactPagesDraft, RedactPrefs, SearchDraft as RedactSearchDraft};
 pub mod i18n;
 
+/// [`PdfCraftApp::date_text`] for callers that already borrow other parts of the app.
+pub(crate) fn date_text(session: &Session, fmt: Option<&str>) -> Result<String, String> {
+    let lang = session.date_language().unwrap_or(i18n::current().code());
+    session.today_text(fmt, Some(lang))
+}
+
+/// Today in Preferences ▸ Date format for stamping into a PDF; refused when it has characters
+/// Fill & Sign can't write yet (see [`pdfcraft_engine::dates::unwritable`]).
+pub(crate) fn date_text_for_pdf(session: &Session) -> Result<String, String> {
+    let lang = session.date_language().unwrap_or(i18n::current().code());
+    session.today_text_for_pdf(None, Some(lang))
+}
+
 /// The longest author name kept (Preferences ▸ Identity, restored settings).
 pub(crate) const MAX_AUTHOR_CHARS: usize = 200;
 pub mod portable;
@@ -352,6 +365,9 @@ pub struct PdfCraftApp {
     /// Documents and view). Continuous scrolling at fit width by default, which never snaps
     /// between pages.
     pub view_defaults: canvas::ViewDefaults,
+    /// The Preferences ▸ Date format box while it's being edited, or while it holds an invalid
+    /// pattern (the session keeps the last valid one).
+    pub date_format_draft: Option<String>,
     /// Explicit CLI/control mode lasts for this session and is never persisted.
     mode_override: Option<Mode>,
     pub left: LeftPanel,
@@ -611,6 +627,7 @@ impl PdfCraftApp {
             mode: Mode::AllTools,
             default_mode: Mode::AllTools,
             view_defaults: Default::default(),
+            date_format_draft: None,
             mode_override: None,
             left: LeftPanel::AllTools,
             left_open: true,
@@ -1172,6 +1189,12 @@ impl PdfCraftApp {
         self.notify_fmt("`{command}` {when}", &[("command", command), ("when", &when)]);
     }
 
+    /// Today in `fmt` (or Preferences ▸ Date format), with month and weekday names in the date
+    /// language, or the interface language when it follows that.
+    pub fn date_text(&self, fmt: Option<&str>) -> Result<String, String> {
+        date_text(&self.session, fmt)
+    }
+
     /// Select the workspace and its matching tool panel, just like the mode bar.
     pub(crate) fn select_mode(&mut self, mode: Mode) {
         self.mode = mode;
@@ -1211,6 +1234,9 @@ impl PdfCraftApp {
             "highlight_fields": self.view_defaults.highlight_fields,
             "language": self.language,
             "flatten_fill_sign": self.flatten_fill_sign_on_save,
+            "date_format": self.session.date_format(),
+            // Null follows the interface language.
+            "date_language": self.session.date_language(),
             "author": self.comment_prefs.author,
             // Drawn signatures keep their original form (older settings read the same).
             "signature": match &self.signature { Some(fill_sign::SavedSig::Drawn(s)) => Some(s), _ => None },
@@ -1268,6 +1294,13 @@ impl PdfCraftApp {
         if let Some(on) = v["flatten_fill_sign"].as_bool() {
             self.flatten_fill_sign_on_save = on;
         }
+        // Settings are untrusted: an unusable pattern keeps the default.
+        if let Some(f) = v["date_format"].as_str() {
+            let _ = self.session.set_date_format(f);
+        }
+        if let Some(l) = v["date_language"].as_str() {
+            let _ = self.session.set_date_language(Some(l));
+        }
         // An empty or missing name keeps the login-name default; settings are untrusted, so the
         // name is cut to a sane length.
