diff --git a/packages/plugins/sandbox-providers/daytona/src/file-sync.ts b/packages/plugins/sandbox-providers/daytona/src/file-sync.ts
index f2350767539..2fa3b40ab2d 100644
--- a/packages/plugins/sandbox-providers/daytona/src/file-sync.ts
+++ b/packages/plugins/sandbox-providers/daytona/src/file-sync.ts
@@ -2,7 +2,7 @@ import path from "node:path";
 import os from "node:os";
 import { promises as fs, createReadStream, createWriteStream } from "node:fs";
 import { randomUUID } from "node:crypto";
-import { execFile } from "node:child_process";
+import { execFile, spawn } from "node:child_process";
 import { promisify } from "node:util";
 import zlib from "node:zlib";
 import { pipeline } from "node:stream/promises";
@@ -250,43 +250,109 @@ export function splitLinkEntryOnce(field: string, delimiter: string): { name: st
  * preserved. Parses the `-tvf` verbose listing so both member names and link
  * targets are inspected; any unparseable line fails closed.
  */
-async function assertTarballEntriesConfined(archivePath: string): Promise<void> {
-  const { stdout } = await execFileAsync("tar", ["-tvf", archivePath], {
+function assertTarListingLineConfined(line: string): void {
+  if (line.trim().length === 0) return;
+  const parsed = parseTarVerboseListingLine(line);
+  if (!parsed) {
+    throw new Error(`Daytona syncOut refusing tarball with an unparseable entry listing: ${line}`);
+  }
+  const typeFlag = parsed.typeFlag;
+  let name = parsed.rest;
+  let linkTarget: string | null = null;
+  if (typeFlag === "l") {
+    const split = splitLinkEntryOnce(name, " -> ");
+    if (!split) throw new Error(`Daytona syncOut refusing unparseable or ambiguous symlink entry: ${line}`);
+    name = split.name;
+    linkTarget = split.target;
+  } else if (typeFlag === "h") {
+    const split = splitLinkEntryOnce(name, " link to ");
+    if (!split) throw new Error(`Daytona syncOut refusing unparseable or ambiguous hardlink entry: ${line}`);
+    name = split.name;
+    linkTarget = split.target;
+  }
+  const cleanName = name.replace(/\/+$/, "");
+  if (cleanName.length > 0 && posixPathEscapes(cleanName)) {
+    throw new Error(`Daytona syncOut refusing tarball member that escapes the extraction dir: ${name}`);
+  }
+  if (linkTarget !== null) {
+    const resolved = path.posix.join(path.posix.dirname(cleanName), linkTarget);
+    if (path.posix.isAbsolute(linkTarget) || posixPathEscapes(resolved)) {
+      throw new Error(
+        `Daytona syncOut refusing tarball link whose target escapes the extraction dir: ${name} -> ${linkTarget}`,
+      );
+    }
+  }
+}
+
+const TAR_LISTING_MAX_LINE_BYTES = 64 * 1024;
+const TAR_LISTING_MAX_STDERR_BYTES = 64 * 1024;
+const TAR_LISTING_TIMEOUT_MS = 120_000;
+
+export async function assertTarballEntriesConfined(
+  archivePath: string,
+  timeoutMs = TAR_LISTING_TIMEOUT_MS,
+): Promise<void> {
+  // Total metadata is unbounded: a valid large workspace can exceed execFile's
+  // buffer. Bound each entry and diagnostic instead, and inspect every entry
+  // before extraction starts. Keep bytes until a full line to preserve UTF-8
+  // characters split across pipe chunks.
