implement basic local cloud handoff UI (#9455)

## Description
<!-- Please remember to add your design buddy onto the PR for review, if
it contains any UI changes! -->

This PR implements the UI for the local -> cloud handoff flow in the
client. This is done levaraging the workspace-discovery and snapshotting
functionality added in the PRs below this one. On chip-click, we
snapshot the conversation's touched files and repos, and create a new
cloud mode pane to kick off a run. When the user submits a query, we
kick that run off.

Don't over-index on the UI too much — in a follow-up PR I'll add the
conversation into the cloud mode pane and also re-use the full cloud
mode setup v2 UI.

The associated server PR for this client PR is here:
warpdotdev/warp-server#10777

## Testing
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didn't add any new tests, what's your justification for not adding any?

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policy:
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demo: https://www.loom.com/share/a6caa2c974e34b49b2b038a8019c062c

## Agent Mode
- [x] Warp Agent Mode - This PR was created via Warp's AI Agent Mode

Author: harryalbert

app/Cargo.toml

@@ -915,6 +915,7 @@ vertical_tabs_summary_mode = []
 tab_configs = []
 agent_harness = []
 oz_handoff = []
+handoff_local_cloud = []
 hoa_notifications = []
 open_code_notifications = []
 transfer_control_tool = []

app/src/ai/agent_sdk/driver.rs

@@ -102,6 +102,7 @@ mod snapshot;
 pub(crate) mod terminal;
 
 use environment::PrepareEnvironmentError;
+pub(crate) use snapshot::upload_snapshot_for_handoff;
 use terminal::TerminalDriverEvent;
 
 const MCP_SERVER_STARTUP_TIMEOUT: Duration = Duration::from_secs(60);

app/src/ai/agent_sdk/driver/snapshot.rs

@@ -741,8 +741,6 @@ async fn upload_snapshot_from_declarations_file(
 ///   it at an incomplete prefix. Manifest-upload failures are also routed through
 ///   `report_error!` so on-call alerting catches the silent regression.
 /// - `Err(_)` only for hard failures of `upload_local_handoff_snapshot` itself (auth, etc.).
-// TODO(REMOTE-1486): drop once the handoff UI in the parent stack branch wires this up.
-#[allow(dead_code)]
 pub(crate) async fn upload_snapshot_for_handoff(
     repo_paths: Vec<PathBuf>,
     orphan_file_paths: Vec<PathBuf>,

app/src/ai/blocklist/agent_view/agent_input_footer/editor.rs

@@ -93,6 +93,19 @@ fn open_toolbar_items_from_settings<V: View>(
             )
         }
     };
+
+    // Drop saved items that are no longer available (e.g. their feature flag was disabled).
+    // Without this, the editor renders chips like `HandoffToCloud` from a prior `Custom`
+    // selection even when the gating flag is off.
+    let filter_unavailable = |items: Vec<AgentToolbarItemKind>| -> Vec<AgentToolbarItemKind> {
+        items
+            .into_iter()
+            .filter(|item| available.contains(item))
+            .collect()
+    };
+    let current_left = filter_unavailable(current_left);
+    let current_right = filter_unavailable(current_right);
+
     chip_configurator.open_left_right_zones_with_items(
         current_left,
         current_right,

app/src/ai/blocklist/agent_view/agent_input_footer/mod.rs

@@ -228,6 +228,11 @@ pub struct AgentInputFooter {
     // Fast-forward (auto-approve) toggle button shown in the agent view footer.
     fast_forward_button: ViewHandle<ActionButton>,
 
+    // "Hand off to cloud" chip. Visibility is gated on native/local handoff
+    // availability. Per-conversation eligibility is enforced by
+    // `Workspace::start_local_to_cloud_handoff`.
+    handoff_to_cloud_button: ViewHandle<ActionButton>,
+
     // CLI agent voice input state (self-contained, bypasses editor voice flow).
     #[cfg(feature = "voice_input")]
     cli_voice_input_state: CLIVoiceInputState,
@@ -349,6 +354,20 @@ impl AgentInputFooter {
                 })
         });
 
