Fix demo-bot cron + cadence math

`*/90 * * * *` is invalid cron (minute field is 0–59) and degrades
to hourly, producing half the intended bot cadence. Switch to
`0,30 * * * *` (every 30 min) and lower the Bernoulli gate from
0.12 to 0.09 so we still hit ~2–3 walks/day during the 07–21
Berlin window.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/journal/app/jobs/demo-bot-generate.ts

@@ -13,17 +13,17 @@ import {
 import { logger } from "../lib/logger.server.ts";
 
 /**
- * Generate job. Fires every 90 minutes via pg-boss cron. Handler steps:
+ * Generate job. Fires every 30 minutes via pg-boss cron. Handler steps:
  *
  * 1. Bail if `DEMO_BOT_ENABLED` is not "true".
  * 2. On first run (no synthetic rows yet) produce a small backfill so the
  *    demo user's profile has content immediately.
- * 3. Otherwise apply the decide-to-walk gate (local hour + p=0.12) and
+ * 3. Otherwise apply the decide-to-walk gate (local hour + p=0.09) and
  *    daily cap; on pass, insert one route+activity via `generateOneWalk`.
  */
 export const demoBotGenerateJob: JobDefinition = {
   name: "demo-bot:generate",
-  cron: "*/90 * * * *",
+  cron: "0,30 * * * *",
   retryLimit: 1,
   expireInSeconds: 120,
   async handler() {

apps/journal/app/lib/demo-bot.server.ts

@@ -640,13 +640,18 @@ export function berlinHour(now: Date): number {
 }
 
 /**
- * The decide-to-walk gate: only within 07–21 local, Bernoulli p=0.12.
+ * The decide-to-walk gate: only within 07–21 local, Bernoulli p=0.09.
  * Factored out so tests can replace `Math.random` / `now`.
+ *
+ * Cadence math: the job ticks every 30 min, so the 14-hour daytime
+ * window (07:00–21:00 Berlin) covers 28 ticks/day. With p=0.09 the
+ * expected walks/day ≈ 28 * 0.09 ≈ 2.52, which lands in the target
+ * 2–3 walks/day band.
  */
 export function shouldWalkNow(now: Date, rand: () => number = Math.random): boolean {
   const hour = berlinHour(now);
   if (hour < 7 || hour >= 21) return false;
-  return rand() < 0.12;
+  return rand() < 0.09;
 }
 
 export const DEMO_DAILY_CAP = 40;