fix(scheduling): enforce one active intervention per current vehicle

Business rule: a running vehicle can hold AT MOST ONE active (sent|executed)
intervention. Switching to a different candidate requires cancelling the
prior one first.

- Server: insertNotification dedup key changes from (suggestion_id,
  candidate_plate) to just suggestion_id; 409 response includes the blocking
  candidate plate
- Detail modal: shows a banner naming the locked candidate; non-active
  candidates render a disabled "该车已有其他干预，请先解除" hint instead
  of the action button
- Batch: pickBestCandidate returns null for any suggestion already holding
  an active intervention — the whole suggestion is excluded

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/modules/scheduling/SchedulingModule.tsx

@@ -147,10 +147,13 @@ function SkeletonPage() {
 }
 
 function pickBestCandidate(s: SchedulingSuggestion): CandidateVehicle | null {
-  // Prefer a candidate that can qualify and isn't already notified
-  const available = s.candidates.filter(c => !c.notificationStatus || c.notificationStatus === 'cancelled');
-  if (available.length === 0) return null;
-  return available.find(c => c.canQualifyAfterSwap) ?? available[0];
+  // Business rule: at most one active intervention per suggestion. If ANY
+  // candidate is already intervened, skip the whole suggestion in batch flow.
+  const hasActive = s.candidates.some(
+    c => c.notificationStatus === 'sent' || c.notificationStatus === 'executed',
+  );
+  if (hasActive) return null;
+  return s.candidates.find(c => c.canQualifyAfterSwap) ?? s.candidates[0] ?? null;
 }
 
 export default function SchedulingModule() {

src/modules/scheduling/SuggestionDetail.tsx

@@ -1,7 +1,7 @@
 import { useState, useMemo } from 'react';
 import {
   X, MapPin, AlertTriangle, CheckCircle, ArrowDown, ArrowUp, ArrowRight, ArrowUpDown,
-  TrendingUp, TrendingDown, Minus,
+  TrendingUp, TrendingDown, Minus, Lock,
 } from 'lucide-react';
 import { motion } from 'motion/react';
 import type { SchedulingSuggestion, CandidateVehicle } from './types';
@@ -36,6 +36,13 @@ export default function SuggestionDetail({ suggestion: s, onClose, onNotifySucce
   const v = s.currentVehicle;
   const isRescue = s.type === 'rescue_hopeless';
 
+  // Business rule: a current vehicle can have AT MOST ONE active intervention.
+  // Find the active candidate (if any) — other candidates are blocked until
+  // this one is cancelled.
+  const activeIntervention = s.candidates.find(
+    cc => cc.notificationStatus === 'sent' || cc.notificationStatus === 'executed',
+  );
+
   // Batch options from candidates
   const batchOptions = useMemo(() => {
     const set = new Set<string>();
@@ -70,8 +77,9 @@ export default function SuggestionDetail({ suggestion: s, onClose, onNotifySucce
       sentPlates.has(c.plateNumber) ||
       c.notificationStatus === 'sent' ||
       c.notificationStatus === 'executed';
+    const blockedByOther = !!activeIntervention && activeIntervention.plateNumber !== c.plateNumber;
     return (
-      <div key={c.plateNumber} className="rounded-xl border border-slate-200 overflow-hidden bg-white">
+      <div key={c.plateNumber} className={`rounded-xl border overflow-hidden bg-white ${blockedByOther ? 'border-slate-200 opacity-60' : 'border-slate-200'}`}>
         <div className="flex items-center justify-between px-3 py-2">
           <div className="flex items-center gap-2 flex-wrap">
             <span className="text-xs font-black text-slate-900 font-mono"><Blur>{c.plateNumber}</Blur></span>
@@ -111,16 +119,22 @@ export default function SuggestionDetail({ suggestion: s, onClose, onNotifySucce
         </div>
 
