Blind packets for the sampled pull requests #1025

Parent

#978

What to build

Each sampled pull request gets its packet, the only thing its Grader will see:

• the issue's title and body as they stood when the pull request merged, read from the issue's edit history;
• the merged diff, without commit messages;
• the pull request's title and body;
• the CI results, as check names and conclusions;
• the repository, as a time-safe clone at the merge commit with no later history.

Every packet loses its identifying lines, whatever built the pull request: the Built-with line and Claude Code's "Generated with Claude Code" line. Co-Authored-By trailers go with the commit messages. A missing line gives the Harness away as surely as a present one, so the lines are always removed. #937 may stop Claude adding its two, but the packet removes them either way.

Acceptance criteria

• A packet holds no Built-with line, no "Generated with Claude Code" line and no commit message, for both Claude-built and other pull requests.
• The issue is shown as it stood at the merge, even after a later edit, tested with a fake edit history.
• The clone has no commit after the merge commit.
• CI results are check names and conclusions only.