feat(w7): recently-joined rooms list with one-click rejoin (P5)

Add a purely-local, most-recent-first recents list so users can hop back
into a room they were just in — meaningful now that rooms carry cosmetic
labels.

- src/recents.rs (new): `Recent {name, ticket, joined_at}`, `push_recent`
  (de-dupes by room `topic_id`, refresh-and-move-to-front, caps at
  RECENTS_MAX=12), `remove_recent`, `relative_time` ("5m ago"). 6 tests.
- PeerSpeakTicket::topic_of — the stable room identity used as the de-dup
  key (host addr + label change between members/sessions; topic doesn't).
- AppConfig.recents (`#[serde(default)]`, back-compat) — local UI state,
  never sent over the wire.
- Recorded on RoomJoined (label via label_of); rendered as a "Recent
  rooms" block in connect_card (each entry → JoinRecent, ✕ → RemoveRecent),
  shown only when non-empty.

Rejoin is best-effort by design: the stored ticket only admits us while
the room is still live and reachable (reliability is P6 discovery + the
member-issued ticket floor, not this list).

263 lib tests green, clippy --all-targets clean. Recents UI
screenshot-verified (seeded config → ages + Untitled-room fallback render).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/mod.rs

@@ -153,6 +153,11 @@ pub enum AppMessage {
     /// Join the gathering a friend is in (W7 B2), via the member ticket their
     /// presence reply carried. Mirrors a manual ticket join.
     JoinFriendRoom(String),
+    /// Rejoin a room from the recents list (W7 P5), via its stored ticket. Mirrors
+    /// a manual ticket join; best-effort (works only while the room is still live).
+    JoinRecent(String),
+    /// Drop a room from the recents list (W7 P5), the × on a recent entry.
+    RemoveRecent(String),
     EventOccurred(Event),
     NavigateToSettings,
     NavigateBack,
@@ -600,6 +605,16 @@ fn update(state: &mut AppState, message: AppMessage) -> Task<AppMessage> {
         AppMessage::UiEventReceived(event) => {
             match event {
                 UiEvent::RoomJoined { ticket, self_id } => {
+                    // Remember this gathering for one-click rejoin (W7 P5). The
+                    // emitted ticket is the canonical room door (topic + member
+                    // addr + label); push_recent de-dupes by topic and persists.
+                    let label = crate::network::PeerSpeakTicket::label_of(&ticket);
+                    let now = std::time::SystemTime::now()
+                        .duration_since(std::time::UNIX_EPOCH)
+                        .map(|d| d.as_secs())
+                        .unwrap_or(0);
+                    crate::recents::push_recent(&mut state.config.recents, label, ticket.clone(), now);
+                    state.config.save();
                     state.ticket = ticket;
                     state.self_id = self_id;
                     state.status_message = "Connected".to_string();
@@ -888,6 +903,29 @@ fn update(state: &mut AppState, message: AppMessage) -> Task<AppMessage> {
                 avatar: state.config.avatar.clone(),
             });
         }
+        AppMessage::JoinRecent(ticket) => {
+            // Rejoin a remembered room (same path as a manual ticket join). It's
+            // best-effort: the door only admits us while the room is still live.
+            let input_device = state.selected_input.as_ref().map(|d| d.name.clone());
+            let output_device = state.selected_output.as_ref().map(|d| d.name.clone());
+            state.status_message = "Rejoining a recent room...".to_string();
+            state.config.username = state.name.clone();
+            state.config.save();
+            state.mic_test_active = false;
+            let _ = state.controller.send(CoreCommand::Join {
+                name: state.name.clone(),
+                ticket,
+                room_name: String::new(), // rejoining: the label comes from the ticket
+                input_device,
+                output_device,
+                echo_cancellation: state.config.echo_cancellation_enabled,
+                avatar: state.config.avatar.clone(),
+            });
+        }
+        AppMessage::RemoveRecent(ticket) => {
+            crate::recents::remove_recent(&mut state.config.recents, &ticket);
+            state.config.save();
+        }
         AppMessage::ToggleNotifications(enabled) => {
             state.config.notifications_enabled = enabled;
             state.config.save();
@@ -1252,6 +1290,7 @@ fn connect_card(state: &AppState) -> Element<'_, AppMessage> {
     let color_subtext = pal.subtext;
     let color_blue = pal.blue;
     let color_lavender = pal.lavender;
+    let color_maroon = pal.maroon;
 
     let c_style = move |bg: Color, b_color: Color, radius: f32| {
         move |_theme: &Theme| container::Style {
@@ -1288,6 +1327,55 @@ fn connect_card(state: &AppState) -> Element<'_, AppMessage> {
         selection: color_blue,
     };
 
+    // Recently-joined rooms (W7 P5): a one-click rejoin list. Only shown when
+    // non-empty so the launch card stays clean on a fresh install.
+    let recents_group: Element<AppMessage> = if state.config.recents.is_empty() {
+        column![].into()
+    } else {
+        let now = std::time::SystemTime::now()
+            .duration_since(std::time::UNIX_EPOCH)
+            .map(|d| d.as_secs())
+            .unwrap_or(0);
+        let mut rows = column![].spacing(6).width(iced::Length::Fill);
+        for r in &state.config.recents {
+            let label = {
+                let n = crate::sanitize::sanitize_name(&r.name);
+                if n.is_empty() { "Untitled room".to_string() } else { n }
+            };
+            let when = crate::recents::relative_time(now, r.joined_at);
+            let entry = button(
+                row![
+                    text(label).size(14).color(color_text),
+                    horizontal_space(),
+                    text(when).size(11).color(color_subtext),
+                ]
+                .align_y(iced::alignment::Vertical::Center),
+            )
+            .on_press(AppMessage::JoinRecent(r.ticket.clone()))
+            .style(b_style(color_crust, color_surface, color_text, 6.0))
+            .padding(8)
+            .width(iced::Length::Fill);
+            rows = rows.push(
+                row![
+                    entry,
+                    button(text("✕").size(12))
+                        .on_press(AppMessage::RemoveRecent(r.ticket.clone()))
+                        .style(b_style(color_surface, color_maroon, color_text, 6.0))
+                        .padding(8),
+                ]
+                .spacing(6)
+                .align_y(iced::alignment::Vertical::Center),
+            );
+        }
+        column![
+            text("Recent rooms").size(14).color(color_subtext),
+            vertical_space(4.0),
+            rows,
+        ]
+        .width(iced::Length::Fill)
+        .into()
+    };
+
     let logo = text("PEERSPEAK").size(36).color(color_blue);
     let subtitle = text("NAT-traversing full-mesh voice chat").size(16).color(color_subtext);
 
@@ -1345,6 +1433,8 @@ fn connect_card(state: &AppState) -> Element<'_, AppMessage> {
             text("— OR —").size(12).color(color_surface).align_x(iced::alignment::Horizontal::Center),
             vertical_space(16.0),
             join_group,
+            vertical_space(16.0),
+            recents_group,
             vertical_space(10.0),
             status
         ]