diff --git a/crates/application/src/storage/commands/ingest_asset.rs b/crates/application/src/storage/commands/ingest_asset.rs
new file mode 100644
index 0000000..eb63007
--- /dev/null
+++ b/crates/application/src/storage/commands/ingest_asset.rs
@@ -0,0 +1,129 @@
+use std::sync::Arc;
+use bytes::Bytes;
+use domain::{
+    entities::{Asset, AssetType, IngestSession, IngestStatus, SourceReference, UsageLedgerEntry, UsageType},
+    errors::DomainError,
+    events::DomainEvent,
+    ports::{
+        AssetRepository, EventPublisher, FileStoragePort,
+        IngestSessionRepository, LibraryPathRepository, QuotaRepository, UsageLedgerRepository,
+    },
+    value_objects::{Checksum, DateTimeStamp, SystemId},
+};
+
+#[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
+pub struct IngestAssetCommand {
+    pub uploader_id: SystemId,
+    pub client_device_id: String,
+    pub filename: String,
+    pub checksum: String,
+    pub target_path_id: SystemId,
+    pub file_size: u64,
+    #[serde(skip)]
+    pub data: Bytes,
+}
+
+pub struct IngestAssetHandler {
+    ingest_repo: Arc<dyn IngestSessionRepository>,
+    path_repo: Arc<dyn LibraryPathRepository>,
+    quota_repo: Arc<dyn QuotaRepository>,
+    ledger_repo: Arc<dyn UsageLedgerRepository>,
+    asset_repo: Arc<dyn AssetRepository>,
+    file_storage: Arc<dyn FileStoragePort>,
+    event_pub: Arc<dyn EventPublisher>,
+}
+
+impl IngestAssetHandler {
+    pub fn new(
+        ingest_repo: Arc<dyn IngestSessionRepository>,
+        path_repo: Arc<dyn LibraryPathRepository>,
+        quota_repo: Arc<dyn QuotaRepository>,
+        ledger_repo: Arc<dyn UsageLedgerRepository>,
+        asset_repo: Arc<dyn AssetRepository>,
+        file_storage: Arc<dyn FileStoragePort>,
+        event_pub: Arc<dyn EventPublisher>,
+    ) -> Self {
+        Self { ingest_repo, path_repo, quota_repo, ledger_repo, asset_repo, file_storage, event_pub }
+    }
+
+    pub async fn execute(&self, cmd: IngestAssetCommand) -> Result<(Asset, IngestSession), DomainError> {
+        let checksum = Checksum::new(&cmd.checksum)?;
+
+        let path = self.path_repo.find_by_id(&cmd.target_path_id).await?
+            .ok_or_else(|| DomainError::NotFound(format!("Library path {} not found", cmd.target_path_id)))?;
+
+        if !path.is_ingest_destination {
+            return Err(DomainError::Validation("Target path is not an ingest destination".to_string()));
+        }
+
+        if let Some(quota) = self.quota_repo.find_by_owner(&cmd.uploader_id).await? {
+            let current = self.ledger_repo.sum_usage(&cmd.uploader_id, UsageType::StorageBytes, None).await?;
+            let result = domain::storage::services::check_quota(&quota, UsageType::StorageBytes, current, cmd.file_size);
+            if !result.allowed {
+                return Err(DomainError::QuotaExceeded(format!(
+                    "Storage quota exceeded: {} / {} bytes", current + cmd.file_size, result.limit
+                )));
+            }
+        }
+
+        let mut session = IngestSession::new(
+            cmd.uploader_id,
+            &cmd.client_device_id,
+            &cmd.filename,
+            checksum.clone(),
+            cmd.target_path_id,
+        );
+
+        let storage_path = format!("{}/{}", path.relative_path, cmd.filename);
+        self.file_storage.store_file(&storage_path, cmd.data).await?;
+
+        let mime_type = mime_type_from_filename(&cmd.filename);
+        let asset_type = if mime_type.starts_with("video") { AssetType::Video } else { AssetType::Image };
+
+        let asset = Asset::new(
+            SourceReference {
+                volume_id: path.volume_id,
+                relative_path: storage_path,
+                checksum,
+            },
+            asset_type,
+            &mime_type,
+            cmd.file_size,
+            cmd.uploader_id,
+        );
+
+        self.asset_repo.save(&asset).await?;
+
+        session.advance_to(IngestStatus::AwaitingProcessing)?;
+        self.ingest_repo.save(&session).await?;
+
+        let entry = UsageLedgerEntry::new(
+            cmd.uploader_id,
+            UsageType::StorageBytes,
+            cmd.file_size,
+            format!("Ingested {}", cmd.filename),
+        );
+        self.ledger_repo.record(&entry).await?;
+
+        self.event_pub.publish(DomainEvent::AssetIngested {
+            asset_id: asset.asset_id,
+            owner_user_id: cmd.uploader_id,
+            timestamp: DateTimeStamp::now(),
+        }).await?;
+
+        Ok((asset, session))
+    }
+}
+
+fn mime_type_from_filename(filename: &str) -> String {
+    let lower = filename.to_lowercase();
+    if lower.ends_with(".jpg") || lower.ends_with(".jpeg") {
+        "image/jpeg".to_string()
+    } else if lower.ends_with(".png") {
+        "image/png".to_string()
+    } else if lower.ends_with(".mp4") {
+        "video/mp4".to_string()
+    } else {
+        "application/octet-stream".to_string()
+    }
+}
diff --git a/crates/application/src/storage/commands/mod.rs b/crates/application/src/storage/commands/mod.rs
new file mode 100644
index 0000000..5e7f5ef
--- /dev/null
+++ b/crates/application/src/storage/commands/mod.rs
@@ -0,0 +1,3 @@
+pub mod register_volume;
+pub mod register_library_path;
+pub mod ingest_asset;
diff --git a/crates/application/src/storage/commands/register_library_path.rs b/crates/application/src/storage/commands/register_library_path.rs
new file mode 100644
index 0000000..1abca06
--- /dev/null
+++ b/crates/application/src/storage/commands/register_library_path.rs
@@ -0,0 +1,43 @@
+use std::sync::Arc;
+use domain::{
+    entities::LibraryPath,
+    errors::DomainError,
+    ports::{LibraryPathRepository, StorageVolumeRepository},
+    value_objects::SystemId,
+};
+
+#[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
+pub struct RegisterLibraryPathCommand {
+    pub volume_id: SystemId,
+    pub relative_path: String,
+    pub owner_id: SystemId,
+    pub is_ingest_destination: bool,
+}
+
+pub struct RegisterLibraryPathHandler {
+    volume_repo: Arc<dyn StorageVolumeRepository>,
+    path_repo: Arc<dyn LibraryPathRepository>,
+}
+
+impl RegisterLibraryPathHandler {
+    pub fn new(
+        volume_repo: Arc<dyn StorageVolumeRepository>,
+        path_repo: Arc<dyn LibraryPathRepository>,
+    ) -> Self {
+        Self { volume_repo, path_repo }
+    }
+
+    pub async fn execute(&self, cmd: RegisterLibraryPathCommand) -> Result<LibraryPath, DomainError> {
+        self.volume_repo.find_by_id(&cmd.volume_id).await?
