diff --git a/bun.lock b/bun.lock
index f5ecec2f9..5f80b89c7 100644
--- a/bun.lock
+++ b/bun.lock
@@ -253,6 +253,14 @@
         "typescript-eslint": "^8.26.0",
       },
     },
+    "packages/stripe-sync": {
+      "name": "@autumn/stripe-sync",
+      "version": "1.0.0",
+      "dependencies": {
+        "@supabase/stripe-sync-engine": "^0.48.5",
+        "stripe": "catalog:",
+      },
+    },
     "scripts": {
       "name": "@autumn/scripts",
       "version": "1.0.0",
@@ -282,6 +290,7 @@
         "@anthropic-ai/sdk": "^0.32.1",
         "@autumn/ksuid": "workspace:*",
         "@autumn/shared": "workspace:*",
+        "@autumn/stripe-sync": "workspace:*",
         "@aws-sdk/client-s3": "^3.1017.0",
         "@aws-sdk/client-scheduler": "^3.1004.0",
         "@aws-sdk/client-sqs": "^3.958.0",
@@ -603,6 +612,8 @@
 
     "@autumn/shared": ["@autumn/shared@workspace:shared"],
 
+    "@autumn/stripe-sync": ["@autumn/stripe-sync@workspace:packages/stripe-sync"],
+
     "@autumn/vite": ["@autumn/vite@workspace:vite"],
 
     "@aws-crypto/crc32": ["@aws-crypto/crc32@5.2.0", "", { "dependencies": { "@aws-crypto/util": "^5.2.0", "@aws-sdk/types": "^3.222.0", "tslib": "^2.6.2" } }, "sha512-nLbCWqQNgUiwwtFsen1AdzAtvuLRsQS8rYgMuxCrdKf9kOssamGLuPwyTY9wyYblNr9+1XM8v6zoDTPPSIeANg=="],
@@ -1921,6 +1932,8 @@
 
     "@supabase/storage-js": ["@supabase/storage-js@2.102.1", "", { "dependencies": { "iceberg-js": "^0.8.1", "tslib": "2.8.1" } }, "sha512-eCL9T4Xpe40nmKlkUJ7Zq/hk34db1xPiT0WL3Iv5MbJqHuCAe5TxhV8Rjqd6DNZrzjtfYObZtYl9jKJaHrivqw=="],
 
+    "@supabase/stripe-sync-engine": ["@supabase/stripe-sync-engine@0.48.5", "", { "dependencies": { "pg": "^8.20.0", "pg-node-migrations": "0.0.8", "yesql": "^7.0.0" }, "peerDependencies": { "stripe": "> 18" } }, "sha512-+LbtJH8n5Xiu289AL3FuWFdKXd0K7kDF0z4Lm+zMYoImWmOuGd3TgSx9gm/nv4nzLooOmIxGZh6LojoYBcJM+g=="],
+
     "@supabase/supabase-js": ["@supabase/supabase-js@2.102.1", "", { "dependencies": { "@supabase/auth-js": "2.102.1", "@supabase/functions-js": "2.102.1", "@supabase/postgrest-js": "2.102.1", "@supabase/realtime-js": "2.102.1", "@supabase/storage-js": "2.102.1" } }, "sha512-bChxPVeLDnYN9M2d/u4fXsvylwSQG5grAl+HN8f+ZD9a9PuVU+Ru+xGmEsk+b9Iz3rJC9ZQnQUJYQ28fApdWYA=="],
 
     "@swc/helpers": ["@swc/helpers@0.5.15", "", { "dependencies": { "tslib": "^2.8.0" } }, "sha512-JQ5TuMi45Owi4/BIMAJBoSQoOJu12oOk/gADqlcUL9JEdHB8vyjUSsxqeNXnmXHjYKMi2WcYtezGEEhqUI/E2g=="],
@@ -4369,6 +4382,8 @@
 
     "pg-int8": ["pg-int8@1.0.1", "", {}, "sha512-WCtabS6t3c8SkpDBUlb1kjOs7l66xsGdKpIPZsg4wR+B3+u9UAum2odSsF9tnvxg80h4ZxLWMy4pRjOsFIqQpw=="],
 
+    "pg-node-migrations": ["pg-node-migrations@0.0.8", "", { "dependencies": { "pg": "^8.6.0", "sql-template-strings": "^2.2.2" }, "bin": { "pg-validate-migrations": "dist/bin/validate.js" } }, "sha512-44cMl9umOmCv0hzZyEcvjEq8Bm8u7mrzggZ06qXTJVSsMMB4j2OsjG+rSp+uzeKWyP2Vu0K9Ye2wKtjFUJwrdw=="],
+
     "pg-pool": ["pg-pool@3.13.0", "", { "peerDependencies": { "pg": ">=8.0" } }, "sha512-gB+R+Xud1gLFuRD/QgOIgGOBE2KCQPaPwkzBBGC9oG69pHTkhQeIuejVIk3/cnDyX39av2AxomQiyPT13WKHQA=="],
 
     "pg-protocol": ["pg-protocol@1.13.0", "", {}, "sha512-zzdvXfS6v89r6v7OcFCHfHlyG/wvry1ALxZo4LqgUoy7W9xhBDMaqOuMiF3qEV45VqsN6rdlcehHrfDtlCPc8w=="],
@@ -4867,6 +4882,8 @@
 
     "sprintf-js": ["sprintf-js@1.0.3", "", {}, "sha512-D9cPgkvLlV3t3IzL0D0YLvGA9Ahk4PcvVwUbN0dSGr1aP0Nrt4AEnTUbuGvquEC0mA64Gqt1fzirlRs5ibXx8g=="],
 
+    "sql-template-strings": ["sql-template-strings@2.2.2", "", {}, "sha512-UXhXR2869FQaD+GMly8jAMCRZ94nU5KcrFetZfWEMd+LVVG6y0ExgHAhatEcKZ/wk8YcKPdi+hiD2wm75lq3/Q=="],
+
     "sqs-consumer": ["sqs-consumer@6.0.2", "", { "dependencies": { "@aws-sdk/client-sqs": "^3.226.0", "debug": "^4.3.4" } }, "sha512-Y8ztFBc1VPj4q72j9Uji4XR6n2O88n9X83aOUaCvz9zZqjpGJaI4PBHBPnE8RDBgD0EQR8Dh+sQwH/+8mzr+Bg=="],
 
