[bshurikan]

Summary

• Before donor remount beside SwitchU (100D up, or SwitchU has AckHeadroom'd this boot), set reserved3 bit 6 (NeedHeadroom) and wait for reclaim.
• Stock users: no wait on remount until/unless SwitchU has ACK'd at least once this boot (review: was always 2s).
• New sftap cmd 15 AckHeadroom(u32 free_kb); file fallback need_headroom / ft_headroom_ready.
• Requested MB via GetDonorCap (cmd 13) while NeedHeadroom is set — not shot_fails.
• HBL 100D as Album for Beside margins; anti-thrash clear; no donor launch on timeout while SwitchU holds the pool.
• Bump sftap max sessions to 4.

Pairs with SwitchU draft PoloNX/SwitchU#177.

Test plan

• Without SwitchU: HOME to game remount does not log NeedHeadroom / 2s wait
• With SwitchU: 100D up then NeedHeadroom + ACK; GetDonorCap returns ask MB; shot_fails stays screenshot fails
• Second+ HOME after a title: Album/hbmenu stream when pool has room
• Overlay / manager GetStatus still works

[TomasUribe]

Thanks! Two things before it can go in: (1) without SwitchU every donor remount now waits the full 2 s - that's 2 s more after each HOME -> game for everyone else. Could the wait run only once SwitchU has acked at least once this boot (the first remount without waiting)? (2) Please don't reuse shot_fails for the MB - the overlay and app show it as screenshot failures; GetDonorCap or a new field would be cleaner.

[bshurikan]

Thanks - both addressed on the latest commits (PR stays draft while we soak SwitchU coexistence):

1. Stock remount wait: NeedHeadroom wait only runs when 100D is up or SwitchU has AckHeadroom'd at least once this boot. Without SwitchU, HOME→game remounts no longer pay the 2 s delay.

2. Requested MB: no longer overloads shot_fails. While NeedHeadroom is set, the MB is via GetDonorCap (cmd 13); shot_fails stays screenshot failures for the overlay/app. File fallback need_headroom still works for older clients.

SwitchU side should read GetDonorCap when bit 6 is set (we're updating that on the menu PR).