fix: open agent dropdown upward in session dialogs (#556)

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: matt2e

apps/staged/src/lib/features/agents/AgentSelector.svelte

@@ -25,9 +25,10 @@
     disabled?: boolean;
     remote?: boolean;
     projectId?: string | null;
+    dropUp?: boolean;
   }
 
-  let { disabled = false, remote = false, projectId = null }: Props = $props();
+  let { disabled = false, remote = false, projectId = null, dropUp = false }: Props = $props();
 
   let showDropdown = $state(false);
 
@@ -86,7 +87,7 @@
       {/if}
     </button>
     {#if showDropdown}
-      <div class="selector-dropdown">
+      <div class="selector-dropdown" class:drop-up={dropUp}>
         {#each agents as provider (provider.id)}
           <button
             type="button"
@@ -155,6 +156,13 @@
     min-width: 140px;
   }
 
+  .selector-dropdown.drop-up {
+    top: auto;
+    bottom: 100%;
+    margin-top: 0;
+    margin-bottom: 4px;
+  }
+
   .selector-option {
     display: flex;
     align-items: center;

apps/staged/src/lib/features/sessions/NewSessionModal.svelte

@@ -371,7 +371,7 @@
       />
 
       <div class="form-actions">
-        <AgentSelector disabled={starting} {remote} />
+        <AgentSelector disabled={starting} {remote} dropUp />
         <div class="form-actions-right">
           <button type="button" class="cancel-btn" onclick={handleClose} disabled={starting}>
             Cancel