feat(flow-chat): browse recent sessions in the context picker

src/apps/desktop/src/api/session_api.rs

@@ -153,7 +153,10 @@ pub struct ExportSessionTranscriptRequest {
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct SearchReferenceableSessionsRequest {
-    pub query: String,
+    /// Omit the query to browse recent sessions. An explicit blank query is
+    /// still an empty search for legacy callers.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub query: Option<String>,
     #[serde(default = "default_session_reference_search_limit")]
     pub limit: usize,
 }
@@ -369,7 +372,7 @@ pub async fn search_session_content(
         })
 }
 
-/// Search lightweight persisted metadata across open local and SSH
+/// Browse or search lightweight persisted metadata across open local and SSH
 /// workspaces. This deliberately never loads dialog turns or generates a
 /// transcript; that work happens only when the selected message is dispatched.
 #[tauri::command]
@@ -378,8 +381,8 @@ pub async fn search_referenceable_sessions(
     runtime: State<'_, DesktopRuntimeContext>,
     app_state: State<'_, AppState>,
 ) -> Result<Vec<SessionReferenceCandidate>, String> {
-    let query = request.query.trim().to_lowercase();
-    if query.is_empty() {
+    let query = request.query.map(|query| query.trim().to_lowercase());
+    if query.as_deref() == Some("") {
         return Ok(Vec::new());
     }
     let limit = request.limit.clamp(1, 30);
@@ -425,7 +428,9 @@ pub async fn search_referenceable_sessions(
                 || scheduler.as_ref().is_some_and(|scheduler| {
                     scheduler.is_session_busy_or_queued(&session.session_id)
                 })
-                || !session.session_name.to_lowercase().contains(&query)
+                || query
+                    .as_ref()
+                    .is_some_and(|query| !session.session_name.to_lowercase().contains(query))
             {
                 continue;
             }
@@ -925,7 +930,24 @@ pub async fn delete_all_archived_sessions(
 
 #[cfg(test)]
 mod catalog_request_tests {
-    use super::ListPersistedSessionsPageRequest;
+    use super::{ListPersistedSessionsPageRequest, SearchReferenceableSessionsRequest};
+
+    #[test]
+    fn session_reference_request_distinguishes_browsing_from_legacy_search() {
+        for query in ["Docs", ""] {
+            let legacy = serde_json::json!({"query": query, "limit": 30});
+            let request: SearchReferenceableSessionsRequest =
+                serde_json::from_value(legacy.clone()).unwrap();
+            assert_eq!(request.query.as_deref(), Some(query));
+            assert_eq!(serde_json::to_value(request).unwrap(), legacy);
+        }
+
+        let browse = serde_json::json!({"limit": 30});
+        let request: SearchReferenceableSessionsRequest =
+            serde_json::from_value(browse.clone()).unwrap();
+        assert!(request.query.is_none());
+        assert_eq!(serde_json::to_value(request).unwrap(), browse);
+    }
 
     #[test]
     fn session_catalog_request_preserves_legacy_payload_and_optional_query() {

src/crates/contracts/product-domains/src/generated/remote-surface-registry.json

@@ -1,6 +1,6 @@
 {
   "schemaVersion": 1,
-  "digest": "fnv1a64:7dadb93da46481aa",
+  "digest": "fnv1a64:ad57aa872484f2a8",
   "retiredCommandPrefixes": [
     {
       "prefix": "lsp_",
@@ -49,6 +49,7 @@
       "workspace_html_preview_v1",
       "whole_session_copy_v1",
       "session_trajectory_v1",
+      "session_reference_browse_v1",
       "user_question_response",
       "user_question_interaction_v1",
       "ssh_none_auth_v1",
@@ -95,6 +96,7 @@
       "workspace_html_preview_v1",
       "whole_session_copy_v1",
       "session_trajectory_v1",
+      "session_reference_browse_v1",
       "user_question_response",
       "user_question_interaction_v1",
       "ssh_none_auth_v1"

src/crates/contracts/product-domains/src/remote_surface/capabilities.rs

@@ -103,6 +103,8 @@ pub enum PeerHostCapability {
     WholeSessionCopyV1,
     /// Bounded session trajectory summaries and host-side body search.
     SessionTrajectoryV1,
+    /// `search_referenceable_sessions` accepts an omitted query to browse.
+    SessionReferenceBrowseV1,
     /// `submit_user_answers` is implemented for Runtime-owned questions.
     UserQuestionResponse,
     /// First human interaction disables the unattended question timeout.
@@ -159,6 +161,7 @@ impl PeerHostCapability {
         Self::WorkspaceHtmlPreviewV1,
         Self::WholeSessionCopyV1,
         Self::SessionTrajectoryV1,
+        Self::SessionReferenceBrowseV1,
         Self::UserQuestionResponse,
         Self::UserQuestionInteractionV1,
         Self::SshNoneAuthV1,
@@ -207,6 +210,7 @@ impl PeerHostCapability {
             Self::WorkspaceIdReferencesV1 => "workspace_id_references_v1",
             Self::WorkspaceHtmlPreviewV1 => "workspace_html_preview_v1",
             Self::SessionTrajectoryV1 => "session_trajectory_v1",
+            Self::SessionReferenceBrowseV1 => "session_reference_browse_v1",
             Self::WholeSessionCopyV1 => "whole_session_copy_v1",
             Self::UserQuestionResponse => "user_question_response",
             Self::UserQuestionInteractionV1 => "user_question_interaction_v1",
@@ -264,6 +268,7 @@ const DESKTOP_CAPABILITIES: &[PeerHostCapability] = &[
     PeerHostCapability::WorkspaceHtmlPreviewV1,
     PeerHostCapability::WholeSessionCopyV1,
     PeerHostCapability::SessionTrajectoryV1,
+    PeerHostCapability::SessionReferenceBrowseV1,
     PeerHostCapability::UserQuestionResponse,
     PeerHostCapability::UserQuestionInteractionV1,
     PeerHostCapability::SshNoneAuthV1,