fix: avoid stale project binding for new sessions

Keeps implicit new sessions tied to the current directory
Prevents unmatched directories from inheriting the active project
Adds regression coverage for draft project selection

packages/ui/src/sync/session-ui-store.test.js

@@ -255,6 +255,17 @@ describe('openNewSessionDraft project binding', () => {
     expect(draft.directoryOverride).toBe(projectB.path);
   });
 
+  test('does not attach active project when current directory is unmatched', () => {
+    useDirectoryStore.getState().setDirectory('/external/worktree', { showOverlay: false });
+
+    useSessionUIStore.getState().openNewSessionDraft();
+    const draft = useSessionUIStore.getState().newSessionDraft;
+
+    expect(draft.open).toBe(true);
+    expect(draft.selectedProjectId).toBeNull();
+    expect(draft.directoryOverride).toBe('/external/worktree');
+  });
+
   test('respects explicit directoryOverride over active project', () => {
     useSessionUIStore.getState().openNewSessionDraft({ directoryOverride: '/projects/beta/src' });
     const draft = useSessionUIStore.getState().newSessionDraft;

packages/ui/src/sync/session-ui-store.ts

@@ -623,10 +623,9 @@ export const useSessionUIStore = create<SessionUIState>()((set, get) => ({
     const currentDirProject = resolveDraftProjectForDirectory(projects, availableWorktreesByProject, currentDirectory)
 
     const selectedProject = (() => {
-      if (explicitProject || explicitDirectory !== null) {
-        return explicitProject ?? inferredProjectFromDir ?? fallbackProject
-      }
-      if (currentDirectory) return currentDirProject ?? fallbackProject
+      if (explicitProject) return explicitProject
+      if (explicitDirectory !== null) return inferredProjectFromDir
+      if (currentDirectory) return currentDirProject
       return persistedProjectByDir ?? persistedProjectById ?? fallbackProject
     })()