feat: optional callback enabling fuel scripts to call simplevrf

apps/web/content/docs/examples.mdx

@@ -25,13 +25,24 @@ fn request_random_number(seed: b256) -> u64 {
     let request_id = simple_vrf.request{
         asset_id: AssetId::base().bits(),
         coins: fee,
-    }(seed);
+    }(seed, None); // Default callback behavior (enabled)
+    request_id
+}
+
+fn request_random_number_no_callback(seed: b256) -> u64 {
+    let simple_vrf = abi(SimpleVrf, vrf_id);
+    let fee = simple_vrf.get_fee(AssetId::base());
+    let request_id = simple_vrf.request{
+        asset_id: AssetId::base().bits(),
+        coins: fee,
+    }(seed, Some(false)); // Disable callback - useful for scripts
     request_id
 }
 ```
 
 - Implement the callback to receive the proof.
-- Call `request_random_number(seed)` to request randomness.
+- Call `request_random_number(seed)` to request randomness with callback enabled (default).
+- Call `request_random_number_no_callback(seed)` to request randomness without callback (useful for scripts).
 
 ---
 
@@ -52,7 +63,7 @@ abi SampleVrfContract {
 
     #[payable]
     #[storage(read, write)]
-    fn request(seed: b256) -> u64;
+    fn request(seed: b256, callback: Option<bool>) -> u64;
 
     #[storage(read)]
     fn get_latest_proof() -> b256;
@@ -85,15 +96,15 @@ impl SampleVrfContract for Contract {
 
     #[payable]
     #[storage(read, write)]
-    fn request(seed: b256) -> u64 {
+    fn request(seed: b256, callback: Option<bool>) -> u64 {
         let vrf_id = storage.vrf_id.try_read().unwrap();
         storage.seed.write(seed);
         let simple_vrf = abi(SimpleVrf, vrf_id);
         let fee = simple_vrf.get_fee(AssetId::base());
         let request_id = simple_vrf.request{
             asset_id: AssetId::base().bits(),
             coins: fee, 
-        }(seed);
+        }(seed, callback);
         request_id
     }
 
@@ -116,10 +127,14 @@ impl SampleVrfContract for Contract {
 
 ### How it works
 - The contract implements a callback interface (`SimpleVrfCallback`) to receive the random proof.
-- The `request(seed)` function stores the seed, fetches the fee, and calls the SimpleVrf contract to request randomness.
-- The callback (`simplevrf_callback` or `simple_callback`) is triggered by SimpleVrf when the proof is ready, storing the result in contract storage.
+- The `request(seed, callback)` function stores the seed, fetches the fee, and calls the SimpleVrf contract to request randomness with optional callback control.
+- The callback (`simplevrf_callback` or `simple_callback`) is triggered by SimpleVrf when the proof is ready (if callback is enabled), storing the result in contract storage.
 - Helper functions allow reading the latest proof and seed, and setting the VRF contract address.
 
+### Callback Parameter Options:
+- `None` or `Some(true)` – Enable callback (default behavior)
+- `Some(false)` – Disable callback, useful when calling from scripts or when you want to manually check for fulfillment
+
 ---
 
 You can use this pattern to integrate verifiable randomness into your own Fuel contracts. For more, see the [SimpleVrf ABI documentation](./smart-contracts/simple-vrf).

apps/web/content/docs/smart-contracts/simple-vrf.mdx

@@ -24,6 +24,7 @@ pub struct Request {
     pub proof: ChunkedProof,
     pub fullfilled_by: Address,
     pub callback_contract: Identity,
+    pub should_callback: bool,
 }
 
 abi SimpleVrfCallback {
@@ -63,7 +64,7 @@ abi SimpleVrf {
 
     #[payable]
     #[storage(read, write)]
-    fn request(seed: b256) -> u64;
+    fn request(seed: b256, callback: Option<bool>) -> u64;
 
     #[storage(read, write)]
     fn submit_proof(seed: b256, proof: ChunkedProof) -> bool;
@@ -74,7 +75,7 @@ The SimpleVrf Fuel contract exposes the following key methods:
 
 ## Request Management
 
-- `request(seed)` – Create a new randomness request
+- `request(seed, callback)` – Create a new randomness request with optional callback control (defaults to true)
 - `get_request(seed)` – Get details of a request
 - `get_request_count()` – Get the total number of requests
 - `get_unfinalized_requests()` – List all pending requests
@@ -98,6 +99,20 @@ The SimpleVrf Fuel contract exposes the following key methods:
 
 - `simplevrf_callback(seed, proof)` – Called by the contract when randomness is fulfilled
 
+### Callback Control
+
+The `request` function now accepts an optional `callback` parameter:
+
+- `callback: Some(true)` (default) – Enable callback when request is fulfilled
+- `callback: Some(false)` – Disable callback, useful when calling from scripts
+- `callback: None` – Defaults to true (enabled)
+
+When `callback` is set to `false`, the contract will fulfill the request and store the proof, but will not attempt to call back to the requesting contract. This is particularly useful when:
+
+- Making requests from Fuel scripts (which cannot receive callbacks)
+- You want to manually check for fulfillment later
+- The requesting contract doesn't implement the callback interface
+
 ---
 
 See [Example Integration](../examples) for usage in your own contracts.