done

lib/signedRequest.ts

@@ -0,0 +1,93 @@
+/**
+ * Signed-request helper. Must match backend/app/services/signed_request.py exactly.
+ *
+ * Message format:
+ *   TrumpSignal · {ACTION}
+ *   wallet: {wallet_lowercase}
+ *   timestamp: {ms}
+ *   body: {sha256_hex or "-"}
+ */
+
+async function sha256Hex(text: string): Promise<string> {
+  const buf = await crypto.subtle.digest('SHA-256', new TextEncoder().encode(text))
+  return Array.from(new Uint8Array(buf))
+    .map((b) => b.toString(16).padStart(2, '0'))
+    .join('')
+}
+
+/** Canonical JSON: sorted keys, no whitespace. Must match Python's json.dumps(..., sort_keys, separators). */
+function canonicalJson(v: unknown): string {
+  if (v === null || typeof v !== 'object') return JSON.stringify(v)
+  if (Array.isArray(v)) return '[' + v.map(canonicalJson).join(',') + ']'
+  const keys = Object.keys(v as object).sort()
+  return '{' + keys.map((k) => JSON.stringify(k) + ':' + canonicalJson((v as Record<string, unknown>)[k])).join(',') + '}'
+}
+
+export async function bodyHash(body: unknown | null): Promise<string> {
+  if (body === null || body === undefined) return '-'
+  return sha256Hex(canonicalJson(body))
+}
+
+export async function buildSignMessage(
+  action: string,
+  wallet: string,
+  timestampMs: number,
+  body: unknown | null,
+): Promise<string> {
+  const h = await bodyHash(body)
+  return `TrumpSignal · ${action}\nwallet: ${wallet.toLowerCase()}\ntimestamp: ${timestampMs}\nbody: ${h}`
+}
+
+export interface SignedEnvelope {
+  wallet: string
+  timestamp: number
+  signature: string
+}
+
+/**
+ * Produce {timestamp, signature} for a given action + optional body.
+ * Caller supplies wagmi's `signMessageAsync`.
+ */
+/**
+ * Get-or-create a cached "view" envelope for a wallet. Reused across page loads
+ * within a 4-minute window (server accepts 5-min skew). Backend's replay-guard
+ * is disabled for the view action so the same sig can be used multiple times.
+ */
+const VIEW_TTL_MS = 4 * 60 * 1000
+
+export async function getOrCreateViewEnvelope(params: {
+  action: string
+  wallet: string
+  signMessageAsync: (args: { message: string }) => Promise<string>
+}): Promise<SignedEnvelope> {
+  if (typeof window === 'undefined') throw new Error('view envelope requires browser')
+  const wallet = params.wallet.toLowerCase()
+  const cacheKey = `ts:view:${params.action}:${wallet}`
+  const raw = sessionStorage.getItem(cacheKey)
+  if (raw) {
+    try {
+      const env = JSON.parse(raw) as SignedEnvelope
+      if (Date.now() - env.timestamp < VIEW_TTL_MS) return env
+    } catch {}
+  }
+  const env = await signRequest({
+    action: params.action,
+    wallet,
+    body: null,
+    signMessageAsync: params.signMessageAsync,
+  })
+  sessionStorage.setItem(cacheKey, JSON.stringify(env))
+  return env
+}
+
+export async function signRequest(params: {
+  action: string
+  wallet: string
+  body: unknown | null
+  signMessageAsync: (args: { message: string }) => Promise<string>
+}): Promise<SignedEnvelope> {
+  const timestamp = Date.now()
+  const message = await buildSignMessage(params.action, params.wallet, timestamp, params.body)
+  const signature = await params.signMessageAsync({ message })
+  return { wallet: params.wallet.toLowerCase(), timestamp, signature }
+}