diff --git a/.github/workflows/node-ci.yml b/.github/workflows/node-ci.yml
index c7a1e08e..60892c1e 100644
--- a/.github/workflows/node-ci.yml
+++ b/.github/workflows/node-ci.yml
@@ -20,11 +20,9 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest, macos-latest, windows-latest]
+        os: [ubuntu-latest, macos-latest]
         node: ["22.13.0"]
         include:
-          - os: windows-latest
-            node: "24"
           - os: ubuntu-latest
             node: "24.0.0"
           - os: ubuntu-latest
@@ -121,3 +119,144 @@ jobs:
           '
           node bin/codex-security.mjs --version
           node bin/codex-security.mjs --help
+
+  windows-test:
+    name: windows-latest / node-${{ matrix.node == '22.13.0' && '22' || matrix.node }} / tests-${{ matrix.shard }}
+    runs-on: windows-latest
+    timeout-minutes: 20
+    strategy:
+      fail-fast: false
+      matrix:
+        node: ["22.13.0", "24"]
+        shard: [1, 2, 3, 4, 5, 6, 7]
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          persist-credentials: false
+
+      - name: Set up Node.js
+        uses: actions/setup-node@53b83947a5a98c8d113130e565377fae1a50d02f # v6
+        with:
+          node-version: ${{ matrix.node }}
+
+      - name: Set up pnpm
+        run: npm install --global pnpm@11.9.0 --no-audit --no-fund
+
+      - name: Set up Bun
+        uses: oven-sh/setup-bun@0c5077e51419868618aeaa5fe8019c62421857d6 # v2
+        with:
+          bun-version: "1.3.14"
+
+      - name: Install dependencies
+        working-directory: sdk/typescript
+        run: pnpm install --frozen-lockfile
+
+      - name: Prepare private Windows test root
+        id: windows-temp
+        shell: pwsh
+        run: |
+          $ErrorActionPreference = 'Stop'
+          $path = Join-Path $env:USERPROFILE '.codex-security-ci-temp'
+          New-Item -ItemType Directory -Path $path -Force | Out-Null
+          $sid = (whoami /user /fo csv /nh | ConvertFrom-Csv -Header Name, Sid).Sid
+          & icacls $path /inheritance:r /grant:r "*${sid}:(OI)(CI)F" '*S-1-5-18:(OI)(CI)F' '*S-1-5-32-544:(OI)(CI)F' | Out-Null
+          if ($LASTEXITCODE -ne 0) { throw 'Could not secure the Windows test root' }
+          "path=$path" >> $env:GITHUB_OUTPUT
+
+      - name: Test shard ${{ matrix.shard }}
+        timeout-minutes: 10
+        env:
+          TEMP: ${{ steps.windows-temp.outputs.path }}
+          TMP: ${{ steps.windows-temp.outputs.path }}
+          TMPDIR: ${{ steps.windows-temp.outputs.path }}
+          CODEX_SECURITY_ALLOW_MACHINE_POLICY_TEST: ${{ runner.environment == 'github-hosted' && 'true' || 'false' }}
+        run: node sdk/typescript/scripts/run-windows-ci-tests.mjs ${{ matrix.shard }}
+
+      - name: Typecheck
+        if: matrix.shard == 7
+        working-directory: sdk/typescript
+        run: pnpm run types
+
+      - name: Check formatting
+        if: matrix.shard == 7
+        working-directory: sdk/typescript
+        run: pnpm run format
+
+  windows-verify:
+    name: windows-latest / node-${{ matrix.node == '22.13.0' && '22' || matrix.node }} / verify
+    runs-on: windows-latest
+    timeout-minutes: 20
+    strategy:
+      fail-fast: false
+      matrix:
+        node: ["22.13.0", "24"]
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          persist-credentials: false
+
+      - name: Set up Node.js
+        uses: actions/setup-node@53b83947a5a98c8d113130e565377fae1a50d02f # v6
