From db12b1bc9095db4be8cf5dc0277f34fef441d6ce Mon Sep 17 00:00:00 2001
From: JUN <jun@lidgeai.com>
Date: Wed, 11 Nov 2026 11:07:23 +0900
Subject: [PATCH] test(link): keep the constrained-mode prefix out of the
 cmd.exe budget

The Windows containment probe for the pinned sync command failed on every
lane=all run since #8505 grew the packed script to 7740 encoded characters. The
test decoded the builder's command, prepended a ConstrainedLanguage line and
re-encoded it through powershellArgv, which also repeats its preamble; that
scaffolding overhead alone pushed it to 8020 and tripped the 8000 cap, so the
test threw before PowerShell ever ran. The production command stays under the
cap and the builder still enforces it.

The prefix is now encoded beside the builder's own argv, and a cross-platform
case pins that each probe runs the builder's command unchanged.
---
 tests/clients/link-ssh-argv-discovery.test.ts | 29 ++++++++++++++++---
 1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/tests/clients/link-ssh-argv-discovery.test.ts b/tests/clients/link-ssh-argv-discovery.test.ts
index 24b46cd7b62..56fb730e830 100644
--- a/tests/clients/link-ssh-argv-discovery.test.ts
+++ b/tests/clients/link-ssh-argv-discovery.test.ts
@@ -317,7 +317,7 @@ test.skipIf(process.platform !== "win32")("a Windows ocx that cannot be containe
   // Constrained Language Mode blocks Add-Type, so the Job helper cannot exist; the session enters
   // it before the unchanged script runs.
   const native = windowsNativeArgv(process.execPath, [script, marker]);
-  const constrained = powershellArgv("$ExecutionContext.SessionState.LanguageMode='ConstrainedLanguage'\n" + Buffer.from(native.at(-1)!, "base64").toString("utf16le"));
+  const constrained = constrainedArgv(native);
   const child = Bun.spawn(constrained, { stdin: "ignore", stdout: "pipe", stderr: "pipe" });
   const code = await child.exited;
   expect(code).toBe(WINDOWS_CONTAINMENT_EXIT);
@@ -327,10 +327,31 @@ test.skipIf(process.platform !== "win32")("a Windows ocx that cannot be containe
 // Every packed command inflates itself before its containment helper exists; a session that cannot
 // inflate must still refuse with 126. The candidate homes and PATH hold no ocx.exe, so 126 can only
 // be that refusal: an unguarded inflate exits 1 and exhausted discovery exits 127.
-for (const [name, build] of [
+const CONTAINMENT_PROBES = [
   ["discovery", () => windowsOcxArgv(["--version"])],
   ["pinned sync", () => windowsPinnedSyncArgv("lnk_0123456789abcdef")],
-] as const) {
+] as const;
+
+// The language-mode prefix is test scaffolding: no command Home sends carries it, so it is encoded
+// beside the builder's own command instead of spending the cmd.exe budget the builder already
+// enforced. Re-encoding through powershellArgv also repeated its preamble, and once the pinned
+// sync script grew to 7740 encoded characters (#8505) that overhead alone crossed the 8000 cap.
+function constrainedArgv(argv: readonly string[]): string[] {
+  const script = "$ExecutionContext.SessionState.LanguageMode='ConstrainedLanguage'\n" + Buffer.from(argv.at(-1)!, "base64").toString("utf16le");
+  return [...argv.slice(0, -1), Buffer.from(script, "utf16le").toString("base64")];
+}
+
+test("the constrained containment probes run each builder's own command unchanged", () => {
+  for (const [, build] of CONTAINMENT_PROBES) {
+    const argv = build();
+    const constrained = constrainedArgv(argv);
+    expect(constrained.slice(0, -1)).toEqual(argv.slice(0, -1));
+    expect(Buffer.from(constrained.at(-1)!, "base64").toString("utf16le"))
+      .toBe("$ExecutionContext.SessionState.LanguageMode='ConstrainedLanguage'\n" + Buffer.from(argv.at(-1)!, "base64").toString("utf16le"));
+  }
+});
+
+for (const [name, build] of CONTAINMENT_PROBES) {
   test.skipIf(process.platform !== "win32")(`a Windows ${name} command that cannot be contained is refused before any candidate is probed`, async () => {
     const empty = mkdtempSync(join(tmpdir(), "ocx-windows-refuse-candidates-")); roots.push(empty);
     const system32 = join(process.env.SystemRoot ?? "C:\\Windows", "System32");
@@ -338,7 +359,7 @@ for (const [name, build] of [
     const env: Record<string, string> = {};
     for (const [key, value] of Object.entries(process.env)) if (value !== undefined && !isolated.has(key.toLowerCase())) env[key] = value;
     Object.assign(env, { PATH: system32, USERPROFILE: empty, LOCALAPPDATA: empty, ProgramFiles: empty });
-    const constrained = powershellArgv("$ExecutionContext.SessionState.LanguageMode='ConstrainedLanguage'\n" + Buffer.from(build().at(-1)!, "base64").toString("utf16le"));
+    const constrained = constrainedArgv(build());
     const child = Bun.spawn([join(system32, "WindowsPowerShell", "v1.0", "powershell.exe"), ...constrained.slice(1)], { env, stdin: "ignore", stdout: "pipe", stderr: "pipe" });
     const [code] = await Promise.all([child.exited, new Response(child.stdout).text(), new Response(child.stderr).text()]);
     expect(code).toBe(WINDOWS_CONTAINMENT_EXIT);