{"slug":"audit-headers","title":"audit-headers","summary":"Audit security headers in a pracht app. The framework sets four defaults on every response path; this covers the exceptions — static output served outside first-party adapters, `headers()` exports that weaken defaults, and the choices only you can make (HSTS, CSP). Use for \"audit","platform":"Claude","tags":[],"authorName":"LLM Mart","authorSlug":"llm-mart","score":0,"source":"github","price":null,"verified":false,"createdAt":"2026-10-19T21:17:24.32627Z","repo":{"url":"https://github.com/JoviDeCroock/pracht","stars":99,"forks":5,"license":"MIT","updatedAt":"2026-10-19T16:43:31Z"},"bodyHtml":"
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name: audit-headers\nversion: 1.2.1\ndescription: |\nAudit security headers in a pracht app. The framework sets four defaults on\nevery response path; this covers the exceptions — static output served outside\nfirst-party adapters, headers() exports that weaken defaults, and the choices\nonly you can make (HSTS, CSP).\nUse for \"audit security headers\", \"check CSP\", \"harden headers\", \"set up HSTS\",\n\"review header policy\".\nallowed-tools:

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Pracht Audit Headers

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What the framework guarantees: four default security headers are applied\nautomatically on EVERY framework response path — SSR pages, API responses,\n404s, and static/ISG output on the first-party adapters (adapter-node,\nadapter-cloudflare) as well as the Vercel headers config generated at build\ntime:

\n\n

The helper behind this (applyDefaultSecurityHeaders) only sets a header\nwhen missing — so a route or shell headers() export always wins,\nincluding when it weakens a default. The framework does NOT set\nstrict-transport-security, content-security-policy, or cross-origin-*\nheaders — those need a project decision.

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One deliberate exception: protocol-switch responses (a 101 WebSocket\nhandshake, or any response carrying a webSocket handle) are returned exactly\nas the handler produced them, with no headers applied. This is not a gap —\ncopying the response would destroy the socket, and a handshake has no body for\na sniffing or framing policy to protect. Do not report it as a finding.

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The audit surface is therefore:

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Prerequisites: pracht inspect requires a vite config that registers the\npracht plugin; pracht inspect build and\ndist/server/headers-manifest.json require a prior pracht build. Every\nserverful target currently publishes a client copy at\ndist/client/_pracht/headers.json; only Cloudflare reads it there. Pure static\nexports deliberately do not publish that copy.

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Step 1: Inventory header sources

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pracht inspect routes --json\npracht inspect api --json\n
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MCP: when the pracht MCP server is registered (pracht dev-mcp), prefer its\ninspect_routes/inspect_api/inspect_build/doctor/verify tools over\nshelling out.

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Only route modules and shells have a headers() export — API handlers do not\n(there is no headers in the API module shape; API handlers set headers\ninline on the Response they build, and the runtime applies the defaults on\ntop). Inventory:

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Step 2: Find weakened defaults and uncovered static hosting

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Defaults are framework-applied, so do not build a \"which route is covered\"\nmatrix — instead:

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    \n
  1. For each headers() source from Step 1, flag any of the four default\nheader names set to a weaker value (e.g. x-frame-options: ALLOWALL,\nan over-permissive permissions-policy, referrer-policy: unsafe-url).\nBecause the defaults are set-when-missing, the route value wins.
    2. \n
  2. Ask how dist/client is deployed. On adapter-node, adapter-cloudflare,\nor the generated Vercel config, static/ISG responses get the defaults. If\na custom CDN or host serves dist/client directly, flag it (warn) and\nrecommend replicating the four defaults in that host's header config.
    3. \n
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Step 3: HSTS

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Grep for strict-transport-security. If absent everywhere, recommend adding\nit (e.g. via a shell headers() export or the host's config):

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\"strict-transport-security\": \"max-age=63072000; includeSubDomains; preload\"\n
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Only recommend preload if the user confirms they want to commit to HTTPS\npermanently and submit to the preload list.

