[BUG] Gmail connector rewrites URLs and bare domains in message bodies into google.com/url redirect links

Summary

When creating or updating a draft via the claude.ai Gmail connector (create_draft / update_draft), every URL and bare domain name in the body is saved as a Google redirect link, e.g.

https://www.example.com/page/ → https://www.google.com/url?q=https://www.example.com/page/&source=gmail&ust=1789465765136000&sa=E

The rewritten link is what gets stored and sent, so recipients receive google.com/url links instead of the original URLs.

Steps to reproduce

1. Call create_draft with plain body:

``
A1 https://www.example.com/page/
A2 example.com
A3 <https://www.example.com/>
``

1. Fetch the draft with get_draft (messageFormat: RAW) and decode the MIME.

Actual

• text/plain part: all three lines contain https://www.google.com/url?q=...&source=gmail&ust=...&sa=E
• text/html part: same, rendered as plain text
• Passing htmlBody with an explicit <a href="https://www.example.com/page/"> also gets its href rewritten; a bare domain inside <code> is wrapped in a redirect <a>.
• Email addresses are not affected (they become mailto links).
• update_draft on a reply draft also drops the thread association (new threadId) and the quoted original.
• Messages previously sent through the connector (send_message) show the same rewritten URLs in the Sent copy's RAW MIME. In one case the plain-text part contains an unescaped =17 (ust^W...), i.e. the rewrite is inserted without proper quoted-printable encoding.

Expected

The body is stored exactly as provided; URLs are not wrapped in google.com/url redirects.

Impact

Any email containing a link (signature website, product page) is sent with Google redirect URLs. We have had to block the connector's write tools with a PreToolUse hook and compose via the Gmail web UI instead.

Environment

• Claude Code desktop app (Code tab), Windows 11
• claude.ai Gmail connector (tools: create_draft, update_draft, send_message)
• Observed 2026-09-04 and reproduced 2026-09-14