Derive the CSP script hashes from app.html

svelte.config.js

@@ -1,5 +1,16 @@
 import adapter from "@sveltejs/adapter-static"
 import {vitePreprocess} from "@sveltejs/vite-plugin-svelte"
+import {createHash} from "node:crypto"
+import {readFileSync} from "node:fs"
+
+// Sveltekit hashes the scripts it injects itself, but not the ones app.html carries, so those
+// have to be named in script-src by hand. Hashing them here rather than pasting a literal is
+// what stops an edit to app.html silently violating the policy.
+const appHtmlScripts = [
+  ...readFileSync(new URL("./src/app.html", import.meta.url), "utf8").matchAll(
+    /<script(?![^>]*\bsrc=)[^>]*>([\s\S]*?)<\/script>/g,
+  ),
+].map(([, script]) => "sha256-" + createHash("sha256").update(script).digest("base64"))
 
 /** @type {import('@sveltejs/kit').Config} */
 export default {
@@ -19,7 +30,7 @@ export default {
     },
     csp: {
       directives: {
-        "script-src": ["self", "wasm-unsafe-eval", "https://plausible.coracle.social", "sha256-NpqGpeZTuPniNAucgyfqzWy9iIHwOswFzPzpigwvp/c="],
+        "script-src": ["self", "wasm-unsafe-eval", "https://plausible.coracle.social", ...appHtmlScripts],
         "worker-src": ["self", "blob:"],
         "style-src": ["self", "unsafe-inline"],
         "frame-src": ["none"],