GeezerVison

Tasks

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• refackiew

Everything below this line was generated by Codex GPT-6.

Created by Codex on behalf of Byron. Byron will review before this is ready to merge.

Fixes #2276.

Stalled fetch, pull, and push commands can deadlock when timeout cleanup closes
stderr while its pump holds the buffered reader lock. Kill Git and its descendants
before closing output streams, then reap the process. Reuse the command watchdog's
process lookup, extending it to grandchildren (including Apple Git's HTTP helper
launcher). Support both POSIX ps and Cygwin ps -ef when pgrep is unavailable.

Both output streams share one deadline. Append timeout diagnostics to captured stderr for
AutoInterrupt.wait() instead of synchronously re-entering callbacks, and preserve
those errors in partial push results, including when Git exits successfully while
a callback remains blocked. Skip process-tree signalling after the child exits.
Ordinary cleanup keeps stdin EOF delivery,
SIGTERM, and output closure before waiting, including buffered/broken input pipes.
Update the public descendant limitations to match the implementation.

The loopback regression covers all nine combinations of fetch/pull/push and
git:///HTTP/HTTPS. All nine failed before the fix, returning only after the
server's five-second safety release; all now pass with 0.5-second timeouts,
including in Cygwin CI. Additional regressions cover buffered stdin, undrained
output, blocked stdout/stderr callbacks, partial pushes, missing process lookup
tools, and POSIX/Cygwin descendant parsing.

Validation:

• All 50 CI checks pass on 30b741c, including Linux, macOS, Windows, Cygwin,
  Alpine, dependency compatibility, lint, types, tests, and documentation.
• Python 3.8 focused timeout and cleanup suite: 24 passed.
• Command, cleanup, and command-deprecation modules: 122 passed, 1 skipped before
  the final callback/parser additions; subsequent focused checks cover those changes.
• All nine loopback cases pass with pgrep disabled, exercising the POSIX ps fallback.
• Cygwin CI passed all nine stalled-remote cases and 1581 tests overall; its sole
  parser-fixture platform mismatch is corrected by explicitly selecting each modeled platform.
• Ruff lint/format, native and Windows-targeted mypy, basedpyright, and diff checks pass.
• Final Codex commit review found no actionable regressions. All six Copilot threads
  were addressed with regressions or documentation and resolved.
• Local TestRemote.test_base fails identically with the unchanged implementation
  due to a missing remote-tracking ref; this limitation was verified against the baseline.

Git reference: local source baseline v2.56.0-rc1, especially
transport-helper.c:get_helper() (inherited stderr), connect.c:git_connect()
(SSH transport children), and run-command.c (descriptor handling and opt-in
child cleanup). Runtime reproduction used Apple Git 2.54.0. Cygwin process
format was checked against upstream winsup/utils/ps.cc.

Process lookup is best-effort if tools are unavailable. Descendants that already
detached or spawn after enumeration may escape signalling. Windows command
timeouts remain unsupported.