Multi-Signature Approval Workflow Sequencer

[Kingsman-99]

Description

Invoices above a configurable threshold require multi-signature approval from multiple authorised signers before the payment transaction is submitted. The SDK has no workflow primitive for collecting signatures in sequence, notifying pending signers, or timing out after a maximum collection window. An approval workflow sequencer should orchestrate the signing round, gathering XDR-encoded signatures until the required signer weight is reached.

Technical Context

Add src/approvalWorkflowSequencer.ts. Reads MultiSigPolicy from src/types.ts. Integrates with src/requestSigner.ts for signature collection and src/txBuilder.ts to inject collected signatures into the transaction. Uses src/scheduler.ts for timeout enforcement. Emits approvalRequested, approvalReceived, and approvalWorkflowComplete via src/events.ts.

Acceptance Criteria

• ApprovalWorkflowSequencer.initiate(txXdr, policy): ApprovalSession creates an approval session and notifies each required signer via the registered notification adapter
• ApprovalSession.submitSignature(signerPublicKey, signatureBase64) records a signer's contribution and checks if the required weight threshold is now met
• Returns the fully-signed transaction XDR via ApprovalSession.getSignedXdr() once the threshold is reached
• Expires the session after policy.timeoutMs and throws ApprovalTimeoutError (added to src/errors.ts)
• Unit tests simulate a 2-of-3 multisig flow and assert the session resolves on the second valid signature
• All CI checks (npm test, npm run build, ESLint/TypeScript) pass and the branch has no merge conflicts

---

[omoh5]

@omoh5 has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Please can you assign this to me please!!!!!!!!!!!!
Thank you very much

ℹ️ Repo Maintainers: To accept this application, review their application or assign @omoh5 to this issue.

[ValJnr-dev1]

@ValJnr-dev1 has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hi Maintainer,

I’m a smart contract and full-stack developer and would love to contribute to this issue. I’m an experienced contributor with hands-on expertise in Rust, Soroban, Cairo, and TypeScript.

I’m passionate about building secure, scalable blockchain solutions, with a strong emphasis on writing clean and maintainable code. Based on the scope of this issue, I’m confident I can deliver a complete solution within 24 hours of assignment.

I’d greatly appreciate the opportunity to contribute and help move this forward.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @ValJnr-dev1 to this issue.

[Peolite1]

@Peolite1 has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

i would love to work on this issue

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Peolite1 to this issue.

[xmendevs]

@xmendevs has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

This is a task I enjoy doing. And I have an optimized way of solving the issue.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @xmendevs to this issue.

[webdevayo]

@webdevayo has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hello Maintainer, i'm an experienced full stack dev and i will like to work on this issue.
if you'll kindly assign, the issue will be resolved.
ETA: 5 Hours

ℹ️ Repo Maintainers: To accept this application, review their application or assign @webdevayo to this issue.

[Busiii-adetiba]

@Busiii-adetiba has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hi can i work on this issue.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Busiii-adetiba to this issue.

[drips-wave]

Congratulations, @Busiii-adetiba! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on July 30, 2026.

🧑‍💻 @Busiii-adetiba: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

Warning

When opening a PR, please link it to this issue to ensure it gets tracked accurately. Points are awarded when this issue is marked as completed by the maintainer.

🤠 Repo maintainers: Please keep an eye on the contributor's progress and review their work before the due date. You can manage this issue, including adjusting its complexity and points, here.

🌊 Happy Wave 🌊

[drips-wave]

This issue has been completed by @Busiii-adetiba as part of the Stellar Wave Program's 7th Wave 🥳

😎 @Busiii-adetiba: You earned 200 Points for completing this issue! After the current Wave ends, you'll be eligible for a percentage of the Wave's reward pool based on the percentage of total points you've earned. Learn more here. You can also Leave a review to share your experience working on this issue.

🧑‍💻 Repo maintainers: How'd the contributor do? Leave a review to share your experience working with them.