+        // "Hand off to cloud" chip. On click dispatches the workspace action that
+        // splits a new cloud-mode pane next to the local pane; that pane handles
+        // the rest of the handoff flow when native/local handoff is available.
+        let handoff_to_cloud_button = ctx.add_typed_action_view(|_ctx| {
+            ActionButton::new("", AgentInputButtonTheme)
+                .with_icon(Icon::UploadCloud)
+                .with_tooltip("Hand off to cloud")
+                .with_size(button_size)
+                .with_tooltip_alignment(TooltipAlignment::Left)
+                .on_click(|ctx| {
+                    ctx.dispatch_typed_action(AgentInputFooterAction::OpenHandoffPane);
+                })
+        });
+
         // CLI agent-specific buttons (only rendered when a CLI agent session is active).
         let cli_button_size = ButtonSize::AgentInputButton;
         let file_explorer_button = ctx.add_typed_action_view(|ctx| {
@@ -770,6 +789,7 @@ impl AgentInputFooter {
             cli_display_chips: vec![],
             display_chip_config,
             fast_forward_button,
+            handoff_to_cloud_button,
             #[cfg(feature = "voice_input")]
             cli_voice_input_state: CLIVoiceInputState::default(),
             #[cfg(feature = "voice_input")]
@@ -1365,7 +1385,8 @@ impl AgentInputFooter {
             AgentToolbarItemKind::ModelSelector
             | AgentToolbarItemKind::NLDToggle
             | AgentToolbarItemKind::ContextWindowUsage
-            | AgentToolbarItemKind::FastForwardToggle => None,
+            | AgentToolbarItemKind::FastForwardToggle
+            | AgentToolbarItemKind::HandoffToCloud => None,
         }
     }
 
@@ -1950,6 +1971,17 @@ impl AgentInputFooter {
             AgentToolbarItemKind::FastForwardToggle => FeatureFlag::FastForwardAutoexecuteButton
                 .is_enabled()
                 .then(|| ChildView::new(&self.fast_forward_button).finish()),
+            AgentToolbarItemKind::HandoffToCloud => {
+                if !AgentToolbarItemKind::handoff_to_cloud_available() {
+                    return None;
+                }
+                // Render the chip when the native/local handoff surface is available.
+                // Per-conversation eligibility (synced server token, non-empty
+                // history) is enforced by `Workspace::start_local_to_cloud_handoff`,
+                // which falls through to splitting a fresh cloud-mode pane when
+                // the active conversation isn't handoff-able.
+                Some(ChildView::new(&self.handoff_to_cloud_button).finish())
+            }
             // Handled by the available_in() guard above; included for exhaustiveness.
             AgentToolbarItemKind::FileExplorer
             | AgentToolbarItemKind::RichInput
@@ -2213,6 +2245,9 @@ pub enum AgentInputFooterAction {
     StartRemoteControl,
     StopRemoteControl,
     OpenCodingAgentSettings,
+    /// Open the local-to-cloud handoff pane. Dispatched by the
+    /// "Hand off to cloud" footer chip.
+    OpenHandoffPane,
     ShowContextMenu {
         position: Vector2F,
     },
@@ -2409,6 +2444,13 @@ impl TypedActionView for AgentInputFooter {
                     widget_id: crate::settings_view::cli_agent_settings_widget_id(),
                 });
             }
+            AgentInputFooterAction::OpenHandoffPane => {
+                if AgentToolbarItemKind::handoff_to_cloud_available() {
+                    ctx.emit(AgentInputFooterEvent::OpenHandoffPane {
+                        initial_prompt: None,
+                    });
+                }
+            }
             AgentInputFooterAction::ShowContextMenu { position } => {
                 ctx.emit(AgentInputFooterEvent::ShowContextMenu {
                     position: *position,
@@ -2455,6 +2497,11 @@ pub enum AgentInputFooterEvent {
     PluginInstalled(CLIAgent),
     #[cfg(not(target_family = "wasm"))]
     OpenPluginInstructionsPane(CLIAgent, PluginModalKind),
+    /// Local-to-cloud handoff chip clicked. The terminal `Input` subscriber
+    /// forwards this to `WorkspaceAction::OpenLocalToCloudHandoffPane`.
+    OpenHandoffPane {
+        initial_prompt: Option<String>,
+    },
 }
 
 impl Entity for AgentInputFooter {

app/src/ai/blocklist/agent_view/agent_input_footer/toolbar_item.rs

@@ -68,9 +68,17 @@ pub enum AgentToolbarItemKind {
 
     // Agent view only – shows fast-forward (auto-approve) toggle in the footer
     FastForwardToggle,
+
+    // Agent view only – "Hand off to cloud" chip.
+    HandoffToCloud,
 }
 