         if let Some(author) = v["author"].as_str().map(str::trim).filter(|a| !a.is_empty()) {
@@ -1352,6 +1385,8 @@ impl PdfCraftApp {
             ("default-mode", _) => {
                 self.default_mode = Mode::parse(value).ok_or("default-mode must be all, read, edit, convert or sign")?;
             }
+            ("date-format", _) => self.session.set_date_format(value)?,
+            ("date-language", _) => self.session.set_date_language(Some(value).filter(|v| *v != "auto"))?,
             ("tool", _) => {
                 let g = pdfcraft_engine::catalog::group(value).ok_or_else(|| format!("unknown tool {value}"))?;
                 self.left = LeftPanel::Tool(g.id);
diff --git a/crates/ui-egui/tests/date_format.rs b/crates/ui-egui/tests/date_format.rs
new file mode 100644
index 000000000..161784c35
--- /dev/null
+++ b/crates/ui-egui/tests/date_format.rs
@@ -0,0 +1,160 @@
+//! Preferences ▸ Date format: the pattern Fill & Sign dates use.
+
+use egui::accesskit::Role;
+use egui::{Key, Modifiers, pos2};
+use egui_kittest::Harness;
+use egui_kittest::kittest::Queryable;
+use pdfcraft_ui_egui::PdfCraftApp;
+
+const PDF: &[u8] = b"%PDF-1.7
+1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj
+2 0 obj << /Type /Pages /Kids [3 0 R] /Count 1 /MediaBox [0 0 300 400] >> endobj
+3 0 obj << /Type /Page /Parent 2 0 R >> endobj
+trailer << /Root 1 0 R >>
+%%EOF";
+
+/// Some widget shows `text`, as its label or its value (a combo box shows its choice as a value).
+fn shows(h: &Harness<'static, PdfCraftApp>, text: &str) -> bool {
+    h.query_all_by(|n| n.label().is_some_and(|l| l.contains(text)) || n.value().is_some_and(|v| v.contains(text))).next().is_some()
+}
+
+fn retype(h: &mut Harness<'static, PdfCraftApp>, text: &str) {
+    h.get_by_role_and_label(Role::TextInput, "Pattern").click();
+    h.run_steps(1);
+    h.key_press_modifiers(Modifiers::COMMAND, Key::A);
+    h.get_by_role_and_label(Role::TextInput, "Pattern").type_text(text);
+    h.run_steps(2);
+}
+
+#[test]
+fn fill_and_sign_dates_follow_the_date_format_preference_and_it_is_remembered() {
+    let mut h = Harness::builder().with_size(egui::vec2(1400.0, 900.0)).build_eframe(|_cc| {
+        let mut app = PdfCraftApp::new();
+        app.open_bytes("form.pdf", None, PDF.to_vec()).expect("opens");
+        app.set_option("left", "closed").unwrap();
+        app.set_option("dialog", "preferences").unwrap();
+        app
+    });
+    h.run_steps(4);
+    assert_eq!(h.state().session.date_format(), "m/d/yyyy");
+    // A valid pattern applies as it's typed, with a preview of today.
+    retype(&mut h, "d \\de mmmm yyyy");
+    assert_eq!(h.state().session.date_format(), "d \\de mmmm yyyy");
+    h.get_by_label_contains("Today: ");
+    // An invalid one stays in the box with the reason, and the last valid one is kept.
+    retype(&mut h, "dd/mm HH");
+    h.get_by_label_contains("is a time letter (H h M s t)");
+    assert_eq!(h.state().session.date_format(), "d \\de mmmm yyyy");
+    assert_eq!(h.state().date_format_draft.as_deref(), Some("dd/mm HH"));
+    // Typed a key at a time, spaces stay where they are typed (the box isn't trimmed under the cursor).
+    h.get_by_role_and_label(Role::TextInput, "Pattern").click();
+    h.run_steps(1);
+    h.key_press_modifiers(Modifiers::COMMAND, Key::A);
+    for c in "yyyy mm dd".chars() {
+        h.get_by_role_and_label(Role::TextInput, "Pattern").type_text(&c.to_string());
+        h.run_steps(1);
+    }
+    assert_eq!(h.state().date_format_draft.as_deref(), Some("yyyy mm dd"));
+    assert_eq!(h.state().session.date_format(), "yyyy mm dd");
+    // A letter group that isn't a date code is refused, not silently shortened.
