DRY pass #2, batch 7, F21: the desktop's main window, clock and launcher dir (#5372)

- lib.rs MAIN_WINDOW: the "main" window label that the reminder worker,
  the capture window and the shell each wrote, 5 sites in all.
- lib.rs now_ms(): the epoch-milliseconds clock that the reminder worker
  and autosync's cycle stamp each computed. LastCycle.at_ms becomes i64,
  the same number on the wire.
- integration.rs applications_dir(): the XDG launcher directory that the
  entry path and the desktop-database refresh each built.

rustfmt --check is clean in the CI image.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

desktop/src-tauri/src/autosync.rs

@@ -46,7 +46,7 @@
 
 use std::sync::mpsc::{self, Receiver, RecvTimeoutError, Sender};
 use std::sync::Mutex;
-use std::time::{Duration, Instant, SystemTime, UNIX_EPOCH};
+use std::time::{Duration, Instant};
 
 use serde::Serialize;
 use tauri::{AppHandle, Emitter, Manager};
@@ -85,7 +85,7 @@ pub enum Trigger {
 #[derive(Debug, Clone, Serialize)]
 pub struct LastCycle {
     /// When it finished, in milliseconds since the epoch — the frontend formats it.
-    pub at_ms: u64,
+    pub at_ms: i64,
     pub trigger: Trigger,
     pub ok: bool,
     /// Why it failed, in words a person can act on. None when `ok`.
@@ -299,9 +299,7 @@ fn worker(app: AppHandle, rx: Receiver<Request>) {
         }
 
         let cycle = LastCycle {
-            at_ms: SystemTime::now()
-                .duration_since(UNIX_EPOCH)
-                .map_or(0, |d| d.as_millis() as u64),
+            at_ms: crate::now_ms(),
             trigger,
             ok: result.is_ok(),
             error: result.as_ref().err().cloned(),

desktop/src-tauri/src/capture.rs

@@ -214,7 +214,7 @@ pub fn capture_done(saved: bool, app: AppHandle) -> Result<(), String> {
         window.hide().map_err(|e| e.to_string())?;
     }
     if saved {
-        if let Some(main) = app.get_webview_window("main") {
+        if let Some(main) = app.get_webview_window(crate::MAIN_WINDOW) {
             // Failure here is cosmetic — the note is saved either way and the board
             // will show it on its next load — so it is logged, not raised.
             if let Err(e) = main.emit(CAPTURED_EVENT, ()) {

desktop/src-tauri/src/integration.rs

@@ -42,8 +42,13 @@ fn appimage_path() -> Option<PathBuf> {
     std::env::var_os("APPIMAGE").map(PathBuf::from)
 }
 
+/// Where per-user launchers live (XDG): `~/.local/share/applications`.
+fn applications_dir(home: &Path) -> PathBuf {
+    home.join(".local/share/applications")
+}
+
 fn desktop_entry_path() -> Option<PathBuf> {
-    home().map(|h| h.join(".local/share/applications").join(DESKTOP_ENTRY_NAME))
+    home().map(|h| applications_dir(&h).join(DESKTOP_ENTRY_NAME))
 }
 
 fn icon_path() -> Option<PathBuf> {
@@ -154,7 +159,7 @@ fn set_executable(_p: &Path) -> Result<(), String> {
 // Best-effort: refresh the desktop database so the entry appears promptly. The entry
 // still works on next login without it, so failures are ignored.
 fn refresh_desktop_database(home: &Path) {
-    let apps = home.join(".local/share/applications");
+    let apps = applications_dir(home);
     let _ = std::process::Command::new("update-desktop-database")
         .arg(&apps)
         .output();

desktop/src-tauri/src/lib.rs

@@ -54,6 +54,18 @@ pub(crate) fn display_version() -> &'static str {
 // this crate — the extraction changed where they live, not what they are.
 use inkwell_core::{local, sync};
 
+/// The app's own window, as `tauri.conf.json` names it. The capture window is the
+/// other one (`capture::CAPTURE_WINDOW`).
+pub(crate) const MAIN_WINDOW: &str = "main";
+
+/// Milliseconds since the Unix epoch: the unit the page's clocks and the reminder
+/// worker count in. 0 for a clock set before 1970.
+pub(crate) fn now_ms() -> i64 {
+    std::time::SystemTime::now()
+        .duration_since(std::time::UNIX_EPOCH)
+        .map_or(0, |d| d.as_millis() as i64)
+}
+
 pub fn run() {
     use tauri_plugin_log::{Target, TargetKind};
 
@@ -156,7 +168,7 @@ pub fn run() {
             reminders::start(app.handle())?;
             // Coming back to the window is when someone is about to look, so it asks
             // for a cycle. Rate-limited in autosync, because focus flaps constantly.
-            if let Some(window) = app.get_webview_window("main") {
+            if let Some(window) = app.get_webview_window(MAIN_WINDOW) {
                 let handle = app.handle().clone();
                 window.on_window_event(move |event| {
                     if let tauri::WindowEvent::Focused(true) = event {
@@ -243,7 +255,7 @@ pub fn run() {
 /// colour, is a cosmetic loss and must never stop the app from opening.
 fn paint_window_before_the_webview_does(app: &tauri::App) {
     use tauri::Manager;
-    let Some(window) = app.get_webview_window("main") else {
+    let Some(window) = app.get_webview_window(MAIN_WINDOW) else {
         return;
     };
     // Unknown theme reads as light, matching the platform default we'd get anyway.

desktop/src-tauri/src/reminders.rs

@@ -21,7 +21,7 @@
 //! reports clicks only on mobile. The toast waiting in the window does.
 
 use std::collections::HashMap;
-use std::time::{Duration, SystemTime, UNIX_EPOCH};
+use std::time::Duration;
 
 use tauri::{AppHandle, Emitter, Manager};
 use tauri_plugin_notification::NotificationExt;
@@ -53,7 +53,7 @@ fn worker(app: AppHandle) {
     let mut announcer = Announcer::default();
     loop {
         std::thread::sleep(TICK);
-        let now = now_ms();
+        let now = crate::now_ms();
         let due = match due(&app, now) {
             Ok(due) => due,
             Err(e) => {
@@ -74,7 +74,7 @@ fn due(app: &AppHandle, now: i64) -> Result<Vec<DueReminder>, String> {
 }
 
 fn announce(app: &AppHandle, reminder: &DueReminder) {
-    if let Err(e) = app.emit_to("main", DUE_EVENT, reminder) {
+    if let Err(e) = app.emit_to(crate::MAIN_WINDOW, DUE_EVENT, reminder) {
         log::warn!("could not tell the window about a due reminder: {e}");
     }
     if main_window_in_front(app) {
@@ -99,16 +99,10 @@ fn announce(app: &AppHandle, reminder: &DueReminder) {
 /// Whether someone is looking at the main window right now. Unknown counts as no:
 /// a duplicate alert is a smaller failure than a missed one.
 fn main_window_in_front(app: &AppHandle) -> bool {
-    app.get_webview_window("main")
+    app.get_webview_window(crate::MAIN_WINDOW)
         .is_some_and(|w| w.is_focused().unwrap_or(false) && !w.is_minimized().unwrap_or(true))
 }
 
-fn now_ms() -> i64 {
-    SystemTime::now()
-        .duration_since(UNIX_EPOCH)
-        .map_or(0, |d| d.as_millis() as i64)
-}
-
 /// Which occurrences have been announced. Keyed by note id, holding the `remind_at`
 /// announced: completing or snoozing a reminder changes that value, so the next
 /// occurrence is new to it.