+            .ok_or_else(|| DomainError::NotFound(format!("Volume {} not found", cmd.volume_id)))?;
+
+        let path = LibraryPath::new_user_owned(
+            cmd.volume_id,
+            cmd.relative_path,
+            cmd.owner_id,
+            cmd.is_ingest_destination,
+        );
+        self.path_repo.save(&path).await?;
+        Ok(path)
+    }
+}
diff --git a/crates/application/src/storage/commands/register_volume.rs b/crates/application/src/storage/commands/register_volume.rs
new file mode 100644
index 0000000..5b6e1f6
--- /dev/null
+++ b/crates/application/src/storage/commands/register_volume.rs
@@ -0,0 +1,32 @@
+use std::sync::Arc;
+use domain::{
+    entities::StorageVolume,
+    errors::DomainError,
+    ports::StorageVolumeRepository,
+};
+
+#[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
+pub struct RegisterVolumeCommand {
+    pub volume_name: String,
+    pub uri_prefix: String,
+    pub is_writable: bool,
+}
+
+pub struct RegisterVolumeHandler {
+    volume_repo: Arc<dyn StorageVolumeRepository>,
+}
+
+impl RegisterVolumeHandler {
+    pub fn new(volume_repo: Arc<dyn StorageVolumeRepository>) -> Self {
+        Self { volume_repo }
+    }
+
+    pub async fn execute(&self, cmd: RegisterVolumeCommand) -> Result<StorageVolume, DomainError> {
+        if cmd.volume_name.is_empty() {
+            return Err(DomainError::Validation("Volume name must not be empty".to_string()));
+        }
+        let volume = StorageVolume::new(cmd.volume_name, cmd.uri_prefix, cmd.is_writable);
+        self.volume_repo.save(&volume).await?;
+        Ok(volume)
+    }
+}
diff --git a/crates/application/src/storage/mod.rs b/crates/application/src/storage/mod.rs
index 180ec5a..1b7b2f0 100644
--- a/crates/application/src/storage/mod.rs
+++ b/crates/application/src/storage/mod.rs
@@ -1 +1,7 @@
-// Storage commands/queries (future: IngestAsset, ManageVolume, etc.)
+pub mod commands;
+pub mod queries;
+
+pub use commands::register_volume::{RegisterVolumeCommand, RegisterVolumeHandler};
+pub use commands::register_library_path::{RegisterLibraryPathCommand, RegisterLibraryPathHandler};
+pub use commands::ingest_asset::{IngestAssetCommand, IngestAssetHandler};
+pub use queries::check_quota::{CheckQuotaQuery, CheckQuotaHandler};
diff --git a/crates/application/src/storage/queries/check_quota.rs b/crates/application/src/storage/queries/check_quota.rs
new file mode 100644
index 0000000..31faa27
--- /dev/null
+++ b/crates/application/src/storage/queries/check_quota.rs
@@ -0,0 +1,45 @@
+use std::sync::Arc;
+use domain::{
+    entities::UsageType,
+    errors::DomainError,
+    ports::{QuotaRepository, UsageLedgerRepository},
+    storage::services::{check_quota, QuotaCheckResult},
+    value_objects::SystemId,
+};
+
+#[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
+pub struct CheckQuotaQuery {
+    pub user_id: SystemId,
+    pub usage_type: UsageType,
+    pub requested_amount: u64,
+}
+
+pub struct CheckQuotaHandler {
+    quota_repo: Arc<dyn QuotaRepository>,
+    ledger_repo: Arc<dyn UsageLedgerRepository>,
+}
+
+impl CheckQuotaHandler {
+    pub fn new(
+        quota_repo: Arc<dyn QuotaRepository>,
+        ledger_repo: Arc<dyn UsageLedgerRepository>,
+    ) -> Self {
+        Self { quota_repo, ledger_repo }
+    }
+
+    pub async fn execute(&self, query: CheckQuotaQuery) -> Result<QuotaCheckResult, DomainError> {
+        let quota = self.quota_repo.find_by_owner(&query.user_id).await?;
+
+        let Some(quota) = quota else {
+            return Ok(QuotaCheckResult {
+                allowed: true,
+                current_usage: 0,
+                limit: 0,
+                is_unlimited: true,
+            });
+        };
+
+        let current = self.ledger_repo.sum_usage(&query.user_id, query.usage_type, None).await?;
+        Ok(check_quota(&quota, query.usage_type, current, query.requested_amount))
+    }
+}
diff --git a/crates/application/src/storage/queries/mod.rs b/crates/application/src/storage/queries/mod.rs
new file mode 100644
index 0000000..384f573
--- /dev/null
+++ b/crates/application/src/storage/queries/mod.rs
@@ -0,0 +1 @@
+pub mod check_quota;
diff --git a/crates/application/src/testing/repositories.rs b/crates/application/src/testing/repositories.rs
index ea59c8e..66edd6a 100644
--- a/crates/application/src/testing/repositories.rs
+++ b/crates/application/src/testing/repositories.rs
@@ -2,13 +2,21 @@ use std::collections::HashMap;
 use async_trait::async_trait;
 use tokio::sync::Mutex;
 use domain::{
-    entities::{Album, Asset, Group, Job, JobStatus, Role, User},
+    entities::{
+        Album, Asset, AssetMetadata, AssetTag, DuplicateGroup, DuplicateStatus,
+        Group, IngestSession, InviteCode, Job, JobStatus, LibraryPath,
+        MetadataSource, QuotaDefinition, Role, ShareLink, ShareScope, ShareTarget,
