forked from unom/punktfunk
enricobuehlerandClaude Fable 5
7ab97bb1a3
Field repro (Mounjay, still present on 0.9.0): the ~4 s double-jolt stutter appears ONLY while the virtual display is the sole active display (Exclusive topology) and stops the instant Windows switches to Extend — live, both ways. Cross-project research (Apollo #179/#358/#368/#563/#776, VDD #36, Tom's HW) points at the display/present path BELOW capture: an inactive-but-connected DisplayPort head being periodically serviced (standby HPD/AUX/link events), with a DWM software-vsync clock beat as the secondary (different-signature) class. Neither ends in anything our recovery-side detector can see unless the client actually loses data — so give the HOST a direct sensor at the ring: - StallWatch (idd_push.rs): a >150 ms hole in DWM frame delivery counts as a capture stall only when the 8 preceding frames arrived within 400 ms — sustained >=20 fps flow, so an idle desktop, a caret blink, or a paused video can never trip it. Per-stall debug line; when stalls settle into an evenly-spaced multi-second cycle, one rate-limited WARN names the class: 'capture stalls are METRONOMIC', with the topology=primary/extend and refresh-rate leads. Ring-recreate recovery gaps reset the watch (self- inflicted, already logged by the recreate path). - The evenly-spaced-cycle detector moves out of punktfunk1.rs into metronome.rs (RecoveryCadence -> Metronome, unchanged logic + tests) so the IDR-serve detector and the stall watch share one implementation; the recovery WARN now cross-references the capture-stall lines. Diagnosis map for an Exclusive-mode stutter log: 'slow display-descriptor poll' = something holds the win32k display lock; 'capture stalls are METRONOMIC' without it = DWM stopped composing (DP servicing / present clock, below us); recovery-IDR METRONOMIC alone = frames flowed but clients lost data. Verified: Linux tests+clippy+fmt clean; Windows (RTX box) 220/220 + clippy clean. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>