前端进度条性能优化、仿真结束后后处理优化；后端C代码生成流程优化：先识别来源，再按照已知未知量需求排序，最后局部求解

frontend/tests/e2e/component-symbols.spec.ts

@@ -1439,7 +1439,6 @@ test("PNCH012 按参考图使用 45% 结构与独立 15px 文字", async ({
 
 test("不同尺寸档位使用紧凑节点框且旋转时保持中心", async ({ page }) => {
   await page.goto("/");
-  await page.getByRole("button", { name: "关闭网格吸附", exact: true }).click();
   const paneBounds = await page.locator(".flow-canvas .react-flow__pane").boundingBox();
   expect(paneBounds).not.toBeNull();
 
@@ -1554,41 +1553,26 @@ test("不同尺寸档位使用紧凑节点框且旋转时保持中心", async ({
     );
   }
 
-  await page.getByRole("button", { name: "开启网格吸附", exact: true }).click();
-  const snappedTarget = { x: 600, y: 610 };
-  const snappedNode = await dragSymbolToCanvas(
+  const placedTarget = { x: 601, y: 613 };
+  const placedNode = await dragSymbolToCanvas(
     page,
     "amesim_f000",
-    snappedTarget,
+    placedTarget,
   );
-  const snappedBounds = await snappedNode.boundingBox();
-  expect(snappedBounds).not.toBeNull();
+  const placedBounds = await placedNode.boundingBox();
+  expect(placedBounds).not.toBeNull();
   expect(
     Math.abs(
-      snappedBounds!.x + snappedBounds!.width / 2 -
-        (paneBounds!.x + snappedTarget.x),
+      placedBounds!.x + placedBounds!.width / 2 -
+        (paneBounds!.x + placedTarget.x),
     ),
-  ).toBeLessThanOrEqual(10);
+  ).toBeLessThan(2);
   expect(
     Math.abs(
-      snappedBounds!.y + snappedBounds!.height / 2 -
-        (paneBounds!.y + snappedTarget.y),
+      placedBounds!.y + placedBounds!.height / 2 -
+        (paneBounds!.y + placedTarget.y),
     ),
-  ).toBeLessThanOrEqual(10);
-  await expect
-    .poll(() =>
-      page.evaluate(() => {
-        const raw = window.localStorage.getItem(
-          "system-simulation-flow:autosave",
-        );
-        const project = raw ? JSON.parse(raw) : null;
-        const position = project?.nodes?.at(-1)?.position;
-        return position
-          ? { xRemainder: position.x % 18, yRemainder: position.y % 18 }
-          : null;
-      }),
-    )
-    .toEqual({ xRemainder: 0, yRemainder: 0 });
+  ).toBeLessThan(2);
 });
 
 test("LMECHN1 按右侧端口数展开工作区画布且组件库图标保持固定", async ({
@@ -1895,7 +1879,6 @@ test("旧版 LMECHN1 工程会把固定参考端口迁移到动态最大编号",
 
 test("LMECHN1 动态参考端口使用实际锚点参与接触吸附", async ({ page }) => {
   await page.goto("/");
-  await page.getByRole("button", { name: "关闭网格吸附", exact: true }).click();
 
   const node = await dragSymbolToCanvas(page, "amesim_lmechn1", {
     x: 600,
@@ -2953,8 +2936,8 @@ test("AMESim canvas nodes use icon anchors and highlight only compatible free po
   await expectSymbolAnchors(firstOrifice, firstOrificeAnchors);
   await expectSymbolAnchors(signalOrifice, [
     { portName: "res", x: 27.35, y: 43.2 },
-    { portName: "port_2", x: 12.8, y: 24 },
-    { portName: "port_3", x: 51.2, y: 24 },
+    { portName: "port_2", x: 51.2, y: 24 },
+    { portName: "port_3", x: 12.8, y: 24 },
   ]);
 
