feat(windows): surface shortcuts on a Help screen; exit fullscreen when the stream stops

The in-stream keyboard shortcuts were only reachable deep in Settings > Input.
Move them to a dedicated Help screen reached from a Help button on the host
list (mirrors the Licenses screen — a hook-free page routed from root), and drop
the reference card out of Settings so there's one home for it.

Fullscreen (F11) was a window-style toggle that stream stop never undid, so
disconnecting while fullscreen left the GUI borderless-fullscreen. Split
toggle_fullscreen into is_fullscreen/enter_fullscreen/exit_fullscreen sharing a
module-level SAVED_PLACEMENT, and have input::uninstall() call exit_fullscreen()
on teardown. exit_fullscreen is a no-op when nothing was saved, so it's safe on
every stream stop and idempotent with F11 — fullscreen is now streaming-only.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

clients/windows/src/app/help.rs

@@ -0,0 +1,90 @@
+//! The Help screen: a short note on the in-stream capture model plus a reference of the keyboard
+//! shortcuts — reached from the Help button on the host list. The Windows counterpart of the GTK
+//! client's Keyboard Shortcuts window; the bindings themselves live in [`crate::input`], so both
+//! clients document the same set.
+
+use super::style::*;
+use super::Screen;
+use windows_reactor::*;
+
+/// The in-stream keyboard shortcuts, in the GTK Shortcuts window's order: the chord, then what it
+/// does. Read-only — the bindings themselves live in the input hook ([`crate::input`]).
+const STREAM_SHORTCUTS: &[(&str, &str)] = &[
+    ("F11", "Toggle fullscreen"),
+    (
+        "Ctrl+Alt+Shift+Q",
+        "Release captured input (click the stream to recapture)",
+    ),
+    ("Ctrl+Alt+Shift+D", "Disconnect"),
+    ("Ctrl+Alt+Shift+S", "Toggle the statistics overlay"),
+];
+
+/// A subtle key-cap chip for the shortcuts reference — the chord on a filled, bordered pill.
+fn key_chip(keys: &str) -> Element {
+    border(text_block(keys).font_size(12.0).semibold())
+        .background(ThemeRef::SubtleFill)
+        .border_brush(ThemeRef::CardStroke)
+        .border_thickness(uniform(1.0))
+        .corner_radius(6.0)
+        .padding(edges(8.0, 3.0, 8.0, 3.0))
+        .horizontal_alignment(HorizontalAlignment::Left)
+        .into()
+}
+
+/// A read-only reference card listing the in-stream keyboard shortcuts. One grid, chord chip then
+/// action, so the actions line up across rows.
+fn shortcuts_reference() -> Element {
+    let mut children: Vec<Element> = Vec::new();
+    for (i, (keys, action)) in STREAM_SHORTCUTS.iter().enumerate() {
+        let row = i as i32;
+        children.push(key_chip(keys).grid_row(row).grid_column(0));
+        let action_cell: Element = text_block(*action)
+            .foreground(ThemeRef::SecondaryText)
+            .vertical_alignment(VerticalAlignment::Center)
+            .into();
+        children.push(action_cell.grid_row(row).grid_column(1));
+    }
+    let table = grid(children)
+        .columns([GridLength::Auto, GridLength::Star(1.0)])
+        .rows(vec![GridLength::Auto; STREAM_SHORTCUTS.len()])
+        .column_spacing(12.0)
+        .row_spacing(6.0);
+    card(vstack((
+        text_block("In-stream keyboard shortcuts")
+            .semibold()
+            .margin(edges(0.0, 0.0, 0.0, 8.0)),
+        table,
+    )))
+    .into()
+}
+
+/// The Help screen: a `page`-column with a Back button to the host list, an intro card on the
+/// capture model, and the shortcuts reference. Hook-free — called inline from `root` like the
+/// other static screens.
+pub(crate) fn help_page(set_screen: &AsyncSetState<Screen>) -> Element {
+    let back_btn = button("Back").accent().icon(Symbol::Back).on_click({
+        let ss = set_screen.clone();
+        move || ss.call(Screen::Hosts)
+    });
+
+    let intro = card(
+        vstack((
+            text_block("During a stream").font_size(15.0).semibold(),
+            text_block(
+                "Click the stream to capture your mouse and keyboard \u{2014} the shortcuts below \
+                 then work while you play. Release capture to hand the cursor back to this \
+                 computer, and click the stream again to retake it.",
+            )
+            .font_size(12.0)
+            .wrap()
+            .foreground(ThemeRef::SecondaryText),
+        ))
+        .spacing(8.0),
+    );
+
+    page(vec![
+        page_header("Help", back_btn),
+        intro.into(),
+        shortcuts_reference(),
+    ])
+}

clients/windows/src/app/hosts.rs

@@ -277,6 +277,10 @@ pub(crate) fn hosts_page(props: &HostsProps, cx: &mut RenderCx) -> Element {
                     let sa = set_show_add.clone();
                     move || sa.call(true)
                 }),
+                button("Help").icon(Symbol::Help).on_click({
+                    let ss = set_screen.clone();
+                    move || ss.call(Screen::Help)
+                }),
                 button("Settings").icon(Symbol::Setting).on_click({
                     let ss = set_screen.clone();
                     move || ss.call(Screen::Settings)

clients/windows/src/app/mod.rs

@@ -8,7 +8,8 @@
 //! * [`connect`] — the trust gate and session lifecycle glue (connect / request-access flows)
 //! * [`pair`] — the SPAKE2 PIN pairing ceremony
 //! * [`speed`] — the per-host network speed test (probe burst over the real data plane)
-//! * [`settings`] — persisted preferences · [`licenses`] — the license notices screen
+//! * [`settings`] — persisted preferences · [`licenses`] — the license notices screen ·
+//!   [`help`] — the in-stream keyboard-shortcuts reference (reached from the host list)
 //! * [`stream`] — the live stream: `SwapChainPanel` + D3D11 presenter + HUD overlay
 //! * [`style`] — the shared look (cards, pills, monograms), following the windows-reactor
 //!   gallery: Mica backdrop, a centred max-width column, theme brushes (`ThemeRef`)
@@ -23,6 +24,7 @@
 //! present must not go through state/rerender.
 
