fix(security): replace static CSP with per-request nonce — #311 broke hydration - #326
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… hydration PR #311 set a static `script-src 'self'` CSP assuming build-time SRI integrity hashes cover all framework scripts. SRI only covers external `<script src>` tags; the App Router RSC streaming payload (`self.__next_f.push(...)`) is delivered via inline scripts, which were all blocked — React never hydrated and every page was left as an inert SSR skeleton (6 blocked inline scripts per page on dev). Move CSP delivery from static next.config headers() into src/proxy.ts: - generate a cryptographic random nonce per request - script-src 'self' 'nonce-<random>' 'strict-dynamic' (no unsafe-inline) - mirror the nonce into request headers so Next.js applies it to framework scripts (verified: inline __next_f scripts carry the nonce) - keep SRI enabled for external scripts The dynamic-rendering cost that motivated SRI over nonce in #311 does not apply here: every page is already server-rendered behind the locale proxy (only /_not-found is static). Verified locally with a production build: zero CSP console errors, login form and market order book hydrate correctly. Adds tests/unit/proxy-csp.test.ts (5 cases).
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Problem
#311 set a static
script-src 'self'CSP assuming build-time SRI integrity hashes cover all framework scripts. SRI only covers external<script src>tags — the App Router RSC streaming payload (self.__next_f.push(...)) is delivered via inline scripts, which were all blocked. React never hydrated: every page was an inert SSR skeleton (6 blocked inline scripts per page observed on dev, e.g. the home page rendered only the static 'Login / Sign Up' shell).Surfaced now because dev last deployed 2026-07-09 (
next-92db9dd), predating #311. Any production deploy of #311+ would break the same way.Fix
Move CSP delivery from static
next.config.ts headers()intosrc/proxy.ts:crypto.getRandomValues, 16 bytes, base64)script-src 'self' 'nonce-<random>' 'strict-dynamic'— nounsafe-inline;'strict-dynamic'covers webpack runtime chunk loading__next_fscripts carry the nonce attribute)/_not-foundis static)Test plan
pnpm verify(type-check + lint + coverage + build) passestests/unit/proxy-csp.test.ts: 5 cases (nonce present / no unsafe-inline in script-src / fresh nonce per request / request-header nonce consistency / healthcheck short-circuit unaffected)