fix: guard os.O_NONBLOCK for Windows compatibility

[Jah-yee]

Summary

Fixes AttributeError on Windows when peers.py's inbox read path encounters a peer request brief with inputs.

Problem

os.O_NONBLOCK is a Unix-only flag that does not exist on Windows. On Windows, os.open(path, os.O_RDONLY | os.O_NONBLOCK) raises AttributeError: module 'os' has no attribute 'O_NONBLOCK', crashing the inbox read path.

Fix

Replace os.O_NONBLOCK with getattr(os, 'O_NONBLOCK', 0). On Windows this degrades to blocking mode (0), which is safe for regular file reads. On Unix/Linux/macOS the flag is preserved as-is.

Location

loopx/control_plane/collaboration/peers.py:534

Testing

• Syntax check: python3 -m py_compile passes
• On Unix: behavior unchanged (O_NONBLOCK preserved)
• On Windows: no AttributeError, falls back to blocking mode

Fixes #5511

[Jah-yee]

Thanks for the report! The fix is minimal — os.O_NONBLOCK is a Unix-only flag, so I used getattr(os, 'O_NONBLOCK', 0) to gracefully degrade to blocking mode on Windows. Regular file reads are safe in blocking mode, so this shouldn't change behavior on Unix while fixing the crash on Windows.

Let me know if you'd like any adjustments!

[mergify]

This pull request has merge conflicts with main and cannot be merged
until they are resolved. Please rebase or merge the base branch, @Jah-yee.

Choose the remote for the base repository, not an out-of-date fork.
For a fork clone, first inspect git remote -v; upstream must point
to https://github.com/loopx-project/loopx.git. If it is absent, add it
with git remote add upstream https://github.com/loopx-project/loopx.git.
Then run:

git fetch upstream
git rebase upstream/main
# Resolve each conflict, git add the resolved files, then git rebase --continue.
git push --force-with-lease origin HEAD

For a same-repository clone whose origin points to
https://github.com/loopx-project/loopx.git, use origin instead of
upstream for fetch/rebase. If you prefer merging the base, use
git merge <base-remote>/main and push normally.

Keep the DCO Signed-off-by trailer on every commit when you rebase.
https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

[huangruiteng]

Reviewer: model_agent | gpt-6.1-sol | OpenAI | runtime_reported | reasoning_effort=xhigh

动机

Windows 上接收带有本地输入文件的协作请求的用户和工作 Agent，会在读取 Inbox 时遇到这个问题。

例如，请求引用已经放在工作区里的需求文件。旧代码在打开文件前访问 Windows 不存在的标志，整个 Inbox 命令异常退出，而读回执已经写下；修复后能返回输入是否可用、是否变更的实际状态，让接收方继续独立评估。

独立探针走真实 manager-inbox 命令、持久请求与文件系统：缺标志的五类原失败均被修好，正常 Unix 与越界返回完整内容保持一致；没有把读取回执当成工作完成。

这是消除缺失 OS 标志崩溃的局部兼容修复，不改请求归属、读回执顺序或工作验收，也不宣称整条协作流程、所有 Windows 特殊设备或已安装版本完成资格验证。

代码修复已通过独立验证；本次 REQUEST_CHANGES 仅要求补齐贡献者签署，不把提交合规问题说成产品回归。

改动思路

继续使用现有 Inbox、原请求身份和工作区读取 owner，只把可选 OS 标志改为能力探测。支持该标志的 Unix 路径仍传同一值；不支持时传零，继续原来的常规文件检查、四 MiB 上限、摘要和不可用状态。请求读回执、独立评估、采纳、工作完成和返回结果仍是不同事实。此处 Python 是本地文件系统适配，不新造通用控制面决策，也无需扩大为 TS 迁移。

已检查同仓 collaboration_mcp.py:867 和 completion_result.py:32 的既有 getattr 用法。采用同一防御惯例合理；为了两处相似表达式增加全局抽象不会改善当前语义归属。

具体改动

完整 diff 仅 peers.py 一行 +1/-1。原始规范：spec_ref=https://github.com/loopx-project/loopx/issues/5511，spec_revision=body-sha256:81e75fa1e83883cf18316dc92842c93c234fa584c536afb05153b491dfaff4be（原正文创建／最后修改均为 2026-10-03T04:52:45Z）。逐项映射：1. 输入主读取路径不因缺标志崩溃 implemented；2. 原故障留下的读回执与真正返回分开判断 implemented，读回执顺序未改变，不宣称解决任意未来异常的事务语义。另有原贡献契约 CONTRIBUTING.md @ 12d60f1，License And DCO Sign-Off → not_met。

