application: channels bounded context

CQRS use cases (create/update/delete/get/list/list_by_owner),
ownership checks, auto-snapshot on config change.
Channel setters added to domain model.

crates/application/src/channels/commands.rs

@@ -0,0 +1,32 @@
+use uuid::Uuid;
+
+use domain::models::ScheduleConfig;
+use domain::value_objects::RecyclePolicy;
+
+/// Create a new channel.
+pub struct CreateChannelCommand {
+    pub owner_id: Uuid,
+    pub name: String,
+    pub timezone: String,
+}
+
+/// Update an existing channel (partial — only `Some` fields are applied).
+pub struct UpdateChannelCommand {
+    pub channel_id: Uuid,
+    /// Used for ownership check.
+    pub owner_id: Uuid,
+    pub name: Option<String>,
+    /// `Some(None)` clears the description; `None` leaves it unchanged.
+    pub description: Option<Option<String>>,
+    pub timezone: Option<String>,
+    pub schedule_config: Option<ScheduleConfig>,
+    pub recycle_policy: Option<RecyclePolicy>,
+    pub auto_schedule: Option<bool>,
+}
+
+/// Delete a channel.
+pub struct DeleteChannelCommand {
+    pub channel_id: Uuid,
+    /// Used for ownership check.
+    pub owner_id: Uuid,
+}

crates/application/src/channels/create.rs

@@ -0,0 +1,29 @@
+use domain::events::DomainEvent;
+use domain::models::Channel;
+use domain::value_objects::UserId;
+use domain::DomainResult;
+
+use super::commands::CreateChannelCommand;
+use super::deps::ChannelCommandDeps;
+
+/// Create a new channel.
+///
+/// Flow: convert raw IDs -> build Channel -> save -> publish event -> return.
+pub async fn execute(deps: &ChannelCommandDeps, cmd: CreateChannelCommand) -> DomainResult<Channel> {
+    let owner_id = UserId::from(cmd.owner_id);
+    let channel = Channel::new(owner_id, cmd.name, cmd.timezone);
+
+    deps.channel_command.save(&channel).await?;
+
+    deps.event_publisher
+        .publish(DomainEvent::ChannelCreated {
+            channel_id: channel.id(),
+        })
+        .await?;
+
+    Ok(channel)
+}
+
+#[cfg(test)]
+#[path = "tests/create.rs"]
+mod tests;

crates/application/src/channels/delete.rs

@@ -0,0 +1,36 @@
+use domain::events::DomainEvent;
+use domain::value_objects::{ChannelId, UserId};
+use domain::{DomainError, DomainResult};
+
+use super::commands::DeleteChannelCommand;
+use super::deps::ChannelCommandDeps;
+
+/// Delete a channel after verifying ownership.
+///
+/// Flow: find channel -> verify ownership -> delete -> publish event.
+pub async fn execute(deps: &ChannelCommandDeps, cmd: DeleteChannelCommand) -> DomainResult<()> {
+    let channel_id = ChannelId::from(cmd.channel_id);
+    let owner_id = UserId::from(cmd.owner_id);
+
+    let channel = deps
+        .channel_query
+        .find_by_id(channel_id)
+        .await?
+        .ok_or(DomainError::ChannelNotFound(cmd.channel_id))?;
+
+    if channel.owner_id() != owner_id {
+        return Err(DomainError::forbidden("You don't own this channel"));
+    }
+
+    deps.channel_command.delete(channel_id).await?;
+
+    deps.event_publisher
+        .publish(DomainEvent::ChannelDeleted { channel_id })
+        .await?;
+
+    Ok(())
+}
+
+#[cfg(test)]
+#[path = "tests/delete.rs"]
+mod tests;

