adr-47 decision 2 says the site build optimises rasters, but the stdlib-only generator copies rasters verbatim; optimisation needs either an image-codec dependency (sign-off gate) or pre-optimised committed assets

adr-47 decision 2 says the site build optimises rasters, but the stdlib-only generator copies rasters verbatim; optimisation needs either an image-codec dependency (sign-off gate) or pre-optimised committed assets

Remedy grounds (2026-09-29)

• image/png exposes CompressionLevel BestCompression (https://pkg.go.dev/image/png, consulted 2026-09-29). Measured on this tree's rasters on 2026-09-29: intro.png 1,096,607 to 904,437 bytes and logo.png 186,761 to 152,744 (about 18 per cent each); the two role portraits about 2 per cent. The re-encode drops ancillary chunks such as a colour profile, hence the identical-pixels test.
• Rejected: an image-codec dependency (WebP, AVIF), which needs a sign-off for a gain the standard library already captures in large part on this tree.