fix(seaweed-volume): eliminate global S3 tier registry races in tests

Multiple Rust tests were racing on the shared global S3TierRegistry by
calling clear(), which wiped entries registered by concurrently running
tests.  Use test-specific backend IDs and targeted remove() instead of
clear() so tests no longer interfere with each other.

seaweed-volume/src/remote_storage/s3_tier.rs

@@ -486,6 +486,11 @@ impl S3TierRegistry {
         self.backends.keys().cloned().collect()
     }
 
+    /// Remove a backend by name.
+    pub fn remove(&mut self, name: &str) {
+        self.backends.remove(name);
+    }
+
     pub fn clear(&mut self) {
         self.backends.clear();
     }

seaweed-volume/src/server/grpc_server.rs

@@ -4311,7 +4311,9 @@ mod tests {
         std::fs::remove_file(&dat_path).unwrap();
 
         let (endpoint, shutdown_tx) = spawn_fake_s3_server(dat_bytes.clone());
-        global_s3_tier_registry().write().unwrap().clear();
+        // Use a test-specific backend_id to avoid racing with other tests
+        // that share the global registry.  Never call clear() — only
+        // register/remove our own entries.
         let tier_config = S3TierConfig {
             access_key: "access".to_string(),
             secret_key: "secret".to_string(),
@@ -4323,14 +4325,16 @@ mod tests {
         };
         {
             let mut registry = global_s3_tier_registry().write().unwrap();
-            registry.register("s3.default".to_string(), S3TierBackend::new(&tier_config));
-            registry.register("s3".to_string(), S3TierBackend::new(&tier_config));
+            registry.register(
+                "s3.incr_copy_test".to_string(),
+                S3TierBackend::new(&tier_config),
+            );
         }
 
         let vif = crate::storage::volume::VifVolumeInfo {
             files: vec![crate::storage::volume::VifRemoteFile {
                 backend_type: "s3".to_string(),
-                backend_id: "default".to_string(),
+                backend_id: "incr_copy_test".to_string(),
                 key: "remote-key".to_string(),
                 offset: 0,
                 file_size: dat_bytes.len() as u64,
@@ -4539,7 +4543,10 @@ mod tests {
         assert_eq!(copied, dat_bytes[super_block_size as usize..]);
 
         let _ = shutdown_tx.send(());
-        global_s3_tier_registry().write().unwrap().clear();
+        global_s3_tier_registry()
+            .write()
+            .unwrap()
+            .remove("s3.incr_copy_test");
     }
 
     #[tokio::test]

seaweed-volume/src/server/heartbeat.rs

@@ -1408,10 +1408,8 @@ mod tests {
     #[test]
     fn test_apply_storage_backends_registers_s3_default_aliases() {
         let state = test_state_with_store(Store::new(NeedleMapKind::InMemory));
-        crate::remote_storage::s3_tier::global_s3_tier_registry()
-            .write()
-            .unwrap()
-            .clear();
+        // Do not call clear() on the global registry — other tests may be
+        // running concurrently.  Just register our entries and verify them.
 
         apply_storage_backends(
             &state,
@@ -1443,10 +1441,8 @@ mod tests {
     #[test]
     fn test_apply_storage_backends_ignores_unsupported_types() {
         let state = test_state_with_store(Store::new(NeedleMapKind::InMemory));
-        crate::remote_storage::s3_tier::global_s3_tier_registry()
-            .write()
-            .unwrap()
-            .clear();
+        // Do not call clear() on the global registry — other tests may be
+        // running concurrently.
 
         apply_storage_backends(
             &state,
@@ -1457,12 +1453,17 @@ mod tests {
             }],
         );
 
+        // The per-state registry is freshly created and should have no entries
+        // since "rclone" is unsupported.
         let registry = state.s3_tier_registry.read().unwrap();
         assert!(registry.names().is_empty());
+        // Only check that the unsupported type was not added to the global
+        // registry.  Other tests may have their own entries present.
         let global_registry = crate::remote_storage::s3_tier::global_s3_tier_registry()
             .read()
             .unwrap();
-        assert!(global_registry.names().is_empty());
+        assert!(global_registry.get("rclone.default").is_none());
+        assert!(global_registry.get("rclone").is_none());
     }
 
     #[test]

seaweed-volume/src/storage/volume.rs

@@ -3917,6 +3917,11 @@ mod tests {
             .unwrap();
         assert!(deleted_size.0 > 0);
         assert_eq!(v.dat_file_size().unwrap(), dat_size_before_reload);
+
+        crate::remote_storage::s3_tier::global_s3_tier_registry()
+            .write()
+            .unwrap()
+            .remove("s3.vif_rw_test");
     }
 
     #[test]
@@ -4079,10 +4084,9 @@ mod tests {
         std::fs::remove_file(&dat_path).unwrap();
 
         let (endpoint, shutdown_tx) = spawn_fake_s3_server(dat_bytes.clone());
-        crate::remote_storage::s3_tier::global_s3_tier_registry()
-            .write()
-            .unwrap()
-            .clear();
+        // Use a test-specific backend_id to avoid racing with other tests
+        // that share the global registry.  Never call clear() — only
+        // register/remove our own entries.
         let tier_config = crate::remote_storage::s3_tier::S3TierConfig {
             access_key: "access".to_string(),
             secret_key: "secret".to_string(),
@@ -4097,11 +4101,7 @@ mod tests {
                 .write()
                 .unwrap();
             registry.register(
-                "s3.default".to_string(),
-                crate::remote_storage::s3_tier::S3TierBackend::new(&tier_config),
-            );
-            registry.register(
-                "s3".to_string(),
+                "s3.remote_only_rw".to_string(),
                 crate::remote_storage::s3_tier::S3TierBackend::new(&tier_config),
             );
         }
@@ -4109,7 +4109,7 @@ mod tests {
         let vif = VifVolumeInfo {
             files: vec![VifRemoteFile {
                 backend_type: "s3".to_string(),
-                backend_id: "default".to_string(),
+                backend_id: "remote_only_rw".to_string(),
                 key: "remote-key".to_string(),
                 offset: 0,
                 file_size: dat_bytes.len() as u64,
@@ -4166,6 +4166,10 @@ mod tests {
         assert_eq!(meta.data_size, 11);
 
         let _ = shutdown_tx.send(());
+        crate::remote_storage::s3_tier::global_s3_tier_registry()
+            .write()
+            .unwrap()
+            .remove("s3.remote_only_rw");
     }
 
     /// Volume destroy removes .vif alongside the primary data files.