refactor: 水平对称双翼布局—左翼(偶索引)+中央主干+右翼(奇索引),实线/虚线区分

frontend/src/components/TaskTree/TaskFlowView.tsx

@@ -121,41 +121,51 @@ export const TaskFlowView = memo(function TaskFlowView({ tasks, onAction, curren
 
       {/* ─── 焦点模式 ─── */}
       {!showFullMap && (
-        <div className="flex flex-col items-center gap-3">
-          {/* 顶部行：遗留分支标记 */}
+        <div className="flex flex-col items-center gap-6">
           {legacySubs.length > 0 && (
-            <div className="mb-2 rounded-lg border border-dashed border-orange-200 bg-orange-50 px-3 py-1.5 text-center">
-              <p className="text-[10px] font-medium text-orange-600">⚠ 以下 {legacySubs.length} 个分支属于已完工的历史主线，仍在进行中</p>
+            <div className="rounded-lg border border-dashed border-orange-200 bg-orange-50 px-3 py-1.5 text-center">
+              <p className="text-[10px] font-medium text-orange-600">⚠ {legacySubs.length} 个遗留分支仍在进行中</p>
             </div>
           )}
-
-          {/* 中央：activeMain 纵向排列 */}
-          <div className="flex flex-col items-center gap-2">
-            {activeMain.map(t => (
-              <SlimCard key={t.id} task={t} assigneeName={assigneeNames?.[t.assignee_id || ""]} active onAction={onAction} currentUser={currentUser} onViewRecords={setRecordsTask} />
-            ))}
-            {activeMain.length === 0 && <p className="text-xs text-gray-400 py-4">当前无活跃主线任务</p>}
-          </div>
-
-          {/* 两侧：activeSubs + legacySubs 与中央同行 */}
-          <div className="flex flex-wrap items-start justify-center gap-4 mt-2">
-            {/* activeSubs（实线） */}
-            {activeSubs.map(t => (
-              <div key={t.id} className="flex flex-col items-center">
-                <div className="h-4 w-0.5 bg-gray-300" />
-                <div className="w-8 border-t-2 border-solid border-gray-400" />
-                <SlimCard task={t} assigneeName={assigneeNames?.[t.assignee_id || ""]} active onAction={onAction} currentUser={currentUser} onViewRecords={setRecordsTask} />
+          {/* 每个活跃主线一行：左翼 + 中央 + 右翼 */}
+          {activeMain.map(mainTask => {
+            const allSubs = [...activeSubs, ...legacySubs];
+            const leftSubs = allSubs.filter((_, i) => i % 2 === 0);
+            const rightSubs = allSubs.filter((_, i) => i % 2 === 1);
+            return (
+              <div key={mainTask.id} className="flex flex-row items-center w-full">
+                {/* 左翼 */}
+                <div className="flex-1 flex justify-end items-center pr-4 gap-1">
+                  {leftSubs.map(t => {
+                    const isLegacy = legacySubs.includes(t);
+                    return (
+                      <div key={t.id} className="flex items-center">
+                        <SlimCard task={t} assigneeName={assigneeNames?.[t.assignee_id || ""]} active legacy={isLegacy} onAction={onAction} currentUser={currentUser} onViewRecords={setRecordsTask} />
+                        <div className={`w-6 border-t-2 ${isLegacy ? "border-dashed border-orange-300" : "border-solid border-gray-400"}`} />
+                      </div>
+                    );
+                  })}
+                </div>
+                {/* 中央主干 */}
+                <div className="shrink-0 z-10">
+                  <SlimCard task={mainTask} assigneeName={assigneeNames?.[mainTask.assignee_id || ""]} active onAction={onAction} currentUser={currentUser} onViewRecords={setRecordsTask} />
+                </div>
+                {/* 右翼 */}
+                <div className="flex-1 flex justify-start items-center pl-4 gap-1">
+                  {rightSubs.map(t => {
+                    const isLegacy = legacySubs.includes(t);
+                    return (
+                      <div key={t.id} className="flex items-center">
+                        <div className={`w-6 border-t-2 ${isLegacy ? "border-dashed border-orange-300" : "border-solid border-gray-400"}`} />
+                        <SlimCard task={t} assigneeName={assigneeNames?.[t.assignee_id || ""]} active legacy={isLegacy} onAction={onAction} currentUser={currentUser} onViewRecords={setRecordsTask} />
+                      </div>
+                    );
+                  })}
+                </div>
               </div>
-            ))}
-            {/* legacySubs（虚线+来源标注） */}
-            {legacySubs.map(t => (
-              <div key={t.id} className="flex flex-col items-center">
-                <div className="h-4 w-0.5 bg-orange-200" />
-                <div className="w-8 border-t-2 border-dashed border-orange-300" />
-                <SlimCard task={t} assigneeName={assigneeNames?.[t.assignee_id || ""]} active legacy onAction={onAction} currentUser={currentUser} onViewRecords={setRecordsTask} />
-              </div>
-            ))}
-          </div>
+            );
+          })}
+          {activeMain.length === 0 && <p className="text-xs text-gray-400 py-4">当前无活跃主线任务</p>}
         </div>
       )}
 
