feat: add update_task tool and return task ID from schedule_task

schedule_task was creating duplicate tasks when users asked to modify
a schedule, because the agent had no way to update an existing task
and didn't know the ID of the task it created. Now schedule_task
generates and returns the task ID, and a new update_task tool allows
modifying prompt, schedule_type, and schedule_value in place.

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

container/agent-runner/src/ipc-mcp-stdio.ts

@@ -64,7 +64,7 @@ server.tool(
 
 server.tool(
   'schedule_task',
-  `Schedule a recurring or one-time task. The task will run as a full agent with access to all tools.
+  `Schedule a recurring or one-time task. The task will run as a full agent with access to all tools. Returns the task ID for future reference. To modify an existing task, use update_task instead.
 
 CONTEXT MODE - Choose based on task type:
 \u2022 "group": Task runs in the group's conversation context, with access to chat history. Use for tasks that need context about ongoing discussions, user preferences, or recent interactions.
@@ -130,8 +130,11 @@ SCHEDULE VALUE FORMAT (all times are LOCAL timezone):
     // Non-main groups can only schedule for themselves
     const targetJid = isMain && args.target_group_jid ? args.target_group_jid : chatJid;
 
+    const taskId = `task-${Date.now()}-${Math.random().toString(36).slice(2, 8)}`;
+
     const data = {
       type: 'schedule_task',
+      taskId,
       prompt: args.prompt,
       schedule_type: args.schedule_type,
       schedule_value: args.schedule_value,
@@ -141,10 +144,10 @@ SCHEDULE VALUE FORMAT (all times are LOCAL timezone):
       timestamp: new Date().toISOString(),
     };
 
-    const filename = writeIpcFile(TASKS_DIR, data);
+    writeIpcFile(TASKS_DIR, data);
 
     return {
-      content: [{ type: 'text' as const, text: `Task scheduled (${filename}): ${args.schedule_type} - ${args.schedule_value}` }],
+      content: [{ type: 'text' as const, text: `Task ${taskId} scheduled: ${args.schedule_type} - ${args.schedule_value}` }],
     };
   },
 );
@@ -244,6 +247,56 @@ server.tool(
   },
 );
 
+server.tool(
+  'update_task',
+  'Update an existing scheduled task. Only provided fields are changed; omitted fields stay the same.',
+  {
+    task_id: z.string().describe('The task ID to update'),
+    prompt: z.string().optional().describe('New prompt for the task'),
+    schedule_type: z.enum(['cron', 'interval', 'once']).optional().describe('New schedule type'),
+    schedule_value: z.string().optional().describe('New schedule value (see schedule_task for format)'),
+  },
+  async (args) => {
+    // Validate schedule_value if provided
+    if (args.schedule_type === 'cron' || (!args.schedule_type && args.schedule_value)) {
+      if (args.schedule_value) {
+        try {
+          CronExpressionParser.parse(args.schedule_value);
+        } catch {
+          return {
+            content: [{ type: 'text' as const, text: `Invalid cron: "${args.schedule_value}".` }],
+            isError: true,
+          };
+        }
+      }
+    }
+    if (args.schedule_type === 'interval' && args.schedule_value) {
+      const ms = parseInt(args.schedule_value, 10);
+      if (isNaN(ms) || ms <= 0) {
+        return {
+          content: [{ type: 'text' as const, text: `Invalid interval: "${args.schedule_value}".` }],
+          isError: true,
+        };
+      }
+    }
+
+    const data: Record<string, string | undefined> = {
+      type: 'update_task',
+      taskId: args.task_id,
+      groupFolder,
+      isMain: String(isMain),
+      timestamp: new Date().toISOString(),
+    };
+    if (args.prompt !== undefined) data.prompt = args.prompt;
+    if (args.schedule_type !== undefined) data.schedule_type = args.schedule_type;
+    if (args.schedule_value !== undefined) data.schedule_value = args.schedule_value;
+
+    writeIpcFile(TASKS_DIR, data);
+
+    return { content: [{ type: 'text' as const, text: `Task ${args.task_id} update requested.` }] };
+  },
+);
+
 server.tool(
   'register_group',
   `Register a new chat/group so the agent can respond to messages there. Main group only.

src/ipc.ts

@@ -247,7 +247,9 @@ export async function processTaskIpc(
           nextRun = scheduled.toISOString();
         }
 
-        const taskId = `task-${Date.now()}-${Math.random().toString(36).slice(2, 8)}`;
+        const taskId =
+          data.taskId ||
+          `task-${Date.now()}-${Math.random().toString(36).slice(2, 8)}`;
         const contextMode =
           data.context_mode === 'group' || data.context_mode === 'isolated'
             ? data.context_mode
@@ -325,6 +327,70 @@ export async function processTaskIpc(
       }
       break;
 
+    case 'update_task':
+      if (data.taskId) {
+        const task = getTaskById(data.taskId);
+        if (!task) {
+          logger.warn(
+            { taskId: data.taskId, sourceGroup },
+            'Task not found for update',
+          );
+          break;
+        }
+        if (!isMain && task.group_folder !== sourceGroup) {
+          logger.warn(
+            { taskId: data.taskId, sourceGroup },
+            'Unauthorized task update attempt',
+          );
+          break;
+        }
+
+        const updates: Parameters<typeof updateTask>[1] = {};
+        if (data.prompt !== undefined) updates.prompt = data.prompt;
+        if (data.schedule_type !== undefined)
+          updates.schedule_type = data.schedule_type as
+            | 'cron'
+            | 'interval'
+            | 'once';
+        if (data.schedule_value !== undefined)
+          updates.schedule_value = data.schedule_value;
+
+        // Recompute next_run if schedule changed
+        if (data.schedule_type || data.schedule_value) {
+          const updatedTask = {
+            ...task,
+            ...updates,
+          };
+          if (updatedTask.schedule_type === 'cron') {
+            try {
+              const interval = CronExpressionParser.parse(
+                updatedTask.schedule_value,
+                { tz: TIMEZONE },
+              );
+              updates.next_run = interval.next().toISOString();
+            } catch {
+              logger.warn(
+                { taskId: data.taskId, value: updatedTask.schedule_value },
+                'Invalid cron in task update',
+              );
+              break;
+            }
+          } else if (updatedTask.schedule_type === 'interval') {
+            const ms = parseInt(updatedTask.schedule_value, 10);
+            if (!isNaN(ms) && ms > 0) {
+              updates.next_run = new Date(Date.now() + ms).toISOString();
+            }
+          }
+        }
+
+        updateTask(data.taskId, updates);
+        logger.info(
+          { taskId: data.taskId, sourceGroup, updates },
+          'Task updated via IPC',
+        );
+      }
+      break;
+
     case 'refresh_groups':
       // Only main group can request a refresh
       if (isMain) {