feat: integrate workspace switching

crates/client/src/backend_runtime.rs

@@ -14,6 +14,8 @@ pub struct BackendRuntimeTarget {
     /// Workspace Backend API root URL, for example `http://127.0.0.1:8787`.
     /// This is intentionally the Backend endpoint, not a Runtime endpoint.
     pub base_url: String,
+    /// Workspace identity used for every Worker lifecycle and protocol operation.
+    pub workspace_id: String,
     /// Backend-owned Runtime identity used as path authority.
     pub runtime_id: String,
     /// Backend-owned Worker identity used as path authority.
@@ -23,11 +25,13 @@ pub struct BackendRuntimeTarget {
 impl BackendRuntimeTarget {
     pub fn new(
         base_url: impl Into<String>,
+        workspace_id: impl Into<String>,
         runtime_id: impl Into<String>,
         worker_id: impl Into<String>,
     ) -> Self {
         Self {
             base_url: base_url.into(),
+            workspace_id: workspace_id.into(),
             runtime_id: runtime_id.into(),
             worker_id: worker_id.into(),
         }
@@ -57,6 +61,36 @@ impl BackendRuntimeListTarget {
             runtime_id,
         }
     }
+
+    pub fn select_workspace(&mut self, workspace_id: impl Into<String>) {
+        self.workspace_id = Some(workspace_id.into());
+    }
+
+    pub fn clear_workspace(&mut self) {
+        self.workspace_id = None;
+    }
+
+    pub fn workspace_id(&self) -> Option<&str> {
+        self.workspace_id.as_deref()
+    }
+
+    pub fn runtime_target(
+        &self,
+        runtime_id: impl Into<String>,
+        worker_id: impl Into<String>,
+    ) -> Result<BackendRuntimeTarget, BackendRuntimeClientError> {
+        let workspace_id = self.workspace_id.clone().ok_or_else(|| {
+            BackendRuntimeClientError::InvalidTarget(
+                "workspace_id is required before selecting a Backend worker".to_string(),
+            )
+        })?;
+        Ok(BackendRuntimeTarget::new(
+            self.base_url.clone(),
+            workspace_id,
+            runtime_id,
+            worker_id,
+        ))
+    }
 }
 
 #[derive(Debug, Clone, Deserialize)]
@@ -186,7 +220,13 @@ pub async fn list_backend_workers(
     validate_list_target(target)?;
     let http = reqwest::Client::new();
     if let Some(runtime_id) = target.runtime_id.as_deref() {
-        let path = backend_runtime_workers_path(target.workspace_id.as_deref(), runtime_id);
+        let path = backend_runtime_workers_path(
+            target
+                .workspace_id
+                .as_deref()
+                .expect("validated Backend Workspace scope"),
+            runtime_id,
+        );
         let url = join_base_and_path(&target.base_url, &path);
         return Ok(http
             .get(url)
@@ -197,7 +237,12 @@ pub async fn list_backend_workers(
             .await?);
     }
 
-    let runtime_path = backend_runtimes_path(target.workspace_id.as_deref());
+    let runtime_path = backend_runtimes_path(
+        target
+            .workspace_id
+            .as_deref()
+            .expect("validated Backend Workspace scope"),
+    );
     let runtime_url = join_base_and_path(&target.base_url, &runtime_path);
     let runtimes = http
         .get(runtime_url)
@@ -210,8 +255,13 @@ pub async fn list_backend_workers(
     let mut items = Vec::new();
     let mut diagnostics = runtimes.diagnostics;
     for runtime in runtimes.items {
-        let path =
-            backend_runtime_workers_path(target.workspace_id.as_deref(), &runtime.runtime_id);
+        let path = backend_runtime_workers_path(
+            target
+                .workspace_id
+                .as_deref()
+                .expect("validated Backend Workspace scope"),
+            &runtime.runtime_id,
+        );
         let url = join_base_and_path(&target.base_url, &path);
         match http
             .get(url)
@@ -256,7 +306,13 @@ pub async fn list_backend_stopped_workers(
         ));
     };
     let http = reqwest::Client::new();
-    let path = backend_runtime_workers_path(target.workspace_id.as_deref(), runtime_id);
+    let path = backend_runtime_workers_path(
+        target
+            .workspace_id
+            .as_deref()
+            .expect("validated Backend Workspace scope"),
+        runtime_id,
+    );
     let url = join_base_and_path(&target.base_url, &format!("{path}?status=stopped"));
     Ok(http
         .get(url)
@@ -272,7 +328,11 @@ pub async fn restore_backend_worker(
 ) -> Result<BackendWorkerRestoreResponse, BackendRuntimeClientError> {
     validate_target(target)?;
     let http = reqwest::Client::new();
-    let path = backend_runtime_worker_restore_path(None, &target.runtime_id, &target.worker_id);
+    let path = backend_runtime_worker_restore_path(
+        &target.workspace_id,
+        &target.runtime_id,
+        &target.worker_id,
+    );
     let url = join_base_and_path(&target.base_url, &path);
     Ok(http
         .post(url)
@@ -440,6 +500,11 @@ fn validate_target(target: &BackendRuntimeTarget) -> Result<(), BackendRuntimeCl
             "Backend API base URL must start with http:// or https://".to_string(),
         ));
     }
+    if target.workspace_id.is_empty() {
+        return Err(BackendRuntimeClientError::InvalidTarget(
+            "workspace_id is required".to_string(),
+        ));
+    }
     if target.runtime_id.is_empty() {
         return Err(BackendRuntimeClientError::InvalidTarget(
             "runtime_id is required".to_string(),
@@ -466,10 +531,18 @@ fn validate_list_target(
             "Backend API base URL must start with http:// or https://".to_string(),
         ));
     }
-    if target.workspace_id.as_deref().is_some_and(str::is_empty) {
-        return Err(BackendRuntimeClientError::InvalidTarget(
-            "workspace_id must not be empty when provided".to_string(),
-        ));
+    match target.workspace_id.as_deref() {
+        Some("") => {
+            return Err(BackendRuntimeClientError::InvalidTarget(
+                "workspace_id must not be empty".to_string(),
+            ));
+        }
+        None => {
+            return Err(BackendRuntimeClientError::InvalidTarget(
+                "workspace selection is required before listing Backend workers".to_string(),
+            ));
+        }
+        Some(_) => {}
     }
     if target.runtime_id.as_deref().is_some_and(str::is_empty) {
         return Err(BackendRuntimeClientError::InvalidTarget(
@@ -479,47 +552,35 @@ fn validate_list_target(
     Ok(())
 }
 
