Cap per-page texture caches to stop unbounded RSS growth

Every page held an uncapped HashMap<String, gdk::Texture> that only ever grew
— gdk textures keep their decoded RGBA resident, so every image/avatar/cover
scrolled past stayed in memory for the session (the multi-GB RSS climb). Add a
bounded TextureCache (insertion-order eviction past 200 textures; the core
disk/byte cache still holds the source for cheap re-decode) and use it on all
seven pages.

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

crates/sunstone-gtk/src/components/media.rs

@@ -1,8 +1,68 @@
 //! Texture helpers: decode-at-size so a 4000px photo never becomes a
 //! 4000px texture for a 34px avatar.
 
+use std::collections::{HashMap, VecDeque};
+
 use relm4::gtk::{gdk, gdk_pixbuf, prelude::*};
 
+/// Bounded texture cache. gdk textures keep their decoded RGBA in memory, so an
+/// uncapped per-page `HashMap<String, Texture>` pinned every image ever
+/// scrolled past — the cause of the multi-GB RSS climb. This evicts in
+/// insertion order past `cap` (the disk/byte cache in core still holds the
+/// source, so re-display just re-decodes, no network). Capacity is in number of
+/// textures; with decode-at-size that bounds the footprint.
+#[derive(Debug)]
+pub struct TextureCache {
+    map: HashMap<String, gdk::Texture>,
+    order: VecDeque<String>,
+    cap: usize,
+}
+
+impl TextureCache {
+    pub fn new(cap: usize) -> Self {
+        Self {
+            map: HashMap::new(),
+            order: VecDeque::new(),
+            cap: cap.max(1),
+        }
+    }
+
+    pub fn get(&self, url: &str) -> Option<&gdk::Texture> {
+        self.map.get(url)
+    }
+
+    pub fn contains_key(&self, url: &str) -> bool {
+        self.map.contains_key(url)
+    }
+
+    pub fn insert(&mut self, url: String, texture: gdk::Texture) {
+        if self.map.insert(url.clone(), texture).is_none() {
+            self.order.push_back(url);
+        }
+        while self.map.len() > self.cap {
+            let Some(old) = self.order.pop_front() else { break };
+            self.map.remove(&old);
+        }
+    }
+
+    pub fn len(&self) -> usize {
+        self.map.len()
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.map.is_empty()
+    }
+
+    pub fn clear(&mut self) {
+        self.map.clear();
+        self.order.clear();
+    }
+
+    pub fn values(&self) -> impl Iterator<Item = &gdk::Texture> {
+        self.map.values()
+    }
+}
+
 /// Avatars and other small chrome.
 pub const AVATAR_PX: i32 = 128;
 /// Inline note images, stream/video thumbnails.

crates/sunstone-gtk/src/pages/bookmarks.rs

@@ -75,7 +75,7 @@ pub struct BookmarksWidgets {
     refresh_btn: gtk::Button,
     avatar_slots: HashMap<String, Vec<adw::Avatar>>,
     picture_slots: HashMap<String, Vec<gtk::Picture>>,
-    textures: HashMap<String, gdk::Texture>,
+    textures: crate::components::media::TextureCache,
 }
 
 fn ref_label(item: &BookmarkRef) -> String {
@@ -589,7 +589,7 @@ impl Component for BookmarksPage {
             refresh_btn,
             avatar_slots: HashMap::new(),
             picture_slots: HashMap::new(),
-            textures: HashMap::new(),
+            textures: crate::components::media::TextureCache::new(200),
         };
         // Data load is triggered lazily by main_view on first view.
         ComponentParts { model, widgets }

crates/sunstone-gtk/src/pages/feed.rs

@@ -275,7 +275,7 @@ pub struct FeedWidgets {
     poll_slots: HashMap<EventId, Vec<(String, gtk::ProgressBar)>>,
     avatar_slots: HashMap<String, Vec<adw::Avatar>>,
     picture_slots: HashMap<String, Vec<gtk::Picture>>,
-    textures: HashMap<String, gdk::Texture>,
+    textures: crate::components::media::TextureCache,
 }
 
 /// Hard caps on the feed list. The ListBox isn't virtualised, so every row
@@ -2148,7 +2148,7 @@ impl Component for FeedPage {
             poll_slots: HashMap::new(),
             avatar_slots: HashMap::new(),
             picture_slots: HashMap::new(),
-            textures: HashMap::new(),
+            textures: crate::components::media::TextureCache::new(200),
         };
         model.rebuild_sources(&mut widgets);
         {

crates/sunstone-gtk/src/pages/groups.rs

@@ -6,7 +6,7 @@ use std::sync::Arc;
 
 use relm4::adw;
 use relm4::adw::prelude::*;
-use relm4::gtk::{gdk, glib};
+use relm4::gtk::glib;
 use relm4::prelude::*;
 use sunstone_core::groups::{Group, GroupRef};
 use sunstone_core::nostr_sdk::prelude::*;
@@ -86,7 +86,7 @@ pub struct GroupsWidgets {
     chat_entry: gtk::Entry,
     leave_btn: gtk::Button,
     avatar_slots: HashMap<String, Vec<adw::Avatar>>,
-    textures: HashMap<String, gdk::Texture>,
+    textures: crate::components::media::TextureCache,
 }
 
 fn chat_row(message: &ChatMessage) -> gtk::ListBoxRow {
@@ -523,7 +523,7 @@ impl Component for GroupsPage {
             chat_entry,
             leave_btn,
             avatar_slots: HashMap::new(),
-            textures: HashMap::new(),
+            textures: crate::components::media::TextureCache::new(200),
         };
 
