[BUG] Session proxy blocks pushes to the target branch specified at session launch

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

When starting a Claude Code remote session, I specified codex/remediate-design-foundation as the target branch. Despite this, the session was provisioned with claude/gallant-dirac-97yoyb as the only writable branch — the local git proxy returned HTTP 403 for any push to codex/remediate-design-foundation.

The session instructions injected into Claude's system prompt reflected this ("Develop on branch claude/gallant-dirac-97yoyb"), so Claude correctly followed those instructions — but they contradicted what I had configured at session launch.

What Should Happen?

The session should be launched against the branch / PR specified by the user.

Error Messages/Logs

HTTP 403 on push attempt

Steps to Reproduce

1. Start a Claude Code remote session targeting an existing PR branch (e.g. codex/remediate-design-foundation)
2. Ask Claude to address review comments on that PR
3. Claude pushes to a different branch (claude/gallant-dirac-97yoyb) and creates a new PR instead of committing to the target branch
4. Manually pushing to the target branch returns HTTP 403 from the local proxy at 127.0.0.1

Expected behaviour: The session should be able to push to the branch specified at launch. The injected system prompt should reflect the actual target branch.

Actual behaviour: The proxy only permits pushes to the auto-generated claude/* branch. The target branch is effectively read-only, making it impossible to work directly on an existing PR.

Impact: Claude created an unnecessary intermediary PR, could not push fixes directly to the original PR, and the session instruction ("develop on claude/gallant-dirac-97yoyb") actively overrode the user's explicit intent.

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

1.14271.0

Platform

Other

Operating System

macOS

Terminal/Shell

Other

Additional Information

_No response_