-fn backend_runtimes_path(workspace_id: Option<&str>) -> String {
-    match workspace_id {
-        Some(workspace_id) => format!("/api/w/{}/runtimes", path_segment_encode(workspace_id)),
-        None => "/api/runtimes".to_string(),
-    }
+fn backend_runtimes_path(workspace_id: &str) -> String {
+    format!("/api/w/{}/runtimes", path_segment_encode(workspace_id))
 }
 
-fn backend_runtime_workers_path(workspace_id: Option<&str>, runtime_id: &str) -> String {
-    match workspace_id {
-        Some(workspace_id) => format!(
-            "/api/w/{}/runtimes/{}/workers",
-            path_segment_encode(workspace_id),
-            path_segment_encode(runtime_id)
-        ),
-        None => format!("/api/runtimes/{}/workers", path_segment_encode(runtime_id)),
-    }
+fn backend_runtime_workers_path(workspace_id: &str, runtime_id: &str) -> String {
+    format!(
+        "/api/w/{}/runtimes/{}/workers",
+        path_segment_encode(workspace_id),
+        path_segment_encode(runtime_id)
+    )
 }
 
 fn backend_runtime_worker_restore_path(
-    workspace_id: Option<&str>,
+    workspace_id: &str,
     runtime_id: &str,
     worker_id: &str,
 ) -> String {
-    match workspace_id {
-        Some(workspace_id) => format!(
-            "/api/w/{}/runtimes/{}/workers/{}/restore",
-            path_segment_encode(workspace_id),
-            path_segment_encode(runtime_id),
-            path_segment_encode(worker_id)
-        ),
-        None => format!(
-            "/api/runtimes/{}/workers/{}/restore",
-            path_segment_encode(runtime_id),
-            path_segment_encode(worker_id)
-        ),
-    }
+    format!(
+        "/api/w/{}/runtimes/{}/workers/{}/restore",
+        path_segment_encode(workspace_id),
+        path_segment_encode(runtime_id),
+        path_segment_encode(worker_id)
+    )
 }
 
 fn protocol_ws_url(target: &BackendRuntimeTarget) -> String {
     let path = format!(
-        "/api/runtimes/{}/workers/{}/protocol/ws",
+        "/api/w/{}/runtimes/{}/workers/{}/protocol/ws",
+        path_segment_encode(&target.workspace_id),
         path_segment_encode(&target.runtime_id),
         path_segment_encode(&target.worker_id)
     );
@@ -573,11 +634,15 @@ mod tests {
 
     #[test]
     fn protocol_url_uses_backend_runtime_worker_identity() {
-        let target =
-            BackendRuntimeTarget::new("http://127.0.0.1:8787/", "runtime/one", "worker one");
+        let target = BackendRuntimeTarget::new(
+            "http://127.0.0.1:8787/",
+            "workspace alpha",
+            "runtime/one",
+            "worker one",
+        );
         assert_eq!(
             protocol_ws_url(&target),
-            "ws://127.0.0.1:8787/api/runtimes/runtime%2Fone/workers/worker%20one/protocol/ws"
+            "ws://127.0.0.1:8787/api/w/workspace%20alpha/runtimes/runtime%2Fone/workers/worker%20one/protocol/ws"
         );
     }
 
