fix(engine): scale V8 heap and GPU budget proportionally on low-memory systems

packages/engine/src/services/browserManager.test.ts

@@ -14,6 +14,15 @@ import {
   resolveBrowserGpuMode,
 } from "./browserManager.js";
 
+vi.mock("./systemMemory.js", async (importOriginal) => {
+  const actual = await importOriginal<typeof import("./systemMemory.js")>();
+  return { ...actual, getSystemTotalMb: vi.fn(() => 32768) };
+});
+
+import { getSystemTotalMb, LOW_MEMORY_TOTAL_MB_THRESHOLD } from "./systemMemory.js";
+
+const mockGetSystemTotalMb = vi.mocked(getSystemTotalMb);
+
 describe("buildChromeArgs browser GPU mode", () => {
   const base = { width: 1920, height: 1080 };
 
@@ -308,3 +317,78 @@ describe("browser pool", () => {
     await acquirePromise.catch(() => {});
   });
 });
+
+describe("memory-adaptive Chrome flags", () => {
+  const base = { width: 1920, height: 1080 };
+
+  beforeEach(() => {
+    mockGetSystemTotalMb.mockReturnValue(32768);
+  });
+
+  afterEach(() => {
+    mockGetSystemTotalMb.mockReturnValue(32768);
+  });
+
+  function heapFlag(args: string[]): number | null {
+    const flag = args.find((a) => a.includes("--max-old-space-size="));
+    if (!flag) return null;
+    return parseInt(flag.match(/--max-old-space-size=(\d+)/)?.[1] ?? "", 10);
+  }
+
+  function gpuBudget(args: string[]): number {
+    const flag = args.find((a) => a.startsWith("--force-gpu-mem-available-mb="))!;
+    return parseInt(flag.split("=")[1]!, 10);
+  }
+
+  it("does not set heap limit above threshold", () => {
+    mockGetSystemTotalMb.mockReturnValue(LOW_MEMORY_TOTAL_MB_THRESHOLD + 1);
+    expect(heapFlag(buildChromeArgs(base))).toBeNull();
+  });
+
+  it("scales heap to total/8 at threshold", () => {
+    mockGetSystemTotalMb.mockReturnValue(LOW_MEMORY_TOTAL_MB_THRESHOLD);
+    expect(heapFlag(buildChromeArgs(base))).toBe(Math.floor(LOW_MEMORY_TOTAL_MB_THRESHOLD / 8));
+  });
+
+  it("scales heap to total/8 on 6 GB systems", () => {
+    mockGetSystemTotalMb.mockReturnValue(6144);
+    expect(heapFlag(buildChromeArgs(base))).toBe(768);
+  });
+
+  it("uses proportional heap at 4 GB boundary", () => {
+    mockGetSystemTotalMb.mockReturnValue(4096);
+    expect(heapFlag(buildChromeArgs(base))).toBe(512);
+  });
+
+  it("uses 256 MB heap floor below 4 GB", () => {
+    mockGetSystemTotalMb.mockReturnValue(3072);
+    expect(heapFlag(buildChromeArgs(base))).toBe(256);
+  });
+
+  it("scales GPU budget to total/4 at threshold", () => {
+    mockGetSystemTotalMb.mockReturnValue(LOW_MEMORY_TOTAL_MB_THRESHOLD);
+    expect(gpuBudget(buildChromeArgs(base))).toBe(Math.floor(LOW_MEMORY_TOTAL_MB_THRESHOLD / 4));
+  });
+
+  it("uses proportional GPU budget at 4 GB boundary", () => {
+    mockGetSystemTotalMb.mockReturnValue(4096);
+    expect(gpuBudget(buildChromeArgs(base))).toBe(1024);
+  });
+
+  it("switches to total/2 GPU and no heap limit just above threshold", () => {
+    const above = LOW_MEMORY_TOTAL_MB_THRESHOLD + 1;
+    mockGetSystemTotalMb.mockReturnValue(above);
+    expect(gpuBudget(buildChromeArgs(base))).toBe(Math.floor(above / 2));
+    expect(heapFlag(buildChromeArgs(base))).toBeNull();
+  });
+
+  it("scales GPU budget to total/2 well above threshold", () => {
+    mockGetSystemTotalMb.mockReturnValue(LOW_MEMORY_TOTAL_MB_THRESHOLD * 2);
+    expect(gpuBudget(buildChromeArgs(base))).toBe(LOW_MEMORY_TOTAL_MB_THRESHOLD);
+  });
+
+  it("uses 512 MB GPU budget below 4 GB", () => {
+    mockGetSystemTotalMb.mockReturnValue(3072);
+    expect(gpuBudget(buildChromeArgs(base))).toBe(512);
+  });
+});

packages/engine/src/services/browserManager.ts

@@ -512,14 +512,14 @@ function getGpuMemBudgetMb(): number {
 
   const total = getSystemTotalMb();
   if (total < 4096) return 512;
-  if (total <= LOW_MEMORY_TOTAL_MB_THRESHOLD) return 1024;
+  if (total <= LOW_MEMORY_TOTAL_MB_THRESHOLD) return Math.floor(total / 4);
   return Math.min(Math.floor(total / 2), 16384);
 }
 
 function getLowMemoryFlags(): string[] {
   const total = getSystemTotalMb();
   if (total > LOW_MEMORY_TOTAL_MB_THRESHOLD) return [];
-  const heapMb = total < 4096 ? 256 : 512;
+  const heapMb = total < 4096 ? 256 : Math.floor(total / 8);
   return [`--js-flags=--max-old-space-size=${heapMb}`];
 }