feat: agent avatars, task tags, search, edit/delete agents, cron readability, timezone fix

- Agent avatars: first-letter + deterministic color avatar in all views
- Agent management: edit (name/description) and delete with confirmation
- Execution API: validates agent existence, returns 410 if deleted
- Task tags: JSON array field, editable with tag pills UI
- Task search: by name (?q=) and by tags (?tags=) and by status
- Task edit: simplified to name/tags/description only (not agent params)
- Cron display: human-readable Chinese (e.g. '每5分钟', '每天 09:00')
- Timezone fix: UTC→local via dayjs.utc().local() across all pages
- Content area: full width (removed max-width:1200px constraints)
- Login page: standalone layout without sidebar

backend/app/api/agents.py

@@ -59,6 +59,17 @@ async def heartbeat(agent_id: int, body: AgentHeartbeat, db: AsyncSession = Depe
     return AgentOut(**{**agent.__dict__, "task_count": cnt})
 
 
+@router.delete("/{agent_id}", status_code=204)
+async def delete_agent(agent_id: int, db: AsyncSession = Depends(get_db)):
+    svc = AgentService(db)
+    agent = await svc.get(agent_id)
+    if not agent:
+        raise HTTPException(404, "Agent not found")
+    # Delete all tasks first, then the agent (cascade)
+    await svc.delete(agent_id)
+    await db.commit()
+
+
 # ── Batch registration: AI agent self-registers with all its tasks ─────
 
 @router.post("/register-with-tasks", response_model=AgentBatchRegisterResult, status_code=201)

backend/app/api/executions.py

@@ -20,6 +20,14 @@ async def report_execution(task_id: int, body: ExecutionReport,
     if not task:
         raise HTTPException(404, "Task not found")
 
+    # Verify agent exists and is active
+    agent_svc = AgentService(db)
+    agent = await agent_svc.get(task.agent_id)
+    if not agent:
+        raise HTTPException(410, "Agent已被删除，请重新注册")
+    if agent.status != "active":
+        raise HTTPException(403, "Agent已停用，无法汇报")
+
     exec_svc = ExecutionService(db)
     record = await exec_svc.report_result(
         task_id=task_id,

backend/app/api/tasks.py

@@ -1,13 +1,28 @@
 """API router — Task management."""
 
-from fastapi import APIRouter, Depends, HTTPException
+import json
+
+from fastapi import APIRouter, Depends, HTTPException, Query
+from sqlalchemy import select, or_
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.database import get_db
 from app.schemas import TaskCreate, TaskOut, TaskUpdate
 from app.services import TaskService, AgentService
+from app.models import ScheduledTask
 
-router = APIRouter(prefix="/api/tasks", tags=["tasks"])
+router = APIRouter(prefix="/api/tasks", tags=["tags"])
+
+
+def _task_to_out(task, agent_name: str = "") -> dict:
+    """Convert task model to TaskOut dict, handling tags JSON deserialization."""
+    data = {**task.__dict__}
+    try:
+        data["tags"] = json.loads(data.get("tags", "[]"))
+    except (json.JSONDecodeError, TypeError):
+        data["tags"] = []
+    data["agent_name"] = agent_name
+    return data
 
 
 @router.post("", response_model=TaskOut, status_code=201)
@@ -25,23 +40,48 @@ async def create_task(body: TaskCreate, agent_id: int, db: AsyncSession = Depend
         description=body.description,
         grace_period=body.grace_period,
     )
-    return TaskOut(**{**task.__dict__, "agent_name": agent.name})
+    # Store tags
+    if body.tags:
+        task.tags = json.dumps(body.tags, ensure_ascii=False)
+        await db.flush()
+        await db.refresh(task)
+    return TaskOut(**_task_to_out(task, agent.name))
 
 
 @router.get("", response_model=list[TaskOut])
-async def list_tasks(agent_id: int | None = None, db: AsyncSession = Depends(get_db)):
-    """List all tasks, optionally filtered by agent_id."""
+async def list_tasks(
+    agent_id: int | None = Query(None),
+    q: str | None = Query(None, description="关键词搜索（任务名称）"),
+    tags: str | None = Query(None, description="标签筛选，逗号分隔"),
+    status: str | None = Query(None),
+    db: AsyncSession = Depends(get_db),
+):
+    """List all tasks, with optional search and filters."""
     svc = TaskService(db)
     agent_svc = AgentService(db)
+
+    # Build query
+    stmt = select(ScheduledTask)
     if agent_id:
-        tasks = await svc.list_by_agent(agent_id)
-    else:
-        tasks = await svc.list_all()
-    result = []
+        stmt = stmt.where(ScheduledTask.agent_id == agent_id)
+    if status:
+        stmt = stmt.where(ScheduledTask.status == status)
+    if q:
+        stmt = stmt.where(ScheduledTask.name.like(f"%{q}%"))
+    if tags:
+        tag_list = [t.strip() for t in tags.split(",") if t.strip()]
+        for tag in tag_list:
+            stmt = stmt.where(ScheduledTask.tags.like(f'%"{tag}"%'))
+
+    stmt = stmt.order_by(ScheduledTask.id)
+    result = await db.execute(stmt)
+    tasks = list(result.scalars().all())
+
+    output = []
     for t in tasks:
         agent = await agent_svc.get(t.agent_id)
-        result.append(TaskOut(**{**t.__dict__, "agent_name": agent.name if agent else ""}))
-    return result
+        output.append(TaskOut(**_task_to_out(t, agent.name if agent else "")))
+    return output
 
 
 @router.get("/{task_id}", response_model=TaskOut)
@@ -52,18 +92,29 @@ async def get_task(task_id: int, db: AsyncSession = Depends(get_db)):
     if not task:
         raise HTTPException(404, "Task not found")
     agent = await agent_svc.get(task.agent_id)
-    return TaskOut(**{**task.__dict__, "agent_name": agent.name if agent else ""})
+    return TaskOut(**_task_to_out(task, agent.name if agent else ""))
 
 
 @router.put("/{task_id}", response_model=TaskOut)
 async def update_task(task_id: int, body: TaskUpdate, db: AsyncSession = Depends(get_db)):
     svc = TaskService(db)
     agent_svc = AgentService(db)
-    task = await svc.update(task_id, **body.model_dump(exclude_none=True))
+
+    # Handle tags separately (JSON serialization)
+    update_data = body.model_dump(exclude_none=True)
+    tags_list = update_data.pop("tags", None)
+
+    task = await svc.update(task_id, **update_data)
     if not task:
         raise HTTPException(404, "Task not found")
+
+    if tags_list is not None:
+        task.tags = json.dumps(tags_list, ensure_ascii=False)
+        await db.flush()
+        await db.refresh(task)
+
     agent = await agent_svc.get(task.agent_id)
-    return TaskOut(**{**task.__dict__, "agent_name": agent.name if agent else ""})
+    return TaskOut(**_task_to_out(task, agent.name if agent else ""))
 
 
 @router.delete("/{task_id}", status_code=204)