@@ -622,8 +687,8 @@ mod tests {
     }
 
     #[test]
-    fn workers_path_can_be_workspace_scoped_for_status_queries() {
-        let path = backend_runtime_workers_path(Some("team main"), "runtime/one");
+    fn workers_path_requires_workspace_scope_for_status_queries() {
+        let path = backend_runtime_workers_path("team main", "runtime/one");
         assert_eq!(
             format!("{path}?status=stopped"),
             "/api/w/team%20main/runtimes/runtime%2Fone/workers?status=stopped"
@@ -631,10 +696,10 @@ mod tests {
     }
 
     #[test]
-    fn restore_worker_path_uses_backend_runtime_worker_identity() {
+    fn restore_worker_path_requires_workspace_scope() {
         assert_eq!(
-            backend_runtime_worker_restore_path(None, "runtime/one", "worker one"),
-            "/api/runtimes/runtime%2Fone/workers/worker%20one/restore"
+            backend_runtime_worker_restore_path("team main", "runtime/one", "worker one"),
+            "/api/w/team%20main/runtimes/runtime%2Fone/workers/worker%20one/restore"
         );
     }
 }

crates/client/src/backend_workspace.rs

@@ -0,0 +1,161 @@
+use serde::{Deserialize, Serialize};
+use std::fmt;
+
+const DEFAULT_WORKSPACE_LIMIT: usize = 200;
+
+#[derive(Debug, Clone, Deserialize, PartialEq, Eq)]
+pub struct BackendWorkspace {
+    pub workspace_id: String,
+    pub owner_account_id: Option<String>,
+    pub display_name: String,
+    pub state: String,
+    pub created_at: String,
+    pub updated_at: String,
+}
+
+#[derive(Debug, Clone, Serialize, PartialEq, Eq)]
+#[serde(deny_unknown_fields)]
+pub struct CreateBackendWorkspaceRequest {
+    pub operation_key: String,
+    pub display_name: String,
+    pub repository: CreateBackendWorkspaceRepository,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
+#[serde(deny_unknown_fields)]
+pub struct CreateBackendWorkspaceRepository {
+    pub uri: String,
+    pub display_name: Option<String>,
+    pub default_ref: Option<String>,
+}
+
+#[derive(Debug, Clone, Deserialize, PartialEq, Eq)]
+pub struct CreateBackendWorkspaceResponse {
+    pub workspace: BackendWorkspace,
+    pub repository: CreateBackendWorkspaceRepositoryRecord,
+    pub config_revision: u64,
+    pub request_fingerprint: String,
+    pub replayed: bool,
+}
+
+#[derive(Debug, Clone, Deserialize, PartialEq, Eq)]
+pub struct CreateBackendWorkspaceRepositoryRecord {
+    pub workspace_id: String,
+    pub repository_id: String,
+    pub name: String,
+    pub kind: String,
+    pub uri: String,
+    pub default_ref: Option<String>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct BackendWorkspaceCatalogTarget {
+    pub base_url: String,
+}
+
+impl BackendWorkspaceCatalogTarget {
+    pub fn new(base_url: impl Into<String>) -> Self {
+        Self {
+            base_url: base_url.into(),
+        }
+    }
+}
+
+#[derive(Debug)]
+pub enum BackendWorkspaceClientError {
+    InvalidTarget(String),
+    RequestFailed { status: u16, message: String },
+    Http(reqwest::Error),
+}
+
+impl fmt::Display for BackendWorkspaceClientError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::InvalidTarget(message) => f.write_str(message),
+            Self::RequestFailed { status, message } => {
+                write!(f, "Backend request failed with HTTP {status}: {message}")
+            }
+            Self::Http(error) => write!(f, "{error}"),
+        }
+    }
+}
+
+impl std::error::Error for BackendWorkspaceClientError {}
+
+impl From<reqwest::Error> for BackendWorkspaceClientError {
+    fn from(error: reqwest::Error) -> Self {
+        Self::Http(error)
+    }
+}
+
+pub async fn list_backend_workspaces(
+    target: &BackendWorkspaceCatalogTarget,
+) -> Result<Vec<BackendWorkspace>, BackendWorkspaceClientError> {
+    validate_target(target)?;
+    let url = format!(
+        "{}/api/workspaces?limit={DEFAULT_WORKSPACE_LIMIT}",
+        target.base_url.trim_end_matches('/')
+    );
+    let response = reqwest::Client::new().get(url).send().await?;
+    let response = require_success(response).await?;
+    Ok(response.json::<Vec<BackendWorkspace>>().await?)
+}
+
+pub async fn create_backend_workspace(
+    target: &BackendWorkspaceCatalogTarget,
+    request: &CreateBackendWorkspaceRequest,
+) -> Result<CreateBackendWorkspaceResponse, BackendWorkspaceClientError> {
+    validate_target(target)?;
+    let url = format!("{}/api/workspaces", target.base_url.trim_end_matches('/'));
+    let response = reqwest::Client::new()
+        .post(url)
+        .json(request)
+        .send()
+        .await?;
+    let response = require_success(response).await?;
+    Ok(response.json::<CreateBackendWorkspaceResponse>().await?)
+}
+
+async fn require_success(
+    response: reqwest::Response,
+) -> Result<reqwest::Response, BackendWorkspaceClientError> {
+    if response.status().is_success() {
+        return Ok(response);
+    }
+    let status = response.status().as_u16();
+    let message = response.text().await.unwrap_or_default();
+    Err(BackendWorkspaceClientError::RequestFailed { status, message })
+}
+
+fn validate_target(
+    target: &BackendWorkspaceCatalogTarget,
+) -> Result<(), BackendWorkspaceClientError> {
+    if !(target.base_url.starts_with("http://") || target.base_url.starts_with("https://")) {
+        return Err(BackendWorkspaceClientError::InvalidTarget(
+            "Backend API base URL must start with http:// or https://".to_string(),
+        ));
+    }
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn create_request_keeps_operation_key_for_exact_retry() {
+        let request = CreateBackendWorkspaceRequest {
+            operation_key: "workspace-create-1".to_string(),
+            display_name: "Alpha".to_string(),
+            repository: CreateBackendWorkspaceRepository {
+                uri: "/srv/repos/alpha".to_string(),
+                display_name: Some("Main".to_string()),
+                default_ref: Some("develop".to_string()),
+            },
+        };
+
+        let retry = request.clone();
+        assert_eq!(retry.operation_key, "workspace-create-1");
+        assert_eq!(retry, request);
+    }
+}

