fix(build): allow tsdown heap override

scripts/tsdown-build.mjs

@@ -7,6 +7,7 @@ import fs from "node:fs";
 import path from "node:path";
 import { pathToFileURL } from "node:url";
 import { BUNDLED_PLUGIN_PATH_PREFIX } from "./lib/bundled-plugin-paths.mjs";
+import { parsePositiveInt } from "./lib/numeric-options.mjs";
 import { TSDOWN_PACKAGE_OUTPUT_ROOTS } from "./lib/tsdown-output-roots.mjs";
 import { resolveWindowsTaskkillPath } from "./lib/windows-taskkill.mjs";
 import { resolvePnpmRunner } from "./pnpm-runner.mjs";
@@ -307,15 +308,7 @@ function parsePositiveIntegerEnv(value, name) {
   if (typeof value !== "string" || value.trim() === "") {
     return null;
   }
-  const text = value.trim();
-  if (!/^\d+$/u.test(text)) {
-    throw new Error(`${name} must be a positive integer`);
-  }
-  const parsed = Number(text);
-  if (!Number.isSafeInteger(parsed) || parsed <= 0) {
-    throw new Error(`${name} must be a positive safe integer`);
-  }
-  return parsed;
+  return parsePositiveInt(value, name);
 }
 
 function parseNonNegativeIntegerEnv(value, name) {

test/scripts/tsdown-build.test.ts

@@ -260,6 +260,17 @@ describe("resolveTsdownBuildInvocation", () => {
     expect(result.options.env.NODE_OPTIONS).toBe("--max-old-space-size=3072");
   });
 
+  it("keeps memory detection when OPENCLAW_TSDOWN_MAX_OLD_SPACE_MB is blank", () => {
+    const result = resolveTsdownBuildInvocation({
+      nodeExecPath: "/usr/bin/node",
+      npmExecPath: "/tmp/pnpm.cjs",
+      env: { OPENCLAW_TSDOWN_MAX_OLD_SPACE_MB: "  " },
+      cgroupMemoryLimitBytes: 7 * 1024 * 1024 * 1024,
+    });
+
+    expect(result.options.env.NODE_OPTIONS).toBe("--max-old-space-size=6400");
+  });
+
   it("uses OPENCLAW_TSDOWN_MAX_OLD_SPACE_MB to normalize inherited NODE_OPTIONS", () => {
     const result = resolveTsdownBuildInvocation({
       platform: "win32",