crates/application/src/channels/deps.rs

@@ -0,0 +1,15 @@
+use std::sync::Arc;
+
+use domain::ports::{ChannelCommand, ChannelQuery, EventPublisher};
+
+/// Dependencies for channel write use cases (create, update, delete).
+pub struct ChannelCommandDeps {
+    pub channel_command: Arc<dyn ChannelCommand>,
+    pub channel_query: Arc<dyn ChannelQuery>,
+    pub event_publisher: Arc<dyn EventPublisher>,
+}
+
+/// Dependencies for channel read use cases (get, list, list_by_owner).
+pub struct ChannelQueryDeps {
+    pub channel_query: Arc<dyn ChannelQuery>,
+}

crates/application/src/channels/get.rs

@@ -0,0 +1,16 @@
+use domain::models::Channel;
+use domain::value_objects::ChannelId;
+use domain::DomainResult;
+
+use super::deps::ChannelQueryDeps;
+use super::queries::GetChannelQuery;
+
+/// Get a single channel by ID.
+pub async fn execute(deps: &ChannelQueryDeps, query: GetChannelQuery) -> DomainResult<Option<Channel>> {
+    let channel_id = ChannelId::from(query.channel_id);
+    deps.channel_query.find_by_id(channel_id).await
+}
+
+#[cfg(test)]
+#[path = "tests/get.rs"]
+mod tests;

crates/application/src/channels/list.rs

@@ -0,0 +1,14 @@
+use domain::models::Channel;
+use domain::DomainResult;
+
+use super::deps::ChannelQueryDeps;
+use super::queries::ListChannelsQuery;
+
+/// List all channels.
+pub async fn execute(deps: &ChannelQueryDeps, _query: ListChannelsQuery) -> DomainResult<Vec<Channel>> {
+    deps.channel_query.find_all().await
+}
+
+#[cfg(test)]
+#[path = "tests/list.rs"]
+mod tests;

crates/application/src/channels/list_by_owner.rs

@@ -0,0 +1,16 @@
+use domain::models::Channel;
+use domain::value_objects::UserId;
+use domain::DomainResult;
+
+use super::deps::ChannelQueryDeps;
+use super::queries::ListByOwnerQuery;
+
+/// List channels belonging to a specific owner.
+pub async fn execute(deps: &ChannelQueryDeps, query: ListByOwnerQuery) -> DomainResult<Vec<Channel>> {
+    let owner_id = UserId::from(query.owner_id);
+    deps.channel_query.find_by_owner(owner_id).await
+}
+
+#[cfg(test)]
+#[path = "tests/list_by_owner.rs"]
+mod tests;

crates/application/src/channels/mod.rs

@@ -0,0 +1,13 @@
+pub mod commands;
+pub mod create;
+pub mod delete;
+pub mod deps;
+pub mod get;
+pub mod list;
+pub mod list_by_owner;
+pub mod queries;
+pub mod update;
+
+pub use commands::{CreateChannelCommand, DeleteChannelCommand, UpdateChannelCommand};
+pub use deps::{ChannelCommandDeps, ChannelQueryDeps};
+pub use queries::{GetChannelQuery, ListByOwnerQuery, ListChannelsQuery};

crates/application/src/channels/queries.rs

@@ -0,0 +1,14 @@
+use uuid::Uuid;
+
+/// Fetch a single channel by ID.
+pub struct GetChannelQuery {
+    pub channel_id: Uuid,
+}
+
+/// List all channels.
+pub struct ListChannelsQuery;
+
+/// List channels belonging to a specific owner.
+pub struct ListByOwnerQuery {
+    pub owner_id: Uuid,
+}

