app: leave SIGHUP alone so nohup keeps the app running (#248 follow-up)

#445 also closed the window on SIGHUP, which overrides the SIG_IGN that
`nohup fieldcraft &` sets so the app outlives its terminal. A safe API cannot
ask whether a signal was ignored at launch, so SIGHUP keeps its default.
SIGTERM and SIGINT still close the window the normal way.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UhhZMBTviDQxZvwnyP89fo

apps/fieldcraft/Cargo.toml

@@ -25,7 +25,7 @@ ureq = { version = "3.4", default-features = false, features = ["rustls-no-provi
 rustls = { version = "0.23", default-features = false, features = ["ring", "std"] }
 getrandom = "0.3"
 
-# A termination signal (SIGTERM, SIGINT, SIGHUP) closes the window the normal way (terminate.rs).
+# A termination signal (SIGTERM, SIGINT) closes the window the normal way (terminate.rs).
 [target.'cfg(unix)'.dependencies]
 signal-hook = "0.3"
 

apps/fieldcraft/src/main.rs

@@ -268,7 +268,7 @@ fn main() -> eframe::Result {
                 log::info!("graphics {:?} {} ({}), MSAA {}x (requested {MSAA}x)", info.backend, info.name, info.driver, rs.msaa_samples);
                 app.set_wgpu(rs, DEPTH_BITS, rs.msaa_samples, &cc.egui_ctx);
             }
-            // `kill`, Ctrl-C or a logout closes the window as Close does: autosaved, no crash (#248).
+            // `kill` or Ctrl-C closes the window as Close does: autosaved, no crash (#248).
             let ctx = cc.egui_ctx.clone();
             if let Err(e) = terminate::watch(move || {
                 ctx.send_viewport_cmd(egui::ViewportCommand::Close);

apps/fieldcraft/src/terminate.rs

@@ -1,6 +1,6 @@
-//! A request to terminate (SIGTERM, SIGINT, SIGHUP on Unix) closes the window the normal way.
+//! A request to terminate (SIGTERM, SIGINT on Unix) closes the window the normal way.
 //!
-//! Without this, `kill PID`, Ctrl-C in the terminal, a session logout or a test harness's timeout
+//! Without this, `kill PID`, Ctrl-C in the terminal, a system shutdown or a test harness's timeout
 //! ended the process on the spot: no `on_exit`, so no last autosave and no clean end of the crash
 //! journal, and the next start filed an `unclean_exit` crash report for what was no crash (#248:
 //! "ended without a clean exit between commands (last: control ui.capture)" was an automation run
@@ -9,6 +9,10 @@
 //! so a run that still dies while closing says why. A second signal, for a window that does not
 //! close, ends the process at once with the signal's default action.
 //!
+//! SIGHUP is left alone: `nohup fieldcraft &` ignores it on purpose so the app outlives its
+//! terminal, and a handler would override that (a safe API cannot ask whether a signal was
+//! ignored at launch).
+//!
 //! Windows has no such signals: a window there is closed through its messages, which eframe
 //! already turns into a normal close.
 
@@ -16,7 +20,7 @@ use std::io;
 
 /// The signals that ask the app to terminate.
 #[cfg(unix)]
-const SIGNALS: [i32; 3] = [signal_hook::consts::SIGTERM, signal_hook::consts::SIGINT, signal_hook::consts::SIGHUP];
+const SIGNALS: [i32; 2] = [signal_hook::consts::SIGTERM, signal_hook::consts::SIGINT];
 
 /// The signal's usual name, for the log and the crash journal.
 #[cfg(unix)]
@@ -24,7 +28,6 @@ fn name(signal: i32) -> &'static str {
     match signal {
         signal_hook::consts::SIGTERM => "SIGTERM",
         signal_hook::consts::SIGINT => "SIGINT",
-        signal_hook::consts::SIGHUP => "SIGHUP",
         _ => "signal",
     }
 }

docs/crash-reports.md

@@ -78,8 +78,8 @@ diagnostics.bug_report` opens the form, `ui.prompt {"answer": "set", …}` sets
 **Check that reporting works:** with `FIELDCRAFT_CRASH_TEST=1`, `diagnostics.crash_test {mode}`
 crashes on purpose: `panic`, `recovered` or `abort` (reported at the next start).
 
-A request to terminate is no crash: on Linux and macOS, SIGTERM (`kill PID`), SIGINT (Ctrl-C)
-and SIGHUP close the window as **Close** does (unsaved work is autosaved for recovery, the
+A request to terminate is no crash: on Linux and macOS, SIGTERM (`kill PID`) and SIGINT (Ctrl-C)
+close the window as **Close** does (unsaved work is autosaved for recovery, the
 journal ends, no report). A second signal ends the app at once.
 
 ### How it stays cheap and small