+        StorageVolume, Tag, UsageLedgerEntry, UsageType, User,
+    },
     errors::DomainError,
     ports::{
-        AlbumRepository, AssetRepository, GroupRepository,
-        JobRepository, RoleRepository, UserRepository,
+        AlbumRepository, AssetMetadataRepository, AssetRepository,
+        DuplicateRepository, GroupRepository, IngestSessionRepository,
+        JobRepository, LibraryPathRepository, QuotaRepository,
+        RoleRepository, ShareRepository, StorageVolumeRepository,
+        TagRepository, UsageLedgerRepository, UserRepository,
     },
-    value_objects::{Checksum, Email, SystemId},
+    value_objects::{Checksum, DateTimeStamp, Email, SystemId},
 };
 
 // --- InMemoryUserRepository ---
@@ -276,3 +284,435 @@ impl GroupRepository for InMemoryGroupRepository {
         Ok(())
     }
 }
+
+// --- InMemoryStorageVolumeRepository ---
+
+pub struct InMemoryStorageVolumeRepository {
+    data: Mutex<HashMap<String, StorageVolume>>,
+}
+
+impl InMemoryStorageVolumeRepository {
+    pub fn new() -> Self {
+        Self { data: Mutex::new(HashMap::new()) }
+    }
+}
+
+impl Default for InMemoryStorageVolumeRepository {
+    fn default() -> Self { Self::new() }
+}
+
+#[async_trait]
+impl StorageVolumeRepository for InMemoryStorageVolumeRepository {
+    async fn find_by_id(&self, id: &SystemId) -> Result<Option<StorageVolume>, DomainError> {
+        Ok(self.data.lock().await.get(&id.to_string()).cloned())
+    }
+
+    async fn find_all(&self) -> Result<Vec<StorageVolume>, DomainError> {
+        Ok(self.data.lock().await.values().cloned().collect())
+    }
+
+    async fn save(&self, volume: &StorageVolume) -> Result<(), DomainError> {
+        self.data.lock().await.insert(volume.volume_id.to_string(), volume.clone());
+        Ok(())
+    }
+
+    async fn delete(&self, id: &SystemId) -> Result<(), DomainError> {
+        self.data.lock().await.remove(&id.to_string());
+        Ok(())
+    }
+}
+
+// --- InMemoryLibraryPathRepository ---
+
+pub struct InMemoryLibraryPathRepository {
+    data: Mutex<HashMap<String, LibraryPath>>,
+}
+
+impl InMemoryLibraryPathRepository {
+    pub fn new() -> Self {
+        Self { data: Mutex::new(HashMap::new()) }
+    }
+}
+
+impl Default for InMemoryLibraryPathRepository {
+    fn default() -> Self { Self::new() }
+}
+
+#[async_trait]
+impl LibraryPathRepository for InMemoryLibraryPathRepository {
+    async fn find_by_id(&self, id: &SystemId) -> Result<Option<LibraryPath>, DomainError> {
+        Ok(self.data.lock().await.get(&id.to_string()).cloned())
+    }
+
+    async fn find_by_volume(&self, volume_id: &SystemId) -> Result<Vec<LibraryPath>, DomainError> {
+        Ok(self.data.lock().await.values()
+            .filter(|p| &p.volume_id == volume_id)
+            .cloned()
+            .collect())
+    }
+
+    async fn find_ingest_destinations(&self, owner_id: &SystemId) -> Result<Vec<LibraryPath>, DomainError> {
+        Ok(self.data.lock().await.values()
+            .filter(|p| p.is_ingest_destination && p.designated_owner_id.as_ref() == Some(owner_id))
+            .cloned()
+            .collect())
+    }
+
+    async fn save(&self, path: &LibraryPath) -> Result<(), DomainError> {
+        self.data.lock().await.insert(path.path_id.to_string(), path.clone());
+        Ok(())
+    }
+
+    async fn delete(&self, id: &SystemId) -> Result<(), DomainError> {
+        self.data.lock().await.remove(&id.to_string());
+        Ok(())
+    }
+}
+
+// --- InMemoryIngestSessionRepository ---
+
+pub struct InMemoryIngestSessionRepository {
+    data: Mutex<HashMap<String, IngestSession>>,
+}
+
+impl InMemoryIngestSessionRepository {
+    pub fn new() -> Self {
+        Self { data: Mutex::new(HashMap::new()) }
+    }
+}
+
+impl Default for InMemoryIngestSessionRepository {
+    fn default() -> Self { Self::new() }
+}
+
+#[async_trait]
+impl IngestSessionRepository for InMemoryIngestSessionRepository {
+    async fn find_by_id(&self, id: &SystemId) -> Result<Option<IngestSession>, DomainError> {
+        Ok(self.data.lock().await.get(&id.to_string()).cloned())
+    }
+
+    async fn find_by_user(&self, user_id: &SystemId) -> Result<Vec<IngestSession>, DomainError> {
+        Ok(self.data.lock().await.values()
+            .filter(|s| &s.uploader_user_id == user_id)
+            .cloned()
+            .collect())
+    }
+
+    async fn save(&self, session: &IngestSession) -> Result<(), DomainError> {
+        self.data.lock().await.insert(session.session_id.to_string(), session.clone());
+        Ok(())
+    }
+}
+
+// --- InMemoryQuotaRepository ---
+
+pub struct InMemoryQuotaRepository {
+    data: Mutex<HashMap<String, QuotaDefinition>>,
+}
+
+impl InMemoryQuotaRepository {
+    pub fn new() -> Self {
