raw.githubusercontent.com ignores If-Modified-Since (always returns
200), but honors If-None-Match with ETag (returns 304). This caused
every esphome compile/config run to re-download every cached external
file (audio_file, micro_wake_word, image, font, bme68x_bsec2, etc.)
sourced from a /raw/ URL.
- Send If-None-Match with the cached ETag when present
- Persist the ETag from each download in a hidden sidecar file
(.{name}.etag) and refresh it when a 304 carries a new ETag
- Replace path.write_bytes() with helpers.write_file() so downloads are
written atomically and can no longer leave partially-written cache
files behind on crash
J. Nick Koston
9f058ac1a6