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Step 4: Content-Security-Policy

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Start from the starter policy in https://pracht.resynapse.dev/docs/recipes/csp,\nthen adjust it for speculation and add observed origins:

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    \n
  1. Check which routes use speculation: read the speculation field from\npracht inspect routes --json (requires a current @pracht/cli; on older\nCLIs, grep the manifest for speculation: instead). Those routes emit an\ninline <script type=\"speculationrules\">, so add\n'inline-speculation-rules' to script-src unless you use a nonce.
    2. \n
  2. Grep the app for fetch URLs, image URLs, CSS @import, <script src>,\n<link href>, font URLs, iframe sources.
    3. \n
  3. Group by directive: default-src, script-src, style-src, img-src,\nfont-src, connect-src, frame-src; always include 'self' per\ndirective, per the starter policy.
    4. \n
  4. Pracht injects hydration state in a non-executable\n<script id=\"pracht-state\" type=\"application/json\"> — it does not need\n'unsafe-inline'. Do not add 'unsafe-inline' unless the app truly emits\nexecutable inline scripts and the tradeoff is documented.
    5. \n
  5. Routes with streaming: true emit executable inline scripts for deferred\ndata and boundary swaps. Under a nonce policy, return the request nonce as\nscriptNonce from the shell head() and allow it in script-src; it also\ncovers the speculation rules script.
    6. \n
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Output a draft CSP referencing https://pracht.resynapse.dev/docs/recipes/csp and explain what each origin is\nfor. Do not hand the user a CSP that breaks their site — present as draft.

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Step 5: Prerendered header manifest safety

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For SSG/ISG output, the framework refuses to prerender any route whose\ndocument headers include dangerous names (set-cookie, authorization,\nproxy-authorization, www-authenticate, proxy-authenticate) or\nsecret-shaped custom x-* names (token/secret/key/credential patterns) — a\nbuild containing them hard-fails. So do not hunt for those at runtime; audit\nthe headers() sources statically to catch them before a build failure,\nand report each as error with the prerender failure it would cause.

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The real target is the warn class the framework cannot catch: innocuously\nnamed headers carrying user-specific values in\ndist/server/headers-manifest.json, which serverful adapters may replay across\nusers on static responses. Every serverful build currently also copies that\nmanifest into public client output; Cloudflare reads it through the assets\nbinding, while the other adapters retain the public copy for compatibility. A\npure static export omits the client copy and has no runtime to replay the server\nmanifest; instead, verify that the deployment's host-header configuration\nmirrors only safe, non-user-specific entries. Missing host configuration means\nroute headers() values are not applied at all.

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Secret VALUES in headers are owned by audit-secrets; this skill owns policy\nheaders. Cross-reference audit-secrets for value-level findings.

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Step 6: Cross-origin isolation (optional)

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If the user mentions SharedArrayBuffer, WASM threading, or high-precision\ntimers, recommend:

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Otherwise leave these unset — they break embedded third-party content.

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Step 7: Report

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Two outputs:

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    \n
  1. Findings table (source × header × severity).
    2. \n
  2. Recommendations, in priority order:\n\n
    3. \n
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Show the exact code change required (e.g. the headers() export to fix, or\nthe CDN header config to add).

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Rules

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    \n
  1. The four defaults are framework-applied — do not recommend re-adding them\nin app code; audit for weakening and for hosting paths outside the\nfirst-party adapters.
    2. \n
  2. Never recommend a CSP with 'unsafe-eval' unless the user has documented\nwhy they need it.
    3. \n
  3. applyDefaultSecurityHeaders is set-when-missing, so per-route headers()\nwins over the defaults — weakened values are the primary finding, not\nmissing ones.
    4. \n
  4. Static/ISG responses already get the defaults on first-party adapters and\nthe generated Vercel config; only flag static hosting that bypasses those.
    5. \n
  5. Treat prerender header manifests as public artifacts.
    6. \n
  6. Do not auto-edit. Headers are policy; surface gaps, propose patches.
    7. \n
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$ARGUMENTS

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