+    retype(&mut h, "yyyyyyyy");
+    h.get_by_label_contains("`yyyyyyyy` is not a date code");
+    assert_eq!(h.state().session.date_format(), "yyyy mm dd");
+    retype(&mut h, "yyyy.mm.dd.");
+    assert_eq!(h.state().session.date_format(), "yyyy.mm.dd.");
+
+    // Fill & Sign ▸ Date stamps today in it.
+    h.state_mut().set_option("dialog", "none").unwrap();
+    h.run_steps(2);
+    assert!(h.state_mut().execute("sign.fill.date"));
+    h.run_steps(2);
+    let r = h.state().views[0].page_screen_rect(0).expect("on screen");
+    let p = pos2(r.left() + r.width() * 0.2, r.top() + r.height() * 0.2);
+    h.hover_at(p);
+    h.run_steps(1);
+    h.drag_at(p);
+    h.run_steps(1);
+    h.drop_at(p);
+    h.run_steps(4);
+    let expected = h.state().date_text(None).unwrap();
+    let s = h.state();
+    let dates: Vec<_> = s.session.get(s.views[0].id).unwrap().info.annotations.iter().filter_map(|a| a.contents.clone()).collect();
+    assert_eq!(dates, std::slice::from_ref(&expected));
+    assert!(expected.ends_with('.') && expected.matches('.').count() == 3, "{expected}");
+
+    // It survives a restart; an unusable saved pattern keeps the default; the control channel checks it too.
+    let mut restored = PdfCraftApp::new();
+    restored.restore(&h.state().persist());
+    assert_eq!(restored.session.date_format(), "yyyy.mm.dd.");
+    let mut fresh = PdfCraftApp::new();
+    fresh.restore(&format!(r#"{{"date_format": "{}"}}"#, "d".repeat(10_000)));
+    fresh.restore(r#"{"date_format": "HH:MM"}"#);
+    assert_eq!(fresh.session.date_format(), "m/d/yyyy");
+    assert!(fresh.set_option("date-format", "Year").is_err());
+    fresh.set_option("date-format", "dd/mm/yyyy").unwrap();
+    assert_eq!(fresh.session.date_format(), "dd/mm/yyyy");
+}
+
+#[test]
+fn month_names_follow_the_date_language_or_else_the_interface_language() {
+    let mut h = Harness::builder().with_size(egui::vec2(1400.0, 900.0)).build_eframe(|_cc| {
+        let mut app = PdfCraftApp::new();
+        app.set_option("date-format", "d mmmm yyyy").unwrap();
+        app.set_option("language", "cs").unwrap();
+        app.set_option("dialog", "preferences").unwrap();
+        app
+    });
+    h.run_steps(3);
+    let text = |h: &Harness<'static, PdfCraftApp>| h.state().date_text(None).unwrap();
+    assert_eq!(text(&h), h.state().session.today_text(None, Some("cs")).unwrap(), "follows the interface (Czech)");
+    // The picker offers following the interface first, then the interface languages.
+    assert!(shows(&h, "Same as interface (Čeština)"));
+    h.state_mut().set_option("date-language", "es").unwrap();
+    h.run_steps(2);
+    assert_eq!(text(&h), h.state().session.today_text(None, Some("es")).unwrap());
+    assert!(shows(&h, "Español"));
+
+    // Remembered; an unknown saved language is ignored; auto follows the interface again.
