diff --git a/crates/qbz-core/src/system_capabilities.rs b/crates/qbz-core/src/system_capabilities.rs
index c9e773a87..aa272bfab 100644
--- a/crates/qbz-core/src/system_capabilities.rs
+++ b/crates/qbz-core/src/system_capabilities.rs
@@ -43,6 +43,11 @@ pub struct MemoryProfile {
     /// (44.1 kHz / 16-bit FLAC) so each cached track stays under ~15 MB
     /// instead of ~60 MB.
     pub allow_hires_prefetch: bool,
+    /// Upper bound for the L1 (in-memory) audio cache. The default
+    /// 400 MB cap is sized for Normal-class desktops; on a Pi 3B (1 GB
+    /// total) that single subsystem could consume 40 % of RAM, which
+    /// guarantees swap thrash before the watchdog can react.
+    pub audio_cache_l1_max_bytes: usize,
 }
 
 impl MemoryProfile {
@@ -61,6 +66,7 @@ impl MemoryProfile {
                 max_initial_buffer_bytes: 2 * 1024 * 1024,
                 max_concurrent_prefetch: 2,
                 allow_hires_prefetch: true,
+                audio_cache_l1_max_bytes: 400 * 1024 * 1024,
             }
         } else {
             Self {
@@ -70,6 +76,7 @@ impl MemoryProfile {
                 max_initial_buffer_bytes: 256 * 1024,
                 max_concurrent_prefetch: 1,
                 allow_hires_prefetch: false,
+                audio_cache_l1_max_bytes: 50 * 1024 * 1024,
             }
         }
     }
@@ -238,6 +245,17 @@ SwapTotal:       2097152 kB
         assert_eq!(profile.max_concurrent_prefetch, 1);
         assert!(!profile.allow_hires_prefetch);
         assert!(profile.max_initial_buffer_bytes <= 256 * 1024);
+        // L1 cap must be a small fraction of total RAM — at most ~10 %
+        // of a Pi 3B, so we don't reserve four-tenths of memory for one
+        // subsystem on a 1 GB host.
+        assert!(profile.audio_cache_l1_max_bytes <= 100 * 1024 * 1024);
+    }
+
+    #[test]
+    fn audio_cache_cap_is_significantly_smaller_on_low_memory() {
+        let normal = MemoryProfile::from_total_kb(8 * 1024 * 1024);
+        let low = MemoryProfile::from_total_kb(938196);
+        assert!(low.audio_cache_l1_max_bytes < normal.audio_cache_l1_max_bytes);
     }
 
     #[test]
diff --git a/src-tauri/src/lib.rs b/src-tauri/src/lib.rs
index e9be222d9..c7dfa6545 100644
--- a/src-tauri/src/lib.rs
+++ b/src-tauri/src/lib.rs
@@ -134,9 +134,13 @@ impl AppState {
             }
         };
 
-        // Create audio cache (L1 - memory, 400MB) with optional disk spillover
+        // Create audio cache (L1 - memory) with optional disk spillover.
+        // The L1 cap is sized per host: Normal hosts get the historical
+        // 400 MB; LowMemory hosts (issue #331) drop to 50 MB so the cache
+        // alone can never claim 40 % of a 1 GB Pi.
+        let l1_cap = qbz_core::system_capabilities::memory_profile().audio_cache_l1_max_bytes;
         let audio_cache = if let Some(pc) = playback_cache {
-            Arc::new(AudioCache::with_playback_cache(400 * 1024 * 1024, pc))
+            Arc::new(AudioCache::with_playback_cache(l1_cap, pc))
         } else {
             Arc::new(AudioCache::default())
         };