refactor(jetstream): extract webhook dispatch and bulk-create modules

dispatchAll, fireWebhooks, and the bulk-create debounce buffer
move out of jetstream.ts into src/jetstream/{webhooks,bulk}.ts.
fireWebhooks and the bulk helpers now take their DB lookup and
dispatch as parameters so tests can inject stubs. Top-level
Jetstream construction, event handlers, ensureIndex call, and
the cursor-saving interval are gated behind import.meta.main so
importing jetstream.ts no longer opens a WebSocket.

src/jetstream/bulk.ts

@@ -0,0 +1,66 @@
+import { log } from "../log.ts";
+import type { GetSubsByVerb, WebhookTarget } from "./webhooks.ts";
+
+export const BULK_CREATE_DEBOUNCE_MS = 500;
+
+export type BulkDeps = {
+  getSubs: GetSubsByVerb;
+  dispatch: (
+    webhooks: WebhookTarget[],
+    payload: Record<string, unknown>,
+    label: string,
+  ) => Promise<void>;
+  debounceMs?: number;
+};
+
+type BulkBuffer = {
+  records: Record<string, unknown>[];
+  timer: number;
+};
+
+const bulkBuffers = new Map<string, BulkBuffer>();
+
+export const flushBulkCreate = async (
+  did: string,
+  deps: BulkDeps,
+): Promise<void> => {
+  const buffer = bulkBuffers.get(did);
+  if (!buffer) return;
+  bulkBuffers.delete(did);
+  const webhooks = deps.getSubs(did, "bulk-create");
+  log(`[jetstream] bulk-create ${did}: ${buffer.records.length} record(s)`);
+  await deps.dispatch(
+    webhooks,
+    { event: "bulk-create", did, records: buffer.records },
+    `bulk-create ${did}`,
+  );
+};
+
+// Buffered records are not persisted: if jetstream restarts mid-window, those
+// `bulk-create` notifications are lost. Subscribers reconcile on cold start
+// because the underlying notes are already saved to the `note` table.
+export const queueBulkCreate = (
+  did: string,
+  record: Record<string, unknown>,
+  deps: BulkDeps,
+): void => {
+  const ms = deps.debounceMs ?? BULK_CREATE_DEBOUNCE_MS;
+  const existing = bulkBuffers.get(did);
+  if (existing) {
+    clearTimeout(existing.timer);
+    existing.records.push(record);
+    existing.timer = setTimeout(() => flushBulkCreate(did, deps), ms);
+    return;
+  }
+  bulkBuffers.set(did, {
+    records: [record],
+    timer: setTimeout(() => flushBulkCreate(did, deps), ms),
+  });
+};
+
+export const _resetBulkBuffersForTest = (): void => {
+  for (const buffer of bulkBuffers.values()) {
+    clearTimeout(buffer.timer);
+  }
+  bulkBuffers.clear();
+};

src/jetstream/webhooks.ts

@@ -0,0 +1,49 @@
+import type { WebhookVerb } from "../data/db.ts";
+import { log } from "../log.ts";
+
+export type WebhookTarget = {
+  method: string;
+  url: string;
+  token?: string;
+};
+
+export const dispatchAll = async (
+  webhooks: WebhookTarget[],
+  payload: Record<string, unknown>,
+  label: string,
+): Promise<void> => {
+  if (webhooks.length === 0) return;
+  const results = await Promise.allSettled(
+    webhooks.map(({ method, url, token }) => {
+      const hasBody = method !== "GET" && method !== "HEAD";
+      return fetch(url, {
+        method,
+        headers: {
+          ...(hasBody ? { "Content-Type": "application/json" } : {}),
+          ...(token ? { Authorization: `Bearer ${token}` } : {}),
+        },
+        body: hasBody ? JSON.stringify(payload) : undefined,
+      });
+    }),
+  );
+  for (const result of results) {
+    if (result.status === "rejected") {
+      log(`[jetstream] ${label} webhook error:`, result.reason);
+    }
+  }
+};
+
+export type GetSubsByVerb = (
+  did: string,
+  verb: WebhookVerb,
+) => WebhookTarget[];
+
+export const fireWebhooks = async (
+  did: string,
+  verb: WebhookVerb,
+  payload: Record<string, unknown>,
+  getSubs: GetSubsByVerb,
+): Promise<void> => {
+  const webhooks = getSubs(did, verb);
+  await dispatchAll(webhooks, payload, `${verb} ${did}`);
+};