crates/application/src/channels/tests/create.rs

@@ -0,0 +1,65 @@
+use std::sync::Arc;
+
+use domain::testing::{InMemoryChannelRepository, NoopEventPublisher};
+use domain::value_objects::UserId;
+
+use crate::channels::commands::CreateChannelCommand;
+use crate::channels::create;
+use crate::channels::deps::ChannelCommandDeps;
+
+fn make_deps() -> (ChannelCommandDeps, Arc<InMemoryChannelRepository>) {
+    let repo = Arc::new(InMemoryChannelRepository::new());
+    let deps = ChannelCommandDeps {
+        channel_command: repo.clone(),
+        channel_query: repo.clone(),
+        event_publisher: Arc::new(NoopEventPublisher::new()),
+    };
+    (deps, repo)
+}
+
+#[tokio::test]
+async fn creates_channel_successfully() {
+    let (deps, repo) = make_deps();
+    let owner = UserId::generate();
+
+    let channel = create::execute(
+        &deps,
+        CreateChannelCommand {
+            owner_id: owner.value(),
+            name: "Movie Night".into(),
+            timezone: "America/New_York".into(),
+        },
+    )
+    .await
+    .unwrap();
+
+    assert_eq!(channel.name(), "Movie Night");
+    assert_eq!(channel.timezone(), "America/New_York");
+    assert_eq!(channel.owner_id(), owner);
+
+    // Verify persisted
+    let stored = repo.channels.lock().unwrap();
+    assert_eq!(stored.len(), 1);
+    let persisted = stored.values().next().unwrap();
+    assert_eq!(persisted.id(), channel.id());
+}
+
+#[tokio::test]
+async fn create_returns_default_config() {
+    let (deps, _) = make_deps();
+
+    let channel = create::execute(
+        &deps,
+        CreateChannelCommand {
+            owner_id: UserId::generate().value(),
+            name: "Defaults".into(),
+            timezone: "UTC".into(),
+        },
+    )
+    .await
+    .unwrap();
+
+    assert!(channel.description().is_none());
+    assert!(!channel.auto_schedule());
+    assert!(channel.schedule_config().day_blocks().is_empty());
+}

crates/application/src/channels/tests/delete.rs

@@ -0,0 +1,101 @@
+use std::sync::Arc;
+
+use domain::testing::{InMemoryChannelRepository, NoopEventPublisher};
+use domain::value_objects::UserId;
+use domain::DomainError;
+
+use crate::channels::commands::{CreateChannelCommand, DeleteChannelCommand};
+use crate::channels::deps::ChannelCommandDeps;
+use crate::channels::{create, delete};
+
+fn make_deps() -> (ChannelCommandDeps, Arc<InMemoryChannelRepository>) {
+    let repo = Arc::new(InMemoryChannelRepository::new());
+    let deps = ChannelCommandDeps {
+        channel_command: repo.clone(),
+        channel_query: repo.clone(),
+        event_publisher: Arc::new(NoopEventPublisher::new()),
+    };
+    (deps, repo)
+}
+
+#[tokio::test]
+async fn deletes_channel_by_owner() {
+    let (deps, repo) = make_deps();
+    let owner = UserId::generate();
+
+    let channel = create::execute(
+        &deps,
+        CreateChannelCommand {
+            owner_id: owner.value(),
+            name: "Doomed".into(),
+            timezone: "UTC".into(),
+        },
+    )
+    .await
+    .unwrap();
+
+    delete::execute(
+        &deps,
+        DeleteChannelCommand {
+            channel_id: channel.id().value(),
+            owner_id: owner.value(),
+        },
+    )
+    .await
+    .unwrap();
+
+    assert!(repo.channels.lock().unwrap().is_empty());
+}
+
+#[tokio::test]
+async fn delete_fails_if_not_owner() {
+    let (deps, _) = make_deps();
+    let owner = UserId::generate();
+    let stranger = UserId::generate();
+
+    let channel = create::execute(
+        &deps,
+        CreateChannelCommand {
+            owner_id: owner.value(),
+            name: "Protected".into(),
+            timezone: "UTC".into(),
+        },
+    )
+    .await
+    .unwrap();
+
+    let result = delete::execute(
+        &deps,
+        DeleteChannelCommand {
+            channel_id: channel.id().value(),
+            owner_id: stranger.value(),
+        },
+    )
+    .await;
+
+    assert!(result.is_err());
+    match result.unwrap_err() {
+        DomainError::Forbidden(_) => {}
+        other => panic!("expected Forbidden, got: {:?}", other),
+    }
+}
+
+#[tokio::test]
+async fn delete_nonexistent_channel_returns_not_found() {
+    let (deps, _) = make_deps();
+
+    let result = delete::execute(
+        &deps,
+        DeleteChannelCommand {
+            channel_id: uuid::Uuid::new_v4(),
+            owner_id: uuid::Uuid::new_v4(),
+        },
+    )
+    .await;
+
+    assert!(result.is_err());
+    assert!(matches!(
+        result.unwrap_err(),
+        DomainError::ChannelNotFound(_)
+    ));
+}