+  const child = spawn("tar", ["-tvf", archivePath], {
     env: { ...process.env, COPYFILE_DISABLE: "1" },
-    maxBuffer: 32 * 1024 * 1024,
+    stdio: ["ignore", "pipe", "pipe"],
   });
-  const lines = stdout.split("\n").filter((line) => line.trim().length > 0);
-  for (const line of lines) {
-    const parsed = parseTarVerboseListingLine(line);
-    if (!parsed) {
-      throw new Error(`Daytona syncOut refusing tarball with an unparseable entry listing: ${line}`);
+  let spawnError: Error | undefined;
+  let failure: Error | undefined;
+  let stderr = Buffer.alloc(0);
+  let pending: Buffer = Buffer.alloc(0);
+  const closed = new Promise<{ code: number | null; signal: NodeJS.Signals | null }>((resolve) => {
+    child.once("error", (error) => { spawnError = error; });
+    child.once("close", (code, signal) => resolve({ code, signal }));
+  });
+  const stop = (error: Error) => {
+    failure ??= error;
+    child.kill("SIGKILL");
+  };
+  const timer = setTimeout(() => {
+    stop(new Error("Daytona syncOut tar listing validation timed out"));
+  }, Math.max(1, Math.min(timeoutMs, TAR_LISTING_TIMEOUT_MS)));
+  child.stderr.on("data", (chunk: Buffer) => {
+    if (stderr.length + chunk.length > TAR_LISTING_MAX_STDERR_BYTES) {
+      stop(new Error("Daytona syncOut tar listing diagnostics exceed the byte limit"));
+      return;
     }
-    const typeFlag = parsed.typeFlag;
-    let name = parsed.rest;
-    let linkTarget: string | null = null;
-    if (typeFlag === "l") {
-      const split = splitLinkEntryOnce(name, " -> ");
-      if (!split) throw new Error(`Daytona syncOut refusing unparseable or ambiguous symlink entry: ${line}`);
-      name = split.name;
-      linkTarget = split.target;
-    } else if (typeFlag === "h") {
-      const split = splitLinkEntryOnce(name, " link to ");
-      if (!split) throw new Error(`Daytona syncOut refusing unparseable or ambiguous hardlink entry: ${line}`);
-      name = split.name;
-      linkTarget = split.target;
-    }
-    const cleanName = name.replace(/\/+$/, "");
-    if (cleanName.length > 0 && posixPathEscapes(cleanName)) {
-      throw new Error(`Daytona syncOut refusing tarball member that escapes the extraction dir: ${name}`);
-    }
-    if (linkTarget !== null) {
-      const resolved = path.posix.join(path.posix.dirname(cleanName), linkTarget);
-      if (path.posix.isAbsolute(linkTarget) || posixPathEscapes(resolved)) {
-        throw new Error(
-          `Daytona syncOut refusing tarball link whose target escapes the extraction dir: ${name} -> ${linkTarget}`,
-        );
+    stderr = Buffer.concat([stderr, chunk]);
+  });
+  try {
+    for await (const chunk of child.stdout) {
+      if (failure) break;
+      const bytes = chunk as Buffer;
+      let start = 0;
+      while (start < bytes.length) {
+        const newline = bytes.indexOf(10, start);
+        const end = newline < 0 ? bytes.length : newline;
+        if (pending.length + end - start > TAR_LISTING_MAX_LINE_BYTES) {
+          throw new Error("Daytona syncOut refusing tarball with an entry listing exceeding the byte limit");
+        }
+        pending = Buffer.concat([pending, bytes.subarray(start, end)]);
+        if (newline < 0) break;
+        assertTarListingLineConfined(pending.toString("utf8"));
+        pending = Buffer.alloc(0);
+        start = newline + 1;
       }
     }
+    if (!failure && pending.length > 0) assertTarListingLineConfined(pending.toString("utf8"));
+    const result = await closed;
+    if (failure) throw failure;
+    if (spawnError) throw spawnError;
+    if (result.code !== 0) {
+      throw new Error(`Daytona syncOut tar listing failed (${result.signal ?? result.code}): ${stderr.toString("utf8").trim()}`);
+    }
+  } catch (error) {
+    stop(error instanceof Error ? error : new Error(String(error)));
+    await closed;
+    throw failure;
+  } finally {
+    clearTimeout(timer);
   }
 }
 
diff --git a/packages/plugins/sandbox-providers/daytona/src/tar-listing.test.ts b/packages/plugins/sandbox-providers/daytona/src/tar-listing.test.ts
new file mode 100644
index 00000000000..286e3839956
--- /dev/null
+++ b/packages/plugins/sandbox-providers/daytona/src/tar-listing.test.ts
@@ -0,0 +1,129 @@
+import { promises as fs } from "node:fs";
+import os from "node:os";
+import path from "node:path";
+import { afterEach, expect, it, vi } from "vitest";
+
+vi.mock("./plugin.js", () => ({ getPluginTracer: () => undefined }));
+import { assertTarballEntriesConfined } from "./file-sync.js";
+
+const temporaryDirectories: string[] = [];
+afterEach(async () => {
+  vi.unstubAllEnvs();
+  await Promise.all(temporaryDirectories.splice(0).map((dir) => fs.rm(dir, { recursive: true, force: true })));
+});
+
+async function temporaryDirectory() {
+  const dir = await fs.mkdtemp(path.join(os.tmpdir(), "daytona-tar-listing-"));
+  temporaryDirectories.push(dir);
+  return dir;
+}
+
+// Empty USTAR members are sufficient to exercise the real host tar listing.
+// Repeating a member is valid tar and avoids creating 145,000 host files just
+// to reproduce the archive metadata buffer limit.
