fix(cron): preserve explicit to on mode override and always include mode in UI patches

- delivery.ts: preserve job-level explicit 'to' when overriding mode
- UI: always include mode in failureAlert patch so users can switch between announce/webhook

src/cron/delivery.ts

@@ -154,6 +154,9 @@ export function resolveFailureDestination(
     const jobAccountId = normalizeAccountId(jobFailureDest.accountId);
     const jobMode = normalizeFailureMode(jobFailureDest.mode);
 
+    // Track if 'to' was explicitly set at job level
+    const jobToExplicit = "to" in jobFailureDest && jobFailureDest.to !== undefined;
+
     // Only override if explicitly set (not undefined)
     if (jobChannel !== undefined) {
       channel = jobChannel;
@@ -167,7 +170,8 @@ export function resolveFailureDestination(
     if (jobMode !== undefined) {
       // Mode was explicitly overridden - clear inherited 'to' since URL semantics differ
       // between announce (channel recipient) and webhook (HTTP endpoint)
-      if (globalConfig?.mode !== jobMode) {
+      // But preserve explicit 'to' that was set at job level
+      if (!jobToExplicit && globalConfig?.mode !== jobMode) {
         to = undefined;
       }
       mode = jobMode;

ui/src/ui/controllers/cron.ts

@@ -608,8 +608,8 @@ function buildFailureAlert(form: CronFormState) {
     ...(cooldownMs !== undefined ? { cooldownMs } : {}),
     ...(accountId ? { accountId } : {}),
   };
-  // Only include mode if explicitly set to non-default value
-  if (deliveryMode && deliveryMode !== "announce") {
+  // Always include mode so users can switch between webhook/announce
+  if (deliveryMode) {
     patch.mode = deliveryMode;
   }
   return patch;