+    let mut restored = PdfCraftApp::new();
+    restored.restore(&h.state().persist());
+    assert_eq!(restored.session.date_language(), Some("es"));
+    let mut fresh = PdfCraftApp::new();
+    fresh.restore(r#"{"date_language": "klingon"}"#);
+    assert_eq!(fresh.session.date_language(), None);
+    assert!(fresh.set_option("date-language", "klingon").is_err());
+    h.state_mut().set_option("date-language", "auto").unwrap();
+    assert_eq!(h.state().session.date_language(), None);
+}
+
+#[test]
+fn a_date_the_pdf_cannot_hold_is_refused_with_a_warning_first() {
+    let mut h = Harness::builder().with_size(egui::vec2(1400.0, 900.0)).build_eframe(|_cc| {
+        let mut app = PdfCraftApp::new();
+        app.open_bytes("form.pdf", None, PDF.to_vec()).expect("opens");
+        app.set_option("left", "closed").unwrap();
+        // Japanese weekday names: Fill & Sign text can't hold them yet.
+        app.set_option("date-format", "dddd").unwrap();
+        app.set_option("date-language", "ja").unwrap();
+        app.set_option("dialog", "preferences").unwrap();
+        app
+    });
+    h.run_steps(3);
+    h.get_by_label_contains("can't be written into the PDF yet");
+
+    h.state_mut().set_option("dialog", "none").unwrap();
+    h.run_steps(2);
+    assert!(h.state_mut().execute("sign.fill.date"));
+    h.run_steps(2);
+    let r = h.state().views[0].page_screen_rect(0).expect("on screen");
+    let p = pos2(r.left() + r.width() * 0.2, r.top() + r.height() * 0.2);
+    h.hover_at(p);
+    h.run_steps(1);
+    h.drag_at(p);
+    h.run_steps(1);
+    h.drop_at(p);
+    h.run_steps(4);
+    let s = h.state();
+    assert!(s.session.get(s.views[0].id).unwrap().info.annotations.is_empty(), "nothing placed");
+    let toast = s.toast.as_ref().map(|t| t.0.clone()).unwrap_or_default();
+    assert!(toast.contains("can't be written into the PDF yet"), "{toast}");
+}
diff --git a/parity/acrobat-features.toml b/parity/acrobat-features.toml
index ab580ddba..4655479a1 100644
--- a/parity/acrobat-features.toml
+++ b/parity/acrobat-features.toml
@@ -5213,9 +5213,9 @@ tier = "P0"
 milestone = "M5"
 status = "shipped"
 commands = ["sign.fill.date"]
-tools = ["fill_sign_add"]
-evidence = ["crates/ui-egui/tests/fill_sign.rs::text_marks_and_date", "crates/automation/tests/automation.rs::fill_and_sign_through_tools"]
-notes = "local date, m/d/yyyy"
+tools = ["fill_sign_add", "fill_sign_date_format"]
+evidence = ["crates/ui-egui/tests/fill_sign.rs::text_marks_and_date", "crates/automation/tests/automation.rs::fill_and_sign_through_tools", "crates/ui-egui/tests/date_format.rs::fill_and_sign_dates_follow_the_date_format_preference_and_it_is_remembered", "crates/engine/src/dates.rs::presets_write_the_day_in_their_own_order", "crates/engine/src/dates.rs::names_follow_the_date_language", "crates/ui-egui/tests/date_format.rs::month_names_follow_the_date_language_or_else_the_interface_language", "crates/ui-egui/tests/date_format.rs::a_date_the_pdf_cannot_hold_is_refused_with_a_warning_first"]
+notes = "local date in Preferences ▸ Date format (default m/d/yyyy; 12 presets or any pattern in Acrobat date letters with \\ escapes, checked and previewed as typed, remembered; only whole date codes accepted; month and weekday names in the interface languages, Czech months in the genitive after a day, following the interface language unless one is picked; fill_sign_add takes a one-off format and language). Beyond Acrobat: its Fill & Sign has no format setting (only Acrobat Sign accounts do). Missing: Fill & Sign text is Helvetica/WinAnsi, so a date with letters outside Western European (Czech ř, Japanese, Chinese names) is refused with a warning instead of being saved as ?; the OS locale's format isn't offered as a preset; names in languages without an interface translation"
 
 [[feature]]
 id = "form.fill-sign-signature"