feat: AI flow builder, visibility model, dashboard tabs, fork UI (#88)

- AI flow builder: scaffold → branch detail → assemble → review flow
- Generate All one-click branch generation with stop/cancel
- Regenerate scaffold suggestions button
- 3-action review screen: Start Flow, Open in Editor, Build Another
- Fix Publish button gated behind !isDirty
- Fix visibility column enforcement in tree access filter
- Add ?visibility filter and author_name to GET /trees
- Dashboard tabbed flows: My Flows / My Team / Public / All
- Create button in My Flows tab, window focus reload (stale data fix)
- Fork UI with optional reason modal
- Fix account_id nullability in User type and schema
- Keep is_public and visibility in sync on updates

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/tests/test_ai_tree_validator.py

@@ -124,6 +124,13 @@ class TestReferenceIntegrity:
         errors = validate_generated_tree(tree)
         assert any("non-existent child" in e for e in errors)
 
+    def test_action_next_node_id_references_nonexistent_node(self):
+        """Action next_node_id pointing to a node that doesn't exist anywhere in the tree."""
+        tree = _make_valid_tree()
+        tree["children"][1]["next_node_id"] = "ghost-node"
+        errors = validate_generated_tree(tree)
+        assert any("ghost-node" in e for e in errors)
+
     def test_duplicate_option_ids(self):
         tree = _make_valid_tree()
         tree["options"][0]["id"] = "same"

backend/tests/test_trees.py

@@ -391,3 +391,59 @@ class TestTrees:
         assert response.status_code == 200
         trees = response.json()
         assert isinstance(trees, list)
+
+
+class TestVisibilityFilter:
+    """Test that visibility filtering and author_name work correctly."""
+
+    @pytest.mark.asyncio
+    async def test_private_tree_only_visible_to_author(
+        self, client: AsyncClient, auth_headers: dict, test_user: dict
+    ):
+        """A private tree created by test_user should appear in their own list."""
+        tree_data = {
+            "name": "Private Flow Test",
+            "tree_structure": {"id": "root", "type": "decision", "question": "Q?", "options": [], "children": []},
+        }
+        create_resp = await client.post("/api/v1/trees", json=tree_data, headers=auth_headers)
+        assert create_resp.status_code == 201
+        tree_id = create_resp.json()["id"]
+
+        # Set visibility to private
+        vis_resp = await client.patch(
+            f"/api/v1/trees/{tree_id}/visibility",
+            json={"visibility": "private"},
+            headers=auth_headers
+        )
+        assert vis_resp.status_code == 200
+
+        # Verify it still appears for the author
+        list_resp = await client.get("/api/v1/trees", headers=auth_headers)
+        assert list_resp.status_code == 200
+        ids = [t["id"] for t in list_resp.json()]
+        assert tree_id in ids
+
+    @pytest.mark.asyncio
+    async def test_visibility_query_param_filters_correctly(
+        self, client: AsyncClient, auth_headers: dict
+    ):
+        """?visibility=public should only return trees with visibility='public'."""
+        resp = await client.get("/api/v1/trees?visibility=public", headers=auth_headers)
+        assert resp.status_code == 200
+        trees = resp.json()
+        for tree in trees:
+            assert tree["visibility"] == "public", f"Tree {tree['id']} has visibility={tree['visibility']}"
+
+    @pytest.mark.asyncio
+    async def test_author_name_present_in_list_response(
+        self, client: AsyncClient, auth_headers: dict, test_tree: dict
+    ):
+        """TreeListResponse should include author_name field."""
+        resp = await client.get("/api/v1/trees", headers=auth_headers)
+        assert resp.status_code == 200
+        trees = resp.json()
+        assert len(trees) >= 1
+        # author_name key should be present (value may be None for system/default trees)
+        assert "author_name" in trees[0]
+        # visibility key should be present
+        assert "visibility" in trees[0]