     "stack-utils": ["stack-utils@2.0.6", "", { "dependencies": { "escape-string-regexp": "^2.0.0" } }, "sha512-XlkWvfIm6RmsWtNJx+uqtKLS8eqFbxUg0ZzLXqY0caEy9l7hruX8IpiDnjsLavoBgqCCR71TqWO8MaXYheJ3RQ=="],
@@ -5377,6 +5394,8 @@
 
     "yauzl": ["yauzl@2.10.0", "", { "dependencies": { "buffer-crc32": "~0.2.3", "fd-slicer": "~1.1.0" } }, "sha512-p4a9I6X6nu6IhoGmBqAcbJy1mlC4j27vEPZX9F4L4/vZT3Lyq1VkFHw/V/PUcB9Buo+DG3iHkT0x3Qya58zc3g=="],
 
+    "yesql": ["yesql@7.0.0", "", {}, "sha512-sosfr7agy4ibLM7BvXBkM6BpBmKMGuBO8DUYQEuey+QqaqrgW+2bsSg6D050ocBYIz0PuHxUyehyzEztZTU4pw=="],
+
     "yn": ["yn@3.1.1", "", {}, "sha512-Ux4ygGWsu2c7isFWe8Yu1YluJmqVhxqK2cLXNQA5AcC3QfbGNpM7fu0Y8b/z16pXLnFxZYvWhd3fhBY9DLmC6Q=="],
 
