perf(desktop): batch workflows overview into one relay query (#h fanout)

L6 finding: WorkflowsView's allWorkflowsQuery issued one get_channel_workflows
relay POST per member channel (Promise.all fanout) — N round-trips scaling with
channel count on the Workflows overview.

A nostr #h filter matches ANY listed value, so one query with all channel ids
returns the identical set. Added get_channels_workflows(channel_ids) which
queries once; each WorkflowWire already carries its own channel_id (from the
event h tag), so WorkflowsView groups results client-side via a channelId->name
map. Neither the per-channel nor the batched command sets a limit, so batching
does not change result completeness (review-bar #3: no shared-limit truncation).
e2eBridge gains a matching get_channels_workflows mock so overview e2e still
resolves. Single-channel get_channel_workflows stays for useChannelWorkflowsQuery.

Co-authored-by: Tyler Longwell <tlongwell@block.xyz>
Signed-off-by: Tyler Longwell <tlongwell@block.xyz>

desktop/src-tauri/src/commands/workflows.rs

@@ -66,6 +66,36 @@ pub async fn get_channel_workflows(
     Ok(events.iter().map(workflow_from_event).collect())
 }
 
+/// Fetch workflows across many channels in a single relay round-trip.
+///
+/// The Workflows overview screen previously issued one `get_channel_workflows`
+/// query per member channel (`Promise.all` fanout in `WorkflowsView`), i.e. N
+/// relay POSTs. A nostr `#h` filter matches ANY of its listed values, so one
+/// query with all channel ids returns the same set. Each `WorkflowWire` carries
+/// its own `channel_id` (from the event's `h` tag), so the frontend can still
+/// group results by channel. Neither this nor the per-channel command sets a
+/// `limit`, so batching does not change result completeness.
+#[tauri::command]
+pub async fn get_channels_workflows(
+    channel_ids: Vec<String>,
+    state: State<'_, AppState>,
+) -> Result<Vec<WorkflowWire>, String> {
+    if channel_ids.is_empty() {
+        return Ok(Vec::new());
+    }
+
+    let events = query_relay(
+        &state,
+        &[serde_json::json!({
+            "kinds": [30620],
+            "#h": channel_ids,
+        })],
+    )
+    .await?;
+
+    Ok(events.iter().map(workflow_from_event).collect())
+}
+
 #[tauri::command]
 pub async fn get_workflow(
     workflow_id: String,

desktop/src-tauri/src/lib.rs

@@ -569,6 +569,7 @@ pub fn run() {
             parse_persona_files,
             export_persona_to_json,
             get_channel_workflows,
+            get_channels_workflows,
             get_workflow,
             create_workflow,
             update_workflow,

desktop/src/features/workflows/ui/WorkflowsView.tsx

@@ -10,7 +10,7 @@ import { WorkflowDialog } from "@/features/workflows/ui/WorkflowDialog";
 import type { Channel, Workflow } from "@/shared/api/types";
 import {
   deleteWorkflow,
-  getChannelWorkflows,
+  getChannelsWorkflows,
   triggerWorkflow,
 } from "@/shared/api/tauriWorkflows";
 import { Button } from "@/shared/ui/button";
@@ -83,15 +83,21 @@ export function WorkflowsView({
   const allWorkflowsQuery = useQuery({
     queryKey: allWorkflowsQueryKey(channelIdKey),
     queryFn: async () => {
-      const results: WorkflowWithChannel[] = [];
-      await Promise.all(
-        memberChannels.map(async (channel) => {
-          const workflows = await getChannelWorkflows(channel.id);
-          for (const workflow of workflows) {
-            results.push({ workflow, channelName: channel.name });
-          }
-        }),
+      // Single batched relay query for all member channels, then group by the
+      // channel_id each workflow carries — replaces the per-channel fanout.
+      const channelNameById = new Map(
+        memberChannels.map((channel) => [channel.id, channel.name]),
       );
+      const workflows = await getChannelsWorkflows(channelIds);
+      const results: WorkflowWithChannel[] = [];
+      for (const workflow of workflows) {
+        results.push({
+          workflow,
+          channelName: workflow.channelId
+            ? (channelNameById.get(workflow.channelId) ?? "")
+            : "",
+        });
+      }
       return results;
     },
     enabled: memberChannels.length > 0,

desktop/src/shared/api/tauriWorkflows.ts

@@ -169,6 +169,22 @@ export async function getChannelWorkflows(
   return raw.map(fromRawWorkflow);
 }
 
+/**
+ * Fetch workflows across many channels in a single relay round-trip.
+ *
+ * Replaces the per-channel `Promise.all(getChannelWorkflows)` fanout on the
+ * Workflows overview: the backend `#h` filter matches any listed channel, and
+ * each returned workflow carries its own `channelId` so callers can group.
+ */
+export async function getChannelsWorkflows(
+  channelIds: string[],
+): Promise<Workflow[]> {
+  const raw = await invokeTauri<RawWorkflow[]>("get_channels_workflows", {
+    channelIds,
+  });
+  return raw.map(fromRawWorkflow);
+}
+
 export async function getWorkflow(workflowId: string): Promise<Workflow> {
   const raw = await invokeTauri<RawWorkflow>("get_workflow", { workflowId });
   return fromRawWorkflow(raw);

desktop/src/testing/e2eBridge.ts

@@ -2368,6 +2368,13 @@ function handleGetChannelWorkflows(args: { channelId: string }) {
   return mockWorkflows.filter((w) => w.channel_id === args.channelId);
 }
 
+function handleGetChannelsWorkflows(args: { channelIds: string[] }) {
+  const ids = new Set(args.channelIds);
+  return mockWorkflows.filter(
+    (w) => w.channel_id != null && ids.has(w.channel_id),
+  );
+}
+
 function handleGetWorkflow(args: { workflowId: string }) {
   const workflow = mockWorkflows.find((w) => w.id === args.workflowId);
   if (!workflow) throw new Error(`Workflow ${args.workflowId} not found`);
@@ -8806,6 +8813,10 @@ export function maybeInstallE2eTauriMocks() {
         return handleGetChannelWorkflows(
           payload as Parameters<typeof handleGetChannelWorkflows>[0],
         );
+      case "get_channels_workflows":
+        return handleGetChannelsWorkflows(
+          payload as Parameters<typeof handleGetChannelsWorkflows>[0],
+        );
       case "get_workflow":
         return handleGetWorkflow(
           payload as Parameters<typeof handleGetWorkflow>[0],