feat(spaceshd): pinned workspace field

Add a `pinned` bool to the workspace model, threaded through proto
(Workspace + WorkspaceView + SetWorkspaceMeta), the registry, the
set_workspace_meta handler, persistence, the CLI mapping, and the Tauri
bridge. serde(default) keeps existing state.json compatible (pinned=false).
Backs the sidebar Favorites section.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/spacesh-cli/src/mapping.rs

@@ -61,6 +61,7 @@ pub fn to_cmd(sub: Sub) -> Cmd {
             group_id: group.map(|g| if g.is_empty() { None } else { Some(GroupId(g)) }),
             unread,
             order,
+            pinned: None,
         },
         Sub::Shutdown => Cmd::Shutdown,
         Sub::Completions { .. } => unreachable!("completions handled before dispatch"),

crates/spacesh-proto/src/message.rs

@@ -104,6 +104,8 @@ pub enum Cmd {
         unread: Option<bool>,
         #[serde(default, skip_serializing_if = "Option::is_none")]
         order: Option<u32>,
+        #[serde(default, skip_serializing_if = "Option::is_none")]
+        pinned: Option<bool>,
     },
     CreateGroup { name: String, color: String },
     SetGroup {

crates/spacesh-proto/src/workspace.rs

@@ -39,6 +39,9 @@ pub struct Workspace {
     pub order: u32,
     #[serde(default)]
     pub unread: bool,
+    /// Pinned to the sidebar's Favorites section.
+    #[serde(default)]
+    pub pinned: bool,
     /// None = empty workspace (no panels yet).
     #[serde(default)]
     pub layout: Option<LayoutNode>,
@@ -68,6 +71,8 @@ pub struct WorkspaceView {
     pub group_id: Option<GroupId>,
     pub order: u32,
     pub unread: bool,
+    #[serde(default)]
+    pub pinned: bool,
     pub layout: Option<LayoutNode>,
     #[serde(default)]
     pub zoomed: Option<SurfaceId>,
@@ -103,6 +108,7 @@ mod tests {
             group_id: None,
             order: 0,
             unread: false,
+            pinned: false,
             layout: None,
             zoomed: None,
             surfaces: HashMap::new(),
@@ -112,11 +118,26 @@ mod tests {
         assert_eq!(back, w);
     }
 
+    #[test]
+    fn workspace_pinned_round_trips_and_defaults_false() {
+        let w = Workspace {
+            id: WorkspaceId("w_1".into()), path: "/tmp/p".into(), name: "p".into(),
+            group_id: None, order: 0, unread: false, pinned: true, layout: None,
+            zoomed: None, surfaces: HashMap::new(),
+        };
+        let back: Workspace = serde_json::from_str(&serde_json::to_string(&w).unwrap()).unwrap();
+        assert!(back.pinned);
+        // Old state.json without the field deserializes to pinned=false.
+        let legacy = r#"{"id":"w_1","path":"/tmp/p","name":"p","order":0,"surfaces":{}}"#;
+        let old: Workspace = serde_json::from_str(legacy).unwrap();
+        assert!(!old.pinned);
+    }
+
     #[test]
     fn workspace_round_trips_with_zoom() {
         let w = Workspace {
             id: WorkspaceId("w_1".into()), path: "/tmp/p".into(), name: "p".into(),
-            group_id: None, order: 0, unread: false, layout: None,
+            group_id: None, order: 0, unread: false, pinned: false, layout: None,
             zoomed: Some(SurfaceId("s_1".into())), surfaces: HashMap::new(),
         };
         let back: Workspace = serde_json::from_str(&serde_json::to_string(&w).unwrap()).unwrap();

crates/spaceshd/src/registry.rs

@@ -51,7 +51,7 @@ impl Registry {
         let order = self.workspaces.len() as u32;
         self.workspaces.insert(id.clone(), Workspace {
             id: id.clone(), path: key.clone(), name, group_id: None, order,
-            unread: false, layout: None, zoomed: None, surfaces: HashMap::new(),
+            unread: false, pinned: false, layout: None, zoomed: None, surfaces: HashMap::new(),
         });
         self.by_path.insert(key, id.clone());
         (id, true)
@@ -168,7 +168,7 @@ impl Registry {
         }).collect();
         WorkspaceView {
             id: w.id.clone(), path: w.path.clone(), name: w.name.clone(),
-            group_id: w.group_id.clone(), order: w.order, unread: w.unread,
+            group_id: w.group_id.clone(), order: w.order, unread: w.unread, pinned: w.pinned,
             layout: w.layout.clone(), zoomed: w.zoomed.clone(), surfaces,
         }
     }

crates/spaceshd/src/server.rs

@@ -461,12 +461,13 @@ async fn handle_request(
             let _ = out.send(ok(id, serde_json::Value::Null)).await;
         }
 
-        Cmd::SetWorkspaceMeta { workspace_id, name, group_id, unread, order } => {
+        Cmd::SetWorkspaceMeta { workspace_id, name, group_id, unread, order, pinned } => {
             let found = reg.workspace_mut(&workspace_id).map(|w| {
                 if let Some(n) = name { w.name = n; }
                 if let Some(g) = group_id { w.group_id = g; }
                 if let Some(u) = unread { w.unread = u; }
                 if let Some(o) = order { w.order = o; }
+                if let Some(p) = pinned { w.pinned = p; }
             }).is_some();
             if found {
                 if let Some(view) = reg.workspace_view(&workspace_id) {

crates/spaceshd/src/state_store.rs

@@ -92,6 +92,7 @@ mod tests {
                 group_id: None,
                 order: 0,
                 unread: false,
+                pinned: false,
                 layout: None,
                 zoomed: None,
                 surfaces: std::collections::HashMap::new(),