fix(tui): sort session picker by timestamp with frozen order while open

The session picker now sorts by actual time.updated timestamp when first
opened, but freezes that order while the user is browsing. This prevents
sessions from jumping around as activity updates arrive, while still
showing the most recently active sessions at the top initially.

Search results continue to sort dynamically since they come from the
server already ordered.

Author: Sleepful

packages/opencode/src/cli/cmd/tui/component/dialog-session-list.tsx

@@ -109,15 +109,26 @@ export function DialogSessionList() {
     ))
   }
 
+  const [frozenOrder, setFrozenOrder] = createSignal<string[]>()
+
+  function computeOrder(allSessions: ReturnType<typeof sessions>) {
+    return allSessions
+      .filter((x) => x.parentID === undefined)
+      .toSorted((a, b) => b.time.updated - a.time.updated)
+      .map((x) => x.id)
+  }
+
   const options = createMemo(() => {
     const today = new Date().toDateString()
-    return sessions()
-      .filter((x) => x.parentID === undefined)
-      .toSorted((a, b) => {
-        const updatedDay = new Date(b.time.updated).setHours(0, 0, 0, 0) - new Date(a.time.updated).setHours(0, 0, 0, 0)
-        if (updatedDay !== 0) return updatedDay
-        return b.time.created - a.time.created
-      })
+    const allSessions = sessions()
+    const isSearching = searchResults() !== undefined
+    const order = isSearching ? computeOrder(allSessions) : (frozenOrder() ?? computeOrder(allSessions))
+
+    const sessionMap = new Map(allSessions.filter((x) => x.parentID === undefined).map((x) => [x.id, x]))
+
+    return order
+      .map((id) => sessionMap.get(id))
+      .filter((x) => x !== undefined)
       .map((x) => {
         const workspace = x.workspaceID ? project.workspace.get(x.workspaceID) : undefined
 
@@ -172,6 +183,7 @@ export function DialogSessionList() {
 
   onMount(() => {
     dialog.setSize("large")
+    setFrozenOrder(computeOrder(sessions()))
   })
 
   return (