attribution setting does not control session URL in commit messages

Problem

The attribution setting in ~/.claude/settings.json allows removing the "Co-authored-by" trailer and "Generated with Claude Code" text from commit messages:

{
  "attribution": {
    "commit": "",
    "pr": ""
  }
}

However, this does not remove the session deep link URL (e.g. https://claude.ai/code/session_01SBzqph11q7ZSHA5QEGgtu5) that Claude Code appends to commit messages and PR descriptions.

There is no documented setting to control this behavior.

<img width="1102" height="506" alt="Image" src="https://github.com/user-attachments/assets/e4a9ec8e-a830-4c6d-a7c5-7604db925f2e" />

Why this matters

• Users who set attribution.commit to "" clearly intend to have clean commit messages with no Claude Code metadata. The session URL should respect this intent.
• The session URL leaks information about the tooling and specific session used to produce the code.
• For users running Claude Code in the cloud (e.g. via claude.ai/code), a local commit-msg git hook is not a viable workaround since the commit is created server-side.

Expected behavior

When attribution.commit is set to "", all Claude Code metadata should be removed from commit messages, including the session URL. Alternatively, provide a separate setting to control the session URL independently.

Reproduction

1. Set ~/.claude/settings.json to:

``json
{
"attribution": {
"commit": "",
"pr": ""
}
}
``

1. Use Claude Code (cloud) to make a commit.
2. Observe that the session URL is still appended to the commit message.