diff --git a/scripts/docker/install-sh-e2e/run.sh b/scripts/docker/install-sh-e2e/run.sh
index b0b2b1e0aa3b..19a2e472b30c 100755
--- a/scripts/docker/install-sh-e2e/run.sh
+++ b/scripts/docker/install-sh-e2e/run.sh
@@ -150,15 +150,21 @@ preinstall_previous_version() {
   fi
 }
 
-run_official_installer() {
+run_official_installer() (
+  local installer
+  # time_phase disables errexit, so setup and download failures must return explicitly.
+  installer="$(mktemp)" || return
+  trap 'rm -f "$installer"' EXIT
+
+  curl -fsSL --connect-timeout 10 --max-time 120 "$INSTALL_URL" -o "$installer" || return
   if [[ "$INSTALL_TAG" == "beta" ]]; then
-    curl -fsSL "$INSTALL_URL" | OPENCLAW_BETA=1 bash
+    OPENCLAW_BETA=1 bash "$installer"
   elif [[ "$INSTALL_TAG" != "latest" ]]; then
-    curl -fsSL "$INSTALL_URL" | OPENCLAW_VERSION="$INSTALL_TAG" bash
+    OPENCLAW_VERSION="$INSTALL_TAG" bash "$installer"
   else
-    curl -fsSL "$INSTALL_URL" | bash
+    bash "$installer"
   fi
-}
+)
 
 verify_installed_version() {
   INSTALLED_VERSION="$(openclaw --version 2>/dev/null | head -n 1 | tr -d '\r')"
diff --git a/test/scripts/docker-build-helper.test.ts b/test/scripts/docker-build-helper.test.ts
index 4c1e8cfd36c7..4516bc6c3524 100644
--- a/test/scripts/docker-build-helper.test.ts
+++ b/test/scripts/docker-build-helper.test.ts
@@ -4348,8 +4348,8 @@ heartbeat_elapsed="\${BASH_REMATCH[1]}"
   it("passes installer tag env to bash, not curl", () => {
     const runner = readFileSync(INSTALL_E2E_RUNNER_PATH, "utf8");
 
-    expect(runner).toContain('curl -fsSL "$INSTALL_URL" | OPENCLAW_BETA=1 bash');
-    expect(runner).toContain('curl -fsSL "$INSTALL_URL" | OPENCLAW_VERSION="$INSTALL_TAG" bash');
+    expect(runner).toContain('OPENCLAW_BETA=1 bash "$installer"');
+    expect(runner).toContain('OPENCLAW_VERSION="$INSTALL_TAG" bash "$installer"');
     expect(runner).not.toContain('OPENCLAW_BETA=1 curl -fsSL "$INSTALL_URL" | bash');
     expect(runner).not.toContain(
       'OPENCLAW_VERSION="$INSTALL_TAG" curl -fsSL "$INSTALL_URL" | bash',
diff --git a/test/scripts/test-install-sh-docker.test.ts b/test/scripts/test-install-sh-docker.test.ts
index 91994e8a474e..1b964576bece 100644
--- a/test/scripts/test-install-sh-docker.test.ts
+++ b/test/scripts/test-install-sh-docker.test.ts
@@ -59,6 +59,87 @@ function extractNonrootNodePreflight(): string {
   return expectDefined(match[1], "non-root smoke Node preflight capture");
 }
 