         // Live chat pump.

crates/sunstone-gtk/src/pages/messages.rs

@@ -7,7 +7,7 @@ use std::time::Duration;
 
 use relm4::adw;
 use relm4::adw::prelude::*;
-use relm4::gtk::{gdk, glib};
+use relm4::gtk::glib;
 use relm4::prelude::*;
 use sunstone_core::dms::{Conversation, DirectMessage};
 use sunstone_core::nostr_sdk::prelude::*;
@@ -59,7 +59,7 @@ pub struct MessagesWidgets {
     chat_entry: gtk::Entry,
     error_label: gtk::Label,
     avatar_slots: HashMap<String, Vec<adw::Avatar>>,
-    textures: HashMap<String, gdk::Texture>,
+    textures: crate::components::media::TextureCache,
 }
 
 fn message_time(at: Timestamp) -> String {
@@ -451,7 +451,7 @@ impl Component for MessagesPage {
             chat_entry,
             error_label,
             avatar_slots: HashMap::new(),
-            textures: HashMap::new(),
+            textures: crate::components::media::TextureCache::new(200),
         };
 
         // Long-lived gift wrap subscription + notification pump.

crates/sunstone-gtk/src/pages/notifications.rs

@@ -6,7 +6,7 @@ use std::sync::Arc;
 
 use relm4::adw;
 use relm4::adw::prelude::*;
-use relm4::gtk::{gdk, glib};
+use relm4::gtk::glib;
 use relm4::prelude::*;
 use sunstone_core::notifications::{Notification, NotificationKind};
 use sunstone_core::nostr_sdk::prelude::*;
@@ -76,7 +76,7 @@ pub struct NotificationsWidgets {
     new_pill: gtk::Label,
     mark_read_btn: gtk::Button,
     avatar_slots: HashMap<String, Vec<adw::Avatar>>,
-    textures: HashMap<String, gdk::Texture>,
+    textures: crate::components::media::TextureCache,
 }
 
 /// Badge icon + colour class per kind. Mention is special-cased to an "@"
@@ -730,7 +730,7 @@ impl Component for NotificationsPage {
             new_pill,
             mark_read_btn,
             avatar_slots: HashMap::new(),
-            textures: HashMap::new(),
+            textures: crate::components::media::TextureCache::new(200),
         };
 
         // Live subscription + notification pump.

crates/sunstone-gtk/src/pages/streams.rs

@@ -5,7 +5,7 @@ use std::sync::Arc;
 
 use relm4::adw;
 use relm4::adw::prelude::*;
-use relm4::gtk::{gdk, glib};
+use relm4::gtk::glib;
 use relm4::prelude::*;
 use sunstone_core::nostr_sdk::prelude::*;
 use sunstone_core::streams::{stream_matches, ChatMessage, Stream, StreamStatus};
@@ -95,7 +95,7 @@ pub struct StreamsWidgets {
     chat_scroll: Option<gtk::ScrolledWindow>,
     picture_slots: HashMap<String, Vec<gtk::Picture>>,
     avatar_slots: HashMap<String, Vec<adw::Avatar>>,
-    textures: HashMap<String, gdk::Texture>,
+    textures: crate::components::media::TextureCache,
     /// Zap buttons per stream index (grid pill + player CTA), so the
     /// sending spinner hits the right button(s).
     zap_slots: HashMap<usize, Vec<gtk::Button>>,
@@ -753,7 +753,7 @@ impl Component for StreamsPage {
             chat_scroll: None,
             picture_slots: HashMap::new(),
             avatar_slots: HashMap::new(),
-            textures: HashMap::new(),
+            textures: crate::components::media::TextureCache::new(200),
             zap_slots: HashMap::new(),
             zap_feedback: crate::components::zap::ZapFeedback::new(),
         };

crates/sunstone-gtk/src/pages/videos.rs

@@ -5,7 +5,6 @@ use std::sync::Arc;
 
 use relm4::adw;
 use relm4::adw::prelude::*;
-use relm4::gtk::gdk;
 use relm4::prelude::*;
 use sunstone_core::video::Video;
 use sunstone_core::Core;
@@ -65,7 +64,7 @@ pub struct VideosWidgets {
     load_more: gtk::Button,
     picture_slots: HashMap<String, Vec<gtk::Picture>>,
     avatar_slots: HashMap<String, Vec<adw::Avatar>>,
-    textures: HashMap<String, gdk::Texture>,
+    textures: crate::components::media::TextureCache,
     /// Zap buttons per video index, for sending/result feedback.
     zap_slots: HashMap<usize, Vec<gtk::Button>>,
     zap_feedback: crate::components::zap::ZapFeedback,
@@ -432,7 +431,7 @@ impl Component for VideosPage {
             load_more,
             picture_slots: HashMap::new(),
             avatar_slots: HashMap::new(),
-            textures: HashMap::new(),
+            textures: crate::components::media::TextureCache::new(200),
             zap_slots: HashMap::new(),
             zap_feedback: crate::components::zap::ZapFeedback::new(),
         };