     "yocto-queue": ["yocto-queue@1.2.2", "", {}, "sha512-4LCcse/U2MHZ63HAJVE+v71o7yOdIe4cZ70Wpf8D/IyjDKYQLV5GD46B+hSTjJsvV5PztjvHoU580EftxjDZFQ=="],
diff --git a/package.json b/package.json
index 9f05e4477..0d571ce90 100644
--- a/package.json
+++ b/package.json
@@ -15,7 +15,8 @@
 			"packages/sdk",
 			"packages/autumn-js",
 			"packages/openapi",
-			"packages/ksuid"
+			"packages/ksuid",
+			"packages/stripe-sync"
 		],
 		"catalog": {
 			"stripe": "19.3.0-beta.1",
@@ -107,7 +108,9 @@
 		"js:publish": "bun js:build && cd packages/autumn-js && npm publish",
 		"js:publish-beta": "bun js:build && cd packages/autumn-js && npm publish --tag beta",
 		"js:publish-dry": "bun js:build && cd packages/autumn-js && npm publish --dry-run",
-		"js:version": "git fetch --tags origin && git tag -l 'autumn-js-v*' --sort=-v:refname | head -1"
+		"js:version": "git fetch --tags origin && git tag -l 'autumn-js-v*' --sort=-v:refname | head -1",
+		"stripe-sync:migrate": "bun packages/stripe-sync/scripts/migrate.ts",
+		"stripe-sync:migrate:prod": "NODE_ENV=production infisical run --env=prod -- bun packages/stripe-sync/scripts/migrate.ts"
 	},
 	"dependencies": {
 		"@aws-sdk/client-sqs": "^3.985.0",
diff --git a/packages/stripe-sync/package.json b/packages/stripe-sync/package.json
new file mode 100644
index 000000000..5249fb210
--- /dev/null
+++ b/packages/stripe-sync/package.json
@@ -0,0 +1,20 @@
+{
+	"name": "@autumn/stripe-sync",
+	"version": "1.0.0",
+	"description": "Stripe-to-Postgres sync engine wrapper for Autumn",
+	"type": "module",
+	"main": "./src/index.ts",
+	"types": "./src/index.ts",
+	"exports": {
+		".": {
+			"types": "./src/index.ts",
+			"import": "./src/index.ts",
+			"default": "./src/index.ts"
+		}
+	},
+	"private": true,
+	"dependencies": {
+		"@supabase/stripe-sync-engine": "^0.48.5",
+		"stripe": "catalog:"
+	}
+}
diff --git a/packages/stripe-sync/scripts/migrate.ts b/packages/stripe-sync/scripts/migrate.ts
new file mode 100644
index 000000000..e80874c6d
--- /dev/null
+++ b/packages/stripe-sync/scripts/migrate.ts
@@ -0,0 +1,26 @@
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+import { config } from "dotenv";
+import { addAutumnColumns, runStripeSyncMigrations } from "../src/index.js";
+
+const scriptDir = path.dirname(fileURLToPath(import.meta.url));
+const repoRoot = path.resolve(scriptDir, "../../..");
+
+config({ path: path.join(repoRoot, "server/.env"), override: true });
+
+const databaseUrl = process.env.STRIPE_SYNC_DATABASE_URL;
+
+if (!databaseUrl) {
+	console.error("STRIPE_SYNC_DATABASE_URL is required");
+	process.exit(1);
+}
+
+console.log("Running stripe sync migrations...");
+await runStripeSyncMigrations({ databaseUrl });
+console.log("Stripe sync migrations complete");
+
+console.log(
+	"Adding Autumn columns (stripe_account_id, org_id) to synced tables...",
+);
+await addAutumnColumns({ databaseUrl });
+console.log("Autumn columns added");
diff --git a/packages/stripe-sync/src/addAccountIdColumn.ts b/packages/stripe-sync/src/addAccountIdColumn.ts
new file mode 100644
index 000000000..95d09c968
--- /dev/null
+++ b/packages/stripe-sync/src/addAccountIdColumn.ts
@@ -0,0 +1,37 @@
+import pg from "pg";
+import { SYNCED_TABLES } from "./eventTypeToTable.js";
+
+/**
+ * Adds `stripe_account_id` and `org_id` columns + indexes to all synced tables.
+ * Idempotent -- safe to run multiple times.
+ */
+export const addAutumnColumns = async ({
+	databaseUrl,
+	schema = "stripe",
+}: {
+	databaseUrl: string;
+	schema?: string;
+}): Promise<void> => {
+	const client = new pg.Client({ connectionString: databaseUrl });
+	await client.connect();
+
+	try {
+		for (const table of SYNCED_TABLES) {
+			await client.query(`
+				ALTER TABLE "${schema}"."${table}"
+				ADD COLUMN IF NOT EXISTS stripe_account_id TEXT,
+				ADD COLUMN IF NOT EXISTS org_id TEXT
+			`);
+			await client.query(`
+				CREATE INDEX IF NOT EXISTS idx_${table}_stripe_account_id
+				ON "${schema}"."${table}" (stripe_account_id)
+			`);
+			await client.query(`
+				CREATE INDEX IF NOT EXISTS idx_${table}_org_id
+				ON "${schema}"."${table}" (org_id)
+			`);
+		}
+	} finally {
+		await client.end();
+	}
+};
diff --git a/packages/stripe-sync/src/eventTypeToTable.ts b/packages/stripe-sync/src/eventTypeToTable.ts
new file mode 100644
index 000000000..6772935b2
--- /dev/null
+++ b/packages/stripe-sync/src/eventTypeToTable.ts
@@ -0,0 +1,61 @@
+/**
+ * Maps a Stripe event type to the sync DB table that stores the object.
+ * Returns undefined for event types that don't map to a known table.
+ */
+export const eventTypeToTable = ({
+	eventType,
+}: {
+	eventType: string;
+}): string | undefined => {
+	if (eventType.startsWith("charge.dispute.")) return "disputes";
+	if (eventType.startsWith("charge.")) return "charges";
+	if (eventType.startsWith("checkout.session.")) return "checkout_sessions";
+	if (eventType.startsWith("customer.subscription.")) return "subscriptions";
+	if (eventType.startsWith("customer.tax_id.")) return "tax_ids";
+	if (eventType.startsWith("customer.")) return "customers";
+	if (eventType.startsWith("invoice.")) return "invoices";
+	if (eventType.startsWith("product.")) return "products";
+	if (eventType.startsWith("price.")) return "prices";
+	if (eventType.startsWith("plan.")) return "plans";
+	if (eventType.startsWith("setup_intent.")) return "setup_intents";
+	if (eventType.startsWith("subscription_schedule."))
+		return "subscription_schedules";
+	if (eventType.startsWith("payment_method.")) return "payment_methods";
+	if (eventType.startsWith("payment_intent.")) return "payment_intents";
+	if (eventType.startsWith("credit_note.")) return "credit_notes";
+	if (eventType.startsWith("radar.early_fraud_warning."))
+		return "early_fraud_warnings";
+	if (eventType.startsWith("refund.")) return "refunds";
+	if (eventType.startsWith("review.")) return "reviews";
+	if (eventType === "invoice_payment.paid") return "invoice_payments";
+
+	return undefined;
+};
+
+/** All tables in the stripe sync schema that store Stripe objects. */
+export const SYNCED_TABLES = [
+	"charges",
+	"checkout_sessions",
+	"checkout_session_line_items",
+	"coupons",
+	"credit_notes",
+	"customers",
+	"disputes",
+	"early_fraud_warnings",
+	"events",
