fn update_plan_amount(env: Env, plan_id: u64, new_amount: i128)
price_ceiling. This allows merchants to adjust pricing without requiring subscribers to re-authorize.
Parameters
| Name | Type | Description |
|---|
plan_id | u64 | The ID of the plan to update. |
new_amount | i128 | The new billing amount per period, in stroops. |
Authorization
The merchant address stored on the plan must sign the transaction.
Return value
None (void).
Events emitted
| Event | Topics | Data |
|---|
plan_updated | plan_id, new_amount | Updated plan details |
Error cases
| Code | Name | Description |
|---|
| 6 | PlanNotFound | No plan exists with the given plan_id. |
| 3 | InvalidAmount | new_amount is zero or negative. |
| 10 | AmountExceedsCeiling | new_amount exceeds the plan’s price_ceiling. |
Examples
import { VowenaClient, NETWORKS, toStroops } from "vowena";
const client = new VowenaClient({
contractId: NETWORKS.testnet.contractId,
rpcUrl: NETWORKS.testnet.rpcUrl,
networkPassphrase: NETWORKS.testnet.networkPassphrase,
});
// Raise the price from 9.99 to 12.99 (within the 14.99 ceiling)
const tx = await client.buildUpdatePlanAmount(
planId, // Plan ID
toStroops("12.99") // 129900000n stroops
);
const signedXdr = await signTransaction(tx);
await client.submitTransaction(signedXdr);
soroban contract invoke \
--id CONTRACT_ID \
--network testnet \
--source MERCHANT_SECRET \
-- \
update_plan_amount \
--plan_id 1 \
--new_amount 129900000
Since the token allowance is set against the price_ceiling (not the current amount), updating the amount within the ceiling does not require subscribers to re-authorize. All existing subscriptions will be charged the new amount on their next billing cycle.
If you need to set a price above the current ceiling, you must create a new plan and use the migration flow to move subscribers. This ensures subscribers always have explicit control over their maximum exposure. 
