P3: rename accounts, one set of period defaults, tax categories warn or refuse (defects 15, 16, 8)

books.rename_account; account names trimmed, bounded, refused when a
sibling's or TIN-shaped; books.show refuses what its target ignores. A
report asked for without dates covers this fiscal year so far, everywhere
(one rule for tools, descriptions and the viewer; the IIF and CPA package
keep their own dates). policy.require_tax_category warns or refuses; a
Form 4797 gain is shown apart on every return.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01T3gXMVt7XJPi6ens1or9Dj

crates/ledger-gui/tests/show.rs

@@ -118,3 +118,194 @@ fn show_requests_navigate_the_viewer() {
     });
     assert_eq!(h.state_mut().route(), &Route::Transactions);
 }
+
+/// The demo books (calendar fiscal year) in a viewer, at `today`.
+fn demo(
+    tag: &str,
+    today: chrono::NaiveDate,
+) -> (TestDir, Harness<'static, App>, ledger_gui::books::Books) {
+    demo_sized(tag, today, 920.0)
+}
+
+/// [`demo`] in a window `height` tall (the register's date row sits below
+/// an account's cards: tall enough to click it).
+fn demo_sized(
+    tag: &str,
+    today: chrono::NaiveDate,
+    height: f32,
+) -> (TestDir, Harness<'static, App>, ledger_gui::books::Books) {
+    let dir = std::env::temp_dir().join(format!("ledger-gui-show-{tag}-{}", std::process::id()));
+    let _ = std::fs::remove_dir_all(&dir);
+    let guard = TestDir(dir.clone());
+    ledger_gui::demo::build(&dir, today).unwrap();
+    let source = Source {
+        data_dir: dir.join("books-data"),
+        today: Some(today),
+    };
+    let books = data::load_once(&source).unwrap();
+    let copy = data::load_once(&source).unwrap();
+    let h = Harness::builder()
+        .with_size(egui::vec2(1440.0, height))
+        .build_eframe(move |cc| App::with_books(&cc.egui_ctx, books, true, Route::Overview));
+    (guard, h, copy)
+}
+
+fn day(y: i32, m: u32, d: u32) -> chrono::NaiveDate {
+    chrono::NaiveDate::from_ymd_opt(y, m, d).unwrap()
+}
+
+/// Defect 15, repros 1.1.1-1.1.2 (rules.md B-30): a target the viewer
+/// can't honour is ignored whole, never swapped or guessed: a start after
+/// the end (an earlier writer's, or a hand-edited ops/show.jsonl), text
+/// that isn't a date, an unknown split or comparison. The page, the
+/// report's range and split, and the register's range stay as they were.
+#[test]
+fn show_never_swaps_an_inverted_target_defect_15() {
+    use ledger_gui::pages::accounts::RegisterRange;
+    use ledger_gui::pages::reports::{Columns, Compare, Range};
+    let (_dir, mut h, _) = demo("inverted", day(2026, 10, 20));
+    h.state_mut().state_mut().reports.range = Range::LastMonth;
+    h.state_mut().state_mut().reports.columns = Columns::Quarter;
+    h.state_mut().state_mut().accounts.range = RegisterRange::All;
+    let report =
+        |start: Option<&str>, end: Option<&str>, columns: Option<&str>, compare: Option<&str>| {
+            ViewerTarget::Report {
+                report: "profit_and_loss".into(),
+                start: start.map(Into::into),
+                end: end.map(Into::into),
+                columns: columns.map(Into::into),
+                compare: compare.map(Into::into),
+            }
+        };
+    for target in [
+        report(Some("2026-12-31"), Some("2026-01-01"), None, None),
+        report(Some("2027-01-01"), None, None, None),
+        report(Some("January"), None, None, None),
+        report(None, Some("2026-13-01"), None, None),
+        report(None, None, Some("weekly"), None),
+        report(None, None, None, Some("prior_decade")),
+        ViewerTarget::Account {
+            code: "1000".into(),
+            start: Some("2026-12-31".into()),
+            end: Some("2026-01-01".into()),
+        },
+        ViewerTarget::Account {
+            code: "1000".into(),
+            start: Some("2027-01-01".into()),
+            end: None,
+        },
+    ] {
+        h.state_mut().show(target.clone());
+        h.run_steps(2);
+        assert_eq!(h.state_mut().route(), &Route::Overview, "{target:?}");
+        let st = h.state_mut().state_mut();
+        assert_eq!(st.reports.range, Range::LastMonth, "{target:?}");
+        assert_eq!(st.reports.columns, Columns::Quarter, "{target:?}");
+        assert_eq!(st.reports.compare, Compare::None, "{target:?}");