@@ -164,40 +174,50 @@ export const TaskFlowView = memo(function TaskFlowView({ tasks, onAction, curren
         <div className="space-y-6">
           {allMains.map(mainTask => {
             const children = Array.from(ALL_TASKS).filter(t => t.parent_task_id === mainTask.id);
-            const activeChildren = children.filter(c => active(c.status));
-            const hasLegacyActive = activeChildren.some(c => !isMain(c) && !active(mainTask.status));
+            const hasLegacyActive = children.some(c => !isMain(c) && !active(mainTask.status));
+            const leftChildren = children.filter((_, i) => i % 2 === 0);
+            const rightChildren = children.filter((_, i) => i % 2 === 1);
 
             return (
               <div key={mainTask.id} className="relative">
-                {/* 垂直轴线 */}
-                <div className="absolute left-1/2 top-0 bottom-0 w-0.5 bg-gray-200 -translate-x-1/2" />
+                {/* 垂直轴线贯穿中央 */}
+                <div className="absolute left-1/2 top-0 bottom-0 w-0.5 bg-gray-200 -translate-x-1/2 z-0" />
 
-                {/* 主干卡片居中 */}
-                <div className="flex justify-center">
-                  <div className="relative z-10">
+                {/* 水平一行：左翼 + 中央 + 右翼 */}
+                <div className="flex flex-row items-center w-full">
+                  {/* 左翼分支 */}
+                  <div className="flex-1 flex justify-end items-center pr-4 gap-1">
+                    {leftChildren.map(c => (
+                      <div key={c.id} className="flex items-center">
+                        <SlimCard task={c} assigneeName={assigneeNames?.[c.assignee_id || ""]}
+                          active={active(c.status)} legacy={hasLegacyActive && !active(mainTask.status)}
+                          onAction={onAction} currentUser={currentUser} onViewRecords={setRecordsTask} />
+                        <div className={`w-6 border-t-2 ${hasLegacyActive && !active(mainTask.status) ? "border-dashed border-orange-300" : "border-solid border-gray-400"}`} />
+                      </div>
+                    ))}
+                  </div>
+                  {/* 中央主干 */}
+                  <div className="shrink-0 z-10 relative">
                     <SlimCard task={mainTask} assigneeName={assigneeNames?.[mainTask.assignee_id || ""]}
                       active={active(mainTask.status)} onAction={onAction} currentUser={currentUser} onViewRecords={setRecordsTask} />
                     {active(mainTask.status) && (
                       <div className="absolute -top-1 -left-1 h-3 w-3 rounded-full bg-green-400 border-2 border-white" />
                     )}
                   </div>
-                </div>
-
-                {/* 分支水平排列 */}
-                {children.length > 0 && (
-                  <div className="flex flex-wrap justify-center gap-3 mt-2">
-                    {children.map(c => (
-                      <div key={c.id} className="flex flex-col items-center">
-                        <div className="w-0.5 h-3 bg-gray-300" />
+                  {/* 右翼分支 */}
+                  <div className="flex-1 flex justify-start items-center pl-4 gap-1">
+                    {rightChildren.map(c => (
+                      <div key={c.id} className="flex items-center">
+                        <div className={`w-6 border-t-2 ${hasLegacyActive && !active(mainTask.status) ? "border-dashed border-orange-300" : "border-solid border-gray-400"}`} />
                         <SlimCard task={c} assigneeName={assigneeNames?.[c.assignee_id || ""]}
                           active={active(c.status)} legacy={hasLegacyActive && !active(mainTask.status)}
                           onAction={onAction} currentUser={currentUser} onViewRecords={setRecordsTask} />
                       </div>
                     ))}
                   </div>
-                )}
+                </div>
 
-                {/* 区间连接线 */}
+                {/* 区间连接 ▼ */}
                 {allMains.indexOf(mainTask) < allMains.length - 1 && (
                   <div className="flex justify-center py-2">
                     <span className="text-[10px] text-gray-300">▼</span>