crates/application/src/channels/tests/get.rs

@@ -0,0 +1,66 @@
+use std::sync::Arc;
+
+use domain::testing::{InMemoryChannelRepository, NoopEventPublisher};
+use domain::value_objects::UserId;
+
+use crate::channels::commands::CreateChannelCommand;
+use crate::channels::deps::{ChannelCommandDeps, ChannelQueryDeps};
+use crate::channels::queries::GetChannelQuery;
+use crate::channels::{create, get};
+
+fn make_deps() -> (ChannelCommandDeps, ChannelQueryDeps) {
+    let repo = Arc::new(InMemoryChannelRepository::new());
+    let cmd_deps = ChannelCommandDeps {
+        channel_command: repo.clone(),
+        channel_query: repo.clone(),
+        event_publisher: Arc::new(NoopEventPublisher::new()),
+    };
+    let query_deps = ChannelQueryDeps {
+        channel_query: repo,
+    };
+    (cmd_deps, query_deps)
+}
+
+#[tokio::test]
+async fn get_existing_channel() {
+    let (cmd_deps, query_deps) = make_deps();
+
+    let channel = create::execute(
+        &cmd_deps,
+        CreateChannelCommand {
+            owner_id: UserId::generate().value(),
+            name: "Findable".into(),
+            timezone: "UTC".into(),
+        },
+    )
+    .await
+    .unwrap();
+
+    let found = get::execute(
+        &query_deps,
+        GetChannelQuery {
+            channel_id: channel.id().value(),
+        },
+    )
+    .await
+    .unwrap();
+
+    assert!(found.is_some());
+    assert_eq!(found.unwrap().name(), "Findable");
+}
+
+#[tokio::test]
+async fn get_nonexistent_returns_none() {
+    let (_, query_deps) = make_deps();
+
+    let found = get::execute(
+        &query_deps,
+        GetChannelQuery {
+            channel_id: uuid::Uuid::new_v4(),
+        },
+    )
+    .await
+    .unwrap();
+
+    assert!(found.is_none());
+}

crates/application/src/channels/tests/list.rs

@@ -0,0 +1,51 @@
+use std::sync::Arc;
+
+use domain::testing::{InMemoryChannelRepository, NoopEventPublisher};
+use domain::value_objects::UserId;
+
+use crate::channels::commands::CreateChannelCommand;
+use crate::channels::deps::{ChannelCommandDeps, ChannelQueryDeps};
+use crate::channels::queries::ListChannelsQuery;
+use crate::channels::{create, list};
+
+fn make_deps() -> (ChannelCommandDeps, ChannelQueryDeps) {
+    let repo = Arc::new(InMemoryChannelRepository::new());
+    let cmd_deps = ChannelCommandDeps {
+        channel_command: repo.clone(),
+        channel_query: repo.clone(),
+        event_publisher: Arc::new(NoopEventPublisher::new()),
+    };
+    let query_deps = ChannelQueryDeps {
+        channel_query: repo,
+    };
+    (cmd_deps, query_deps)
+}
+
+#[tokio::test]
+async fn list_empty_returns_empty() {
+    let (_, query_deps) = make_deps();
+
+    let channels = list::execute(&query_deps, ListChannelsQuery).await.unwrap();
+    assert!(channels.is_empty());
+}
+
+#[tokio::test]
+async fn list_returns_all_channels() {
+    let (cmd_deps, query_deps) = make_deps();
+
+    for name in ["A", "B", "C"] {
+        create::execute(
+            &cmd_deps,
+            CreateChannelCommand {
+                owner_id: UserId::generate().value(),
+                name: name.into(),
+                timezone: "UTC".into(),
+            },
+        )
+        .await
+        .unwrap();
+    }
+
+    let channels = list::execute(&query_deps, ListChannelsQuery).await.unwrap();
+    assert_eq!(channels.len(), 3);
+}

