fix: resolve all three functional issues in trial execution

- WebSocket broadcasts: Next.js tRPC router now routes broadcasts via
  POST /internal/broadcast on the Bun ws-server process, which holds
  the actual client connections. Broadcasts were previously silently
  dropped due to the split singleton across processes.

- ws-server stubs: request_trial_status and request_trial_events now
  use the real async DB methods instead of the stub getTrialStatusSync/
  getTrialEventsSync that always returned null/[].

- Duplicate branch case: removed the unreachable second case "branch"
  block in executeAction switch; server-side branching is a pass-through
  since routing is client-orchestrated.

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

src/components/experiments/designer/PropertiesPanel.tsx

@@ -835,6 +835,40 @@ export function PropertiesPanelBase({
                   </SelectContent>
                 </Select>
               </div>
+              <div>
+                <Label className="text-xs">After this step, go to</Label>
+                <p className="text-muted-foreground mb-1 text-[10px]">
+                  Override the next step (use to converge branch paths).
+                </p>
+                <Select
+                  value={(selectedStep.trigger.conditions as any)?.nextStepId ?? "__linear__"}
+                  onValueChange={(val) => {
+                    onStepUpdate(selectedStep.id, {
+                      trigger: {
+                        ...selectedStep.trigger,
+                        conditions: {
+                          ...(selectedStep.trigger.conditions as any),
+                          nextStepId: val === "__linear__" ? undefined : val,
+                        },
+                      },
+                    });
+                  }}
+                >
+                  <SelectTrigger className="mt-1 h-7 w-full text-xs">
+                    <SelectValue placeholder="Next step (default)" />
+                  </SelectTrigger>
+                  <SelectContent>
+                    <SelectItem value="__linear__">Next step (default)</SelectItem>
+                    {design.steps
+                      .filter((s) => s.id !== selectedStep.id)
+                      .map((s) => (
+                        <SelectItem key={s.id} value={s.id}>
+                          {s.name}
+                        </SelectItem>
+                      ))}
+                  </SelectContent>
+                </Select>
+              </div>
             </div>
           </div>
         </div>

src/components/trials/wizard/WizardInterface.tsx

@@ -792,8 +792,11 @@ export const WizardInterface = React.memo(function WizardInterface({
       );
     }
 
-    // Default: Linear progression
-    const nextIndex = currentStepIndex + 1;
+    // Default: Linear progression (skip steps marked as skipped by branching)
+    let nextIndex = currentStepIndex + 1;
+    while (nextIndex < steps.length && skippedSteps.has(nextIndex)) {
+      nextIndex++;
+    }
     if (nextIndex < steps.length) {
       // Mark current step as complete
       setCompletedSteps((prev) => {
@@ -922,8 +925,8 @@ export const WizardInterface = React.memo(function WizardInterface({
       // Log action execution
       console.log("Executing action:", actionId, parameters);
 
-      // Handle branching logic (wizard_wait_for_response)
-      if (parameters?.value && parameters?.label) {
+      // Handle branching logic (wizard_wait_for_response / branch)
+      if (parameters?.label || parameters?.nextStepId) {
         setLastResponse(String(parameters.value));
 
         // If nextStepId is provided, jump immediately
@@ -942,6 +945,24 @@ export const WizardInterface = React.memo(function WizardInterface({
             console.log(
               `[WizardInterface] Choice-based jump to step ${targetIndex} (${nextId})`,
             );
+
+            // Mark other branch targets as skipped so linear progression bypasses them
+            const branchingStep = steps[currentStepIndex];
+            const allOptions =
+              (branchingStep?.conditions?.options as any[]) ?? [];
+            setSkippedSteps((prev) => {
+              const next = new Set(prev);
+              for (const opt of allOptions) {
+                if (opt.nextStepId && opt.nextStepId !== nextId) {
+                  const otherIdx = steps.findIndex(
+                    (s) => s.id === opt.nextStepId,
+                  );
+                  if (otherIdx !== -1) next.add(otherIdx);
+                }
+              }
+              return next;
+            });
+
             handleNextStep(targetIndex);
             return; // Exit after jump
           } else {

src/components/trials/wizard/panels/WizardActionItem.tsx

@@ -499,6 +499,7 @@ export function WizardActionItem({
                 // Manual/Wizard Actions (Leaf nodes)
                 !isContainer &&
                 action.type !== "wizard_wait_for_response" &&
+                !isBranch &&
                 !isCompleted && (
                   <Button
                     size="sm"
@@ -524,7 +525,7 @@ export function WizardActionItem({
               <div className="grid grid-cols-1 gap-2 pt-3 sm:grid-cols-2">
                 {(action.parameters.options as any[]).map((opt, optIdx) => {
                   const label = typeof opt === "string" ? opt : opt.label;
-                  const value = typeof opt === "string" ? opt : opt.value;
+                  const value = typeof opt === "string" ? opt : (opt.value ?? opt.label);
                   const nextStepId =
                     typeof opt === "object" ? opt.nextStepId : undefined;
 

src/server/api/routers/trials.ts

@@ -593,7 +593,7 @@ export const trialsRouter = createTRPCRouter({
       });
 
       // Broadcast trial status update
-      await wsManager.broadcast(input.id, {
+      await wsManager.broadcastExternal(input.id, {
         type: "trial_status",
         data: {
           trial: trial[0],
@@ -655,7 +655,7 @@ export const trialsRouter = createTRPCRouter({
       });
 
