docs: record post-deploy QSV/OpenCL runtime fixes in spec

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

docs/superpowers/specs/2026-07-26-jellyfin-hw-transcoding.md

@@ -106,3 +106,40 @@ show up as low CPU, some GPU (`intel_gpu_top`) activity instead.
 - Exact supported codec list depends on the iGPU generation (device ID
   `9a49`) — confirm via `vainfo` output once run, and enable only the
   hardware decode paths it actually reports.
+
+## Post-deploy fix: two additional runtime packages required
+
+After the initial deploy (Task 1's `SupplementaryGroups` grant) and
+enabling QSV in the dashboard, HEVC HDR playback hung indefinitely
+(Direct Play worked for some titles; titles that needed a real
+transcode+tonemap never produced output). Root-caused via
+`journalctl -u jellyfin` and the per-session ffmpeg transcode log
+(`find / -xdev -iname '*ffmpeg-transcode*'`) — two separate runtimes
+were missing beyond `intel-media-driver` (which only provides VAAPI):
+
+1. **QSV session creation failed:** `Error creating a MFX session: -9`
+   / `Error initializing an MFX session: -3` on
+   `-init_hw_device qsv=qs@va`. VAAPI and QSV are separate runtimes on
+   Linux — QSV needs the oneVPL/MFX GPU implementation. Fix: added
+   `pkgs.vpl-gpu-rt` ("oneAPI Video Processing Library Intel GPU
+   implementation"; note `onevpl-intel-gpu` is the old, renamed
+   attribute) to `hardware.graphics.extraPackages` in
+   `machines/jupiter/hardware-configuration.nix`.
+
+2. **OpenCL device creation failed:** `Failed to get number of OpenCL
+   platforms: -1001` (`CL_PLATFORM_NOT_FOUND_KHR`) on
+   `-init_hw_device opencl=ocl@va`. The `tonemap_opencl` filter jellyfin
+   uses for HDR→SDR tone-mapping needs a working OpenCL ICD, which
+   nothing installed so far provides. Fix: added
+   `pkgs.intel-compute-runtime` ("Intel Graphics Compute Runtime oneAPI
+   Level Zero and OpenCL, supporting 12th Gen and newer" — matches
+   jupiter's Tiger Lake/Xe iGPU) to the same `extraPackages` list.
+
+Confirmed working end-to-end: HEVC HDR transcode with QSV encode +
+OpenCL tone-map runs at `speed=2.68x` realtime on jupiter's iGPU, and
+plays smoothly on Apple TV (JellyTV app).
+
+Both packages live in `machines/jupiter/hardware-configuration.nix`
+(`hardware.graphics.extraPackages`), alongside `intel-media-driver`,
+rather than in the jellyfin module itself — they're iGPU runtime
+capabilities, not something specific to the jellyfin service.