crates/client/src/lib.rs

@@ -10,6 +10,7 @@
 
 pub mod backend_auth;
 pub mod backend_runtime;
+pub mod backend_workspace;
 pub mod runtime_command;
 pub mod spawn;
 pub mod target;
@@ -28,6 +29,11 @@ pub use backend_runtime::{
     BackendWorkerWorkspaceSummary, BackendWorkingDirectorySummary, list_backend_stopped_workers,
     list_backend_workers, restore_backend_worker,
 };
+pub use backend_workspace::{
+    BackendWorkspace, BackendWorkspaceCatalogTarget, BackendWorkspaceClientError,
+    CreateBackendWorkspaceRepository, CreateBackendWorkspaceRequest,
+    CreateBackendWorkspaceResponse, create_backend_workspace, list_backend_workspaces,
+};
 pub use runtime_command::WorkerRuntimeCommand;
 pub use target::{
     BackendTarget, Dashboard, LocalTarget, Target, TargetError, TargetKind, WorkerByName,

crates/client/src/target.rs

@@ -132,6 +132,12 @@ impl TargetError {
         }
     }
 
+    fn invalid(target: TargetKind, message: impl Into<String>) -> Self {
+        Self {
+            message: format!("invalid {target} target: {}", message.into()),
+        }
+    }
+
     fn local_runtime_command(error: std::io::Error) -> Self {
         Self {
             message: format!("failed to resolve local Worker runtime command: {error}"),
@@ -260,9 +266,16 @@ impl Target for BackendTarget {
         &self,
         selector: WorkerConnectionSelector,
     ) -> Result<WorkerConnection, TargetError> {
+        let workspace_id = self.workspace_id.clone().ok_or_else(|| {
+            TargetError::invalid(
+                self.kind(),
+                "workspace selection is required before connecting to a Backend Worker",
+            )
+        })?;
         Ok(WorkerConnection {
             target: BackendRuntimeTarget::new(
                 self.base_url.clone(),
+                workspace_id,
                 selector.runtime_id,
                 selector.worker_id,
             ),
@@ -313,10 +326,27 @@ mod tests {
             .unwrap();
 
         assert_eq!(connection.target.base_url, "http://127.0.0.1:8787");
+        assert_eq!(connection.target.workspace_id, "workspace-a");
         assert_eq!(connection.target.runtime_id, "runtime-a");
         assert_eq!(connection.target.worker_id, "worker-b");
     }
 
