[dgsienko]

• With ignore whitespace on, a tracked file with no remaining diff showed as a brand-new file. Only untracked files fall through to the new-file diff now.
• A failed agent spawn leaked the parent pty fd, and a failure in pty setup leaked both. Both fds now close on any failure.
• The "No pending agent start" guard gets a websocket-level test (no source change).
• Removed lines starting with -- (SQL or Lua comments) and added lines starting with ++ lost their word highlights. Header detection uses is_meta_line now.
• A diagram fence in a comment showed "Loading diagram..." forever. Comments now render diagram fences as code blocks, so comment text never goes to kroki.io. Previews still render diagrams.
• Blame never refreshed after edits or commits, and could show another repo's blame after a repo switch. The cache now clears on file and git changes and on repo switch.
• The keyboard handler threw on keydown events targeted at the document.

Each Python fix has a regression test that failed before it. The frontend fixes were checked in a browser against a scratch repo, since the repo has no JS test harness.

Version 0.11.2.