 impl AgentToolbarItemKind {
+    pub fn handoff_to_cloud_available() -> bool {
+        FeatureFlag::OzHandoff.is_enabled()
+            && FeatureFlag::HandoffLocalCloud.is_enabled()
+            && cfg!(all(feature = "local_fs", not(target_family = "wasm")))
+    }
     pub fn available_in(&self) -> ToolbarAvailability {
         match self {
             Self::ContextChip(_) | Self::VoiceInput | Self::FileAttach | Self::ShareSession => {
@@ -79,7 +87,8 @@ impl AgentToolbarItemKind {
             Self::ModelSelector
             | Self::NLDToggle
             | Self::ContextWindowUsage
-            | Self::FastForwardToggle => ToolbarAvailability::AgentViewOnly,
+            | Self::FastForwardToggle
+            | Self::HandoffToCloud => ToolbarAvailability::AgentViewOnly,
             Self::FileExplorer | Self::RichInput | Self::Settings => {
                 ToolbarAvailability::CLIAgentOnly
             }
@@ -98,6 +107,8 @@ impl AgentToolbarItemKind {
             Self::Settings | Self::ShareSession | Self::FileExplorer => !status.is_viewer(),
             Self::FileAttach => !status.is_viewer() || is_cloud_mode,
             Self::FastForwardToggle => !status.is_viewer() || status.is_executor(),
+            // Handoff is host-initiated; viewers cannot hand off another user's conversation.
+            Self::HandoffToCloud => !status.is_viewer(),
             Self::ContextChip(_)
             | Self::ModelSelector
             | Self::NLDToggle
@@ -120,6 +131,7 @@ impl AgentToolbarItemKind {
             Self::ShareSession => "/remote-control",
             Self::Settings => "Settings",
             Self::FastForwardToggle => "Fast Forward",
+            Self::HandoffToCloud => "Hand off to cloud",
         }
     }
 
@@ -136,6 +148,9 @@ impl AgentToolbarItemKind {
             Self::ShareSession => Some(Icon::Phone01),
             Self::Settings => Some(Icon::Settings),
             Self::FastForwardToggle => Some(Icon::FastForward),
+            // The bundled `upload-cloud-01.svg` (cloud-with-upward-arrow) is the
+            // closest fit among the existing icons for V0; design may swap it later.
+            Self::HandoffToCloud => Some(Icon::UploadCloud),
         }
     }
 
@@ -177,6 +192,9 @@ impl AgentToolbarItemKind {
         {
             items.push(Self::ShareSession);
         }
+        if Self::handoff_to_cloud_available() {
+            items.push(Self::HandoffToCloud);
+        }
         items.push(Self::VoiceInput);
         items.push(Self::FileAttach);
         items
@@ -203,6 +221,9 @@ impl AgentToolbarItemKind {
         {
             items.push(Self::ShareSession);
         }
+        if Self::handoff_to_cloud_available() {
+            items.push(Self::HandoffToCloud);
+        }
         items
     }
 

app/src/ai/blocklist/agent_view/zero_state_block.rs

@@ -177,22 +177,31 @@ impl AgentViewZeroStateBlock {
         if let Some(cloud_agent_view_model) = cloud_agent_view_model {
             let model_events_clone = model_events_dispatcher.clone();
             ctx.subscribe_to_model(cloud_agent_view_model, move |me, model, event, ctx| {
-                if FeatureFlag::CloudModeSetupV2.is_enabled() {
-                    match event {
+                if me.should_hide {
+                    return;
+                }
+
+                // Hide the zero state when this pane becomes a local-to-cloud handoff
+                // pane (REMOTE-1486). The fresh cloud-mode banner is suppressed because
+                // the pane is actually pre-loaded with a forked source conversation, not
+                // a brand-new one.
+                if matches!(event, AmbientAgentViewModelEvent::PendingHandoffChanged)
+                    && model.as_ref(ctx).is_local_to_cloud_handoff()
+                {
+                    me.should_hide = true;
+                } else if FeatureFlag::CloudModeSetupV2.is_enabled() {
+                    if matches!(
+                        event,
                         AmbientAgentViewModelEvent::DispatchedAgent
-                        | AmbientAgentViewModelEvent::Cancelled
-                            if !me.should_hide =>
-                        {
-                            me.should_hide = true;
-                            ctx.unsubscribe_to_model(&model);
-                            ctx.unsubscribe_to_model(&model_events_clone);
-                            ctx.unsubscribe_to_model(&BlocklistAIHistoryModel::handle(ctx));
-                            ctx.notify();
-                        }
-                        _ => (),
+                            | AmbientAgentViewModelEvent::Cancelled
+                    ) {
+                        me.should_hide = true;
                     }
                 } else if model.as_ref(ctx).should_show_status_footer() {
                     me.should_hide = true;
+                }
+
+                if me.should_hide {
                     ctx.unsubscribe_to_model(&model);
                     ctx.unsubscribe_to_model(&model_events_clone);
                     ctx.unsubscribe_to_model(&BlocklistAIHistoryModel::handle(ctx));
@@ -203,6 +212,8 @@ impl AgentViewZeroStateBlock {
 
