feat: ledger-gui — a read-only, live desktop view of the books

egui/wgpu app for owners and their accountant: Overview, Cash, Profit,
Transactions (with rendered receipts and journal history), Reports
(statements with interval columns, comparisons, drill-down), Accounts,
Documents, Company, Journal; Ctrl+K palette; back/forward; light/dark.
Follows the journal live (~30 ms from write to screen). --demo opens a
deterministic demo company, also used for screenshot tests.

Engine: ledger-store Snapshot (read-only, incremental, tolerant of a
half-written tail); ledger-core analysis (intervals, balance series,
P&L by interval, cash flows); ledger-config extracted from ledger-mcp
with the full company profile and cash_accounts.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MtYEaR6M6Ybdhm6X98BWNu

crates/ledger-gui/src/main.rs

@@ -0,0 +1,72 @@
+//! `ledger-gui [--data-dir PATH] [--books-toml PATH] [--today YYYY-MM-DD] [--demo]`
+//!
+//! Opens the books read-only and follows them live. With no flags it looks
+//! for `books-data/` and `wanderbooks.toml` in the current directory.
+//! `--demo` builds a demo company in a temp directory and opens that.
+
+use ledger_gui::{App, Source};
+use std::path::PathBuf;
+
+fn main() -> eframe::Result<()> {
+    let mut data_dir: Option<PathBuf> = None;
+    let mut books_toml: Option<PathBuf> = None;
+    let mut today = None;
+    let mut demo = false;
+    let mut args = std::env::args().skip(1);
+    while let Some(a) = args.next() {
+        match a.as_str() {
+            "--data-dir" => data_dir = args.next().map(PathBuf::from),
+            "--books-toml" => books_toml = args.next().map(PathBuf::from),
+            "--today" => today = args.next().and_then(|d| d.parse().ok()),
+            "--demo" => demo = true,
+            "-h" | "--help" => {
+                println!(
+                    "usage: ledger-gui [--data-dir PATH] [--books-toml PATH] [--today YYYY-MM-DD] [--demo]"
+                );
+                return Ok(());
+            }
+            other => {
+                eprintln!("unknown argument {other}");
+                std::process::exit(2);
+            }
+        }
+    }
+    if demo {
+        let d = today.unwrap_or_else(|| chrono::Local::now().date_naive());
+        let dir = std::env::temp_dir().join(format!("wanderbooks-demo-{d}"));
+        let _ = std::fs::remove_dir_all(&dir);
+        if let Err(e) = ledger_gui::demo::build(&dir, d) {
+            eprintln!("building the demo books failed: {e}");
+            std::process::exit(1);
+        }
+        eprintln!("demo books: {}", dir.display());
+        data_dir = Some(dir.join("books-data"));
+        books_toml = Some(dir.join("wanderbooks.toml"));
+    }
+    let data_dir = data_dir.unwrap_or_else(|| PathBuf::from("books-data"));
+    let books_toml = books_toml.or_else(|| {
+        let guess = data_dir
+            .parent()
+            .unwrap_or(&data_dir)
+            .join("wanderbooks.toml");
+        guess.exists().then_some(guess)
+    });
+    let source = Source {
+        data_dir,
+        books_toml,
+        today,
+    };
+    let options = eframe::NativeOptions {
+        viewport: egui::ViewportBuilder::default()
+            .with_title("wanderbooks")
+            .with_app_id("wanderbooks")
+            .with_inner_size([1440.0, 920.0])
+            .with_min_inner_size([900.0, 600.0]),
+        ..Default::default()
+    };
+    eframe::run_native(
+        "wanderbooks",
+        options,
+        Box::new(move |cc| Ok(Box::new(App::new(cc, source)))),
+    )
+}