+    #[test]
+    fn backend_target_rejects_worker_connection_before_workspace_selection() {
+        let target = BackendTarget::new("http://127.0.0.1:8787", None::<String>);
+        let error =
+            match target.connect_worker(WorkerConnectionSelector::new("runtime-a", "worker-b")) {
+                Ok(_) => panic!("unscoped connection must fail"),
+                Err(error) => error,
+            };
+
+        assert!(
+            error
+                .to_string()
+                .contains("workspace selection is required")
+        );
+    }
+
     #[test]
     fn backend_target_rejects_local_worker_operations() {
         let target = BackendTarget::new("http://127.0.0.1:8787", None::<String>);

crates/client/tests/backend_workspace.rs

@@ -0,0 +1,36 @@
+use client::{
+    BackendTarget, CreateBackendWorkspaceRepository, CreateBackendWorkspaceRequest, Target,
+    WorkerConnectionSelector,
+};
+
+#[test]
+fn workspace_creation_request_preserves_operation_key_for_retry() {
+    let request = CreateBackendWorkspaceRequest {
+        operation_key: "workspace-create-1".to_string(),
+        display_name: "Alpha".to_string(),
+        repository: CreateBackendWorkspaceRepository {
+            uri: "/srv/repos/alpha".to_string(),
+            display_name: Some("Main".to_string()),
+            default_ref: Some("develop".to_string()),
+        },
+    };
+
+    assert_eq!(request.clone(), request);
+    assert_eq!(request.operation_key, "workspace-create-1");
+}
+
+#[test]
+fn backend_worker_connection_requires_explicit_workspace_scope() {
+    let target = BackendTarget::new("http://127.0.0.1:8787", None::<String>);
+    let error = match target.connect_worker(WorkerConnectionSelector::new("runtime-a", "worker-a"))
+    {
+        Ok(_) => panic!("unscoped Backend worker connection must fail"),
+        Err(error) => error,
+    };
+
+    assert!(
+        error
+            .to_string()
+            .contains("workspace selection is required")
+    );
+}

crates/tui/src/backend_worker_picker.rs

@@ -3,8 +3,8 @@ use std::io;
 use std::time::Duration;
 
 use client::{
-    BackendRuntimeListTarget, BackendRuntimeTarget, BackendWorkerSummary,
-    list_backend_stopped_workers, list_backend_workers, restore_backend_worker,
+    BackendRuntimeListTarget, BackendWorkerSummary, list_backend_stopped_workers,
+    list_backend_workers, restore_backend_worker,
 };
 use crossterm::event::{self, Event as TermEvent, KeyCode, KeyEventKind, KeyModifiers};
 use ratatui::backend::CrosstermBackend;
@@ -14,77 +14,94 @@ use ratatui::text::{Line, Span};
 use ratatui::widgets::Paragraph;
 use ratatui::{Frame, Terminal, TerminalOptions, Viewport};
 
+use crate::backend_workspace_picker::select_backend_workspace;
 use crate::console;
 
 const MAX_ROWS: usize = 10;
 const VIEWPORT_LINES: u16 = MAX_ROWS as u16 + 4;
 
 pub(crate) async fn run(
-    target: BackendRuntimeListTarget,
+    mut target: BackendRuntimeListTarget,
     include_stopped: bool,
 ) -> Result<(), Box<dyn Error>> {
-    let mut response = list_backend_workers(&target).await.map_err(|error| {
-        io::Error::other(format!(
-            "failed to list Backend runtime workers from {}: {error}",
-            target.base_url
-        ))
-    })?;
-    if include_stopped {
-        match list_backend_stopped_workers(&target).await {
-            Ok(stopped) => {
-                response.items.extend(stopped.items);
-                response.diagnostics.extend(stopped.diagnostics);
+    loop {
+        if target.workspace_id().is_none() {
+            let workspace_id = select_backend_workspace(&target.base_url)
+                .await
+                .map_err(|error| io::Error::other(error.to_string()))?
+                .ok_or_else(|| io::Error::other("Backend workspace picker cancelled"))?;
+            target.select_workspace(workspace_id);
+        }
+        let mut response = list_backend_workers(&target).await.map_err(|error| {
+            io::Error::other(format!(
+                "failed to list Backend runtime workers from {}: {error}",
+                target.base_url
+            ))
+        })?;
+        if include_stopped {
+            match list_backend_stopped_workers(&target).await {
+                Ok(stopped) => {
+                    response.items.extend(stopped.items);
+                    response.diagnostics.extend(stopped.diagnostics);
+                }
+                Err(error) => response.diagnostics.push(client::BackendDiagnostic {
+                    code: "backend_stopped_workers_list_failed".to_string(),
+                    severity: Some("error".to_string()),
+                    message: error.to_string(),
+                }),
             }
-            Err(error) => response.diagnostics.push(client::BackendDiagnostic {
-                code: "backend_stopped_workers_list_failed".to_string(),
-                severity: Some("error".to_string()),
-                message: error.to_string(),
-            }),
+        }
+        dedup_workers(&mut response.items);
+        if response.items.is_empty() {
+            let diagnostics = response
+                .diagnostics
+                .iter()
+                .map(|diagnostic| format!("{}: {}", diagnostic.code, diagnostic.message))
+                .collect::<Vec<_>>()
+                .join("; ");
+            let detail = if diagnostics.is_empty() {
+                "no backend diagnostics".to_string()
+            } else {
+                diagnostics
+            };
+            eprintln!(
+                "Backend returned no runtime workers for workspace {} ({detail}); choose another Workspace",
+                response.workspace_id
+            );
+            target.clear_workspace();
+            continue;
         }
-    }
-    dedup_workers(&mut response.items);
-    if response.items.is_empty() {
-        let diagnostics = response
-            .diagnostics
-            .iter()
-            .map(|diagnostic| format!("{}: {}", diagnostic.code, diagnostic.message))
-            .collect::<Vec<_>>()
-            .join("; ");
-        let detail = if diagnostics.is_empty() {
-            "no backend diagnostics".to_string()
-        } else {
-            diagnostics
-        };
-        return Err(Box::new(io::Error::other(format!(
-            "Backend returned no runtime workers for workspace {} ({detail})",
-            response.workspace_id
-        ))));
-    }
 
