Agent 6 applied SW-pin fix and marked verified via element state
(currentTime advancing, videoWidth=1920, readyState=4). Headless pixel
histogram still showed darkPct=100% — element decoded fine but CSS
overlay covered it.
Real cause: branding.xml BLACK-PASS paints .libraryPage with
#000 !important. Jellyfin OSD page renders <div id=videoOsdPage
class=libraryPage>; class match -> opaque black div above <video>.
Fix: extend transparent-scope using :has(.htmlVideoPlayer) +
#videoOsdPage selector. Post-fix darkPct=9.8% (was 100%), MNS S1E4
video frame visually paints.
Removed INC6 clear-cache-only middleware (no longer needed, was
burning HTTP cache every visit).
bin/apply-26-incident-fixes.sh extended with INC7 patch (idempotent
re-apply if branding.xml ever drifts back).
Lesson: video-element state alone is insufficient verification.
Always sample pixel histogram + canvas drawImage on the painted
viewport.
Two regressions slipped through INC1-3:
INC4a -- BLACK BAND behind every detail-page carousel
Pre-existing 2026-05-08 home-page rule painted .emby-scroller {bg:#000
!important} UNSCOPED. Hits every carousel inside .itemDetailPage incl
admin-only More from Season N, More Like This. INC1-3 transparent-scope
list missed .emby-scroller / .verticalSection / .padded-top-focusscale.
Fixed by extending scope.
INC4b -- VIDEO 'BLACK SCREEN' on play
Not actually black-screen. CPU-only nullstone cannot sustain real-time
4K HEVC HDR tonemap+x264 transcode -- 0.5x realtime, ffmpeg takes ~6s
per 3s segment. With user resume seeks adding restart overhead, total
wait ~18s before browser readyState rises. User saw black, gave up.
Fix: disable EnableTonemapping (R&M fake HDR per doc 21) + cap
RemoteClientBitrateLimit=20Mbps on every user (1080p target, no 4K
scale). Headless v2 test confirms HEVC + AV1 episodes now hit
readyState=3/4 within wait window; 4K HDR R&M still slow (heaviest).
INC4 testing methodology audit -- bin/headless-test-v2.py
v1 only logged in as guest and never clicked Play. v2 runs both admin
and guest, walks 3 codec-tagged items per role (HEVC/AV1/H.264),
clicks Play, captures <video> state, sweeps DOM for opaque bgs over
backdrop layer. False positives: off-viewport #reactRoot + collapsed
.mainDrawer (negative coords). Allowlist refinement TODO.
Open: 4K HDR sources still slow even post-fix. Real fix path = pre-
transcode masters to 1080p H.264 SDR via separate batch, OR migrate to
10.11.8 with vaapi/qsv driver fixed.
After INC1 fixed the Abspielen + first-fold backdrop, owner reported black
band hiding artwork in More from Season 1 / below-fold sections. Two more
patches required:
INC2 — pin .backdropContainer + .backgroundContainer position:fixed; height
100vh so backdrop persists during scroll. Added vertical fade ::after.
INC3 — extend transparent-scope to ALL detail-page sub-sections
(.detailVerticalSection, .scrollSlider, .padded-bottom-page,
.itemsContainer etc) so section wrappers don't paint over the pinned
backdrop section by section.
bin/headless-test.py now takes top + scrolled viewport screenshots.
full_page=True hides position:fixed regressions, dual-screenshot exposes
them. Use both to bisect.
bin/apply-26-incident-fixes.sh updated with INC2+INC3.
Open: AV1+Opus playback (Mike Nolan Show) still tracked for 10.11.8
migration. .detailLogo regression possible — test in actual browser.
Symptoms: Page Unresponsive on poster grid, posters missing then black
backdrops, 'Abspielen' German Play button surviving Traefik+force-english
chases, video black-screen on play.
Root causes (different from initial guesses):
- Browser hangs: deployed index.html drifted ahead of repo; uncommitted
forceEnglishUI() text-walker MutationObserver froze main thread on poster
lazy-load. Reverted to repo HEAD.
- 'Abspielen': Cineplex theme HARDCODES German via 'content:' ::after rule
-- not a Jellyfin locale issue. Doc 25 already proved per-user UICulture
is theatre. Override CSS with content: 'Play'.
- Backdrops black: BLACK-PASS CustomCss block paints #000 !important on
.layout-desktop / .pageContainer -- occludes backdrop layer (z-index:-1).
Existing transparent-scope rule used body.itemDetailPage selector that
doesn't match in 10.10.3 (body class is libraryDocument). Replaced with
:has(.itemDetailPage) ancestor scoping.
- HLS 499: encoding.xml had EnableThrottling+EnableSegmentDeletion=true,
segments reaped before browser re-request. Disabled both.
Verified via new bin/headless-test.py (playwright Chromium login + screenshot
+ computed-style probe). Fixes idempotent and re-runnable via new
bin/apply-26-incident-fixes.sh.
Open: AV1+Opus items still black-screen in Chrome due to DirectStream
codec-tag mislabel bug. Tracked for 10.11.8 migration.