+        Self { data: Mutex::new(HashMap::new()) }
+    }
+}
+
+impl Default for InMemoryQuotaRepository {
+    fn default() -> Self { Self::new() }
+}
+
+#[async_trait]
+impl QuotaRepository for InMemoryQuotaRepository {
+    async fn find_by_owner(&self, owner_id: &SystemId) -> Result<Option<QuotaDefinition>, DomainError> {
+        Ok(self.data.lock().await.values()
+            .find(|q| &q.owner_scope == owner_id)
+            .cloned())
+    }
+
+    async fn save(&self, quota: &QuotaDefinition) -> Result<(), DomainError> {
+        self.data.lock().await.insert(quota.quota_id.to_string(), quota.clone());
+        Ok(())
+    }
+
+    async fn delete(&self, id: &SystemId) -> Result<(), DomainError> {
+        self.data.lock().await.remove(&id.to_string());
+        Ok(())
+    }
+}
+
+// --- InMemoryUsageLedgerRepository ---
+
+pub struct InMemoryUsageLedgerRepository {
+    entries: Mutex<Vec<UsageLedgerEntry>>,
+}
+
+impl InMemoryUsageLedgerRepository {
+    pub fn new() -> Self {
+        Self { entries: Mutex::new(Vec::new()) }
+    }
+}
+
+impl Default for InMemoryUsageLedgerRepository {
+    fn default() -> Self { Self::new() }
+}
+
+#[async_trait]
+impl UsageLedgerRepository for InMemoryUsageLedgerRepository {
+    async fn record(&self, entry: &UsageLedgerEntry) -> Result<(), DomainError> {
+        self.entries.lock().await.push(entry.clone());
+        Ok(())
+    }
+
+    async fn sum_usage(
+        &self,
+        user_id: &SystemId,
+        usage_type: UsageType,
+        since: Option<DateTimeStamp>,
+    ) -> Result<u64, DomainError> {
+        let entries = self.entries.lock().await;
+        let total = entries.iter()
+            .filter(|e| &e.user_id == user_id && e.usage_type == usage_type)
+            .filter(|e| match &since {
+                Some(ts) => &e.timestamp >= ts,
+                None => true,
+            })
+            .map(|e| e.consumed_amount)
+            .sum();
+        Ok(total)
+    }
+}
+
+// --- InMemoryAssetMetadataRepository ---
+
+pub struct InMemoryAssetMetadataRepository {
+    data: Mutex<HashMap<String, AssetMetadata>>,
+}
+
+impl InMemoryAssetMetadataRepository {
+    pub fn new() -> Self {
+        Self { data: Mutex::new(HashMap::new()) }
+    }
+
+    fn key(asset_id: &SystemId, source: MetadataSource) -> String {
+        format!("{asset_id}:{source:?}")
+    }
+}
+
+impl Default for InMemoryAssetMetadataRepository {
+    fn default() -> Self { Self::new() }
+}
+
+#[async_trait]
+impl AssetMetadataRepository for InMemoryAssetMetadataRepository {
+    async fn find_by_asset(&self, asset_id: &SystemId) -> Result<Vec<AssetMetadata>, DomainError> {
+        let prefix = format!("{asset_id}:");
+        Ok(self.data.lock().await.iter()
+            .filter(|(k, _)| k.starts_with(&prefix))
+            .map(|(_, v)| v.clone())
+            .collect())
+    }
+
+    async fn find_by_asset_and_source(&self, asset_id: &SystemId, source: MetadataSource) -> Result<Option<AssetMetadata>, DomainError> {
+        Ok(self.data.lock().await.get(&Self::key(asset_id, source)).cloned())
+    }
+
+    async fn save(&self, metadata: &AssetMetadata) -> Result<(), DomainError> {
+        let key = Self::key(&metadata.asset_id, metadata.metadata_source);
+        self.data.lock().await.insert(key, metadata.clone());
+        Ok(())
+    }
+
+    async fn delete_by_asset_and_source(&self, asset_id: &SystemId, source: MetadataSource) -> Result<(), DomainError> {
+        self.data.lock().await.remove(&Self::key(asset_id, source));
+        Ok(())
+    }
+}
+
+// --- InMemoryShareRepository ---
+
+pub struct InMemoryShareRepository {
+    scopes: Mutex<HashMap<String, ShareScope>>,
+    targets: Mutex<HashMap<String, ShareTarget>>,
+    links: Mutex<HashMap<String, ShareLink>>,
+    invites: Mutex<HashMap<String, InviteCode>>,
+}
+
+impl InMemoryShareRepository {
+    pub fn new() -> Self {
+        Self {
+            scopes: Mutex::new(HashMap::new()),
+            targets: Mutex::new(HashMap::new()),
+            links: Mutex::new(HashMap::new()),
+            invites: Mutex::new(HashMap::new()),
+        }
+    }
+}
+
+impl Default for InMemoryShareRepository {
+    fn default() -> Self { Self::new() }
+}
+
+#[async_trait]
+impl ShareRepository for InMemoryShareRepository {
+    async fn save_scope(&self, scope: &ShareScope) -> Result<(), DomainError> {
+        self.scopes.lock().await.insert(scope.scope_id.to_string(), scope.clone());
+        Ok(())
+    }
+
+    async fn find_scope_by_id(&self, id: &SystemId) -> Result<Option<ShareScope>, DomainError> {
+        Ok(self.scopes.lock().await.get(&id.to_string()).cloned())
+    }
+
+    async fn find_scopes_for_resource(&self, resource_id: &SystemId) -> Result<Vec<ShareScope>, DomainError> {
+        Ok(self.scopes.lock().await.values()
