[compression]

Brotli and gzip compression of responses, negotiated from Accept-Encoding.

gio.toml

[compression]
enabled = true
min_size_bytes = 1024
prefer_brotli = true

Reference

Key	Default	Description
`enabled`boolean	`true`	Compress responses for clients that accept it. Turn it off when a proxy or CDN in front compresses: compressing twice only costs CPU.`0` / `false` / empty: Every response is sent uncompressed
`min_size_bytes`integer	`1024`	Responses with a known length below this many bytes are sent as-is - compressing them costs more than it saves. Streamed responses have no known length and are always compressed. At most 65535; a larger value is a startup error.
`prefer_brotli`boolean	`true`	`true`: Brotli for clients that accept it, gzip otherwise. `false`: gzip only, which costs less CPU per response (every client that accepts Brotli also accepts gzip).`0` / `false` / empty: gzip only

Brotli (br) and gzip are the only encodings; a client that accepts neither gets the plain body.
Never compressed: images (image/*), server-sent events (text/event-stream), gRPC, responses that already carry a Content-Encoding, and partial (Content-Range) responses. A route.ts returning fetch(upstream) does not count: the body fetch() decoded is sent without the upstream's encoding and compressed here.
Every response the layer could compress carries Vary: accept-encoding, so caches keep one copy per encoding. With enabled = false no response gets it.
Compression is the outermost response step: it runs after the security headers, CSP nonces and <html lang> have been written into the body.

Startup logs response compression disabled ([compression] enabled = false) when it is off. No key in this section logs a warning.

gio.toml

[compression]
enabled = false

gio.toml

[compression]
prefer_brotli = false       # gzip is cheaper to produce
min_size_bytes = 4096

A cached page's weak ETag stands for all of its encodings, and a 304 keeps the Vary its 200 would carry.
While CSP nonces are on, a route handler must not compress its own body: a response with its own Content-Encoding is refused with 500. Leave compression to the server.

Version	Changes
`v0.1.0-beta.8`	Introduced as a gio.toml section: `enabled`, `min_size_bytes` and `prefer_brotli` are honored.
`v0.1.0-beta.1`	Brotli and gzip compression of responses of 1 KB and more, not configurable.