diff --git a/packages/safe-bash/tests/integration/s3-http-exports/archive-controls.test.mjs b/packages/safe-bash/tests/integration/s3-http-exports/archive-controls.test.mjs
index 8ba07012c..6df60cd07 100644
--- a/packages/safe-bash/tests/integration/s3-http-exports/archive-controls.test.mjs
+++ b/packages/safe-bash/tests/integration/s3-http-exports/archive-controls.test.mjs
@@ -1018,6 +1018,7 @@ test("maintained outer launcher rejects inherited startup settings before the ve
     writeFileSync(join(directory, "exports.test.mjs"), launcher);
     assert.deepEqual(readFileSync(join(directory, "exports.test.mjs")), launcher);
     writeFileSync(join(directory, "archive-controls.test.mjs"), "export {};\n");
+    writeFileSync(join(directory, "archive-parser.test.mjs"), "export {};\n");
     writeFileSync(join(directory, "committed-archive.mjs"), `export { cleanEnvironment } from ${JSON.stringify(new URL("./committed-archive.mjs", import.meta.url).href)};\n`);
     const startupMarker = join(directory, "startup-ran");
     const verifierMarker = join(directory, "synthetic-verifier-ran");
diff --git a/packages/safe-bash/tests/integration/s3-http-exports/archive-parser.test.mjs b/packages/safe-bash/tests/integration/s3-http-exports/archive-parser.test.mjs
new file mode 100644
index 000000000..e8d5bce16
--- /dev/null
+++ b/packages/safe-bash/tests/integration/s3-http-exports/archive-parser.test.mjs
@@ -0,0 +1,36 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+import { digest, readArchive, resolveTools } from "./committed-archive.mjs";
+
+// Exercise both public constructor names with the actual npm-bundled parser.
+// In-memory archive bytes keep these controls independent of package staging.
+for (const exportName of ["Parse", "Parser"]) {
+  test(`archive admission preserves safety with the ${exportName} tar API`, async () => {
+    const { tar } = resolveTools();
+    const Parser = tar.Parser ?? tar.Parse;
+    const parserApi = { [exportName]: Parser };
+    const archive = (path, type = "File") => {
+      const payload = Buffer.from("admitted bytes");
+      const header = new tar.Header({ path, type, size: type === "File" ? payload.length : 0, linkpath: type === "SymbolicLink" ? "allowed.txt" : "", mode: 0o644 });
+      const bytes = Buffer.alloc(2048);
+      header.encode(bytes);
+      if (type === "File") payload.copy(bytes, 512);
+      return bytes;
+    };
+    const read = (bytes, admit = () => {}, expectedHash = digest(bytes)) => readArchive(parserApi, "/control.tar", expectedHash, admit, {
+      lstatSync: () => ({ isFile: () => true, size: bytes.length }),
+      readFileSync: () => bytes,
+    });
+    const bytes = archive("allowed.txt");
+    const admitted = [];
+    const files = await read(bytes, path => admitted.push(path));
+    assert.deepEqual(admitted, ["allowed.txt"]);
+    assert.equal(files.get("allowed.txt").toString(), "admitted bytes");
+    await assert.rejects(read(bytes, () => assert.fail("must authenticate first"), "0".repeat(64)), /identity changed/);
+    await assert.rejects(read(bytes, () => assert.fail("unbound entry")), /unbound entry/);
+    await assert.rejects(read(archive("../escape")), /nonliteral input path/);
+    await assert.rejects(read(archive("link.txt", "SymbolicLink")), /nonregular archive entry/);
+    const duplicate = Buffer.concat([bytes.subarray(0, 1024), bytes]);
+    await assert.rejects(read(duplicate), /duplicate or excessive archive entries/);
+  });
+}
diff --git a/packages/safe-bash/tests/integration/s3-http-exports/committed-archive.mjs b/packages/safe-bash/tests/integration/s3-http-exports/committed-archive.mjs
index 492935191..5e7dcde4b 100644
--- a/packages/safe-bash/tests/integration/s3-http-exports/committed-archive.mjs
+++ b/packages/safe-bash/tests/integration/s3-http-exports/committed-archive.mjs
@@ -551,7 +551,8 @@ export async function readArchive(tar, filename, expectedHash, admit, fileSystem
   const files = new Map();
   let expanded = 0;
   await new Promise((resolvePromise, reject) => {
-    const parser = new tar.Parser({ strict: true, maxMetaEntrySize: 1024 * 1024 });
+    const Parser = tar.Parser ?? tar.Parse;
+    const parser = new Parser({ strict: true, maxMetaEntrySize: 1024 * 1024 });
     parser.on("error", reject);
     parser.on("end", resolvePromise);
     parser.on("entry", entry => {
diff --git a/packages/safe-bash/tests/integration/s3-http-exports/exports.test.ts b/packages/safe-bash/tests/integration/s3-http-exports/exports.test.ts
index 51fecdd39..924a36799 100644
--- a/packages/safe-bash/tests/integration/s3-http-exports/exports.test.ts
+++ b/packages/safe-bash/tests/integration/s3-http-exports/exports.test.ts
@@ -7,6 +7,7 @@ import { test } from "node:test";
 import { fileURLToPath } from "node:url";
 
 await import(new URL("./archive-controls.test.mjs", import.meta.url).href);
+await import(new URL("./archive-parser.test.mjs", import.meta.url).href);
 const { cleanEnvironment } = await import(new URL("./committed-archive.mjs", import.meta.url).href);
 
 test("S3 HTTP root/subpath exports work from a clean packed revision without source fallback", { timeout: 300_000 }, () => {