+	"invoices",
+	"invoice_payments",
+	"payment_intents",
+	"payment_methods",
+	"payouts",
+	"plans",
+	"prices",
+	"products",
+	"refunds",
+	"reviews",
+	"setup_intents",
+	"subscription_items",
+	"subscription_schedules",
+	"subscriptions",
+	"tax_ids",
+] as const;
diff --git a/packages/stripe-sync/src/index.ts b/packages/stripe-sync/src/index.ts
new file mode 100644
index 000000000..dc23b3719
--- /dev/null
+++ b/packages/stripe-sync/src/index.ts
@@ -0,0 +1,12 @@
+export { addAutumnColumns } from "./addAccountIdColumn.js";
+export { eventTypeToTable, SYNCED_TABLES } from "./eventTypeToTable.js";
+export {
+	closeStripeSyncEngine,
+	getStripeSyncEngine,
+	processStripeSyncEvent,
+} from "./initStripeSync.js";
+export { runStripeSyncMigrations } from "./runStripeSyncMigrations.js";
+export {
+	isSyncableEvent,
+	SYNCABLE_EVENT_PREFIXES,
+} from "./syncableResources.js";
diff --git a/packages/stripe-sync/src/initStripeSync.ts b/packages/stripe-sync/src/initStripeSync.ts
new file mode 100644
index 000000000..510d4e756
--- /dev/null
+++ b/packages/stripe-sync/src/initStripeSync.ts
@@ -0,0 +1,99 @@
+import { StripeSync } from "@supabase/stripe-sync-engine";
+import type Stripe from "stripe";
+import { eventTypeToTable } from "./eventTypeToTable.js";
+
+const SCHEMA = "stripe";
+
+let instance: StripeSync | null = null;
+let initAttempted = false;
+
+/**
+ * Lazily creates a singleton StripeSync instance.
+ * Returns null if STRIPE_SYNC_DATABASE_URL is not configured or init fails.
+ */
+export const getStripeSyncEngine = (): StripeSync | null => {
+	if (instance) return instance;
+	if (initAttempted) return null;
+
+	initAttempted = true;
+
+	const databaseUrl = process.env.STRIPE_SYNC_DATABASE_URL;
+	const stripeSecretKey =
+		process.env.STRIPE_LIVE_SECRET_KEY || process.env.STRIPE_SANDBOX_SECRET_KEY;
+
+	if (!databaseUrl || !stripeSecretKey) return null;
+
+	try {
+		instance = new StripeSync({
+			poolConfig: {
+				connectionString: databaseUrl,
+				max: 5,
+				keepAlive: true,
+				connectionTimeoutMillis: 5_000,
+				idleTimeoutMillis: 30_000,
+			},
+			stripeSecretKey,
+			stripeWebhookSecret: "unused-processEvent-only",
+			schema: SCHEMA,
+		});
+	} catch {
+		instance = null;
+	}
+
+	return instance;
+};
+
+/**
+ * Upserts the Stripe event into the sync DB, then stamps the row
+ * with the originating Stripe account ID and org ID for multi-tenancy.
+ * Fully fail-open: any error is swallowed and returns silently.
+ */
+export const processStripeSyncEvent = async ({
+	event,
+	stripeAccountId,
+	orgId,
+}: {
+	event: Stripe.Event;
+	stripeAccountId?: string;
+	orgId?: string;
+}): Promise<void> => {
+	const engine = getStripeSyncEngine();
+	if (!engine) return;
+
+	try {
+		await engine.processEvent(event);
+	} catch {
+		return;
+	}
+
+	const table = eventTypeToTable({ eventType: event.type });
+	if (!table) return;
+
+	const objectId = (event.data.object as { id?: string }).id;
+	if (!objectId) return;
+
+	const accountId = stripeAccountId ?? event.account ?? null;
+
+	if (!accountId && !orgId) return;
+
+	try {
+		await engine.postgresClient.pool.query(
+			`UPDATE "${SCHEMA}"."${table}" SET stripe_account_id = COALESCE($1, stripe_account_id), org_id = COALESCE($2, org_id) WHERE id = $3`,
+			[accountId, orgId, objectId],
+		);
+	} catch {
+		// Fail-open: metadata stamp is best-effort
+	}
+};
+
+/** Gracefully close the sync engine's PG pool (call on server shutdown). */
+export const closeStripeSyncEngine = async (): Promise<void> => {
+	if (!instance) return;
+	try {
+		await instance.close();
+	} catch {
+		// Best-effort cleanup
+	}
+	instance = null;
+	initAttempted = false;
+};
diff --git a/packages/stripe-sync/src/runStripeSyncMigrations.ts b/packages/stripe-sync/src/runStripeSyncMigrations.ts
new file mode 100644
index 000000000..565c7b95a
--- /dev/null
+++ b/packages/stripe-sync/src/runStripeSyncMigrations.ts
@@ -0,0 +1,15 @@
+import { runMigrations } from "@supabase/stripe-sync-engine";
+
+/**
+ * Run stripe-sync-engine migrations against the sync DB.
+ * Idempotent -- safe to run multiple times.
+ */
+export const runStripeSyncMigrations = async ({
+	databaseUrl,
+	schema = "stripe",
+}: {
+	databaseUrl: string;
+	schema?: string;
+}): Promise<void> => {
+	await runMigrations({ databaseUrl, schema });
+};
diff --git a/packages/stripe-sync/src/syncableResources.ts b/packages/stripe-sync/src/syncableResources.ts
new file mode 100644
index 000000000..1317051e5
--- /dev/null
+++ b/packages/stripe-sync/src/syncableResources.ts
@@ -0,0 +1,16 @@
+export const SYNCABLE_EVENT_PREFIXES = [
+	"customer.subscription.",
+	"payment_intent.",
+	"invoice.",
+	"customer.",
+	"product.",
+	"price.",
+] as const;
+
+export const isSyncableEvent = ({
+	eventType,
+}: {
+	eventType: string;
+}): boolean => {
+	return SYNCABLE_EVENT_PREFIXES.some((prefix) => eventType.startsWith(prefix));
+};
diff --git a/packages/stripe-sync/tsconfig.json b/packages/stripe-sync/tsconfig.json
new file mode 100644
index 000000000..6efa41163
--- /dev/null
+++ b/packages/stripe-sync/tsconfig.json
@@ -0,0 +1,16 @@
+{
+	"compilerOptions": {
+		"strict": true,
+		"composite": true,
+		"declaration": true,
+		"declarationMap": true,
+		"esModuleInterop": true,
+		"skipLibCheck": true,
+		"module": "Preserve",
+		"moduleResolution": "bundler",
+		"target": "ES2020",
+		"outDir": "./dist",
+		"rootDir": "."
+	},
+	"include": ["src/**/*"]
+}
diff --git a/server/package.json b/server/package.json
index 5cfedf8a2..a5b82626b 100644
--- a/server/package.json
+++ b/server/package.json
@@ -46,6 +46,7 @@
 		"@anthropic-ai/sdk": "^0.32.1",
 		"@autumn/ksuid": "workspace:*",
 		"@autumn/shared": "workspace:*",
+		"@autumn/stripe-sync": "workspace:*",
 		"@aws-sdk/client-s3": "^3.1017.0",
 		"@aws-sdk/client-scheduler": "^3.1004.0",
 		"@aws-sdk/client-sqs": "^3.958.0",
diff --git a/server/register.ts b/server/register.ts
index 3a3699a77..df0fc8eec 100644
--- a/server/register.ts
+++ b/server/register.ts
@@ -1,29 +1,23 @@
 import "dotenv/config";
 import { loadLocalEnv } from "./src/utils/envUtils";
 import Stripe from "stripe";
+import {
+	MAIN_STRIPE_EVENT_TYPES,
+	SYNC_STRIPE_EVENT_TYPES,
+} from "./src/external/stripe/common/stripeConstants";
 