+            .filter(|s| &s.shareable_id == resource_id)
+            .cloned()
+            .collect())
+    }
+
+    async fn delete_scope(&self, id: &SystemId) -> Result<(), DomainError> {
+        self.scopes.lock().await.remove(&id.to_string());
+        Ok(())
+    }
+
+    async fn save_target(&self, target: &ShareTarget) -> Result<(), DomainError> {
+        let key = format!("{}:{}", target.scope_id, target.target_id);
+        self.targets.lock().await.insert(key, target.clone());
+        Ok(())
+    }
+
+    async fn find_targets_for_scope(&self, scope_id: &SystemId) -> Result<Vec<ShareTarget>, DomainError> {
+        Ok(self.targets.lock().await.values()
+            .filter(|t| &t.scope_id == scope_id)
+            .cloned()
+            .collect())
+    }
+
+    async fn find_targets_for_user(&self, user_id: &SystemId) -> Result<Vec<ShareTarget>, DomainError> {
+        Ok(self.targets.lock().await.values()
+            .filter(|t| &t.target_id == user_id)
+            .cloned()
+            .collect())
+    }
+
+    async fn save_link(&self, link: &ShareLink) -> Result<(), DomainError> {
+        self.links.lock().await.insert(link.token.clone(), link.clone());
+        Ok(())
+    }
+
+    async fn find_link_by_token(&self, token: &str) -> Result<Option<ShareLink>, DomainError> {
+        Ok(self.links.lock().await.get(token).cloned())
+    }
+
+    async fn save_invite(&self, invite: &InviteCode) -> Result<(), DomainError> {
+        self.invites.lock().await.insert(invite.code_id.to_string(), invite.clone());
+        Ok(())
+    }
+
+    async fn find_invite_by_id(&self, id: &SystemId) -> Result<Option<InviteCode>, DomainError> {
+        Ok(self.invites.lock().await.get(&id.to_string()).cloned())
+    }
+}
+
+// --- InMemoryTagRepository ---
+
+pub struct InMemoryTagRepository {
+    tags: Mutex<HashMap<String, Tag>>,
+    asset_tags: Mutex<HashMap<String, AssetTag>>,
+}
+
+impl InMemoryTagRepository {
+    pub fn new() -> Self {
+        Self {
+            tags: Mutex::new(HashMap::new()),
+            asset_tags: Mutex::new(HashMap::new()),
+        }
+    }
+}
+
+impl Default for InMemoryTagRepository {
+    fn default() -> Self { Self::new() }
+}
+
+#[async_trait]
+impl TagRepository for InMemoryTagRepository {
+    async fn find_by_id(&self, id: &SystemId) -> Result<Option<Tag>, DomainError> {
+        Ok(self.tags.lock().await.get(&id.to_string()).cloned())
+    }
+
+    async fn find_by_name(&self, name: &str) -> Result<Option<Tag>, DomainError> {
+        Ok(self.tags.lock().await.values()
+            .find(|t| t.name == name)
+            .cloned())
+    }
+
+    async fn find_tags_for_asset(&self, asset_id: &SystemId) -> Result<Vec<(Tag, AssetTag)>, DomainError> {
+        let asset_tags = self.asset_tags.lock().await;
+        let tags = self.tags.lock().await;
+        let mut result = Vec::new();
+        for at in asset_tags.values() {
+            if &at.asset_id == asset_id && let Some(tag) = tags.get(&at.tag_id.to_string()) {
+                result.push((tag.clone(), at.clone()));
+            }
+        }
+        Ok(result)
+    }
+
+    async fn save_tag(&self, tag: &Tag) -> Result<(), DomainError> {
+        self.tags.lock().await.insert(tag.tag_id.to_string(), tag.clone());
+        Ok(())
+    }
+
+    async fn save_asset_tag(&self, asset_tag: &AssetTag) -> Result<(), DomainError> {
+        let key = format!("{}:{}", asset_tag.asset_id, asset_tag.tag_id);
+        self.asset_tags.lock().await.insert(key, asset_tag.clone());
+        Ok(())
+    }
+
+    async fn remove_asset_tag(&self, asset_id: &SystemId, tag_id: &SystemId) -> Result<(), DomainError> {
+        let key = format!("{asset_id}:{tag_id}");
+        self.asset_tags.lock().await.remove(&key);
+        Ok(())
+    }
+}
+
+// --- InMemoryDuplicateRepository ---
+
+pub struct InMemoryDuplicateRepository {
+    data: Mutex<HashMap<String, DuplicateGroup>>,
+}
+
+impl InMemoryDuplicateRepository {
+    pub fn new() -> Self {
+        Self { data: Mutex::new(HashMap::new()) }
+    }
+}
+
+impl Default for InMemoryDuplicateRepository {
+    fn default() -> Self { Self::new() }
+}
+
+#[async_trait]
+impl DuplicateRepository for InMemoryDuplicateRepository {
+    async fn find_by_id(&self, id: &SystemId) -> Result<Option<DuplicateGroup>, DomainError> {
+        Ok(self.data.lock().await.get(&id.to_string()).cloned())
+    }
+
+    async fn find_unresolved(&self) -> Result<Vec<DuplicateGroup>, DomainError> {
+        Ok(self.data.lock().await.values()
+            .filter(|g| g.status == DuplicateStatus::Unresolved)
+            .cloned()
+            .collect())
+    }
+
+    async fn find_by_asset(&self, asset_id: &SystemId) -> Result<Vec<DuplicateGroup>, DomainError> {
+        Ok(self.data.lock().await.values()
