fix(cron): preserve overrides and harden next-run calculation

src/cron/isolated-agent/session.test.ts

@@ -150,12 +150,8 @@ describe("resolveCronSession", () => {
         "webhook:stable-key": {
           updatedAt: Date.now() - 1000,
           modelOverride: "some-model",
-        } as unknown as {
-          sessionId: string;
-          updatedAt: number;
-          modelOverride?: string;
         },
-      });
+      } as ReturnType<typeof loadSessionStore>);
       vi.mocked(evaluateSessionFreshness).mockReturnValue({ fresh: true });
 
       const result = resolveCronSession({

src/cron/isolated-agent/session.ts

@@ -59,9 +59,8 @@ export function resolveCronSession(params: {
   }
 
   const sessionEntry: SessionEntry = {
-    // Spread existing entry to preserve conversation context when reusing
-    // (the spread already copies all fields when !isNewSession, no need to re-assign)
-    ...(isNewSession ? undefined : entry),
+    // Preserve existing per-session overrides even when rolling to a new sessionId.
+    ...entry,
     // Always update these core fields
     sessionId,
     updatedAt: params.nowMs,

src/cron/schedule.ts

@@ -62,13 +62,12 @@ export function computeNextRunAtMs(schedule: CronSchedule, nowMs: number): numbe
   }
 
   // Guard against same-second rescheduling loops: if croner returns
-  // "now" (or an earlier instant) when the job completed mid-second,
-  // retry from the next whole second.
+  // "now" (or an earlier instant), retry from the next whole second.
   const nextSecondMs = Math.floor(nowMs / 1000) * 1000 + 1000;
   const retry = cron.nextRun(new Date(nextSecondMs));
   if (!retry) {
     return undefined;
   }
   const retryMs = retry.getTime();
-  return Number.isFinite(retryMs) ? retryMs : undefined;
+  return Number.isFinite(retryMs) && retryMs > nowMs ? retryMs : undefined;
 }