+        with:
+          node-version: ${{ matrix.node }}
+          cache: npm
+          cache-dependency-path: sdk/typescript/pnpm-lock.yaml
+
+      - name: Set up pnpm
+        run: npm install --global pnpm@11.9.0 --no-audit --no-fund
+
+      - name: Set up Bun
+        uses: oven-sh/setup-bun@0c5077e51419868618aeaa5fe8019c62421857d6 # v2
+        with:
+          bun-version: "1.3.14"
+
+      - name: Install dependencies
+        working-directory: sdk/typescript
+        run: pnpm install --frozen-lockfile
+
+      - name: Build
+        working-directory: sdk/typescript
+        run: pnpm run build
+
+      - name: Pack
+        working-directory: sdk/typescript
+        run: pnpm pack --pack-destination ../../dist
+
+      - name: Inspect package
+        working-directory: sdk/typescript
+        shell: bash
+        run: pnpm run check:package ../../dist/*.tgz
+
+      - name: Smoke-test Node.js runtime
+        working-directory: sdk/typescript
+        shell: bash
+        run: |
+          set -euo pipefail
+          node --input-type=module --eval '
+            import { CodexSecurity } from "@openai/codex-security";
+
+            if (typeof CodexSecurity !== "function") {
+              throw new Error("The SDK does not export CodexSecurity.");
+            }
+          '
+          node bin/codex-security.mjs --version
+          node bin/codex-security.mjs --help
+
+  windows:
+    name: windows-latest / node-${{ matrix.node == '22.13.0' && '22' || matrix.node }}
+    runs-on: ubuntu-latest
+    if: always()
+    needs: [windows-test, windows-verify]
+    strategy:
+      fail-fast: false
+      matrix:
+        node: ["22.13.0", "24"]
+
+    steps:
+      - name: Require every Windows coverage job
+        if: needs.windows-test.result != 'success' || needs.windows-verify.result != 'success'
+        run: exit 1
diff --git a/sdk/typescript/scripts/check-package.mjs b/sdk/typescript/scripts/check-package.mjs
index c4a04a57..731a289f 100644
--- a/sdk/typescript/scripts/check-package.mjs
+++ b/sdk/typescript/scripts/check-package.mjs
@@ -44,6 +44,7 @@ function tar(args, encoding = "buffer") {
 }
 
 let offset = 0;
+const archiveFiles = new Map();
 for (; offset + 512 <= archiveBytes.byteLength; ) {
   const header = archiveBytes.subarray(offset, offset + 512);
   if (header.every((byte) => byte === 0)) {
@@ -65,12 +66,31 @@ for (; offset + 512 <= archiveBytes.byteLength; ) {
     throw new Error("npm tarball contains an invalid tar entry.");
   }
   const size = Number.parseInt(sizeField || "0", 8);
-  offset += 512 + Math.ceil(size / 512) * 512;
+  const contentsStart = offset + 512;
+  const nextOffset = contentsStart + Math.ceil(size / 512) * 512;
+  if (nextOffset > archiveBytes.byteLength) {
+    throw new Error("npm tarball contains an invalid tar entry.");
+  }
+  if (header[156] === 0 || header[156] === 0x30) {
+    archiveFiles.set(
+      path,
+      archiveBytes.subarray(contentsStart, contentsStart + size),
+    );
+  }
+  offset = nextOffset;
 }
 if (archiveBytes.subarray(offset).some((byte) => byte !== 0)) {
   throw new Error("npm tarball contains trailing tar data.");
 }
 
+function archiveFile(path) {
+  const contents = archiveFiles.get(path);
+  if (contents === undefined) {
+    throw new Error("npm tarball contains an invalid tar entry: " + path + ".");
+  }
+  return contents;
+}
+
