Add asObfuscatedString cleaner

Decodes strings stored as arrays of XOR-masked char codes, with a
scripts/obfuscateString.ts helper to generate the arrays for env.json.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: peachbits

scripts/obfuscateString.ts

@@ -0,0 +1,16 @@
+// Generates the obfuscated char-code array to paste into env.json for
+// fields cleaned by asObfuscatedString.
+//
+// Usage:
+//   node -r sucrase/register scripts/obfuscateString.ts <plaintext...>
+
+import { wasObfuscatedString } from '../src/util/cleaners/asObfuscatedString'
+
+const plaintext = process.argv.slice(2).join(' ')
+
+if (plaintext === '') {
+  console.error('Usage: obfuscateString.ts <plaintext>')
+  process.exit(1)
+}
+
+console.log(JSON.stringify(wasObfuscatedString(plaintext)))

src/util/cleaners/asObfuscatedString.ts

@@ -0,0 +1,19 @@
+import { asArray, asCodec, asNumber, uncleaner } from 'cleaners'
+
+// XOR mask applied to each char code. Not a secret.
+const MASK = 0x5a
+
+/**
+ * Decodes a string stored as an array of XOR-masked char codes,
+ * e.g. "hi" <-> [0x32, 0x33]. Use `wasObfuscatedString` or
+ * scripts/obfuscateString.ts to generate the array.
+ */
+export const asObfuscatedString = asCodec<string>(
+  raw =>
+    asArray(asNumber)(raw)
+      .map(code => String.fromCharCode(code ^ MASK))
+      .join(''),
+  clean => clean.split('').map(ch => ch.charCodeAt(0) ^ MASK)
+)
+
+export const wasObfuscatedString = uncleaner(asObfuscatedString)