crates/application/src/channels/tests/list_by_owner.rs

@@ -0,0 +1,83 @@
+use std::sync::Arc;
+
+use domain::testing::{InMemoryChannelRepository, NoopEventPublisher};
+use domain::value_objects::UserId;
+
+use crate::channels::commands::CreateChannelCommand;
+use crate::channels::deps::{ChannelCommandDeps, ChannelQueryDeps};
+use crate::channels::queries::ListByOwnerQuery;
+use crate::channels::{create, list_by_owner};
+
+fn make_deps() -> (ChannelCommandDeps, ChannelQueryDeps) {
+    let repo = Arc::new(InMemoryChannelRepository::new());
+    let cmd_deps = ChannelCommandDeps {
+        channel_command: repo.clone(),
+        channel_query: repo.clone(),
+        event_publisher: Arc::new(NoopEventPublisher::new()),
+    };
+    let query_deps = ChannelQueryDeps {
+        channel_query: repo,
+    };
+    (cmd_deps, query_deps)
+}
+
+#[tokio::test]
+async fn filters_by_owner() {
+    let (cmd_deps, query_deps) = make_deps();
+    let alice = UserId::generate();
+    let bob = UserId::generate();
+
+    // Alice: 2 channels
+    for name in ["Alice-1", "Alice-2"] {
+        create::execute(
+            &cmd_deps,
+            CreateChannelCommand {
+                owner_id: alice.value(),
+                name: name.into(),
+                timezone: "UTC".into(),
+            },
+        )
+        .await
+        .unwrap();
+    }
+
+    // Bob: 1 channel
+    create::execute(
+        &cmd_deps,
+        CreateChannelCommand {
+            owner_id: bob.value(),
+            name: "Bob-1".into(),
+            timezone: "UTC".into(),
+        },
+    )
+    .await
+    .unwrap();
+
+    let alice_channels = list_by_owner::execute(
+        &query_deps,
+        ListByOwnerQuery {
+            owner_id: alice.value(),
+        },
+    )
+    .await
+    .unwrap();
+
+    assert_eq!(alice_channels.len(), 2);
+    assert!(alice_channels.iter().all(|c| c.owner_id() == alice));
+}
+
+#[tokio::test]
+async fn no_channels_returns_empty() {
+    let (_, query_deps) = make_deps();
+
+    let channels = list_by_owner::execute(
+        &query_deps,
+        ListByOwnerQuery {
+            owner_id: UserId::generate().value(),
+        },
+    )
+    .await
+    .unwrap();
+
+    assert!(channels.is_empty());
+}

