The previous runner encoded everything at a fixed -cq 27 with -maxrate = 1.5x the FILE bitrate,
which is how a library ended up at 111% of its source size. This replaces the encode step with the
policy the skill documents, and adds the gates that make it a guarantee:
* classify by bpp: <0.025 copy the video (bit-identical), 0.025-0.040 hevc_nvenc, >0.040 libx265
* -maxrate = 1.0x the source's VIDEO bitrate (never the file total) + a post-encode assertion
* SSIM gate: per-frame comparison of a 60 s window against the source, retry once at +2 quality
if it fails, then fail the item (the original is never touched)
* audio: copy when AAC, else AAC at the SOURCE's bitrate (a fixed 256k cancelled the video saving)
* x265 tier pinned to the E-cores; --tier to run tiers separately; --keep-local for a pilot that
touches nothing
* defaults cq31 / crf26 from the measurement below, not cq27
Measured on three real sources (60 s window, video-only): cq27 GROWS two of three files (115%,
119%); cq31 lands at 43-74%; x265 crf26 at 34-67% with min SSIM 0.988-0.993 - and x265 beats NVENC
by 10-22% at matched SSIM. Pinning min SSIM >= 0.996 leaves only cq27, which is bigger than the
source, so ~0.99 is the usable quality frontier and the owner gets to make that call explicitly
(references/hevc-conversion-policy.md section 11, SKILL.md scope section).