+function extractInstallE2eInstallerFunction(): string {
+  const script = readFileSync(INSTALL_E2E_RUNNER_PATH, "utf8");
+  const startMarker = "run_official_installer() (\n";
+  const endMarker = "\n\nverify_installed_version()";
+  const start = script.indexOf(startMarker);
+  const end = script.indexOf(endMarker, start + startMarker.length);
+  if (start < 0 || end <= start) {
+    throw new Error("install E2E installer function was not found");
+  }
+  return script.slice(start, end);
+}
+
+function runInstallE2eInstallerFixture(params: {
+  curlExitCode?: number;
+  installTag: string;
+  installerBody: string;
+}) {
+  const root = tempDirs.make("openclaw-install-e2e-download-");
+  const binDir = join(root, "bin");
+  const curlPath = join(binDir, "curl");
+  const curlArgsPath = join(root, "curl-args.txt");
+  const installerSourcePath = join(root, "installer-source.sh");
+  const markerPath = join(root, "installer-marker.txt");
+  const outputPathCapture = join(root, "curl-output-path.txt");
+  mkdirSync(binDir, { recursive: true });
+  writeFileSync(installerSourcePath, params.installerBody);
+  writeFileSync(
+    curlPath,
+    [
+      "#!/bin/sh",
+      "set -eu",
+      'printf \'%s\\n\' "$*" >"$CURL_ARGS_PATH"',
+      'output=""',
+      'while [ "$#" -gt 0 ]; do',
+      '  if [ "$1" = "-o" ]; then',
+      "    shift",
+      '    output="$1"',
+      "  fi",
+      "  shift",
+      "done",
+      'cp "$FAKE_INSTALLER_SOURCE" "$output"',
+      'printf "%s" "$output" >"$OUTPUT_PATH_CAPTURE"',
+      'exit "$FAKE_CURL_EXIT"',
+      "",
+    ].join("\n"),
+    { mode: 0o755 },
+  );
+
+  const env: NodeJS.ProcessEnv = {
+    ...process.env,
+    CURL_ARGS_PATH: curlArgsPath,
+    FAKE_CURL_EXIT: String(params.curlExitCode ?? 0),
+    FAKE_INSTALLER_SOURCE: installerSourcePath,
+    INSTALL_MARKER: markerPath,
+    OUTPUT_PATH_CAPTURE: outputPathCapture,
+    PATH: `${binDir}:${process.env.PATH ?? ""}`,
+  };
+  delete env.OPENCLAW_BETA;
+  delete env.OPENCLAW_VERSION;
+
+  const result = spawnSync(
+    "/bin/bash",
+    [
+      "-c",
+      [
+        "set -u",
+        extractInstallE2eInstallerFunction(),
+        'INSTALL_URL="https://installer.example.test/install.sh"',
+        `INSTALL_TAG=${JSON.stringify(params.installTag)}`,
+        "run_official_installer",
+      ].join("\n"),
+    ],
+    {
+      encoding: "utf8",
+      env,
+    },
+  );
+
+  return { curlArgsPath, markerPath, outputPathCapture, result };
+}
+
 function runNonrootNodePreflight(
   version: string,
   options: { sqlite?: boolean; sqliteVersion?: string } = {},
@@ -960,6 +1041,40 @@ printf 'status=%s\\n' "$status"
 });
 
 describe("install-sh E2E runner", () => {
+  it("does not execute a partial installer after a bounded download fails", () => {
+    const fixture = runInstallE2eInstallerFixture({
+      curlExitCode: 28,
+      installerBody: 'touch "$INSTALL_MARKER"\n',
+      installTag: "latest",
+    });
+
+    expect(fixture.result.status).toBe(28);
+    expect(readFileSync(fixture.curlArgsPath, "utf8")).toContain(
+      "-fsSL --connect-timeout 10 --max-time 120 https://installer.example.test/install.sh -o",
+    );
+    expect(existsSync(fixture.markerPath)).toBe(false);
+    expect(existsSync(readFileSync(fixture.outputPathCapture, "utf8"))).toBe(false);
+  });
+
+  it.each([
+    ["latest", "|"],
+    ["beta", "1|"],
+    ["2026.7.1", "|2026.7.1"],
+  ])(
+    "executes a complete %s installer with the expected tag environment",
+    (installTag, expected) => {
+      const fixture = runInstallE2eInstallerFixture({
+        installTag,
+        installerBody:
+          'printf "%s|%s" "${OPENCLAW_BETA-}" "${OPENCLAW_VERSION-}" >"$INSTALL_MARKER"\n',
+      });
+
+      expect(fixture.result.status, fixture.result.stderr).toBe(0);
+      expect(readFileSync(fixture.markerPath, "utf8")).toBe(expected);
+      expect(existsSync(readFileSync(fixture.outputPathCapture, "utf8"))).toBe(false);
+    },
+  );
+
   it("normalizes Docker wrapper timing and toggle knobs before forwarding", () => {
     const wrapper = readFileSync(INSTALL_E2E_DOCKER_PATH, "utf8");