crates/application/src/channels/tests/update.rs

@@ -0,0 +1,251 @@
+use std::sync::Arc;
+
+use domain::testing::{InMemoryChannelRepository, NoopEventPublisher};
+use domain::value_objects::UserId;
+use domain::DomainError;
+
+use crate::channels::commands::{CreateChannelCommand, UpdateChannelCommand};
+use crate::channels::deps::ChannelCommandDeps;
+use crate::channels::{create, update};
+
+fn make_deps() -> (ChannelCommandDeps, Arc<InMemoryChannelRepository>) {
+    let repo = Arc::new(InMemoryChannelRepository::new());
+    let deps = ChannelCommandDeps {
+        channel_command: repo.clone(),
+        channel_query: repo.clone(),
+        event_publisher: Arc::new(NoopEventPublisher::new()),
+    };
+    (deps, repo)
+}
+
+#[tokio::test]
+async fn updates_channel_name() {
+    let (deps, _) = make_deps();
+    let owner = UserId::generate();
+
+    let channel = create::execute(
+        &deps,
+        CreateChannelCommand {
+            owner_id: owner.value(),
+            name: "Original".into(),
+            timezone: "UTC".into(),
+        },
+    )
+    .await
+    .unwrap();
+
+    let updated = update::execute(
+        &deps,
+        UpdateChannelCommand {
+            channel_id: channel.id().value(),
+            owner_id: owner.value(),
+            name: Some("Renamed".into()),
+            description: None,
+            timezone: None,
+            schedule_config: None,
+            recycle_policy: None,
+            auto_schedule: None,
+        },
+    )
+    .await
+    .unwrap();
+
+    assert_eq!(updated.name(), "Renamed");
+    assert_eq!(updated.timezone(), "UTC"); // unchanged
+}
+
+#[tokio::test]
+async fn update_fails_if_not_owner() {
+    let (deps, _) = make_deps();
+    let owner = UserId::generate();
+    let stranger = UserId::generate();
+
+    let channel = create::execute(
+        &deps,
+        CreateChannelCommand {
+            owner_id: owner.value(),
+            name: "Protected".into(),
+            timezone: "UTC".into(),
+        },
+    )
+    .await
+    .unwrap();
+
+    let result = update::execute(
+        &deps,
+        UpdateChannelCommand {
+            channel_id: channel.id().value(),
+            owner_id: stranger.value(),
+            name: Some("Hacked".into()),
+            description: None,
+            timezone: None,
+            schedule_config: None,
+            recycle_policy: None,
+            auto_schedule: None,
+        },
+    )
+    .await;
+
+    assert!(result.is_err());
+    match result.unwrap_err() {
+        DomainError::Forbidden(_) => {}
+        other => panic!("expected Forbidden, got: {:?}", other),
+    }
+}
+
+#[tokio::test]
+async fn update_nonexistent_channel_returns_not_found() {
+    let (deps, _) = make_deps();
+
+    let result = update::execute(
+        &deps,
+        UpdateChannelCommand {
+            channel_id: uuid::Uuid::new_v4(),
+            owner_id: uuid::Uuid::new_v4(),
+            name: Some("Ghost".into()),
+            description: None,
+            timezone: None,
+            schedule_config: None,
+            recycle_policy: None,
+            auto_schedule: None,
+        },
+    )
+    .await;
+
+    assert!(result.is_err());
+    assert!(matches!(
+        result.unwrap_err(),
+        DomainError::ChannelNotFound(_)
+    ));
+}
+
+#[tokio::test]
+async fn update_config_creates_snapshot() {
+    let (deps, repo) = make_deps();
+    let owner = UserId::generate();
+
+    let channel = create::execute(
+        &deps,
+        CreateChannelCommand {
+            owner_id: owner.value(),
+            name: "Snapshotted".into(),
+            timezone: "UTC".into(),
+        },
+    )
+    .await
+    .unwrap();
+
+    // Update with new schedule_config
+    let new_config = domain::models::ScheduleConfig::default();
+    update::execute(
+        &deps,
+        UpdateChannelCommand {
+            channel_id: channel.id().value(),
+            owner_id: owner.value(),
+            name: None,
+            description: None,
+            timezone: None,
+            schedule_config: Some(new_config),
+            recycle_policy: None,
+            auto_schedule: None,
+        },
+    )
+    .await
+    .unwrap();
+
+    // Verify a config snapshot was created
+    let snapshots = repo.snapshots.lock().unwrap();
+    assert_eq!(snapshots.len(), 1);
+    assert_eq!(snapshots[0].channel_id(), channel.id());
+}
+
+#[tokio::test]
+async fn update_without_config_skips_snapshot() {
+    let (deps, repo) = make_deps();
+    let owner = UserId::generate();
+
+    let channel = create::execute(
+        &deps,
+        CreateChannelCommand {
+            owner_id: owner.value(),
+            name: "NoSnapshot".into(),
+            timezone: "UTC".into(),
+        },
+    )
+    .await
+    .unwrap();
+
+    // Update name only — no config change
+    update::execute(
+        &deps,
+        UpdateChannelCommand {
+            channel_id: channel.id().value(),
+            owner_id: owner.value(),
+            name: Some("Renamed".into()),
+            description: None,
+            timezone: None,
+            schedule_config: None,
+            recycle_policy: None,
+            auto_schedule: None,
+        },
+    )
+    .await
+    .unwrap();
+
+    // No snapshot should exist
+    let snapshots = repo.snapshots.lock().unwrap();
+    assert!(snapshots.is_empty());
+}
+
+#[tokio::test]
+async fn update_description_clear() {
+    let (deps, _) = make_deps();
+    let owner = UserId::generate();
+
+    let channel = create::execute(
+        &deps,
+        CreateChannelCommand {
+            owner_id: owner.value(),
+            name: "Desc Test".into(),
+            timezone: "UTC".into(),
+        },
+    )
+    .await
+    .unwrap();
+
+    // Set description
+    let updated = update::execute(
+        &deps,
+        UpdateChannelCommand {
+            channel_id: channel.id().value(),
+            owner_id: owner.value(),
+            name: None,
+            description: Some(Some("A description".into())),
+            timezone: None,
+            schedule_config: None,
+            recycle_policy: None,
+            auto_schedule: None,
+        },
+    )
+    .await
+    .unwrap();
+    assert_eq!(updated.description(), Some("A description"));
+
+    // Clear description with Some(None)
+    let cleared = update::execute(
+        &deps,
+        UpdateChannelCommand {
+            channel_id: channel.id().value(),
+            owner_id: owner.value(),
+            name: None,
+            description: Some(None),
+            timezone: None,
+            schedule_config: None,
+            recycle_policy: None,
+            auto_schedule: None,
+        },
+    )
+    .await
+    .unwrap();
+    assert!(cleared.description().is_none());
+}