         <div className="px-3 pb-2.5">
-          <button
-            onClick={() => setPreviewCandidate(c)}
-            className={`w-full flex items-center justify-center gap-1.5 text-[11px] font-bold py-2 rounded-lg transition-all cursor-pointer ${
-              sent
-                ? 'bg-emerald-50 hover:bg-emerald-100 text-emerald-700 border border-emerald-200'
-                : 'bg-slate-800 hover:bg-slate-900 text-white active:scale-[0.98] shadow-sm'
-            }`}
-          >
-            {sent ? <><CheckCircle size={12} /> 已干预 · 查看 <ArrowRight size={12} /></> : <>查看替换方案 <ArrowRight size={12} /></>}
-          </button>
+          {blockedByOther ? (
+            <div className="w-full flex items-center justify-center gap-1.5 text-[11px] font-medium py-2 rounded-lg bg-slate-50 text-slate-400 cursor-not-allowed">
+              <Lock size={11} /> 该车已有其他干预，请先解除
+            </div>
+          ) : (
+            <button
+              onClick={() => setPreviewCandidate(c)}
+              className={`w-full flex items-center justify-center gap-1.5 text-[11px] font-bold py-2 rounded-lg transition-all cursor-pointer ${
+                sent
+                  ? 'bg-emerald-50 hover:bg-emerald-100 text-emerald-700 border border-emerald-200'
+                  : 'bg-slate-800 hover:bg-slate-900 text-white active:scale-[0.98] shadow-sm'
+              }`}
+            >
+              {sent ? <><CheckCircle size={12} /> 已干预 · 查看 <ArrowRight size={12} /></> : <>查看替换方案 <ArrowRight size={12} /></>}
+            </button>
+          )}
         </div>
       </div>
     );
@@ -240,6 +254,15 @@ export default function SuggestionDetail({ suggestion: s, onClose, onNotifySucce
               <span className="text-[10px] text-slate-400">{displayCount}/{s.candidates.length} 辆</span>
             </div>
 
+            {activeIntervention && (
+              <div className="mb-2.5 flex items-start gap-2 rounded-lg bg-emerald-50 border border-emerald-200 px-3 py-2 text-[11px] text-emerald-800">
+                <Lock size={12} className="mt-0.5 flex-shrink-0" />
+                <span>
+                  此车已干预替换为 <b className="font-mono"><Blur>{activeIntervention.plateNumber}</Blur></b>。如需更换方案，请先在该候选车处解除干预。
+                </span>
+              </div>
+            )}
+
             {/* Filter + Sort controls */}
             <div className="flex items-center gap-2 mb-2.5 flex-wrap">
               {/* Batch multi-select pills */}

src/server/routes/scheduling/notify.ts

@@ -61,16 +61,20 @@ export async function fetchActiveNotificationMap(): Promise<
 async function insertNotification(
   req: NotifyRequest,
   operator: { id: string | null; name: string | null },
-): Promise<NotificationRecord | { skipped: true }> {
-  // Check if a non-cancelled notification already exists for this pair
+): Promise<NotificationRecord | { skipped: true; existingPlate: string }> {
+  // Business rule: each current vehicle (suggestion) can have AT MOST ONE
+  // active intervention at a time. Any non-cancelled record for the same
+  // suggestion_id blocks further interventions until it is cancelled.
   const [existing] = (await pool.execute(
-    `SELECT id FROM tab_scheduling_notifications
-     WHERE suggestion_id = ? AND candidate_plate = ? AND status != 'cancelled'
+    `SELECT id, candidate_plate FROM tab_scheduling_notifications
+     WHERE suggestion_id = ? AND status != 'cancelled'
      LIMIT 1`,
-    [req.suggestionId, req.candidatePlate],
+    [req.suggestionId],
   )) as [any[], unknown];
 
-  if (existing.length > 0) return { skipped: true };
+  if (existing.length > 0) {
+    return { skipped: true, existingPlate: existing[0].candidate_plate as string };
+  }
 
   const [result] = (await pool.execute(
     `INSERT INTO tab_scheduling_notifications
@@ -110,7 +114,10 @@ app.post('/', async (c) => {
 
     const result = await insertNotification(body, operator);
     if ('skipped' in result) {
-      return c.json({ success: false, message: '该建议已处理' }, 409);
+      return c.json(
+        { success: false, message: `此车已有干预（候选车 ${result.existingPlate}），请先解除` },
+        409,
+      );
     }
 
     console.log(