docs(run-engine): the gate cap is three, matching the schema

Author: matt-aitken

internal-packages/run-engine/src/run-queue/types.ts

@@ -32,7 +32,8 @@ export const InputPayload = z.object({
   attempt: z.number(),
   /** TTL expiration timestamp (unix ms). If set, run will be expired when this time is reached. */
   ttlExpiresAt: z.number().optional(),
-  /** Additional queues this run must also hold a slot in while executing. At most two. */
+  /** Additional queues this run must also hold a slot in while executing. At most
+   * three: a task's anonymous inline-limit gate plus two named limits. */
   gates: QueueGate.array().max(3).optional(),
 });
 export type InputPayload = z.infer<typeof InputPayload>;