crates/application/src/channels/update.rs

@@ -0,0 +1,68 @@
+use domain::events::DomainEvent;
+use domain::models::Channel;
+use domain::value_objects::{ChannelId, UserId};
+use domain::{DomainError, DomainResult};
+
+use super::commands::UpdateChannelCommand;
+use super::deps::ChannelCommandDeps;
+
+/// Update an existing channel.
+///
+/// Flow: find channel -> verify ownership -> snapshot config if changed ->
+/// apply updates -> save -> publish event -> return.
+pub async fn execute(deps: &ChannelCommandDeps, cmd: UpdateChannelCommand) -> DomainResult<Channel> {
+    let channel_id = ChannelId::from(cmd.channel_id);
+    let owner_id = UserId::from(cmd.owner_id);
+
+    let mut channel = deps
+        .channel_query
+        .find_by_id(channel_id)
+        .await?
+        .ok_or(DomainError::ChannelNotFound(cmd.channel_id))?;
+
+    // Ownership check
+    if channel.owner_id() != owner_id {
+        return Err(DomainError::forbidden("You don't own this channel"));
+    }
+
+    // Auto-snapshot the current config before overwriting
+    if cmd.schedule_config.is_some() {
+        deps.channel_command
+            .save_config_snapshot(channel_id, channel.schedule_config(), None)
+            .await?;
+    }
+
+    // Apply partial updates
+    if let Some(name) = cmd.name {
+        channel.set_name(name);
+    }
+    if let Some(description) = cmd.description {
+        channel.set_description(description);
+    }
+    if let Some(timezone) = cmd.timezone {
+        channel.set_timezone(timezone);
+    }
+    if let Some(config) = cmd.schedule_config {
+        channel.set_schedule_config(config);
+    }
+    if let Some(policy) = cmd.recycle_policy {
+        channel.set_recycle_policy(policy);
+    }
+    if let Some(auto) = cmd.auto_schedule {
+        channel.set_auto_schedule(auto);
+    }
+
+    deps.channel_command.save(&channel).await?;
+
+    deps.event_publisher
+        .publish(DomainEvent::ChannelUpdated {
+            channel_id: channel.id(),
+        })
+        .await?;
+
+    Ok(channel)
+}
+
+#[cfg(test)]
+#[path = "tests/update.rs"]
+mod tests;

crates/application/src/lib.rs

@@ -1 +1,2 @@
 pub mod auth;
+pub mod channels;