Pull Request: [Feature] Streaming-to-Staking Direct Pipeline (#53, #43)

[JamesEjembi]

This PR introduces the "Direct Pipeline" feature, allowing grantees to automate their savings by redirecting streamed funds directly into a staking pool or a secondary secure address. This bypasses the need for manual withdrawals to a hot wallet, reducing gas costs and improving security for the user.

🎯 Key Changes
Data Structure Update: Added an optional redirect_address: Option

field to the Grant struct.

Logic Enhancement: Updated the withdraw() function to check for a redirect_address. If present, the unlocked funds are transferred directly to that target instead of the caller's address.

Permissioning: Ensured that only the grantee can set or update the redirect_address to prevent unauthorized diversion of funds.

💻 Implementation Snippet (Soroban/Rust)
The core logic shift in the withdrawal process:

Rust
pub fn withdraw(e: Env, grant_id: Symbol) {
let mut grant: Grant = e.storage().persistent().get(&grant_id).unwrap();
grant.grantee.require_auth();

let amount_to_withdraw = calculate_unlocked_amount(&e, &grant);

// Determine the recipient: redirect target or the grantee
let recipient = grant.redirect_address.unwrap_or(grant.grantee.clone());

// Execute transfer to the pipeline target
token::Client::new(&e, &grant.token).transfer(
    &e.current_contract_address(),
    &recipient,
    &amount_to_withdraw,
);

// Update internal state...

}
✅ Acceptance Criteria Checklist
[x] Grant Struct: Added redirect_address to the Grant definition.

[x] Withdraw Logic: The withdraw() function now respects the redirect target.

[x] State Management: Properly handles cases where no redirect is set (defaults to standard withdrawal).

[x] Security: Verified that redirection does not bypass require_auth() from the grantee.

🚀 How to Test
Initialize Grant: Create a grant with a redirect_address set to a mock staking contract.

Advance Ledger: Move the ledger time forward to unlock funds.

Withdraw: Call withdraw from the grantee's account.

Verify: Assert that the mock staking contract's balance increased, while the grantee's balance remained the same.

🔗 Linked Issues
Closes #43
Closes #53