docs(setup-browser-cookies): warn that the bundled Chromium still trusts the eMudhra intermediates (#3338)

Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>

changelog.d/garrytan-gsta-84-cookie-import-trust-note.md

@@ -0,0 +1,4 @@
+**/setup-browser-cookies now warns that the fallback browser still trusts the compromised eMudhra intermediates (#3338).** BROWSER.md carried this warning since v1.91.239.0, but the cookie import skill did not, so an agent importing signed-in cookies into the bundled Chromium never told the user.
+
+### Changed
+- **`setup-browser-cookies/SKILL.md.tmpl`**: before the import, the agent tells the user once that gstack's bundled Chromium still accepts certificates from those intermediates, says not to use the imported sessions on a network they do not trust until the Playwright bump, and points to `BROWSER.md`, **TLS trust: the bundled Chromium's root store**.

setup-browser-cookies/SKILL.md

@@ -175,6 +175,8 @@ Use the picker when any of answers 1-2 is still open; it asks for them. Use dire
 $B goto "<url>"
 ```
 
+Tell the user once, before the import: this browser trusts the root store built into gstack's bundled Chromium, which still accepts certificates from the compromised eMudhra intermediates ([#3338](https://github.com/garrytan/gstack/issues/3338)). Until gstack moves to a Playwright release that drops them, don't use the imported sessions on a network the user does not trust. That same root's `BROWSER.md`, **TLS trust: the bundled Chromium's root store**, has the details and the check.
+
 ## 4. Import
 
 Picker (the user confirms the browser, profile and domains there, ticks verification if they asked for it, then tells you when done; the link works once, for five minutes, so rerun the command if it expires):

setup-browser-cookies/SKILL.md.tmpl

@@ -51,6 +51,8 @@ Use the picker when any of answers 1-2 is still open; it asks for them. Use dire
 $B goto "<url>"
 ```
 
+Tell the user once, before the import: this browser trusts the root store built into gstack's bundled Chromium, which still accepts certificates from the compromised eMudhra intermediates ([#3338](https://github.com/garrytan/gstack/issues/3338)). Until gstack moves to a Playwright release that drops them, don't use the imported sessions on a network the user does not trust. That same root's `BROWSER.md`, **TLS trust: the bundled Chromium's root store**, has the details and the check.
+
 ## 4. Import
 
 Picker (the user confirms the browser, profile and domains there, ticks verification if they asked for it, then tells you when done; the link works once, for five minutes, so rerun the command if it expires):

test/helpers/manual-judge-review-fixture.ts

@@ -61,10 +61,18 @@ const LATER_COOKIE_ORDER_EDITS: Array<[string, string]> = [
   ["# view the page; only --verify-auth proves sign-in", "# confirm the intended account"],
 ];
 
+// The #3338 trust warning (GSTA-84) added one paragraph after step 3's goto
+// (two lines longer). Removing it first lets the GSTA-49 reversal match.
+const LATER_TRUST_PARAGRAPH = "Tell the user once, before the import: this browser trusts the root store built into gstack's bundled Chromium, which still accepts certificates from the compromised eMudhra intermediates ([#3338](https://github.com/garrytan/gstack/issues/3338)). Until gstack moves to a Playwright release that drops them, don't use the imported sessions on a network the user does not trust. That same root's `BROWSER.md`, **TLS trust: the bundled Chromium's root store**, has the details and the check.\n\n";
+
 export function approvedCookieWorkflowSource(source: string): string {
   let removedLines = 0;
   let removedEntrypointLines = 0;
   let reordered = source;
+  if (reordered.includes(LATER_TRUST_PARAGRAPH)) {
+    removedEntrypointLines += LATER_TRUST_PARAGRAPH.split('\n').length - 1;
+    reordered = reordered.replace(LATER_TRUST_PARAGRAPH, '');
+  }
   for (const [later, earlier] of LATER_COOKIE_ORDER_EDITS) {
     if (!reordered.includes(later)) continue;
     removedEntrypointLines += later.split('\n').length - earlier.split('\n').length;