 loadLocalEnv();
 
+const allEventTypes = [
+	...new Set([...MAIN_STRIPE_EVENT_TYPES, ...SYNC_STRIPE_EVENT_TYPES]),
+] as Stripe.WebhookEndpointCreateParams.EnabledEvent[];
+
 const main = async () => {
 	const stripe = new Stripe(process.env.STRIPE_SANDBOX_SECRET_KEY || "");
-	
 
 	const result = await stripe.webhookEndpoints.create({
 		url: `${process.env.STRIPE_WEBHOOK_URL}/webhooks/connect/sandbox`,
-		enabled_events: [
-			"checkout.session.completed",
-			"customer.subscription.created",
-			"customer.subscription.updated",
-			"customer.subscription.deleted",
-			"customer.discount.deleted",
-			"invoice.paid",
-			"invoice.upcoming",
-			"invoice.created",
-			"invoice.finalized",
-			"invoice.updated",
-			"subscription_schedule.canceled",
-			"subscription_schedule.updated",
-		],
+		enabled_events: allEventTypes,
 		connect: true,
 	});
 
diff --git a/server/src/external/stripe/common/stripeConstants.ts b/server/src/external/stripe/common/stripeConstants.ts
new file mode 100644
index 000000000..9a9bf261c
--- /dev/null
+++ b/server/src/external/stripe/common/stripeConstants.ts
@@ -0,0 +1,64 @@
+import type Stripe from "stripe";
+
+type StripeEventType = Stripe.WebhookEndpointCreateParams.EnabledEvent;
+
+/** Events Autumn actively handles in its webhook handler. */
+export const MAIN_STRIPE_EVENT_TYPES: StripeEventType[] = [
+	"checkout.session.completed",
+	"customer.subscription.created",
+	"customer.subscription.updated",
+	"customer.subscription.deleted",
+	"customer.discount.deleted",
+	"invoice.paid",
+	"invoice.upcoming",
+	"invoice.created",
+	"invoice.finalized",
+	"invoice.updated",
+	"subscription_schedule.canceled",
+	"subscription_schedule.updated",
+];
+
+/** Additional events needed to keep the stripe-sync DB up to date. */
+export const SYNC_STRIPE_EVENT_TYPES: StripeEventType[] = [
+	// customers
+	"customer.created",
+	"customer.updated",
+	"customer.deleted",
+
+	// subscriptions (extras beyond main)
+	"customer.subscription.paused",
+	"customer.subscription.resumed",
+
+	// subscription schedules (extras beyond main)
+	"subscription_schedule.created",
+	"subscription_schedule.completed",
+	"subscription_schedule.released",
+
+	// payment methods
+	"payment_method.attached",
+	"payment_method.detached",
+	"payment_method.updated",
+
+	// products
+	"product.created",
+	"product.updated",
+	"product.deleted",
+
+	// prices
+	"price.created",
+	"price.updated",
+	"price.deleted",
+
+	// invoices (extras beyond main)
+	"invoice.deleted",
+	"invoice.payment_failed",
+	"invoice.payment_succeeded",
+	"invoice.voided",
+	"invoice.marked_uncollectible",
+
+	// payment intents
+	"payment_intent.created",
+	"payment_intent.succeeded",
+	"payment_intent.payment_failed",
+	"payment_intent.canceled",
+];
diff --git a/server/src/external/stripe/stripeOnboardingUtils.ts b/server/src/external/stripe/stripeOnboardingUtils.ts
index 70e8b6f4e..5f6f1d43d 100644
--- a/server/src/external/stripe/stripeOnboardingUtils.ts
+++ b/server/src/external/stripe/stripeOnboardingUtils.ts
@@ -1,6 +1,10 @@
 import { type AppEnv, ErrCode } from "@autumn/shared";
 import Stripe from "stripe";
 import RecaseError from "@/utils/errorUtils.js";
+import {
+	MAIN_STRIPE_EVENT_TYPES,
+	SYNC_STRIPE_EVENT_TYPES,
+} from "./common/stripeConstants";
 
 export const checkKeyValid = async (apiKey: string) => {
 	const stripe = new Stripe(apiKey);
@@ -29,20 +33,22 @@ export const createWebhookEndpoint = async (
 
 	const endpoint = await stripe.webhookEndpoints.create({
 		url: `${webhookBaseUrl}/webhooks/stripe/${orgId}/${env}`,
-		enabled_events: [
-			"customer.subscription.created",
-			"customer.subscription.updated",
-			"customer.subscription.deleted",
-			"checkout.session.completed",
-			"invoice.paid",
-			"invoice.upcoming",
-			"invoice.created",
-			"invoice.finalized",
-			"invoice.updated",
-			"subscription_schedule.canceled",
-			"subscription_schedule.updated",
-			"customer.discount.deleted",
-		],
+		enabled_events: [...MAIN_STRIPE_EVENT_TYPES, ...SYNC_STRIPE_EVENT_TYPES],
+
+		// [
+		// 	"customer.subscription.created",
+		// 	"customer.subscription.updated",
+		// 	"customer.subscription.deleted",
+		// 	"checkout.session.completed",
+		// 	"invoice.paid",
+		// 	"invoice.upcoming",
+		// 	"invoice.created",
+		// 	"invoice.finalized",
+		// 	"invoice.updated",
+		// 	"subscription_schedule.canceled",
+		// 	"subscription_schedule.updated",
+		// 	"customer.discount.deleted",
+		// ],
 	});
 