 const entries = tar(["-tzf", archive], "utf8").split(/\r?\n/u).filter(Boolean);
 const files = new Set(entries);
 if (files.size !== entries.length) {
@@ -211,7 +231,7 @@ if ([3, 6, 9].some((index) => launcherPermissions[index] !== "x")) {
   throw new Error("npm package CLI launcher is not executable.");
 }
 const packageJson = JSON.parse(
-  tar(["-xOf", archive, "package/package.json"]).toString("utf8"),
+  archiveFile("package/package.json").toString("utf8"),
 );
 if (
   packageJson.name !== "@openai/codex-security" ||
@@ -251,22 +271,16 @@ function brotliPayload(bytes, file) {
 }
 
 for (const file of compressedFiles) {
-  payloads.push(
-    brotliPayload(tar(["-xOf", archive, file]), file).toString("utf8"),
-  );
+  payloads.push(brotliPayload(archiveFile(file), file).toString("utf8"));
 }
 for (const parts of compressedParts.values()) {
   parts.sort((left, right) => left.part - right.part);
-  const bytes = Buffer.concat(
-    parts.map(({ file }) => tar(["-xOf", archive, file])),
-  );
+  const bytes = Buffer.concat(parts.map(({ file }) => archiveFile(file)));
   payloads.push(brotliPayload(bytes, parts[0].file).toString("utf8"));
 }
 for (const file of files) {
   if (/\.png$/iu.test(file)) {
-    const digest = createHash("sha256")
-      .update(tar(["-xOf", archive, file]))
-      .digest("hex");
+    const digest = createHash("sha256").update(archiveFile(file)).digest("hex");
     if (digest !== PUBLIC_LOGO_SHA256) {
       throw new Error(`npm tarball contains an unexpected PNG asset: ${file}.`);
     }
diff --git a/sdk/typescript/scripts/run-windows-ci-tests.mjs b/sdk/typescript/scripts/run-windows-ci-tests.mjs
new file mode 100644
index 00000000..f0fa31ad
--- /dev/null
+++ b/sdk/typescript/scripts/run-windows-ci-tests.mjs
@@ -0,0 +1,116 @@
+import { spawn } from "node:child_process";
+import { readdir } from "node:fs/promises";
+import { fileURLToPath } from "node:url";
+
+const testsDirectory = new URL("../tests-ts/", import.meta.url);
+const packageDirectory = fileURLToPath(new URL("../", import.meta.url));
+const tests = (await readdir(testsDirectory))
+  .filter((file) => file.endsWith(".test.ts"))
+  .sort();
+const slowApiTests = [
+  "keeps a private preflight snapshot isolated from persistent credentials",
+  "reuses keyring-compatible credentials across separate scan clients",
+  "serializes parallel scans sharing a managed credential home",
+  "recreates isolated and managed runtimes when scan authentication changes",
+  "does not reimport ambient credentials after an explicit logout",
+].join("|");
+const shardSeeds = [
+  {
+    files: ["api.test.ts"],
+    testNamePattern: slowApiTests,
+  },
+  {
+    files: ["api.test.ts"],
+    testNamePattern: `^(?!.*(?:${slowApiTests})).*$`,
+  },
+  { files: ["runtime.test.ts"] },
+  { files: ["cli-authentication.test.ts"] },
+  { files: ["scan-recovery.test.ts"] },
+  { files: [] },
+  { files: [] },
+];
+const assigned = new Set(shardSeeds.flatMap(({ files }) => files));
+for (const file of assigned) {
+  if (!tests.includes(file)) {
+    throw new Error("Windows CI test shard references a missing file: " + file);
+  }
+}
+const unassigned = tests.filter((file) => !assigned.has(file));
+const slowRemainderFiles = new Set([
+  "deep-scan-workbench.test.ts",
+  "release-automation.test.ts",
+  "scan-comparison.test.ts",
+]);
+for (const [index, file] of unassigned.entries()) {
