swarm-ui: give the new-flow draft a route no flow id can take, and drop the dead hit-count rule

/notifications/new could be a saved flow's own page, so the draft now opens at
/notifications/draft/new, which has a segment more than any flow's route. The
placeholder id no longer needs reserving. The .notify-node-hits rule styled the
removed tree rows; nothing renders it.

docs/swarm/ui.md

@@ -251,7 +251,7 @@ works. See [deliveries and dry runs](notify-router.md#deliveries-and-dry-runs).
 
 #### Editing a flow
 
-`/notifications/<flow id>` edits one custom flow, and `/notifications/new` makes
+`/notifications/<flow id>` edits one custom flow, and `/notifications/draft/new` makes
 one: it opens on an empty flow, or on a copy of a flow with `?from=<flow id>`, as
 **create flow** and **duplicate** do. A new flow takes its id from its name when
 you save it, and **save** needs a name. The canvas draws the flow left

frontend/packages/swarm-ui/src/App.tsx

@@ -9,6 +9,7 @@ import { AlertsPage } from "./pages/AlertsPage.js";
 import { BuildsPage } from "./pages/builds/BuildsPage.js";
 import { BroadcastPage } from "./pages/broadcast/BroadcastPage.js";
 import { MessagesPage } from "./pages/messages/MessagesPage.js";
+import { NEW_FLOW_PATH } from "./pages/notifications/FlowDraft.js";
 import { FlowEditorPage } from "./pages/notifications/FlowEditorPage.js";
 import { NotificationsPage } from "./pages/notifications/NotificationsPage.js";
 import { ComponentsPage } from "./pages/ComponentsPage.js";
@@ -48,6 +49,9 @@ export function App() {
           <Route path="/broadcast" component={BroadcastPage} />
           <Route path="/messages" component={MessagesPage} />
           <Route path="/notifications" component={NotificationsPage} />
+          <Route path={NEW_FLOW_PATH}>
+            <FlowEditorPage params={{ flowId: "" }} isNew />
+          </Route>
           <Route path="/notifications/:flowId" component={FlowEditorPage} />
           <Route path="/issues" component={IssueReportPage} />
           <Route path="/review" component={ReviewPage} />

frontend/packages/swarm-ui/src/pages/notifications/FlowDraft.ts

@@ -356,16 +356,15 @@ export function duplicateFlow(
   });
 }
 
-// The id of a flow nobody has saved yet. It is the editor's route for one, so
-// no saved flow may take it.
+// The editor's route for a flow nobody has saved yet. It has a segment more
+// than a flow's own route, so no flow's id can reach it.
+export const NEW_FLOW_PATH = "/notifications/draft/new";
+
+// The id a draft carries until it is saved (see `savedAs`).
 export const NEW_FLOW_ID = "new";
 
 function savedIds(view: FlowsView): string[] {
-  return [
-    NEW_FLOW_ID,
-    ...view.builtins.map((f) => f.id),
-    ...view.flows.map((f) => f.id),
-  ];
+  return [...view.builtins.map((f) => f.id), ...view.flows.map((f) => f.id)];
 }
 
 // The draft the editor opens for a flow not saved yet: an empty one, or a copy

frontend/packages/swarm-ui/src/pages/notifications/FlowEditorPage.tsx

@@ -3,7 +3,7 @@
 // document back at the revision it was read. Edits stay in a draft until
 // then, so a half-built flow never reaches the router.
 //
-// The same page makes a flow: `/notifications/new` is an empty draft, and
+// The same page makes a flow: `NEW_FLOW_PATH` is an empty draft, and
 // `?from=<id>` a copy of a flow to start from. Nothing exists until Save, which
 // gives the flow an id made of its name.
 //
@@ -33,7 +33,6 @@ import {
   isDirty,
   limitsOf,
   moveAmongSiblings,
-  NEW_FLOW_ID,
   paletteKinds,
   removeNode,
   reparent,
@@ -59,9 +58,12 @@ function rootOf(flow: Flow): string | null {
 
 export function FlowEditorPage({
   params,
-}: RouteComponentProps<{ flowId: string }>) {
+  isNew = false,
+}: RouteComponentProps<{ flowId: string }> & {
+  // The page for a flow not saved yet, which has no flow id.
+  isNew?: boolean;
+}) {
   const flowId = decodeURIComponent(params.flowId);
-  const isNew = flowId === NEW_FLOW_ID;
   const from = new URLSearchParams(useSearch()).get("from");
   const [, navigate] = useLocation();
   const [view, setView] = useState<FlowsView | null>(null);

frontend/packages/swarm-ui/src/pages/notifications/NotificationsPage.css

@@ -272,14 +272,7 @@
   flex: 0 1 24em;
 }
 
-/* The dry run's counts beside each node, and the router's "not available". */
-.notify-node-hits {
-  margin-left: auto;
-  flex: none;
-  color: var(--muted);
-  font-variant-numeric: tabular-nums;
-}
-
+/* The dry run's header line, and the router's "not available". */
 .notify-dry-run {
   margin: 0;
   color: var(--muted);

frontend/packages/swarm-ui/src/pages/notifications/NotificationsPage.tsx

@@ -20,7 +20,7 @@ import {
 } from "../../ui/refresh-interval/RefreshInterval.js";
 import { fetchJson, usePolled } from "../../ui/polled/usePolled.js";
 import { Deliveries } from "./Deliveries.js";
-import { NEW_FLOW_ID } from "./FlowDraft.js";
+import { NEW_FLOW_PATH } from "./FlowDraft.js";
 import { FlowGraph } from "./FlowGraph.js";
 import { withBuiltin, type FlowsView } from "./FlowTypes.js";
 import {
@@ -91,8 +91,8 @@ export function NotificationsPage() {
   const draftFrom = (from?: string) =>
     navigate(
       from === undefined
-        ? `/notifications/${NEW_FLOW_ID}`
-        : `/notifications/${NEW_FLOW_ID}?from=${encodeURIComponent(from)}`,
+        ? NEW_FLOW_PATH
+        : `${NEW_FLOW_PATH}?from=${encodeURIComponent(from)}`,
     );
 
   return (

frontend/packages/swarm-ui/test/flow-draft.test.mjs

@@ -388,9 +388,4 @@ test("savedAs takes the id from the name, clear of every saved id", () => {
   assert.equal(savedAs(view, { ...draft, name: "Closed" }).id, "closed");
   assert.equal(savedAs(view, { ...draft, name: "Assigned" }).id, "assigned-2");
   assert.equal(savedAs(view, { ...draft, name: "mine" }).id, "mine-2");
-  assert.equal(
-    savedAs(view, { ...draft, name: "New" }).id,
-    "new-2",
-    "no flow takes the id of the new-flow route",
-  );
 });