 	return endpoint;
diff --git a/server/src/external/stripe/stripeWebhookRouter.ts b/server/src/external/stripe/stripeWebhookRouter.ts
index f1cbe08ac..9a07d41ce 100644
--- a/server/src/external/stripe/stripeWebhookRouter.ts
+++ b/server/src/external/stripe/stripeWebhookRouter.ts
@@ -4,6 +4,7 @@ import { handleStripeWebhookEvent } from "./handleStripeWebhookEvent.js";
 import { stripeConnectSeederMiddleware } from "./webhookMiddlewares/stripeConnectSeederMiddleware.js";
 import { stripeIdempotencyMiddleware } from "./webhookMiddlewares/stripeIdempotencyMiddleware.js";
 import { stripeLegacySeederMiddleware } from "./webhookMiddlewares/stripeLegacySeederMiddleware.js";
+import { stripeSyncMiddleware } from "./webhookMiddlewares/stripeSyncMiddleware.js";
 import { stripeToAutumnCustomerMiddleware } from "./webhookMiddlewares/stripeToAutumnCustomerMiddleware.js";
 import type { StripeWebhookHonoEnv } from "./webhookMiddlewares/stripeWebhookContext.js";
 import { stripeWebhookRefreshMiddleware } from "./webhookMiddlewares/stripeWebhookRefreshMiddleware.js";
@@ -15,6 +16,7 @@ stripeWebhookRouter.post(
 	"/webhooks/stripe/:orgId/:env",
 	stripeLegacySeederMiddleware,
 	stripeWebhookRefreshMiddleware,
+	stripeSyncMiddleware,
 	stripeToAutumnCustomerMiddleware,
 	stripeLoggerMiddleware,
 	stripeIdempotencyMiddleware,
@@ -26,6 +28,7 @@ stripeWebhookRouter.post(
 	"/webhooks/connect/:env",
 	stripeConnectSeederMiddleware,
 	stripeWebhookRefreshMiddleware,
+	stripeSyncMiddleware,
 	stripeToAutumnCustomerMiddleware,
 	stripeLoggerMiddleware,
 	stripeIdempotencyMiddleware,
diff --git a/server/src/external/stripe/webhookMiddlewares/stripeSyncMiddleware.ts b/server/src/external/stripe/webhookMiddlewares/stripeSyncMiddleware.ts
new file mode 100644
index 000000000..d75fb66bd
--- /dev/null
+++ b/server/src/external/stripe/webhookMiddlewares/stripeSyncMiddleware.ts
@@ -0,0 +1,57 @@
+import { isSyncableEvent, processStripeSyncEvent } from "@autumn/stripe-sync";
+import type { Context, Next } from "hono";
+import { isStripeSyncEnabled } from "@/internal/misc/stripeSync/stripeSyncStore.js";
+import type {
+	StripeWebhookContext,
+	StripeWebhookHonoEnv,
+} from "./stripeWebhookContext.js";
+
+/**
+ * Post-handler middleware that syncs Stripe events to the sync DB.
+ * Fire-and-forget -- errors are caught and logged, never propagated.
+ */
+export const stripeSyncMiddleware = async (
+	c: Context<StripeWebhookHonoEnv>,
+	next: Next,
+) => {
+	await next();
+
+	const ctx = c.get("ctx") as StripeWebhookContext;
+	const { logger, org, stripeEvent } = ctx;
+
+	if (!org || !stripeEvent) return;
+	if (
+		process.env.NODE_ENV === "production" &&
+		!isStripeSyncEnabled({ orgId: org.id })
+	)
+		return;
+
+	if (!isSyncableEvent({ eventType: stripeEvent.type })) return;
+
+	try {
+		const stripeAccountId = stripeEvent.account ?? undefined;
+
+		void processStripeSyncEvent({
+			event: stripeEvent,
+			stripeAccountId,
+			orgId: org.id,
+		}).catch((error) => {
+			logger.error(`Stripe sync failed for event ${stripeEvent.id}: ${error}`, {
+				error: {
+					message: error instanceof Error ? error.message : String(error),
+				},
+				data: {
+					eventId: stripeEvent.id,
+					eventType: stripeEvent.type,
+					orgId: org.id,
+				},
+			});
+		});
+	} catch (error) {
+		logger.error(`Stripe sync middleware error: ${error}`, {
+			error: {
+				message: error instanceof Error ? error.message : String(error),
+			},
+		});
+	}
+};
diff --git a/server/src/init.ts b/server/src/init.ts
index 57dd13765..37d441293 100644
--- a/server/src/init.ts
+++ b/server/src/init.ts
@@ -20,6 +20,8 @@ import {
 import "./internal/misc/requestBlocks/requestBlockStore.js";
 import "./internal/misc/featureFlags/featureFlagStore.js";
 import "./internal/misc/customerBlocks/customerBlockStore.js";
+import "./internal/misc/stripeSync/stripeSyncStore.js";
+import { closeStripeSyncEngine } from "@autumn/stripe-sync";
 import { warmupRegionalRedis } from "./external/redis/initRedis.js";
 import { createHonoApp } from "./initHono.js";
 import { otelSdk } from "./instrumentation.js";
@@ -117,6 +119,7 @@ async function gracefulShutdown() {
 			client.end(),
 			clientCritical.end(),
 			clientReplica?.end(),
+			closeStripeSyncEngine(),
 		]);
 		console.log("Shutdown complete. Exiting process.");
 		process.exit(0);
diff --git a/server/src/internal/customers/cancel/handleCancelV2.ts b/server/src/internal/customers/cancel/handleCancelV2.ts
index 930368e3f..61427da8b 100644
--- a/server/src/internal/customers/cancel/handleCancelV2.ts
+++ b/server/src/internal/customers/cancel/handleCancelV2.ts
@@ -8,10 +8,27 @@ import { executeBillingPlan } from "@/internal/billing/v2/execute/executeBilling
 import { evaluateStripeBillingPlan } from "@/internal/billing/v2/providers/stripe/actionBuilders/evaluateStripeBillingPlan";
 import { logStripeBillingPlan } from "@/internal/billing/v2/providers/stripe/logs/logStripeBillingPlan";
 import { logStripeBillingResult } from "@/internal/billing/v2/providers/stripe/logs/logStripeBillingResult";
+import { buildBillingLockKey } from "@/internal/billing/v2/utils/billingLock/buildBillingLockKey";
 import { logAutumnBillingPlan } from "@/internal/billing/v2/utils/logs/logAutumnBillingPlan";
 
 export const handleCancelV2 = createRoute({
-	// body: CancelBodySchema,
+	lock:
+		process.env.NODE_ENV !== "development"
+			? {
+					ttlMs: 120000,
+					errorMessage:
+						"Cancel already in progress for this customer, try again in a few seconds",
+					getKey: (c) => {
+						const ctx = c.get("ctx");
+						if (!ctx.customerId) return null;
+						return buildBillingLockKey({
+							orgId: ctx.org.id,
+							env: ctx.env,
+							customerId: ctx.customerId,
+						});
+					},
+				}
+			: undefined,
 	handler: async (c) => {
 		const ctx = c.get("ctx");
 
