🐛 fix: inject timezone and cron jobs list into cron tool system prompt (#14012)

* 🐛 fix: inject timezone and cron jobs list into cron tool system prompt

Add {{timezone}} to cron systemRole session_context so the model knows
the user's local timezone when creating scheduled tasks. Wire up the
{{CRON_JOBS_LIST}} placeholder that was already referenced in the
systemRole but never populated — now fetches the agent's existing cron
jobs via tRPC and injects them, following the same pattern as CREDS_LIST.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* 🐛 fix: limit cron jobs context to 4 items to save context window

Only inject a preview of up to 4 cron jobs into the system prompt.
When there are more, append a hint directing the model to call
listCronJobs API for the full list. This avoids bloating the context
window for agents with many scheduled tasks.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/builtin-tool-cron/src/helpers.ts

@@ -0,0 +1,25 @@
+import type { CronJobSummaryForContext } from './types';
+
+const formatCronJob = (job: CronJobSummaryForContext): string => {
+  const status = job.enabled ? 'enabled' : 'disabled';
+  const execInfo =
+    job.remainingExecutions != null ? `${job.remainingExecutions} remaining` : 'unlimited';
+  const lastRun = job.lastExecutedAt ?? 'never';
+  const desc = job.description ? ` - ${job.description}` : '';
+
+  return `  - ${job.name || 'Unnamed'} (id: ${job.id}): ${job.cronPattern} [${job.timezone}] [${status}, ${execInfo}, ${job.totalExecutions} completed, last run: ${lastRun}]${desc}`;
+};
+
+export const generateCronJobsList = (jobs: CronJobSummaryForContext[], total?: number): string => {
+  if (jobs.length === 0) {
+    return 'No scheduled tasks configured for this agent.';
+  }
+
+  const lines = jobs.map(formatCronJob);
+
+  if (total && total > jobs.length) {
+    lines.push(`  (showing ${jobs.length} of ${total} tasks — use listCronJobs to see all)`);
+  }
+
+  return lines.join('\n');
+};

packages/builtin-tool-cron/src/index.ts

@@ -1,4 +1,5 @@
 export { CronExecutionRuntime, type ICronService } from './ExecutionRuntime';
+export { generateCronJobsList } from './helpers';
 export { CronIdentifier, CronManifest } from './manifest';
 export { systemPrompt } from './systemRole';
 export {

packages/builtin-tool-cron/src/systemRole.ts

@@ -4,6 +4,7 @@ export const systemPrompt = `You have access to a LobeHub Scheduled Tasks Tool.
 Current user: {{username}}
 Session date: {{date}}
 Current agent: {{agent_id}}
+User timezone: {{timezone}}
 </session_context>
 
 <existing_scheduled_tasks>

src/services/chat/mecha/contextEngineering.ts

@@ -2,6 +2,11 @@ import { LobeActivatorIdentifier } from '@lobechat/builtin-tool-activator';
 import { AgentBuilderIdentifier } from '@lobechat/builtin-tool-agent-builder';
 import { AgentManagementIdentifier } from '@lobechat/builtin-tool-agent-management';
 import { CredsIdentifier, type CredSummary, generateCredsList } from '@lobechat/builtin-tool-creds';
+import {
+  CronIdentifier,
+  type CronJobSummaryForContext,
+  generateCronJobsList,
+} from '@lobechat/builtin-tool-cron';
 import { GroupAgentBuilderIdentifier } from '@lobechat/builtin-tool-group-agent-builder';
 import { GTDIdentifier } from '@lobechat/builtin-tool-gtd';
 import { WebOnboardingIdentifier } from '@lobechat/builtin-tool-web-onboarding';
@@ -377,6 +382,42 @@ export const contextEngineering = async ({
     }
   }
 
+  // Resolve cron jobs context for cron tool
+  // Only inject a small preview (up to 4) to save context window;
+  // the model can call listCronJobs API for the full list.
+  const isCronEnabled = tools?.includes(CronIdentifier) ?? false;
+  let cronJobsList: CronJobSummaryForContext[] | undefined;
+  let cronJobsTotal = 0;
+
+  if (isCronEnabled && agentId) {
+    try {
+      const cronResult = await lambdaClient.agentCronJob.list.query({ agentId, limit: 4 });
+      const jobs = (cronResult as any)?.data ?? [];
+      cronJobsTotal = (cronResult as any)?.pagination?.total ?? jobs.length;
+      cronJobsList = jobs.map(
+        (job: any): CronJobSummaryForContext => ({
+          cronPattern: job.cronPattern,
+          description: job.description,
+          enabled: job.enabled,
+          id: job.id,
+          lastExecutedAt: job.lastExecutedAt,
+          name: job.name,
+          remainingExecutions: job.remainingExecutions,
+          timezone: job.timezone ?? 'UTC',
+          totalExecutions: job.totalExecutions ?? 0,
+        }),
+      );
+      log(
+        'Cron jobs context resolved: count=%d, total=%d',
+        cronJobsList?.length ?? 0,
+        cronJobsTotal,
+      );
+    } catch (error) {
+      // Silently fail - cron context is optional
+      log('Failed to resolve cron jobs context:', error);
+    }
+  }
+
   const userMemoryConfig =
     enableUserMemories && userMemoryData
       ? {
@@ -694,6 +735,8 @@ export const contextEngineering = async ({
       ...VARIABLE_GENERATORS,
       // NOTICE: required by builtin-tool-creds/src/systemRole.ts
       CREDS_LIST: () => (credsList ? generateCredsList(credsList) : ''),
+      // NOTICE: required by builtin-tool-cron/src/systemRole.ts
+      CRON_JOBS_LIST: () => (cronJobsList ? generateCronJobsList(cronJobsList, cronJobsTotal) : ''),
       // NOTICE(@nekomeowww): required by builtin-tool-memory/src/systemRole.ts
       memory_effort: () => (userMemoryConfig ? (memoryContext?.effort ?? '') : ''),
       // Current agent + topic identity — referenced by the LobeHub builtin