feat(simulation): read-only Conversation view for completed runs

Step 3 (Step3Simulation.vue) called doStartSimulation({force:true}) on every
onMounted, so opening a finished simulation force-restarted it — wiping the run
and re-spending tokens. There was also no way to revisit a completed run's
timeline from history.

- Step3Simulation: add initSimulation() that checks run-status first. If the
  simulation already ran (completed/stopped/running, or has actions), load the
  existing timeline read-only (resume polling only if still running) instead of
  force-starting. Genuinely fresh simulations start as before.
- HistoryDatabase: add a "Step3 · Conversation" button to the history modal
  that routes to the SimulationRun view for the selected simulation.
- locales: add history.step3Button (en/zh) and update replayHint to reflect
  that completed runs are now viewable read-only.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/src/components/HistoryDatabase.vue

@@ -161,16 +161,25 @@
                 <span class="btn-icon">◇</span>
                 <span class="btn-text">{{ $t('history.step1Button') }}</span>
               </button>
-              <button 
-                class="modal-btn btn-simulation" 
+              <button
+                class="modal-btn btn-simulation"
                 @click="goToSimulation"
               >
                 <span class="btn-step">Step2</span>
                 <span class="btn-icon">◈</span>
                 <span class="btn-text">{{ $t('history.step2Button') }}</span>
               </button>
-              <button 
-                class="modal-btn btn-report" 
+              <button
+                class="modal-btn btn-simulation"
+                @click="goToSimulationRun"
+                :disabled="!selectedProject.simulation_id"
+              >
+                <span class="btn-step">Step3</span>
+                <span class="btn-icon">◈</span>
+                <span class="btn-text">{{ $t('history.step3Button') }}</span>
+              </button>
+              <button
+                class="modal-btn btn-report"
                 @click="goToReport"
                 :disabled="!selectedProject.report_id"
               >
@@ -425,6 +434,17 @@ const goToSimulation = () => {
   }
 }
 
+// 导航到模拟运行/对话时间轴页面（Step3，已完成的模拟为只读查看）
+const goToSimulationRun = () => {
+  if (selectedProject.value?.simulation_id) {
+    router.push({
+      name: 'SimulationRun',
+      params: { simulationId: selectedProject.value.simulation_id }
+    })
+    closeModal()
+  }
+}
+
 // 导航到分析报告页面（Report）
 const goToReport = () => {
   if (selectedProject.value?.report_id) {

frontend/src/components/Step3Simulation.vue

@@ -687,10 +687,43 @@ watch(() => props.systemLogs?.length, () => {
   })
 })
 
+// 初始化：已运行过的模拟用只读模式加载现有时间轴，避免 onMounted 自动 force-restart
+const initSimulation = async () => {
+  if (!props.simulationId) return
+  try {
+    const res = await getRunStatus(props.simulationId)
+    const data = res && res.data
+    const alreadyRan = data && (
+      data.runner_status === 'completed' ||
+      data.runner_status === 'stopped' ||
+      data.runner_status === 'running' ||
+      (data.total_actions_count || 0) > 0
+    )
+    if (alreadyRan) {
+      addLog('Loading existing run (view mode — no restart)')
+      runStatus.value = data
+      await fetchRunStatusDetail() // 加载已有动作到时间轴
+      if (data.runner_status === 'running') {
+        phase.value = 1
+        startStatusPolling()
+        startDetailPolling()
+      } else {
+        phase.value = 2
+        emit('update-status', 'completed')
+      }
+      return
+    }
+  } catch (err) {
+    console.warn('初始化状态检查失败，将按新模拟启动:', err)
+  }
+  // 全新模拟才启动
+  doStartSimulation()
+}
+
 onMounted(() => {
   addLog(t('log.step3Init'))
   if (props.simulationId) {
-    doStartSimulation()
+    initSimulation()
   }
 })
 

locales/en.json

@@ -311,8 +311,9 @@
     "replayTitle": "Simulation Replay",
     "step1Button": "Graph Build",
     "step2Button": "Env Setup",
+    "step3Button": "Conversation",
     "step4Button": "Analysis Report",
-    "replayHint": "Step 3 'Run Simulation' and Step 5 'Deep Interaction' must be started during runtime and do not support history replay",
+    "replayHint": "Step 5 'Deep Interaction' must be started during runtime; completed runs can be viewed read-only via 'Conversation'",
     "notStarted": "Not started",
     "roundsProgress": "{current}/{total} rounds",
     "untitledSimulation": "Untitled simulation",

locales/zh.json

@@ -311,8 +311,9 @@
     "replayTitle": "推演回放",
     "step1Button": "图谱构建",
     "step2Button": "环境搭建",
+    "step3Button": "模拟对话",
     "step4Button": "分析报告",
-    "replayHint": "Step3「开始模拟」与 Step5「深度互动」需在运行中启动，不支持历史回放",
+    "replayHint": "Step5「深度互动」需在运行中启动；已完成的模拟可通过「模拟对话」只读查看",
     "notStarted": "未开始",
     "roundsProgress": "{current}/{total} 轮",
     "untitledSimulation": "未命名模拟",