diff --git a/server/src/internal/misc/stripeSync/stripeSyncSchemas.ts b/server/src/internal/misc/stripeSync/stripeSyncSchemas.ts
new file mode 100644
index 000000000..1a91f653f
--- /dev/null
+++ b/server/src/internal/misc/stripeSync/stripeSyncSchemas.ts
@@ -0,0 +1,7 @@
+import { z } from "zod/v4";
+
+export const StripeSyncConfigSchema = z.object({
+	enabledOrgIds: z.array(z.string()).default([]),
+});
+
+export type StripeSyncConfig = z.infer<typeof StripeSyncConfigSchema>;
diff --git a/server/src/internal/misc/stripeSync/stripeSyncStore.ts b/server/src/internal/misc/stripeSync/stripeSyncStore.ts
new file mode 100644
index 000000000..e711de5d0
--- /dev/null
+++ b/server/src/internal/misc/stripeSync/stripeSyncStore.ts
@@ -0,0 +1,20 @@
+import { registerEdgeConfig } from "@/internal/misc/edgeConfig/edgeConfigRegistry.js";
+import { createEdgeConfigStore } from "@/internal/misc/edgeConfig/edgeConfigStore.js";
+import {
+	type StripeSyncConfig,
+	StripeSyncConfigSchema,
+} from "./stripeSyncSchemas.js";
+
+const store = createEdgeConfigStore<StripeSyncConfig>({
+	s3Key: "admin/stripe-sync-config.json",
+	schema: StripeSyncConfigSchema,
+	defaultValue: () => ({ enabledOrgIds: [] }),
+	pollIntervalMs: 60_000,
+});
+
+registerEdgeConfig({ store });
+
+/** Pure in-memory lookup -- zero I/O, sync. */
+export const isStripeSyncEnabled = ({ orgId }: { orgId: string }): boolean => {
+	return store.get().enabledOrgIds.includes(orgId);
+};
diff --git a/server/tests/_temp/temp2.test.ts b/server/tests/_temp/temp2.test.ts
index e846fc0c9..edced424c 100644
--- a/server/tests/_temp/temp2.test.ts
+++ b/server/tests/_temp/temp2.test.ts
@@ -1,67 +1,106 @@
-import { expect, test } from "bun:test";
+import { test } from "bun:test";
+import type { AttachParamsV1Input } from "@autumn/shared";
+import {
+	applySubscriptionDiscount,
+	createPercentCoupon,
+	getStripeSubscription,
+} from "@tests/integration/billing/utils/discounts/discountTestUtils";
+import { TestFeature } from "@tests/setup/v2Features.js";
 import { items } from "@tests/utils/fixtures/items";
 import { products } from "@tests/utils/fixtures/products";
 import { initScenario, s } from "@tests/utils/testInitUtils/initScenario";
 import chalk from "chalk";
-import { CusService } from "@/internal/customers/CusService";
 
-test(`${chalk.yellowBright("check where default payment method lives after attach")}`, async () => {
-	const customerId = "pm-location-check";
+/**
+ * Repro for Mintlify multi-entity discount bug.
+ *
+ * Production sequence (from Axiom logs):
+ *  1. Entity 1 attaches pro (upgrade from Hobby) — creates subscription
+ *  2. Discount applied to subscription
+ *  3. Entity 1 cancels pro (end_of_cycle) — creates subscription schedule
+ *  4. Entity 1 uncancels pro — schedule modified
+ *  5. Entity 2 attaches pro — subscription update succeeds but schedule
+ *     creation/update fails: "Discount di_xxx has exceeded its maximum
+ *     number of applications and cannot be reused"
+ *
+ * The error is in stripeDiscountsToPhaseDiscounts which passes
+ * { discount: "di_xxx" } to schedule phases — but the discount is bound
+ * to the subscription, not the schedule.
+ */
+test(`${chalk.yellowBright("bug repro: entity 2 attach after cancel+uncancel with discount on sub")}`, async () => {
+	const customerId = "multi-ent-cancel-uncancel";
 
 	const messagesItem = items.monthlyMessages({ includedUsage: 100 });
+
 	const pro = products.pro({
-		id: "pro-pm-check",
+		id: "pro",
 		items: [messagesItem],
 	});
 
-	const { ctx } = await initScenario({
+	// Step 1: Entity 1 attaches pro
+	const { autumnV2_2, autumnV1, entities } = await initScenario({
 		customerId,
 		setup: [
 			s.customer({ paymentMethod: "success" }),
 			s.products({ list: [pro] }),
+			s.entities({ count: 2, featureId: TestFeature.Users }),
+		],
+		actions: [
+			s.billing.attach({ productId: pro.id, entityIndex: 0 }),
 		],
-		actions: [s.attach({ productId: pro.id })],
 	});
 
-	const fullCustomer = await CusService.getFull({
-		ctx,
-		idOrInternalId: customerId,
+	// Step 2: Apply a discount to entity 1's subscription
+	const { stripeCli, subscription } = await getStripeSubscription({
+		customerId,
 	});
 
-	const stripeCustomerId = fullCustomer.processor?.id;
-	expect(stripeCustomerId).toBeDefined();
-
-	const subs = await ctx.stripeCli.subscriptions.list({
-		customer: stripeCustomerId!,
-		status: "all",
+	const coupon = await createPercentCoupon({
+		stripeCli,
+		percentOff: 10,
 	});
 
-	const subscription = subs.data.find(
-		(sub) => sub.status === "active" || sub.status === "trialing",
-	);
-	expect(subscription).toBeDefined();
+	await applySubscriptionDiscount({
+		stripeCli,
+		subscriptionId: subscription.id,
+		couponIds: [coupon.id],
+	});
 
-	const subDefaultPm = subscription!.default_payment_method;
-	console.log(`Subscription default_payment_method: ${JSON.stringify(subDefaultPm)}`);
+	// Step 3: Entity 1 cancels pro (end_of_cycle) — creates subscription schedule
+	console.log("Canceling entity 1 pro (end of cycle)...");
+	await autumnV2_2.subscriptions.update({
+		customer_id: customerId,
+		entity_id: entities[0].id,
+		plan_id: pro.id,
+		cancel_action: "cancel_end_of_cycle",
+	});
 
-	const stripeCustomer = await ctx.stripeCli.customers.retrieve(stripeCustomerId!);
-	const customerDefaultPm = "deleted" in stripeCustomer
-		? null
-		: stripeCustomer.invoice_settings?.default_payment_method;
-	console.log(`Customer invoice_settings.default_payment_method: ${JSON.stringify(customerDefaultPm)}`);
+	await new Promise((resolve) => setTimeout(resolve, 3000));
 