-    let selected = pick_worker(target.clone(), response.items)?;
-    let worker = if selected.state == "stopped" {
-        let restore_target = BackendRuntimeTarget::new(
-            target.base_url.clone(),
-            selected.runtime_id.clone(),
-            selected.worker_id.clone(),
-        );
-        restore_backend_worker(&restore_target)
-            .await
-            .map_err(|error| {
-                io::Error::other(format!(
-                    "failed to restore Backend worker {}/{}: {error}",
-                    selected.runtime_id, selected.worker_id
-                ))
-            })?
-            .result
-            .worker
-            .unwrap_or(selected)
-    } else {
-        selected
-    };
-    let attach_target =
-        BackendRuntimeTarget::new(target.base_url, worker.runtime_id, worker.worker_id);
-    console::run_backend_runtime(attach_target).await
+        let selected = match pick_worker(target.clone(), response.items)? {
+            WorkerPickerResult::SwitchWorkspace => {
+                target.clear_workspace();
+                continue;
+            }
+            WorkerPickerResult::Selected(selected) => selected,
+        };
+        let worker = if selected.state == "stopped" {
+            let restore_target = target
+                .runtime_target(selected.runtime_id.clone(), selected.worker_id.clone())
+                .map_err(|error| io::Error::other(error.to_string()))?;
+            restore_backend_worker(&restore_target)
+                .await
+                .map_err(|error| {
+                    io::Error::other(format!(
+                        "failed to restore Backend worker {}/{}: {error}",
+                        selected.runtime_id, selected.worker_id
+                    ))
+                })?
+                .result
+                .worker
+                .unwrap_or(selected)
+        } else {
+            selected
+        };
+        let attach_target = target
+            .runtime_target(worker.runtime_id, worker.worker_id)
+            .map_err(|error| io::Error::other(error.to_string()))?;
+        return console::run_backend_runtime(attach_target).await;
+    }
 }
 
 fn dedup_workers(workers: &mut Vec<BackendWorkerSummary>) {
@@ -92,10 +109,15 @@ fn dedup_workers(workers: &mut Vec<BackendWorkerSummary>) {
     workers.retain(|worker| seen.insert((worker.runtime_id.clone(), worker.worker_id.clone())));
 }
 
+enum WorkerPickerResult {
+    Selected(BackendWorkerSummary),
+    SwitchWorkspace,
+}
+
 fn pick_worker(
     target: BackendRuntimeListTarget,
     mut workers: Vec<BackendWorkerSummary>,
-) -> Result<BackendWorkerSummary, Box<dyn Error>> {
+) -> Result<WorkerPickerResult, Box<dyn Error>> {
     workers.sort_by(|a, b| {
         a.runtime_id
             .cmp(&b.runtime_id)
@@ -114,7 +136,13 @@ fn pick_worker(
             Some(Action::Down) => state.next(),
             Some(Action::Submit) => {
                 close_viewport(&mut terminal)?;
-                return Ok(state.selected_worker().clone());
+                return Ok(WorkerPickerResult::Selected(
+                    state.selected_worker().clone(),
+                ));
+            }
+            Some(Action::SwitchWorkspace) => {
+                close_viewport(&mut terminal)?;
+                return Ok(WorkerPickerResult::SwitchWorkspace);
             }
             Some(Action::Cancel) => {
                 close_viewport(&mut terminal)?;
@@ -181,6 +209,7 @@ enum Action {
     Up,
     Down,
     Submit,
+    SwitchWorkspace,
     Cancel,
 }
 