+        assert_eq!(st.accounts.range, RegisterRange::All, "{target:?}");
+    }
+}
+
+/// Defect 16, repro 1.1.4 (rules.md B-30): a report target with only an
+/// end covers that end's fiscal year to it (2025-01-01 to 2025-06-30, not
+/// the swapped 2025-06-30 to 2026-01-01); with no dates, the default (the
+/// fiscal year to date, named "Year to date"); dates that are a preset's
+/// show under its name; an account target with no dates opens the
+/// register on the default.
+#[test]
+fn show_report_with_only_end_uses_that_years_start_defect_16() {
+    use ledger_gui::pages::accounts::RegisterRange;
+    use ledger_gui::pages::reports::Range;
+    let today = day(2026, 10, 20);
+    let (_dir, mut h, books) = demo("only-end", today);
+    let report = |start: Option<&str>, end: Option<&str>| ViewerTarget::Report {
+        report: "profit_and_loss".into(),
+        start: start.map(Into::into),
+        end: end.map(Into::into),
+        columns: None,
+        compare: None,
+    };
+    h.state_mut().show(report(None, Some("2025-06-30")));
+    h.run_steps(2);
+    assert_eq!(
+        h.state_mut().state_mut().reports.range,
+        Range::Custom(day(2025, 1, 1), day(2025, 6, 30))
+    );
+    h.state_mut().state_mut().reports.range = Range::LastMonth;
+    h.state_mut().show(report(None, None));
+    h.run_steps(2);
+    assert_eq!(h.state_mut().state_mut().reports.range, Range::YearToDate);
+    assert_eq!(Range::YearToDate.dates(&books), (day(2026, 1, 1), today));
+    // What books.show sends for no dates: the same, by name.
+    h.state_mut()
+        .show(report(Some("2026-01-01"), Some("2026-10-20")));
+    h.run_steps(2);
+    assert_eq!(h.state_mut().state_mut().reports.range, Range::YearToDate);
+    h.state_mut()
+        .show(report(Some("2026-09-01"), Some("2026-09-30")));
+    h.run_steps(2);
+    assert_eq!(h.state_mut().state_mut().reports.range, Range::LastMonth);
+    // Only a start: through today.
+    h.state_mut().show(report(Some("2026-03-15"), None));
+    h.run_steps(2);
+    assert_eq!(
+        h.state_mut().state_mut().reports.range,
+        Range::Custom(day(2026, 3, 15), today)
+    );
+    // An account with no dates (an earlier writer's): the default.
+    h.state_mut().state_mut().accounts.range = RegisterRange::All;
+    h.state_mut().show(ViewerTarget::Account {
+        code: "1000".into(),
+        start: None,
+        end: None,
+    });
+    h.run_steps(2);
+    assert_eq!(
+        h.state_mut().state_mut().accounts.range,
+        RegisterRange::Default
+    );
+    assert_eq!(
+        RegisterRange::Default.dates(&books),
+        (day(2026, 1, 1), today)
+    );
+}
+
+/// Settled in design (P3, defect 16): an account's register opens on the
+/// fiscal year to date with "Show all dates" one click away: after
+/// books.show of an account (which sends the resolved dates), the button
+/// shows every date, the books' first entry through today; from there,
+/// "Fiscal year to date" goes back.
+#[test]
+fn show_all_dates_is_one_click_from_a_shown_register() {
+    use egui_kittest::kittest::Queryable;
+    use ledger_gui::pages::accounts::RegisterRange;
+    let today = day(2026, 10, 20);
+    let (_dir, mut h, books) = demo_sized("all-dates", today, 3000.0);
+    let id = books.ledger.chart().find_by_code("1000").unwrap().id;
+    h.state_mut().show(ViewerTarget::Account {
+        code: "1000".into(),
+        start: Some("2026-01-01".into()),
+        end: Some("2026-10-20".into()),
+    });
+    h.run_steps(2);
+    assert_eq!(h.state_mut().route(), &Route::Account(id));
+    assert_eq!(
+        h.state_mut().state_mut().accounts.range,
+        RegisterRange::Dates(day(2026, 1, 1), today)
+    );
+    h.get_by_label("Show all dates").click();
+    h.run_steps(2);
+    assert_eq!(h.state_mut().state_mut().accounts.range, RegisterRange::All);
+    let first = books.kpis.first_entry.unwrap();
+    assert_eq!(RegisterRange::All.dates(&books), (first.min(today), today));
+    assert!(
+        first < day(2026, 1, 1),
+        "the demo's books began before this year"
+    );
+    h.get_by_label("Fiscal year to date").click();
+    h.run_steps(2);
+    assert_eq!(
+        h.state_mut().state_mut().accounts.range,
+        RegisterRange::Default
+    );
+}