         let has_parent_terminal =
             cloud_agent_view_model.is_none_or(|model| !model.as_ref(ctx).is_ambient_agent());
+        let is_local_to_cloud_handoff = cloud_agent_view_model
+            .is_some_and(|model| model.as_ref(ctx).is_local_to_cloud_handoff());
         let changelog_model = ChangelogModel::handle(ctx);
         ctx.subscribe_to_model(&changelog_model, |me, changelog_model, event, ctx| {
             if let changelog_model::Event::ChangelogRequestComplete { .. } = event {
@@ -259,7 +270,8 @@ impl AgentViewZeroStateBlock {
             terminal_model,
             current_working_directory,
             cached_recent_conversations,
-            should_hide: matches!(origin, AgentViewEntryOrigin::AcceptedPassiveCodeDiff),
+            should_hide: matches!(origin, AgentViewEntryOrigin::AcceptedPassiveCodeDiff)
+                || is_local_to_cloud_handoff,
             should_show_init_callout,
             has_parent_terminal,
             state_handles,

app/src/ai/blocklist/handoff/touched_repos.rs

@@ -17,9 +17,6 @@
 //! (one `git remote get-url origin` per unique repo). Callers run them in sequence
 //! off the main thread; see `app/src/workspace/view.rs::start_local_to_cloud_handoff`.
 
-// TODO(REMOTE-1486): drop once the handoff UI in the parent stack branch wires this up.
-#![allow(dead_code)]
-
 use std::collections::HashSet;
 use std::path::{Path, PathBuf};
 use std::time::Duration;

app/src/lib.rs

@@ -2849,6 +2849,8 @@ pub fn enabled_features() -> HashSet<FeatureFlag> {
         FeatureFlag::AgentHarness,
         #[cfg(feature = "oz_handoff")]
         FeatureFlag::OzHandoff,
+        #[cfg(feature = "handoff_local_cloud")]
+        FeatureFlag::HandoffLocalCloud,
         #[cfg(feature = "hoa_notifications")]
         FeatureFlag::HOANotifications,
         #[cfg(feature = "open_code_notifications")]

app/src/search/slash_command_menu/static_commands/commands.rs

@@ -171,6 +171,21 @@ pub static FORK: LazyLock<StaticCommand> = LazyLock::new(|| {
     }
 });
 
+pub static MOVE_TO_CLOUD: LazyLock<StaticCommand> = LazyLock::new(|| StaticCommand {
+    name: "/move-to-cloud",
+    description: "Hand off this conversation to a cloud agent",
+    icon_path: "bundled/svg/upload-cloud-01.svg",
+    availability: Availability::AGENT_VIEW
+        | Availability::ACTIVE_CONVERSATION
+        | Availability::AI_ENABLED,
+    auto_enter_ai_mode: false,
+    argument: Some(
+        Argument::optional()
+            .with_hint_text("<optional follow-up prompt>")
+            .with_execute_on_selection(),
+    ),
+});
+
 pub const OPEN_CODE_REVIEW: StaticCommand = StaticCommand {
     name: "/open-code-review",
     description: "Open code review",
@@ -686,6 +701,13 @@ fn all_commands() -> Vec<StaticCommand> {
         commands.push(CLOUD_AGENT.clone());
     }
 
+    if FeatureFlag::OzHandoff.is_enabled()
+        && FeatureFlag::HandoffLocalCloud.is_enabled()
+        && cfg!(all(feature = "local_fs", not(target_family = "wasm")))
+    {
+        commands.push(MOVE_TO_CLOUD.clone());
+    }
+
     if FeatureFlag::InlineProfileSelector.is_enabled() {
         commands.push(PROFILE.clone());
     }