fix: 压缩合同与报价单 PDF 并按实际内容分页，避免文件过大和空白尾页。

web-admin/src/utils/crm/contract-pdf-pages.test.ts

@@ -0,0 +1,40 @@
+import assert from 'node:assert/strict'
+import { describe, it } from 'node:test'
+import { countContractPdfPages } from './contract-pdf-pages'
+
+function pixels(width: number, height: number, marks: number[]) {
+  const data = new Uint8ClampedArray(width * height * 4).fill(255)
+  for (const row of marks) data[(row * width + 1) * 4] = 0
+  return { width, height, data }
+}
+
+describe('countContractPdfPages', () => {
+  it('ignores trailing white padding that crosses onto a second page', () => {
+    assert.equal(countContractPdfPages(pixels(210, 330, [20, 295])), 1)
+  })
+
+  it('keeps even a single visible pixel on a second page', () => {
+    assert.equal(countContractPdfPages(pixels(210, 330, [20, 297])), 2)
+  })
+
+  it('does not add a page when content ends exactly at the page boundary', () => {
+    assert.equal(countContractPdfPages(pixels(210, 330, [296])), 1)
+  })
+
+  it('removes only trailing blank pages from a multipage contract', () => {
+    assert.equal(countContractPdfPages(pixels(210, 900, [20, 580])), 2)
+  })
+
+  it('keeps one page for an empty document', () => {
+    assert.equal(countContractPdfPages(pixels(210, 330, [])), 1)
+  })
+
+  it('keeps faint content while ignoring fully transparent pixels', () => {
+    const image = pixels(210, 330, [20, 310])
+    const offset = (310 * image.width + 1) * 4
+    image.data[offset] = 254
+    assert.equal(countContractPdfPages(image), 2)
+    image.data[offset + 3] = 0
+    assert.equal(countContractPdfPages(image), 1)
+  })
+})

web-admin/src/utils/crm/contract-pdf-pages.ts

@@ -0,0 +1,18 @@
+/** 按不含水印的截图计算页数，仅移除没有任何可见像素的尾页。 */
+export function countContractPdfPages(image: Pick<ImageData, 'width' | 'height' | 'data'>): number {
+  const { width, height, data } = image
+  const pageHeight = (width * 297) / 210
+  for (let y = height - 1; y >= 0; y -= 1) {
+    for (let x = 0; x < width; x += 1) {
+      const offset = (y * width + x) * 4
+      // 不使用深色阈值，保留浅色文字、细表格线和印章。
+      if (
+        data[offset + 3] > 0 &&
+        (data[offset] < 255 || data[offset + 1] < 255 || data[offset + 2] < 255)
+      ) {
+        return Math.max(1, Math.ceil((y + 1) / pageHeight))
+      }
+    }
+  }
+  return 1
+}