@@ -197,6 +226,7 @@ fn poll_event() -> io::Result<Option<Action>> {
                 KeyCode::Char('k') if !ctrl => Some(Action::Up),
                 KeyCode::Char('j') if !ctrl => Some(Action::Down),
                 KeyCode::Enter => Some(Action::Submit),
+                KeyCode::Char('w') if !ctrl => Some(Action::SwitchWorkspace),
                 KeyCode::Esc => Some(Action::Cancel),
                 KeyCode::Char('c') if ctrl => Some(Action::Cancel),
                 _ => None,
@@ -239,6 +269,8 @@ fn draw(frame: &mut Frame<'_>, state: &BackendWorkerPickerState) {
             Span::raw(" select   "),
             Span::styled("[enter]", Style::default().fg(Color::Green)),
             Span::raw(" attach   "),
+            Span::styled("[w]", Style::default().fg(Color::Cyan)),
+            Span::raw(" switch Workspace   "),
             Span::styled("[esc]", Style::default().fg(Color::Yellow)),
             Span::raw(" cancel"),
         ])),

crates/tui/src/backend_workspace_picker.rs

@@ -0,0 +1,240 @@
+use client::{
+    BackendWorkspace, BackendWorkspaceCatalogTarget, CreateBackendWorkspaceRepository,
+    CreateBackendWorkspaceRequest, create_backend_workspace, list_backend_workspaces,
+};
+use crossterm::event::{self, Event, KeyCode, KeyEventKind};
+use crossterm::terminal::{disable_raw_mode, enable_raw_mode};
+use ratatui::Terminal;
+use ratatui::backend::CrosstermBackend;
+use ratatui::layout::{Constraint, Direction, Layout};
+use ratatui::style::{Modifier, Style};
+use ratatui::text::{Line, Span};
+use ratatui::widgets::{Block, Borders, List, ListItem, ListState, Paragraph};
+use std::error::Error;
+use std::io::{self, IsTerminal, Write};
+use std::time::{SystemTime, UNIX_EPOCH};
+
+type PickerResult<T> = Result<T, Box<dyn Error>>;
+
+pub(crate) async fn select_backend_workspace(base_url: &str) -> PickerResult<Option<String>> {
+    let target = BackendWorkspaceCatalogTarget::new(base_url);
+    let mut workspaces = Vec::new();
+
+    'catalog: loop {
+        let error = match list_backend_workspaces(&target).await {
+            Ok(items) => {
+                workspaces = items;
+                None
+            }
+            Err(fetch_error) => Some(format!("failed to refresh workspaces: {fetch_error}")),
+        };
+
+        match pick_workspace(&workspaces, error.as_deref())? {
+            WorkspacePickerAction::Select(index) => {
+                return Ok(workspaces.get(index).map(|item| item.workspace_id.clone()));
+            }
+            WorkspacePickerAction::Refresh => continue,
+            WorkspacePickerAction::Create => {
+                let Some(request) = prompt_create_request()? else {
+                    continue;
+                };
+                loop {
+                    match create_backend_workspace(&target, &request).await {
+                        Ok(response) => return Ok(Some(response.workspace.workspace_id)),
+                        Err(create_error) => {
+                            let creation_error =
+                                format!("workspace creation failed: {create_error}");
+                            match pick_workspace(&workspaces, Some(&creation_error))? {
+                                WorkspacePickerAction::Select(index) => {
+                                    return Ok(workspaces
+                                        .get(index)
+                                        .map(|item| item.workspace_id.clone()));
+                                }
+                                // Retry the exact request and operation key.
+                                WorkspacePickerAction::Create => continue,
+                                WorkspacePickerAction::Refresh => continue 'catalog,
+                                WorkspacePickerAction::Cancel => return Ok(None),
+                            }
+                        }
+                    }
+                }
+            }
+            WorkspacePickerAction::Cancel => return Ok(None),
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+enum WorkspacePickerAction {
+    Select(usize),
+    Create,
+    Refresh,
+    Cancel,
+}
+
+fn pick_workspace(
+    workspaces: &[BackendWorkspace],
+    error: Option<&str>,
+) -> PickerResult<WorkspacePickerAction> {
+    if !io::stdin().is_terminal() || !io::stdout().is_terminal() {
+        return Err(
+            "Backend target has no configured workspace; an interactive terminal is required to choose one"
+                .into(),
+        );
+    }
+    let mut terminal = Terminal::new(CrosstermBackend::new(io::stdout()))?;
+    let mut selected = 0usize;
+    loop {
+        terminal.draw(|frame| {
+            let chunks = Layout::default()
+                .direction(Direction::Vertical)
+                .constraints([
+                    Constraint::Length(3),
+                    Constraint::Min(3),
+                    Constraint::Length(if error.is_some() { 3 } else { 1 }),
+                ])
+                .split(frame.area());
+            frame.render_widget(
+                Paragraph::new("Choose the Workspace for this Backend session")