+            .filter(|g| g.candidates.iter().any(|c| &c.asset_id == asset_id))
+            .cloned()
+            .collect())
+    }
+
+    async fn save(&self, group: &DuplicateGroup) -> Result<(), DomainError> {
+        self.data.lock().await.insert(group.group_id.to_string(), group.clone());
+        Ok(())
+    }
+}
diff --git a/crates/application/tests/app_tests.rs b/crates/application/tests/app_tests.rs
index 6b57d05..5310b62 100644
--- a/crates/application/tests/app_tests.rs
+++ b/crates/application/tests/app_tests.rs
@@ -1,2 +1,3 @@
 mod identity;
 mod organization;
+mod storage;
diff --git a/crates/application/tests/storage/commands/ingest_asset.rs b/crates/application/tests/storage/commands/ingest_asset.rs
new file mode 100644
index 0000000..90ed05c
--- /dev/null
+++ b/crates/application/tests/storage/commands/ingest_asset.rs
@@ -0,0 +1,181 @@
+use std::sync::Arc;
+use bytes::Bytes;
+use application::testing::{
+    InMemoryAssetRepository, InMemoryIngestSessionRepository,
+    InMemoryLibraryPathRepository, InMemoryQuotaRepository,
+    InMemoryStorageVolumeRepository, InMemoryUsageLedgerRepository,
+    InMemoryFileStorage, StubEventPublisher,
+};
+use application::storage::{
+    IngestAssetCommand, IngestAssetHandler,
+    RegisterVolumeCommand, RegisterVolumeHandler,
+    RegisterLibraryPathCommand, RegisterLibraryPathHandler,
+};
+use domain::entities::{IngestStatus, QuotaDefinition, TimePeriod, UsageType};
+use domain::errors::DomainError;
+use domain::ports::QuotaRepository;
+use domain::value_objects::SystemId;
+
+struct Harness {
+    ingest_repo: Arc<InMemoryIngestSessionRepository>,
+    path_repo: Arc<InMemoryLibraryPathRepository>,
+    quota_repo: Arc<InMemoryQuotaRepository>,
+    ledger_repo: Arc<InMemoryUsageLedgerRepository>,
+    asset_repo: Arc<InMemoryAssetRepository>,
+    file_storage: Arc<InMemoryFileStorage>,
+    event_pub: Arc<StubEventPublisher>,
+    vol_repo: Arc<InMemoryStorageVolumeRepository>,
+}
+
+impl Harness {
+    fn new() -> Self {
+        Self {
+            ingest_repo: Arc::new(InMemoryIngestSessionRepository::new()),
+            path_repo: Arc::new(InMemoryLibraryPathRepository::new()),
+            quota_repo: Arc::new(InMemoryQuotaRepository::new()),
+            ledger_repo: Arc::new(InMemoryUsageLedgerRepository::new()),
+            asset_repo: Arc::new(InMemoryAssetRepository::new()),
+            file_storage: Arc::new(InMemoryFileStorage::new()),
+            event_pub: Arc::new(StubEventPublisher::new()),
+            vol_repo: Arc::new(InMemoryStorageVolumeRepository::new()),
+        }
+    }
+
+    fn ingest_handler(&self) -> IngestAssetHandler {
+        IngestAssetHandler::new(
+            self.ingest_repo.clone(),
+            self.path_repo.clone(),
+            self.quota_repo.clone(),
+            self.ledger_repo.clone(),
+            self.asset_repo.clone(),
+            self.file_storage.clone(),
+            self.event_pub.clone(),
+        )
+    }
+
+    async fn setup_volume_and_path(&self, owner: SystemId) -> SystemId {
+        let vol_handler = RegisterVolumeHandler::new(self.vol_repo.clone());
+        let vol = vol_handler.execute(RegisterVolumeCommand {
+            volume_name: "main".into(),
+            uri_prefix: "file:///data".into(),
+            is_writable: true,
+        }).await.unwrap();
+
+        let path_handler = RegisterLibraryPathHandler::new(self.vol_repo.clone(), self.path_repo.clone());
+        let path = path_handler.execute(RegisterLibraryPathCommand {
+            volume_id: vol.volume_id,
+            relative_path: "photos/inbox".into(),
+            owner_id: owner,
+            is_ingest_destination: true,
+        }).await.unwrap();
+        path.path_id
+    }
+}
+
+fn valid_checksum() -> String {
+    "a".repeat(64)
+}
+
+#[tokio::test]
+async fn ingests_successfully() {
+    let h = Harness::new();
+    let user = SystemId::new();
+    let path_id = h.setup_volume_and_path(user).await;
+
+    let handler = h.ingest_handler();
+    let (asset, session) = handler.execute(IngestAssetCommand {
+        uploader_id: user,
+        client_device_id: "iphone-1".into(),
+        filename: "photo.jpg".into(),
+        checksum: valid_checksum(),
+        target_path_id: path_id,
+        file_size: 1024,
+        data: Bytes::from(vec![0u8; 1024]),
+    }).await.unwrap();
+
+    assert_eq!(asset.mime_type, "image/jpeg");
+    assert_eq!(asset.file_size, 1024);
+    assert_eq!(asset.owner_user_id, user);
+    assert_eq!(session.status, IngestStatus::AwaitingProcessing);
+    assert!(!h.event_pub.published().await.is_empty());
+}
+
+#[tokio::test]
+async fn rejects_quota_exceeded() {
+    let h = Harness::new();
+    let user = SystemId::new();
+    let path_id = h.setup_volume_and_path(user).await;
