fix(api): add Access-Control-Max-Age 86400 to CORS preflight (BUG-API-303)#187
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…-303)
Without Access-Control-Max-Age the browser re-issues an OPTIONS preflight
before every CORS request. An SPA making 5 cross-origin API calls fires
5 extra preflight roundtrips. 24h (86400) is the modern browsers' clamp
ceiling — Chrome caps at 2h, Firefox at 24h, Safari at 7d — so we ask
for the maximum standard value and let each browser apply its own clamp.
The dashboard SPA is the main beneficiary: every authed call from
instanode.dev → api.instanode.dev used to pay the preflight cost. After
this change cooperative browsers cache the preflight result for up to
2h (Chrome) / 24h (Firefox).
Coverage block:
Symptom: OPTIONS preflight responses missing Access-Control-Max-Age
Enumeration: rg -F "fiberCORS" internal/ — 1 emit site in router.go
Sites found: 1
Sites touched: 1
Coverage test: TestCORSPreflight_HasMaxAgeHeader (new file
cors_maxage_test.go) — drives an OPTIONS preflight
through a fiberCORS-mirrored config and asserts
Access-Control-Max-Age=86400 on the response. Fails
today before the router.go change.
Live verified: pending merge + auto-deploy + curl -X OPTIONS -H
"Origin: https://instanode.dev" -H "Access-Control-
Request-Method: POST" https://api.instanode.dev/api/v1/whoami
| grep access-control-max-age
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Summary
OPTIONSpreflight responses had noAccess-Control-Max-Age, so browsers re-issue a preflight before every CORS request — every authed call frominstanode.dev→api.instanode.devpaid the extra roundtripMaxAge: 86400(24h) on the fiberCORS middleware. Chrome clamps to 2h, Firefox 24h, Safari 7d — we ask for the max standard value and let each browser apply its clampRule-17 coverage block
OPTIONSpreflight missingAccess-Control-Max-Agerg -F 'fiberCORS' internal/— 1 emit site (router.go)TestCORSPreflight_HasMaxAgeHeader(new fileinternal/router/cors_maxage_test.go) — drives an OPTIONS preflight through a config that mirrorsrouter.Newverbatim and assertsAccess-Control-Max-Age=86400on the response. Fails today before therouter.gochange.curl -X OPTIONS -H "Origin: https://instanode.dev" -H "Access-Control-Request-Method: POST" https://api.instanode.dev/api/v1/whoami | grep access-control-max-ageTest plan
go build ./.../go vet ./...go test ./internal/router/... -short -count=1(all pass including the new test)curl -X OPTIONS -H "Origin: https://instanode.dev" ...returnsaccess-control-max-age: 86400