+                    .block(Block::default().title("Workspace").borders(Borders::ALL)),
+                chunks[0],
+            );
+            let rows = workspaces
+                .iter()
+                .map(|workspace| {
+                    ListItem::new(Line::from(vec![
+                        Span::styled(
+                            workspace.display_name.clone(),
+                            Style::default().add_modifier(Modifier::BOLD),
+                        ),
+                        Span::raw(format!("  {}  {}", workspace.workspace_id, workspace.state)),
+                    ]))
+                })
+                .collect::<Vec<_>>();
+            let rows = if rows.is_empty() {
+                vec![ListItem::new("No accessible Workspaces")]
+            } else {
+                rows
+            };
+            let mut state = ListState::default();
+            if !workspaces.is_empty() {
+                state.select(Some(selected));
+            }
+            frame.render_stateful_widget(
+                List::new(rows)
+                    .block(Block::default().borders(Borders::ALL))
+                    .highlight_symbol("▶ "),
+                chunks[1],
+                &mut state,
+            );
+            let footer = error
+                .map(|message| {
+                    format!(
+                        "{message}  [n] create/retry  [r] refresh  [Enter] select  [Esc] cancel"
+                    )
+                })
+                .unwrap_or_else(|| {
+                    "[Enter] select  [n] new  [r] refresh  [Esc] cancel".to_string()
+                });
+            frame.render_widget(Paragraph::new(footer), chunks[2]);
+        })?;
+
+        if let Event::Key(key) = event::read()?
+            && key.kind == KeyEventKind::Press
+        {
+            match key.code {
+                KeyCode::Up if !workspaces.is_empty() => {
+                    selected = selected.saturating_sub(1);
+                }
+                KeyCode::Down if !workspaces.is_empty() => {
+                    selected = (selected + 1).min(workspaces.len() - 1);
+                }
+                KeyCode::Enter if !workspaces.is_empty() => {
+                    terminal.clear()?;
+                    return Ok(WorkspacePickerAction::Select(selected));
+                }
+                KeyCode::Char('n') => {
+                    terminal.clear()?;
+                    return Ok(WorkspacePickerAction::Create);
+                }
+                KeyCode::Char('r') => {
+                    terminal.clear()?;
+                    return Ok(WorkspacePickerAction::Refresh);
+                }
+                KeyCode::Esc | KeyCode::Char('q') => {
+                    terminal.clear()?;
+                    return Ok(WorkspacePickerAction::Cancel);
+                }
+                _ => {}
+            }
+        }
+    }
+}
+
+fn prompt_create_request() -> PickerResult<Option<CreateBackendWorkspaceRequest>> {
+    disable_raw_mode()?;
+    let result = prompt_create_request_inner();
+    enable_raw_mode()?;
+    result
+}
+
+fn prompt_create_request_inner() -> PickerResult<Option<CreateBackendWorkspaceRequest>> {
+    println!("Create Workspace (leave display name empty to cancel)");
+    let display_name = prompt_line("Workspace display name: ")?;
+    if display_name.is_empty() {
+        return Ok(None);
+    }
+    let uri = prompt_line("Initial repository absolute path/URI: ")?;
+    if uri.is_empty() {
+        println!("Repository path/URI is required.");
+        return Ok(None);
+    }
+    let repository_name = prompt_line("Repository display name [Main]: ")?;
+    let default_ref = prompt_line("Default ref [repository default]: ")?;
+    let operation_key = format!(
+        "tui-workspace-create-{}-{}",
+        std::process::id(),
+        SystemTime::now()
+            .duration_since(UNIX_EPOCH)
+            .unwrap_or_default()
+            .as_nanos()
+    );
+    Ok(Some(CreateBackendWorkspaceRequest {
+        operation_key,
+        display_name,
+        repository: CreateBackendWorkspaceRepository {
+            uri,
+            display_name: Some(if repository_name.is_empty() {
+                "Main".to_string()
+            } else {
+                repository_name
+            }),
+            default_ref: (!default_ref.is_empty()).then_some(default_ref),
+        },
+    }))
+}
+
+fn prompt_line(prompt: &str) -> PickerResult<String> {
+    print!("{prompt}");
+    io::stdout().flush()?;
+    let mut value = String::new();
+    io::stdin().read_line(&mut value)?;
+    Ok(value.trim().to_string())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn picker_actions_distinguish_switch_refresh_create_and_cancel() {
+        assert_ne!(
+            WorkspacePickerAction::Create,
+            WorkspacePickerAction::Refresh
+        );
+        assert_ne!(
+            WorkspacePickerAction::Select(0),
+            WorkspacePickerAction::Cancel
+        );
+    }
+}

crates/tui/src/lib.rs

@@ -1,5 +1,6 @@
 mod app;
 mod backend_worker_picker;
+mod backend_workspace_picker;
 mod block;
 mod cache;
 mod command;