[jm-rivera]

Next 16.4.5, on dev since #120, strips content-encoding, content-length and transfer-encoding from every route-handler Response in sendResponse (next/dist/server/send-response.js; 16.4.4 has no such filter). src/lib/proxy/compress.ts gzipped relayed bodies and labelled them, so the bytes reached clients unlabelled and any client that accepts gzip, Node's fetch included, failed to parse the JSON. Next's own compression cannot take over: sendResponse copies headers with appendHeader, which stores Content-Type as an array, and the compression middleware skips a non-string type, so even /sitemap.xml goes out uncompressed.

The proxy therefore stops encoding bodies. compress.ts and its test are deleted, and forward() relays the body as fetch decoded it. Cloudflare compresses responses in front of production; staging's run.app host has no Cloudflare and serves the API uncompressed. Clients see chunked responses with no Content-Length, which Next strips whatever the proxy does. main is still on Next 16.3.0, so production is unaffected until the next release.

forward() reads the first chunk of every body except event streams and /mcp before the response goes out, so a body that fails before its first byte still gets a logged 502 problem document, as it did on the gzip path. Everything after the first chunk streams unread.

src/lib/proxy/test/forward.test.ts runs forward() against a local upstream that gzips: with and without Accept-Encoding: gzip the client gets no Content-Encoding and the decoded bytes; a body that fails before its first byte gets the 502; one that fails later gets a 200 whose body errors; an event stream reaches the client before the upstream ends. forward() imports server-only, @/ paths and extensionless modules, so the test loads it through resolve hooks in src/lib/test/serverModules.ts, registered with module.register. Once @types/node is at 22 or later, module.registerHooks can replace the two files with one call.

Closes #128

Testing: pnpm lint, pnpm lint:css, pnpm typecheck, pnpm test (2267 pass), pnpm build. The gzip and 502 tests fail on dev. On the built standalone server with a gzipping fake upstream, /api/v1/graph/schema and /openapi.json return plain JSON with no Content-Encoding, with and without Accept-Encoding: gzip, and Node fetch parses both.

scripts/share-migration-round-trip.ts passes on a build of this branch against the seeded dfo-apis local stack with no Accept-Encoding override, and proxied /api/v1/datasets responses arrive as plain JSON.