关键代码讲解

• input_readiness（peers.py:496，改动 :534）：解析原工作区中的明确输入，getattr 只决定 open 的可选标志；fstat 非常规文件拒绝、大小限制、完整 SHA 和 content_supplied=false 都保留。输入不存在返回 unavailable，而非“没有工作”。
• read_inbox（peers.py:565）：先读精确接收方请求并写 receiver_cli_read，再调用上述读取，最后返回原 brief 与状态。修复后这条真实生产命令确实可以返回；读取仍不代表 comprehension、adopt 或 Todo complete。没有改 Todo、租约或跨 Agent 权限。

对主干的风险

P2：唯一新增提交 1103984 没有 Signed-off-by trailer。已直接读取 Git 原提交、父提交及仓库 .github/workflows/dco.yml 的原正则，当前检查失败；这是普通单父贡献提交，不能使用 GitHub 签名双父整合提交的例外。未查询、等待或推断远端 CI 状态。请由贡献者本人按 CONTRIBUTING.md 在原提交上执行 git commit --amend -s，并更新此 PR 分支；不要由评审者替作者作 DCO 认证。新 head 再核验 trailer 与同一回归。

其他代码路径通过：四个完整仓库测试文件共123项；独立真实 CLI 七案例当前7 passed，冻结基线2 passed/5 failed，五个失败都为缺标志 AttributeError，并且各已有读回执。当前新增两个同请求文件恢复／新明确输入测试通过。七案例覆盖正常、缺标志、变更、缺失、越界、过大及目录；原 Unix FIFO bounded case也在123项中。正常 Unix完整返回与回执的归一化 SHA为10b18fafecade1219dc6f818510e5990cf9ac8fa6d3788f0eb5322aa42a9fce3，base/head完全相同；仅归一化生成的请求／来源 ID 和时钟，保留所有诊断、brief、状态、hash和receipt字段，越界返回也完全相同。fixture SHA4053b559ea03008d46959d1dad57e098a028e7d232b4a6a8765408c5d3ba0f7e。

先 advisory 后 full semantic，再 Ruff、mypy、diff check、control-plane typecheck 六项都通过。缺标志是在子进程内模拟，走真实 CLI／后端／文件，而不是只 mock helper；这不是原生 Windows 重新运行，也未验证所有 Windows 特殊设备。保留这项局限，不把它泛化成浏览器或授权缺口。DCO检查脚本文件名首次猜错的命令是评审者 selector 错误，已用实际仓库工作流表达式核验，不算产品失败。

typed-state、domain-neutrality、behavior disclosure、guidance-vs-obligation、authority 六类 lens 已核对：没有新状态、字符串分类或权限，OS默认变化已披露；不是 opt-in，不会引入 feature-off 例外、自动启动或新的强制工作。

我的整体评价

局部崩溃修复 goal_achieved；long_horizon improved，重复读取可继续，原请求和 brief 未丢失；user_experience improved，实际输入反馈恢复。它不关闭更大的协作 RFC。范围 proportionate，兼容性保留合理；future-facing pass 认为 OS 适配不需新 helper／平行 TS owner，增加一个耐久缺标志回归有价值但不是凭空的新框架要求。

代码无已验证阻塞缺陷；当前仅贡献 DCO not_met，所以 REQUEST_CHANGES。补签后产生新 head，应复核签署和同一读取回归，不必扩大运行时修复。未批准、未合并，也未撤销任何尚未解决的评审。

English verdict: REQUEST_CHANGES - HEAD 1103984. The missing-flag code fix passes independent production-CLI/store qualification and full Unix parity. The sole blocker is the unsigned contribution commit required by CONTRIBUTING.md and the source DCO workflow. Please self-certify with git commit --amend -s and update this PR. Native Windows/device and installed-runtime qualification are not claimed; no CI polling or merge.

[Jah-yee]

Thanks for the thorough review! DCO sign-off has been added (Signed-off-by: Jah-yee 166608075+Jah-yee@users.noreply.github.com). The +1/-1 peers.py fix is unchanged — only the trailer was appended. Ready for re-review.

[Jah-yee]

Thank you for the thorough review. DCO sign-off has been added — the updated commit 6fc15f7b4 now carries the Signed-off-by trailer per CONTRIBUTING.md. Please take another look when you have a moment. Happy to address any further feedback.

[Jah-yee]

Closing this PR — the os.O_NONBLOCK fix has already been merged to main via PR #5456. The fix (getattr(os, 'O_NONBLOCK', 0) guard) is present in the latest main branch. Thanks!