       // Broadcast trial status update
-      await wsManager.broadcast(input.id, {
+      await wsManager.broadcastExternal(input.id, {
         type: "trial_status",
         data: {
           trial,
@@ -718,7 +718,7 @@ export const trialsRouter = createTRPCRouter({
       });
 
       // Broadcast trial status update
-      await wsManager.broadcast(input.id, {
+      await wsManager.broadcastExternal(input.id, {
         type: "trial_status",
         data: {
           trial: trial[0],
@@ -878,7 +878,7 @@ export const trialsRouter = createTRPCRouter({
         .returning();
 
       // Broadcast new event to all subscribers
-      await wsManager.broadcast(input.trialId, {
+      await wsManager.broadcastExternal(input.trialId, {
         type: "trial_event",
         data: {
           event,
@@ -922,7 +922,7 @@ export const trialsRouter = createTRPCRouter({
         .returning();
 
       // Broadcast intervention to all subscribers
-      await wsManager.broadcast(input.trialId, {
+      await wsManager.broadcastExternal(input.trialId, {
         type: "intervention_logged",
         data: {
           intervention,
@@ -986,7 +986,7 @@ export const trialsRouter = createTRPCRouter({
       }
 
       // Broadcast annotation to all subscribers
-      await wsManager.broadcast(input.trialId, {
+      await wsManager.broadcastExternal(input.trialId, {
         type: "annotation_added",
         data: {
           annotation,
@@ -1380,7 +1380,7 @@ export const trialsRouter = createTRPCRouter({
         .returning();
 
       // Broadcast robot action to all subscribers
-      await wsManager.broadcast(input.trialId, {
+      await wsManager.broadcastExternal(input.trialId, {
         type: "trial_action_executed",
         data: {
           action_type: `${input.pluginName}.${input.actionId}`,
@@ -1439,7 +1439,7 @@ export const trialsRouter = createTRPCRouter({
         .returning();
 
       // Broadcast robot action to all subscribers
-      await wsManager.broadcast(input.trialId, {
+      await wsManager.broadcastExternal(input.trialId, {
         type: "trial_action_executed",
         data: {
           action_type: `${input.pluginName}.${input.actionId}`,

src/server/services/trial-execution.ts

@@ -441,10 +441,6 @@ export class TrialExecutionEngine {
       case "hristudio-core.loop":
         return await this.executeLoopAction(trialId, action);
 
-      case "branch":
-      case "hristudio-core.branch":
-        return await this.executeBranchAction(trialId, action);
-
       default:
         // Check if it's a robot action (contains plugin prefix)
         if (

src/server/services/websocket-manager.ts

@@ -146,6 +146,24 @@ class WebSocketManager {
     );
   }
 
+  // Called from Next.js tRPC router — POSTs to the Bun ws-server process
+  // which holds the actual client connections.
+  async broadcastExternal(
+    trialId: string,
+    message: OutgoingMessage,
+  ): Promise<void> {
+    const wsPort = process.env.WS_PORT ?? "3001";
+    try {
+      await fetch(`http://localhost:${wsPort}/internal/broadcast`, {
+        method: "POST",
+        headers: { "Content-Type": "application/json" },
+        body: JSON.stringify({ trialId, message }),
+      });
+    } catch (error) {
+      console.error(`[WS] Failed to broadcast externally for trial ${trialId}:`, error);
+    }
+  }
+
   async broadcastToAll(message: OutgoingMessage): Promise<void> {
     const messageStr = JSON.stringify(message);
     const disconnectedClients: string[] = [];

tsconfig.json

@@ -30,7 +30,7 @@
     ],
     "incremental": true,
     /* Path Aliases */
-    "baseUrl": ".",
+    // "baseUrl": ".",
     "paths": {
       "~/*": [
         "./src/*"

ws-server.ts

@@ -46,9 +46,22 @@ console.log(`Starting WebSocket server on port ${port}...`);
 
 serve<WSData>({
   port,
-  fetch(req, server) {
+  async fetch(req, server) {
     const url = new URL(req.url);
 
+    // Internal broadcast endpoint — called by Next.js tRPC router
+    if (url.pathname === "/internal/broadcast") {
+      if (req.method !== "POST") {
+        return new Response("Method not allowed", { status: 405 });
+      }
+      const { trialId, message } = (await req.json()) as {
+        trialId: string;
+        message: { type: string; data: Record<string, unknown> };
+      };
+      await wsManager.broadcast(trialId, message);
+      return new Response("OK", { status: 200 });
+    }
+
     if (url.pathname === "/api/websocket") {
       if (req.headers.get("upgrade") !== "websocket") {
         return new Response("WebSocket upgrade required", { status: 426 });
@@ -114,7 +127,7 @@ serve<WSData>({
         }),
       );
     },
-    message(ws: ServerWebSocket<WSData>, message) {
+    async message(ws: ServerWebSocket<WSData>, message) {
       const { clientId, trialId } = ws.data;
 
       try {
@@ -131,7 +144,7 @@ serve<WSData>({
             break;
 
           case "request_trial_status": {
-            const status = wsManager.getTrialStatusSync(trialId);
+            const status = await wsManager.getTrialStatus(trialId);
             ws.send(
               JSON.stringify({
                 type: "trial_status",
@@ -146,7 +159,7 @@ serve<WSData>({
           }
 
           case "request_trial_events": {
-            const events = wsManager.getTrialEventsSync(
+            const events = await wsManager.getTrialEvents(
               trialId,
               msg.data?.limit ?? 100,
             );