+
+    let mut quota = QuotaDefinition::new(user);
+    quota.add_rule(UsageType::StorageBytes, 500, TimePeriod::Lifetime);
+    h.quota_repo.save(&quota).await.unwrap();
+
+    let handler = h.ingest_handler();
+    let result = handler.execute(IngestAssetCommand {
+        uploader_id: user,
+        client_device_id: "iphone-1".into(),
+        filename: "big.jpg".into(),
+        checksum: valid_checksum(),
+        target_path_id: path_id,
+        file_size: 1024,
+        data: Bytes::from(vec![0u8; 1024]),
+    }).await;
+
+    assert!(matches!(result, Err(DomainError::QuotaExceeded(_))));
+}
+
+#[tokio::test]
+async fn rejects_invalid_checksum() {
+    let h = Harness::new();
+    let user = SystemId::new();
+    let path_id = h.setup_volume_and_path(user).await;
+
+    let handler = h.ingest_handler();
+    let result = handler.execute(IngestAssetCommand {
+        uploader_id: user,
+        client_device_id: "iphone-1".into(),
+        filename: "photo.jpg".into(),
+        checksum: "tooshort".into(),
+        target_path_id: path_id,
+        file_size: 1024,
+        data: Bytes::from(vec![0u8; 1024]),
+    }).await;
+
+    assert!(matches!(result, Err(DomainError::Validation(_))));
+}
+
+#[tokio::test]
+async fn rejects_non_ingest_path() {
+    let h = Harness::new();
+    let user = SystemId::new();
+
+    // Create volume + non-ingest path directly
+    let vol_handler = RegisterVolumeHandler::new(h.vol_repo.clone());
+    let vol = vol_handler.execute(RegisterVolumeCommand {
+        volume_name: "main".into(),
+        uri_prefix: "file:///data".into(),
+        is_writable: true,
+    }).await.unwrap();
+
+    let path = domain::entities::LibraryPath::new_user_owned(
+        vol.volume_id,
+        "photos/archive",
+        user,
+        false, // not an ingest destination
+    );
+    use domain::ports::LibraryPathRepository;
+    h.path_repo.save(&path).await.unwrap();
+
+    let handler = h.ingest_handler();
+    let result = handler.execute(IngestAssetCommand {
+        uploader_id: user,
+        client_device_id: "iphone-1".into(),
+        filename: "photo.jpg".into(),
+        checksum: valid_checksum(),
+        target_path_id: path.path_id,
+        file_size: 1024,
+        data: Bytes::from(vec![0u8; 1024]),
+    }).await;
+
+    assert!(matches!(result, Err(DomainError::Validation(_))));
+}
diff --git a/crates/application/tests/storage/commands/mod.rs b/crates/application/tests/storage/commands/mod.rs
new file mode 100644
index 0000000..c15fb27
--- /dev/null
+++ b/crates/application/tests/storage/commands/mod.rs
@@ -0,0 +1,3 @@
+mod register_volume;
+mod register_library_path;
+mod ingest_asset;
diff --git a/crates/application/tests/storage/commands/register_library_path.rs b/crates/application/tests/storage/commands/register_library_path.rs
new file mode 100644
index 0000000..e02635f
--- /dev/null
+++ b/crates/application/tests/storage/commands/register_library_path.rs
@@ -0,0 +1,47 @@
+use std::sync::Arc;
+use application::testing::{InMemoryStorageVolumeRepository, InMemoryLibraryPathRepository};
+use application::storage::{RegisterVolumeCommand, RegisterVolumeHandler, RegisterLibraryPathCommand, RegisterLibraryPathHandler};
+use domain::errors::DomainError;
+use domain::value_objects::SystemId;
+
+#[tokio::test]
+async fn creates_path() {
+    let vol_repo = Arc::new(InMemoryStorageVolumeRepository::new());
+    let path_repo = Arc::new(InMemoryLibraryPathRepository::new());
+
+    let vol_handler = RegisterVolumeHandler::new(vol_repo.clone());
+    let vol = vol_handler.execute(RegisterVolumeCommand {
+        volume_name: "main".into(),
+        uri_prefix: "file:///data".into(),
+        is_writable: true,
+    }).await.unwrap();
+
+    let handler = RegisterLibraryPathHandler::new(vol_repo, path_repo);
+    let owner = SystemId::new();
+    let path = handler.execute(RegisterLibraryPathCommand {
+        volume_id: vol.volume_id,
+        relative_path: "photos/inbox".into(),
+        owner_id: owner,
+        is_ingest_destination: true,
+    }).await.unwrap();
+
+    assert_eq!(path.volume_id, vol.volume_id);
+    assert_eq!(path.relative_path, "photos/inbox");
+    assert!(path.is_ingest_destination);
+    assert_eq!(path.designated_owner_id, Some(owner));
+}
+
+#[tokio::test]
+async fn rejects_nonexistent_volume() {
+    let vol_repo = Arc::new(InMemoryStorageVolumeRepository::new());
+    let path_repo = Arc::new(InMemoryLibraryPathRepository::new());
+    let handler = RegisterLibraryPathHandler::new(vol_repo, path_repo);
+
+    let result = handler.execute(RegisterLibraryPathCommand {
+        volume_id: SystemId::new(),
+        relative_path: "photos/inbox".into(),
+        owner_id: SystemId::new(),
+        is_ingest_destination: true,