+  shardSeeds[slowRemainderFiles.has(file) ? 6 : 5 + (index % 2)].files.push(
+    file,
+  );
+}
+
+const assignments = new Map();
+for (const { files } of shardSeeds) {
+  for (const file of files) {
+    assignments.set(file, (assignments.get(file) ?? 0) + 1);
+  }
+}
+for (const file of tests) {
+  const expectedAssignments = file === "api.test.ts" ? 2 : 1;
+  if (assignments.get(file) !== expectedAssignments) {
+    throw new Error("Windows CI test shards must run every test file.");
+  }
+}
+
+const requestedShard =
+  process.argv[2] === undefined
+    ? undefined
+    : Number.parseInt(process.argv[2], 10);
+if (
+  requestedShard !== undefined &&
+  (!Number.isSafeInteger(requestedShard) ||
+    requestedShard < 1 ||
+    requestedShard > shardSeeds.length)
+) {
+  throw new Error("Usage: node scripts/run-windows-ci-tests.mjs [1-7]");
+}
+const selectedShards =
+  requestedShard === undefined
+    ? shardSeeds.map((shard, index) => ({ ...shard, index }))
+    : [{ ...shardSeeds[requestedShard - 1], index: requestedShard - 1 }];
+
+const results = await Promise.all(
+  selectedShards.map(
+    ({ files, index, testNamePattern }) =>
+      new Promise((resolve, reject) => {
+        const paths = files.map((file) => "./tests-ts/" + file);
+        console.log(
+          "Windows CI test shard " +
+            (index + 1) +
+            "/" +
+            shardSeeds.length +
+            ": " +
+            paths.join(" ") +
+            (testNamePattern === undefined
+              ? ""
+              : " --test-name-pattern " + testNamePattern),
+        );
+        const args = ["test", "--timeout", "30000"];
+        if (testNamePattern !== undefined) {
+          args.push("--test-name-pattern", testNamePattern);
+        }
+        args.push(...paths);
+        const child = spawn("bun", args, {
+          cwd: packageDirectory,
+          stdio: "inherit",
+          windowsHide: true,
+        });
+        child.once("error", reject);
+        child.once("close", (code) => {
+          resolve(code ?? 1);
+        });
+      }),
+  ),
+);
+
+if (results.some((code) => code !== 0)) {
+  process.exitCode = 1;
+}
diff --git a/sdk/typescript/scripts/smoke-package.mjs b/sdk/typescript/scripts/smoke-package.mjs
index 0cd6b116..3ccb900a 100644
--- a/sdk/typescript/scripts/smoke-package.mjs
+++ b/sdk/typescript/scripts/smoke-package.mjs
@@ -314,6 +314,7 @@ try {
       "--prefer-offline",
       "--include=optional",
       "--ignore-scripts",
+      "--package-lock=false",
       "--no-audit",
       "--no-fund",
       archive,
diff --git a/sdk/typescript/tests-ts/skeleton.test.ts b/sdk/typescript/tests-ts/skeleton.test.ts
index 128ec67b..1226a2b0 100644
--- a/sdk/typescript/tests-ts/skeleton.test.ts
+++ b/sdk/typescript/tests-ts/skeleton.test.ts
@@ -82,7 +82,13 @@ describe("TypeScript package skeleton", () => {
     expect(packageJson.scripts.test).toBe(
       "bun test --timeout 30000 ./tests-ts",
     );
-    expect(ciWorkflow).toContain("run: pnpm --dir sdk/typescript run test\n");
+    expect(ciWorkflow).toContain(
+      "run: node sdk/typescript/scripts/run-windows-ci-tests.mjs ${{ matrix.shard }}",
+    );
+    expect(ciWorkflow).toContain(
+      "name: windows-latest / node-${{ matrix.node == '22.13.0' && '22' || matrix.node }}",
+    );
+    expect(ciWorkflow).toContain("run: pnpm --dir sdk/typescript run test");
     expect(ciWorkflow).not.toContain("--timeout 60000");
   });