 mod connect;
+mod help;
 mod hosts;
 mod licenses;
 mod pair;
@@ -57,6 +59,9 @@ pub(crate) enum Screen {
     Settings,
     /// Open-source / third-party license notices (reached from Settings).
     Licenses,
+    /// In-stream keyboard-shortcuts reference + capture help (reached from the host list's Help
+    /// button).
+    Help,
     Pair,
     /// Per-host network speed test (probe burst + recommended bitrate).
     SpeedTest,
@@ -382,8 +387,8 @@ fn root(cx: &mut RenderCx, ctx: &Arc<AppCtx>) -> Element {
                 set_hover,
             },
         ),
-        // connecting_page / request_access_page / waking_page / settings_page / licenses_page use
-        // no hooks (they never touch `cx`), so calling them inline is sound.
+        // connecting_page / request_access_page / waking_page / settings_page / licenses_page /
+        // help_page use no hooks (they never touch `cx`), so calling them inline is sound.
         Screen::Connecting => connect::connecting_page(ctx, &status),
         Screen::RequestAccess => connect::request_access_page(ctx, &set_screen),
         Screen::Waking => connect::waking_page(ctx, &set_screen),
@@ -395,6 +400,7 @@ fn root(cx: &mut RenderCx, ctx: &Arc<AppCtx>) -> Element {
             nav_progress,
         ),
         Screen::Licenses => licenses::licenses_page(&set_screen),
+        Screen::Help => help::help_page(&set_screen),
         Screen::Pair => component(pair::pair_page, svc),
         Screen::SpeedTest => component(speed::speed_page, SpeedProps { svc, state: speed }),
         Screen::Stream => component(stream::stream_page, StreamProps { svc, hud }),

clients/windows/src/app/settings.rs

@@ -109,59 +109,6 @@ fn settings_card(controls: Vec<Element>) -> Element {
     card(vstack(controls).spacing(10.0)).into()
 }
 
-/// The in-stream keyboard shortcuts, in the GTK Shortcuts window's order: the chord, then what it
-/// does. Read-only — the bindings themselves live in the input hook (`crate::input`); this is the
-/// Windows analogue of that window, so both clients document the same set.
-const STREAM_SHORTCUTS: &[(&str, &str)] = &[
-    ("F11", "Toggle fullscreen"),
-    (
-        "Ctrl+Alt+Shift+Q",
-        "Release captured input (click the stream to recapture)",
-    ),
-    ("Ctrl+Alt+Shift+D", "Disconnect"),
-    ("Ctrl+Alt+Shift+S", "Toggle the statistics overlay"),
-];
-
-/// A subtle key-cap chip for the shortcuts reference — the chord on a filled, bordered pill.
-fn key_chip(keys: &str) -> Element {
-    border(text_block(keys).font_size(12.0).semibold())
-        .background(ThemeRef::SubtleFill)
-        .border_brush(ThemeRef::CardStroke)
-        .border_thickness(uniform(1.0))
-        .corner_radius(6.0)
-        .padding(edges(8.0, 3.0, 8.0, 3.0))
-        .horizontal_alignment(HorizontalAlignment::Left)
-        .into()
-}
-
-/// A read-only reference card listing the in-stream keyboard shortcuts — the Windows counterpart of
-/// the GTK client's Keyboard Shortcuts window. One grid, chord chip then action, so the actions
-/// line up across rows.
-fn shortcuts_reference() -> Element {
-    let mut children: Vec<Element> = Vec::new();
-    for (i, (keys, action)) in STREAM_SHORTCUTS.iter().enumerate() {
-        let row = i as i32;
-        children.push(key_chip(keys).grid_row(row).grid_column(0));
-        let action_cell: Element = text_block(*action)
-            .foreground(ThemeRef::SecondaryText)
-            .vertical_alignment(VerticalAlignment::Center)
-            .into();
-        children.push(action_cell.grid_row(row).grid_column(1));
-    }
-    let table = grid(children)
-        .columns([GridLength::Auto, GridLength::Star(1.0)])
-        .rows(vec![GridLength::Auto; STREAM_SHORTCUTS.len()])
-        .column_spacing(12.0)
-        .row_spacing(6.0);
-    card(vstack((
-        text_block("In-stream keyboard shortcuts")
-            .semibold()
-            .margin(edges(0.0, 0.0, 0.0, 8.0)),
-        table,
-    )))
-    .into()
-}
-
 /// The settings screen: a stock WinUI `NavigationView` (the Windows-Settings sidebar pattern) —
 /// one pane item per section, the section's card as the content, the built-in back arrow
 /// returning to the host list. `section`/`set_section` are the selected pane tag, held in ROOT
@@ -399,16 +346,11 @@ pub(crate) fn settings_page(
         ),
         "input" => (
             "Input",
-            vstack((
-                settings_card(vec![
-                    forward_combo.into(),
-                    pad_combo.into(),
-                    shortcuts_toggle.into(),
-                ]),
-                shortcuts_reference(),
-            ))
-            .spacing(14.0)
-            .into(),
+            settings_card(vec![
+                forward_combo.into(),
+                pad_combo.into(),
+                shortcuts_toggle.into(),
+            ]),
         ),
         "audio" => (
             "Audio",