+    }).await;
+    assert!(matches!(result, Err(DomainError::NotFound(_))));
+}
diff --git a/crates/application/tests/storage/commands/register_volume.rs b/crates/application/tests/storage/commands/register_volume.rs
new file mode 100644
index 0000000..602fa53
--- /dev/null
+++ b/crates/application/tests/storage/commands/register_volume.rs
@@ -0,0 +1,30 @@
+use std::sync::Arc;
+use application::testing::InMemoryStorageVolumeRepository;
+use application::storage::{RegisterVolumeCommand, RegisterVolumeHandler};
+use domain::errors::DomainError;
+
+#[tokio::test]
+async fn creates_volume() {
+    let repo = Arc::new(InMemoryStorageVolumeRepository::new());
+    let handler = RegisterVolumeHandler::new(repo);
+    let vol = handler.execute(RegisterVolumeCommand {
+        volume_name: "primary".into(),
+        uri_prefix: "file:///data".into(),
+        is_writable: true,
+    }).await.unwrap();
+    assert_eq!(vol.volume_name, "primary");
+    assert_eq!(vol.uri_prefix, "file:///data");
+    assert!(vol.is_writable);
+}
+
+#[tokio::test]
+async fn rejects_empty_name() {
+    let repo = Arc::new(InMemoryStorageVolumeRepository::new());
+    let handler = RegisterVolumeHandler::new(repo);
+    let result = handler.execute(RegisterVolumeCommand {
+        volume_name: "".into(),
+        uri_prefix: "file:///data".into(),
+        is_writable: true,
+    }).await;
+    assert!(matches!(result, Err(DomainError::Validation(_))));
+}
diff --git a/crates/application/tests/storage/mod.rs b/crates/application/tests/storage/mod.rs
new file mode 100644
index 0000000..2406e7d
--- /dev/null
+++ b/crates/application/tests/storage/mod.rs
@@ -0,0 +1,2 @@
+mod commands;
+mod queries;
diff --git a/crates/application/tests/storage/queries/check_quota.rs b/crates/application/tests/storage/queries/check_quota.rs
new file mode 100644
index 0000000..b3a1b45
--- /dev/null
+++ b/crates/application/tests/storage/queries/check_quota.rs
@@ -0,0 +1,71 @@
+use std::sync::Arc;
+use application::testing::{InMemoryQuotaRepository, InMemoryUsageLedgerRepository};
+use application::storage::{CheckQuotaQuery, CheckQuotaHandler};
+use domain::entities::{QuotaDefinition, TimePeriod, UsageLedgerEntry, UsageType};
+use domain::ports::UsageLedgerRepository;
+use domain::value_objects::SystemId;
+
+#[tokio::test]
+async fn returns_allowed() {
+    let quota_repo = Arc::new(InMemoryQuotaRepository::new());
+    let ledger_repo = Arc::new(InMemoryUsageLedgerRepository::new());
+
+    let user = SystemId::new();
+    let mut quota = QuotaDefinition::new(user);
+    quota.add_rule(UsageType::StorageBytes, 10_000, TimePeriod::Lifetime);
+    use domain::ports::QuotaRepository;
+    quota_repo.save(&quota).await.unwrap();
+
+    let handler = CheckQuotaHandler::new(quota_repo, ledger_repo);
+    let result = handler.execute(CheckQuotaQuery {
+        user_id: user,
+        usage_type: UsageType::StorageBytes,
+        requested_amount: 5_000,
+    }).await.unwrap();
+
+    assert!(result.allowed);
+    assert_eq!(result.limit, 10_000);
+    assert!(!result.is_unlimited);
+}
+
+#[tokio::test]
+async fn returns_denied() {
+    let quota_repo = Arc::new(InMemoryQuotaRepository::new());
+    let ledger_repo = Arc::new(InMemoryUsageLedgerRepository::new());
+
+    let user = SystemId::new();
+    let mut quota = QuotaDefinition::new(user);
+    quota.add_rule(UsageType::StorageBytes, 1_000, TimePeriod::Lifetime);
+    use domain::ports::QuotaRepository;
+    quota_repo.save(&quota).await.unwrap();
+
+    // record existing usage
+    let entry = UsageLedgerEntry::new(user, UsageType::StorageBytes, 900, "prior upload");
+    ledger_repo.record(&entry).await.unwrap();
+
+    let handler = CheckQuotaHandler::new(quota_repo, ledger_repo);
+    let result = handler.execute(CheckQuotaQuery {
+        user_id: user,
+        usage_type: UsageType::StorageBytes,
+        requested_amount: 200,
+    }).await.unwrap();
+
+    assert!(!result.allowed);
+    assert_eq!(result.current_usage, 900);
+}
+
+#[tokio::test]
+async fn returns_unlimited_when_no_quota() {
+    let quota_repo = Arc::new(InMemoryQuotaRepository::new());
+    let ledger_repo = Arc::new(InMemoryUsageLedgerRepository::new());
+
+    let handler = CheckQuotaHandler::new(quota_repo, ledger_repo);
+    let result = handler.execute(CheckQuotaQuery {
+        user_id: SystemId::new(),
+        usage_type: UsageType::StorageBytes,
+        requested_amount: 999_999,
+    }).await.unwrap();
+
+    assert!(result.allowed);
+    assert!(result.is_unlimited);
+}
diff --git a/crates/application/tests/storage/queries/mod.rs b/crates/application/tests/storage/queries/mod.rs
new file mode 100644
index 0000000..9859251
--- /dev/null
+++ b/crates/application/tests/storage/queries/mod.rs
@@ -0,0 +1 @@
+mod check_quota;