[wanglz111]

Fixes #27

GNOME scaling changes can leave Portal capture paused without a negotiated format until the existing five-second failure threshold expires. This change uses Mutter MonitorsChanged to check that failure sooner and reuse the existing serialized session recovery.

实现 / Implementation

• 每个 GNOME Portal 会话在已有 D-Bus context 订阅显示变化；只有已推流且连续「暂停、无格式」的采集与通知相关联，才在两者就绪后的 200 ms 宽限结束后提前恢复。
• 有效格式或重新推流清除提前检查提示；重复通知不延长同次异常的判定。保留原有 5 秒兜底，输入和剪贴板存活判断不变。
• Subscribe per GNOME Portal handle on its existing D-Bus context. Require a continuously paused, format-less stream and a correlated notification, then allow 200 ms from the later condition before reporting capture failure.
• Healthy renegotiation clears the hint; repeated notifications do not postpone the interruption. Preserve the five-second fallback and existing input/clipboard health checks.

实测 / Measurements

Ubuntu 26.04, GNOME 50 Wayland, one 3840x2160 display, 200% ↔ 166.67% scaling:

• 原路径中，PAUSED 在通知前 5–9 ms，格式清空在通知后 10–36 ms。通知后仅检查一次会漏掉格式稍后清空的情况。
• 独立真实采集/编码探针中，通知到会话恢复从约 6.15–6.18 s 降至 1.396 / 1.360 s。
• 相隔 163 ms 的连续双切换只恢复一次；静态观察 30 s 无额外恢复；探针正常编码 3,600 帧，首帧为 IDR。
• Before the change, PAUSED preceded notification receipt by 5–9 ms and NULL format followed by 10–36 ms. Independent real capture/encoding tests reduced notification-to-restored time from about 6.15–6.18 s to 1.396 / 1.360 s.
• A pair of changes 163 ms apart caused one recovery; 30 seconds of static observation caused none. The probe completed 3,600 encoded frames with an initial IDR.

200 ms 是本机测量后的初始宽限，不是所有 GNOME 版本的保证。候选版官方客户端的渲染、鼠标和黑屏耗时尚未完成验收；上述数字是主机会话恢复时间。其他桌面保留兜底；多屏、物理分辨率和旋转不在本次范围。

The 200 ms grace is an initial measured value, not a guarantee across GNOME versions. Official-viewer rendering, pointer acceptance and black-screen duration remain unverified for the candidate; these measurements cover host session recovery. Other desktops retain the fallback. Multi-monitor, physical-resolution and rotation support remain outside this change.

Details: docs/experiments/issue-27-display-recovery.md.

验证 / Validation

• cargo test --locked --features wayland,portal
• cargo build --locked --release --features wayland,portal
• Four native suites under ASan/UBSan, including 13 EIS geometries.
• Coverage includes all six event orders, grace boundaries, stale/repeated/delayed notifications, natural recovery, clipboard readiness, and private D-Bus subscription teardown with/without a worker.

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Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	⚠️ Failed 2026-10-17T05:46:35.866632Z	b18a77e	PR opened

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[VallierDev]

感谢！实现很克制（只在 GNOME 会话订阅 Mutter MonitorsChanged、全部在锁内、保留 5 秒兜底、无新日志），测量也很清楚。和 #34 一样，我补了一个小提交把 docs/experiments/ 移出仓库（实验/验收记录按约定放在 PR 里，你的描述已完整保留），README 链接改指向本 PR。CI 通过后合并。

Thanks — tight change and clear measurements. As with #34 I pushed a small commit moving docs/experiments/ out of the repository (README now links here). Will merge once CI passes.

[VallierDev]

已合并，感谢！将随下一个版本发布。/ Merged, thanks — ships in the next release.