   await firstOrifice.locator('[data-symbol-envelope="true"]').click();
@@ -3143,13 +3126,17 @@ test("AMESim canvas nodes use icon anchors and highlight only compatible free po
   await signalOutput.click();
   await expect(signalOutput).toHaveAttribute("data-connection-state", "origin");
   await clickLocatorCenter(page, firstPhysicalOutput);
-  await expectNoActivePortConnection(page);
+  await expect(signalOutput).toHaveAttribute("data-connection-state", "origin");
+  await expect(manualDraft.locator(".manual-connection-waypoint")).toHaveCount(1);
   await expect(page.locator(".flow-canvas .react-flow__edge")).toHaveCount(1);
   await expect(firstPhysicalOutput).toHaveAttribute("data-connected", "true");
   await expect(compatiblePhysicalPort).toHaveAttribute("data-connected", "true");
   await expect(physicalEdge).not.toHaveClass(/selected|editor-edge-selected/);
 
   await clickLocatorCenter(page, compatiblePhysicalPort);
+  await expect(signalOutput).toHaveAttribute("data-connection-state", "origin");
+  await expect(manualDraft.locator(".manual-connection-waypoint")).toHaveCount(2);
+  await page.keyboard.press("Escape");
   await expectNoActivePortConnection(page);
   await expect(physicalEdge).not.toHaveClass(/selected|editor-edge-selected/);
 
@@ -3507,7 +3494,6 @@ test("兼容接口接近时吸附为无连线接触连接，拖开后自动断
   page,
 }) => {
   await page.goto("/");
-  await page.getByRole("button", { name: "关闭网格吸附", exact: true }).click();
 
   const firstOrifice = await dragSymbolToCanvas(page, "amesim_pnor001", {
     x: 280,
@@ -3597,11 +3583,16 @@ test("兼容接口接近时吸附为无连线接触连接，拖开后自动断
   await unusedPort.click();
   await expect(unusedPort).toHaveAttribute("data-connection-state", "origin");
   await page.mouse.click(firstPortCenter.x, firstPortCenter.y);
-  await expectNoActivePortConnection(page);
+  // 连线模式下点击已连接端口所在元件只确定转角，不取消连线或改选元件。
+  await expect(unusedPort).toHaveAttribute("data-connection-state", "origin");
+  await expect(page.locator(".manual-connection-waypoint")).toHaveCount(1);
   await expect(contactEdge).not.toHaveClass(/selected|editor-edge-selected/);
   await expect(page.locator(".flow-canvas .react-flow__edge")).toHaveCount(1);
   await expect(firstPort).toHaveAttribute("data-connected", "true");
   await expect(secondPort).toHaveAttribute("data-connected", "true");
+  await page.keyboard.press("Escape");
+  await expectNoActivePortConnection(page);
+  await secondOrifice.locator(".node-symbol").click();
 
   await page.getByRole("button", { name: "生成系统 XML", exact: true }).click();
   await expandSimulationConsole(page);
@@ -3658,7 +3649,6 @@ test("PNCH012 四端口接触连接后主体各方向仍可直接选中", async
   page,
 }) => {
   await page.goto("/");
-  await page.getByRole("button", { name: "关闭网格吸附", exact: true }).click();
 
   const chamber = await dragSymbolToCanvas(page, "amesim_pnch012", {
     x: 500,
@@ -3835,7 +3825,6 @@ test("信号输出连接后隐藏且拒绝第二条连接", async ({ page }) =>
 
 test("一次拖动会吸附同一落点内的全部兼容接口", async ({ page }) => {
   await page.goto("/");
-  await page.getByRole("button", { name: "关闭网格吸附", exact: true }).click();
 
   const targetChamber = await dragSymbolToCanvas(page, "amesim_pnch023", {
     x: 300,
@@ -3929,7 +3918,6 @@ test("一次拖动会吸附同一落点内的全部兼容接口", async ({ page
 
 test("不同类型接口接近时不会吸附或建立逻辑连接", async ({ page }) => {
   await page.goto("/");
-  await page.getByRole("button", { name: "关闭网格吸附", exact: true }).click();
 
   const orifice = await dragSymbolToCanvas(page, "amesim_pnor001", {
     x: 280,
@@ -3966,7 +3954,6 @@ test("不同类型接口接近时不会吸附或建立逻辑连接", async ({ pa
 
 test("旋转后的接口可以与方向不同的兼容接口接触连接", async ({ page }) => {
   await page.goto("/");
-  await page.getByRole("button", { name: "关闭网格吸附", exact: true }).click();
 
   const horizontalOrifice = await dragSymbolToCanvas(page, "amesim_pnor001", {
     x: 300,