feat: expose fund ownership assertions

src/lnurlcash/ops/shared.ts

@@ -19,45 +19,102 @@ export class UncertainOutcomeError extends Error {
   }
 }
 
+// the wait was interrupted from outside (service shutdown) - distinct
+// from budget exhaustion so the caller can treat it as normal teardown
+export class PollAbortedError extends Error {
+  constructor() {
+    super('The wait was interrupted by shutdown.')
+    this.name = 'PollAbortedError'
+  }
+}
+
+export type FundOperationOptions = LnurlcashOptions & {
+  readonly assertOwner?: () => void
+}
+
+export const assertFundOwner = (options: FundOperationOptions): void => {
+  options.assertOwner?.()
+}
+
 export type PollOptions = {
   // first delay between checks (doubles each round up to intervalCapMs)
   intervalMs?: number
   intervalCapMs?: number
   // total budget before giving up
   maxWaitMs?: number
+  // aborts the wait promptly (shutdown). Only the WAIT is interruptible:
+  // callers pass this for work whose observation phase may outlive the
+  // caller - once pollVerifyUntilSettled has returned, the signal no
+  // longer reaches anything
+  signal?: AbortSignal
 }
 
-const DEFAULT_POLL: Required<PollOptions> = {
+const DEFAULT_POLL: Required<Omit<PollOptions, 'signal'>> = {
   intervalMs: 1000,
   intervalCapMs: 5000,
-  maxWaitMs: 120_000
+  maxWaitMs: 120_000,
 }
 
-const sleep = (ms: number): Promise<void> =>
-  new Promise(resolve => setTimeout(resolve, ms))
+const sleep = (ms: number): Promise<void> => new Promise((resolve) => setTimeout(resolve, ms))
+
+// a sleep that ends immediately on abort instead of riding out its timer
+const abortableSleep = (ms: number, signal: AbortSignal): Promise<void> =>
+  new Promise((resolve, reject) => {
+    const onAbort = (): void => {
+      clearTimeout(timer)
+      reject(new PollAbortedError())
+    }
+    const timer = setTimeout(() => {
+      signal.removeEventListener('abort', onAbort)
+      resolve()
+    }, ms)
+    if (signal.aborted) {
+      clearTimeout(timer)
+      reject(new PollAbortedError())
+      return
+    }
+    signal.addEventListener('abort', onAbort, {once: true})
+  })
 
 // polls a LUD-21/LUD-25 verify endpoint until it reports settled, with
 // backoff, inside a total time budget. A single failed check isn't fatal -
 // the next round tries again. Returns the settled VerifyResult; throws on
-// budget exhaustion.
+// budget exhaustion, or PollAbortedError when the caller's signal fires
+// (a hung fetch is interrupted too: the signal is bound into the request).
 export const pollVerifyUntilSettled = async (
   verifyUrl: string,
   poll: PollOptions,
-  options: LnurlcashOptions
+  options: LnurlcashOptions,
 ): Promise<VerifyResult> => {
-  const {intervalMs, intervalCapMs, maxWaitMs} = {...DEFAULT_POLL, ...poll}
+  const {intervalMs, intervalCapMs, maxWaitMs, signal} = {
+    ...DEFAULT_POLL,
+    ...poll,
+  }
+  const fetchOptions: LnurlcashOptions = signal
+    ? {
+        ...options,
+        fetch: (input, init) => {
+          const base = options.fetch ?? globalThis.fetch
+          return base(input, {...init, signal})
+        },
+      }
+    : options
   const deadline = Date.now() + maxWaitMs
   let delay = intervalMs
   let lastError: unknown = null
   while (Date.now() < deadline) {
+    if (signal?.aborted) throw new PollAbortedError()
     try {
-      const result = await fetchInvoiceVerification(verifyUrl, options)
+      const result = await fetchInvoiceVerification(verifyUrl, fetchOptions)
       if (result.settled) return result
       lastError = null
     } catch (err) {
+      // the signal's own AbortError lands here on an interrupted fetch
+      if (signal?.aborted) throw new PollAbortedError()
       lastError = err
     }
-    await sleep(Math.min(delay, Math.max(0, deadline - Date.now())))
+    if (signal) await abortableSleep(Math.min(delay, Math.max(0, deadline - Date.now())), signal)
+    else await sleep(Math.min(delay, Math.max(0, deadline - Date.now())))
     delay = Math.min(delay * 2, intervalCapMs)
   }
   if (lastError instanceof Error) {