+function tarHeader(name: string, prefix = "", target?: string): Buffer {
+  const header = Buffer.alloc(512);
+  header.write(name, 0, 100);
+  header.write("0000644\0", 100);
+  header.write("0000000\0", 108);
+  header.write("0000000\0", 116);
+  header.write("00000000000\0", 124);
+  header.write("00000000000\0", 136);
+  header.fill(32, 148, 156);
+  header.write(target === undefined ? "0" : "2", 156);
+  if (target !== undefined) header.write(target, 157, 100);
+  header.write("ustar\0", 257);
+  header.write("00", 263);
+  header.write(prefix, 345, 155);
+  const sum = header.reduce((total, value) => total + value, 0);
+  header.write(`${sum.toString(8).padStart(6, "0")}\0 `, 148);
+  return header;
+}
+
+it.each([false, true])("validates every member beyond 32 MiB of real tar names (unsafe suffix: %s)", async (unsafeSuffix) => {
+  const archive = path.join(await temporaryDirectory(), "large.tar");
+  const prefix = "nested-".repeat(21);
+  const name = "asset-".repeat(15);
+  const count = 145_000;
+  expect((prefix.length + 1 + name.length) * count).toBeGreaterThan(32 * 1024 * 1024);
+  const header = tarHeader(name, prefix);
+  const batch = Buffer.concat(Array.from({ length: 1_000 }, () => header));
+  const file = await fs.open(archive, "w");
+  try {
+    for (let written = 0; written < count; written += 1_000) await file.write(batch);
+    if (unsafeSuffix) await file.write(tarHeader("escape", "", "../../outside"));
+    await file.write(Buffer.alloc(1_024));
+  } finally {
+    await file.close();
+  }
+  if (unsafeSuffix) {
+    await expect(assertTarballEntriesConfined(archive)).rejects.toThrow("link whose target escapes");
+  } else {
+    await expect(assertTarballEntriesConfined(archive)).resolves.toBeUndefined();
+  }
+}, 30_000);
+
+async function fakeTar(script: string) {
+  const directory = await temporaryDirectory();
+  const pidFile = path.join(directory, "pid");
+  await fs.writeFile(path.join(directory, "tar"), `#!${process.execPath}\n` +
+    `require("node:fs").writeFileSync(${JSON.stringify(pidFile)}, String(process.pid));\n${script}\n`, { mode: 0o755 });
+  vi.stubEnv("PATH", `${directory}${path.delimiter}${process.env.PATH}`);
+  return async () => {
+    const pid = Number(await fs.readFile(pidFile, "utf8"));
+    expect(() => process.kill(pid, 0)).toThrow();
+  };
+}
+
+const safeLine = "-rw-r--r-- 0/0 0 2026-09-27 12:00 nested/café.txt";
+it("preserves UTF-8 split across chunks and checks a final line without a newline", async () => {
+  const checkReaped = await fakeTar(`
+    const bytes = Buffer.from(${JSON.stringify(safeLine)});
+    const split = bytes.indexOf(Buffer.from("é")) + 1;
+    process.stdout.write(bytes.subarray(0, split));
+    setTimeout(() => process.stdout.write(bytes.subarray(split)), 30);
+  `);
+  await expect(assertTarballEntriesConfined("unused.tar")).resolves.toBeUndefined();
+  await checkReaped();
+});
+
+it.each([
+  "not a tar listing",
+  "-rw-r--r-- 0/0 0 2026-09-27 12:00 ../escape",
+  "lrwxrwxrwx 0/0 0 2026-09-27 12:00 link -> /outside",
+  "hrw-r--r-- 0/0 0 2026-09-27 12:00 link link to ../../outside",
+  "lrwxrwxrwx 0/0 0 2026-09-27 12:00 link -> decoy -> ../../outside",
+])("rejects an unsafe final listing and reaps the child: %s", async (line) => {
+  const checkReaped = await fakeTar(`process.stdout.write(${JSON.stringify(line)});`);
+  await expect(assertTarballEntriesConfined("unused.tar")).rejects.toThrow("Daytona syncOut refusing");
+  await checkReaped();
+});
+
+it("bounds an unterminated entry instead of buffering it indefinitely", async () => {
+  const checkReaped = await fakeTar(`process.stdout.write("x".repeat(65_537)); setInterval(() => {}, 1_000);`);
+  await expect(assertTarballEntriesConfined("unused.tar")).rejects.toThrow("entry listing exceeding the byte limit");
+  await checkReaped();
+});
+
+it("bounds stderr and reaps a noisy tar process", async () => {
+  const checkReaped = await fakeTar(`process.stderr.write("x".repeat(65_537)); setInterval(() => {}, 1_000);`);
+  await expect(assertTarballEntriesConfined("unused.tar")).rejects.toThrow("diagnostics exceed the byte limit");
+  await checkReaped();
+});
+
+it("rejects nonzero tar exit even after a valid listing", async () => {
+  const checkReaped = await fakeTar(`process.stdout.write(${JSON.stringify(safeLine + "\n")}); process.exitCode = 2;`);
+  await expect(assertTarballEntriesConfined("unused.tar")).rejects.toThrow("tar listing failed (2)");
+  await checkReaped();
+});
+
+it("times out and reaps a stalled listing process", async () => {
+  const checkReaped = await fakeTar(`setInterval(() => {}, 1_000);`);
+  await expect(assertTarballEntriesConfined("unused.tar", 200)).rejects.toThrow("timed out");
+  await checkReaped();
+});
+
+it("rejects spawn failures without hanging", async () => {
+  vi.stubEnv("PATH", await temporaryDirectory());
+  await expect(assertTarballEntriesConfined("unused.tar")).rejects.toThrow("ENOENT");
+});