-	const customerDefaultSource = "deleted" in stripeCustomer
-		? null
-		: stripeCustomer.default_source;
-	console.log(`Customer default_source: ${JSON.stringify(customerDefaultSource)}`);
+	// Step 4: Entity 1 uncancels pro — schedule released/modified
+	console.log("Uncanceling entity 1 pro...");
+	await autumnV2_2.subscriptions.update({
+		customer_id: customerId,
+		entity_id: entities[0].id,
+		plan_id: pro.id,
+		cancel_action: "uncancel",
+	});
 
-	if (subDefaultPm) {
-		console.log(chalk.green("Payment method is set at the SUBSCRIPTION level"));
-	} else if (customerDefaultPm) {
-		console.log(chalk.green("Payment method is set at the CUSTOMER level (invoice_settings)"));
-	} else if (customerDefaultSource) {
-		console.log(chalk.green("Payment method is set at the CUSTOMER level (default_source)"));
-	} else {
-		console.log(chalk.red("No default payment method found on subscription or customer"));
+	await new Promise((resolve) => setTimeout(resolve, 3000));
+
+	// Step 5: Entity 2 attaches pro
+	console.log("Attaching pro to entity 2...");
+	try {
+		const result = await autumnV2_2.billing.attach<AttachParamsV1Input>({
+			customer_id: customerId,
+			entity_id: entities[1].id,
+			plan_id: pro.id,
+			redirect_mode: "if_required",
+		});
+		console.log("Entity 2 result:", JSON.stringify(result, null, 2));
+		console.log(chalk.red("BUG NOT REPRODUCED — entity 2 attach succeeded"));
+	} catch (error: any) {
+		console.log(chalk.green("BUG REPRODUCED — entity 2 attach failed:"));
+		console.log("Error:", JSON.stringify(error, null, 2));
 	}
 });
diff --git a/server/tests/integration/billing/attach/new-plan/schedule-addon-attach.test.ts b/server/tests/integration/billing/attach/new-plan/schedule-addon-attach.test.ts
new file mode 100644
index 000000000..9df42def7
--- /dev/null
+++ b/server/tests/integration/billing/attach/new-plan/schedule-addon-attach.test.ts
@@ -0,0 +1,113 @@
+import { test } from "bun:test";
+import type { ApiCustomerV3 } from "@autumn/shared";
+import {
+	applySubscriptionDiscount,
+	createPercentCoupon,
+	getStripeSubscription,
+} from "@tests/integration/billing/utils/discounts/discountTestUtils";
+import { expectCustomerFeatureCorrect } from "@tests/integration/billing/utils/expectCustomerFeatureCorrect";
+import { expectCustomerInvoiceCorrect } from "@tests/integration/billing/utils/expectCustomerInvoiceCorrect";
+import {
+	expectProductCanceling,
+	expectProductScheduled,
+} from "@tests/integration/billing/utils/expectCustomerProductCorrect";
+import { TestFeature } from "@tests/setup/v2Features";
+import { items } from "@tests/utils/fixtures/items.js";
+import { products } from "@tests/utils/fixtures/products.js";
+import { initScenario, s } from "@tests/utils/testInitUtils/initScenario.js";
+import chalk from "chalk";
+
+/**
+ * Reproduces: attaching a one-off add-on to a subscription that already
+ * has a schedule (from a prior downgrade) fails with Stripe error
+ * "You cannot migrate a subscription that is already attached to a schedule".
+ *
+ * The root cause is that setupStripeBillingContext skips fetching the schedule
+ * when targetCustomerProduct is undefined (new attachment, no transition).
+ * buildStripeSubscriptionScheduleAction then sees hasSchedule=false and emits
+ * type:"create" instead of type:"update", which Stripe rejects.
+ */
+test.concurrent(`${chalk.yellowBright("bug-repro: attach one-off add-on after scheduled downgrade hits 'subscription already attached to schedule'")}`, async () => {
+	const customerId = "repro-schedule-addon-attach";
+
+	const messagesItem = items.monthlyMessages({ includedUsage: 100 });
+
+	const premium = products.premium({
+		id: "premium",
+		items: [messagesItem],
+	});
+
+	const pro = products.pro({
+		id: "pro",
+		items: [messagesItem],
+	});
+
+	const topupAddon = products.base({
+		id: "topup-addon",
+		items: [
+			items.oneOffWords({
+				includedUsage: 0,
+				billingUnits: 100,
+				price: 25,
+			}),
+		],
+	});
+
+	const { autumnV1 } = await initScenario({
+		customerId,
+		setup: [
+			s.customer({ paymentMethod: "success" }),
+			s.products({ list: [premium, pro, topupAddon] }),
+		],
+		actions: [s.billing.attach({ productId: premium.id })],
+	});
+
+	// Apply a 20% discount to the subscription (matches production scenario)
+	const { stripeCli, subscription: subBefore } = await getStripeSubscription({
+		customerId,
+	});
+
+	const coupon = await createPercentCoupon({
+		stripeCli,
+		percentOff: 20,
+	});
+
+	await applySubscriptionDiscount({
+		stripeCli,
+		subscriptionId: subBefore.id,
+		couponIds: [coupon.id],
+	});
+
+	// Schedule downgrade: Premium -> Pro (creates a subscription schedule)
+	await autumnV1.billing.attach({
+		customer_id: customerId,
+		product_id: pro.id,
+		redirect_mode: "if_required",
+	});
+
+	// Verify the downgrade was scheduled correctly
+	const customer = await autumnV1.customers.get<ApiCustomerV3>(customerId);
+	await expectProductCanceling({ customer, productId: premium.id });
+	await expectProductScheduled({ customer, productId: pro.id });
+
+	await autumnV1.billing.attach({
+		customer_id: customerId,
+		product_id: topupAddon.id,
+		redirect_mode: "if_required",
+		options: [{ feature_id: TestFeature.Words, quantity: 100 }],
+	});
+
+	const customerAfter = await autumnV1.customers.get<ApiCustomerV3>(customerId);
+	expectCustomerFeatureCorrect({
+		customer: customerAfter,
+		featureId: TestFeature.Words,
+		balance: 100,
+		usage: 0,
+	});
+
+	await expectCustomerInvoiceCorrect({
+		customer: customerAfter,
+		count: 2,
+		latestTotal: 25,
+	});
+});