viewer: click to copy values, amounts, and identifiers

Company details (EIN, state number, address, every profile value), an
entry's number and amount, an account's code and balance, a document's
file name and SHA-256 copy on click: a pointer and copy icon on hover,
a check for a moment after. Amounts copy as their exact plain decimal
(fmt::plain: no "$", commas, or parentheses; "-" for negatives); where a
click already drills down (report cells, register and transaction rows,
general ledger lines), a right-click menu copies the amounts, the entry
number, or the description. The sidebar's chain check copies the
journal head and data folder.

tests/copy.rs: every display style copies back to the exact value
(property), and clicking the EIN, an entry's amount, and its number puts
exactly that on the clipboard.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GWVo7x3UHw5kwCUaWxiejX

crates/ledger-gui/tests/copy.rs

@@ -0,0 +1,106 @@
+//! Click to copy: values leave the viewer exactly.
+//!
+//! ```text
+//! GOAL: what people retype into forms (the EIN, an amount, an entry
+//!       number) can be copied instead, and copies exactly.
+//! SOURCE: DECISION (Stephen, 2026-10-14: click-to-copy on the company
+//!         page, amounts, and identifiers).
+//! INVARIANTS:
+//!   1. An amount copies as its plain decimal: fmt::plain of money,
+//!      accounting, or dollars text is the exact value, with "-" for a
+//!      negative and no "$", commas, or parentheses.
+//!   2. Clicking a company value or an entry's amount puts exactly that
+//!      value on the clipboard.
+//! ```
+
+use egui::OutputCommand;
+use egui_kittest::Harness;
+use egui_kittest::kittest::Queryable;
+use ledger_gui::nav::Route;
+use ledger_gui::{App, Source, data, fmt};
+use proptest::prelude::*;
+use rust_decimal::Decimal;
+
+proptest! {
+    /// INVARIANT 1: every display style copies back to the same value.
+    #[test]
+    fn an_amount_copies_as_its_exact_value(
+        mantissa in -10i128.pow(16)..10i128.pow(16),
+        scale in 0u32..8,
+    ) {
+        let d = Decimal::from_i128_with_scale(mantissa, scale);
+        for shown in [fmt::money(d), fmt::accounting(d), fmt::dollars(d)] {
+            let plain = fmt::plain(&shown).expect("an amount");
+            prop_assert!(!plain.contains(['$', ',', '(', ')', '\u{2212}']), "{}", plain);
+            prop_assert_eq!(plain.parse::<Decimal>().unwrap(), d, "{} copied as {}", shown, plain);
+        }
+    }
+}
+
+fn copied(h: &Harness<'_, App>) -> Vec<String> {
+    h.output()
+        .platform_output
+        .commands
+        .iter()
+        .filter_map(|c| match c {
+            OutputCommand::CopyText(t) => Some(t.clone()),
+            _ => None,
+        })
+        .collect()
+}
+
+/// INVARIANT 2, on the demo books.
+#[test]
+fn clicking_a_value_copies_it() {
+    let dir = std::env::temp_dir().join(format!("ledger-gui-copy-{}", std::process::id()));
+    let _ = std::fs::remove_dir_all(&dir);
+    let today = chrono::NaiveDate::from_ymd_opt(2026, 10, 12).unwrap();
+    ledger_gui::demo::build(&dir, today).unwrap();
+    let source = Source {
+        data_dir: dir.join("books-data"),
+        books_toml: Some(dir.join("wanderbooks.toml")),
+        today: Some(today),
+    };
+    let open = |route: Route| {
+        let books = data::load_once(&source).unwrap();
+        let mut h = Harness::builder()
+            .with_size(egui::vec2(1280.0, 900.0))
+            .build_eframe(|cc| App::with_books(&cc.egui_ctx, books, false, route));
+        h.run_steps(3);
+        h
+    };
+
+    // The company's EIN, as written in wanderbooks.toml.
+    let ein = data::load_once(&source)
+        .unwrap()
+        .settings
+        .company
+        .profile
+        .iter()
+        .find(|(k, _)| k == "ein")
+        .map(|(_, v)| v.clone())
+        .expect("the demo has an EIN");
+    let mut h = open(Route::Company);
+    h.get_by_label(&ein).click();
+    h.step();
+    assert_eq!(copied(&h), [ein]);
+
+    // An entry's amount, as a plain decimal.
+    let books = data::load_once(&source).unwrap();
+    let e = books.entries.iter().find(|e| !e.amount.is_zero()).unwrap();
+    let (id, amount) = (e.id, e.amount);
+    drop(books);
+    let mut h = open(Route::Entry(id));
+    let shown = fmt::dollars(amount);
+    h.get_by_label(&shown).click();
+    h.step();
+    assert_eq!(copied(&h), [fmt::plain(&shown).unwrap()]);
+    assert_eq!(copied(&h)[0].parse::<Decimal>().unwrap(), amount);
+
+    // The entry number.
+    let mut h = open(Route::Entry(id));
+    h.get_by_label(&format!("Entry #{id}")).click();
+    h.step();
+    assert_eq!(copied(&h), [format!("#{id}")]);
+    let _ = std::fs::remove_dir_all(&dir);
+}