feat: capture raw body bytes for v4 hmac calculation

[MohammedRyaan786]

TICKET: CAAS-659

This pull request improves how HTTP request bodies are handled in the Express app, specifically to support v4 HMAC authentication that requires the exact raw request bytes. The main changes add logic to preserve the raw request body and ensure it is sent unchanged when proxying requests, which is important for signature verification.

Enhancements for request body handling and HMAC authentication:

• The Express app now stores the raw request body buffer on each request before JSON parsing, enabling downstream code to access the exact bytes received from the client. This is necessary for v4 HMAC authentication, which relies on the unmodified request body.
• A new sendRequestBody helper function is introduced in clientRoutes.ts to send the raw request body buffer when available, falling back to the parsed body for backward compatibility.
• The redirectRequest function is updated to use sendRequestBody for all HTTP methods that send a body, ensuring the raw bytes are forwarded when possible.

Current PR is related to this BGMS PR

[MohammedRyaan786]

@claude please review this PR

[Copilot]

Pull request overview

This PR aims to preserve exact incoming HTTP request body bytes in the Express app so downstream v4 HMAC/signature verification can use the unmodified payload, and to forward that raw payload unchanged when proxying requests.

Changes:

• Capture and store the raw JSON request body buffer during parsing (req.rawBodyBuffer).
• Add a helper to prefer forwarding the raw body when proxying (sendRequestBody) and apply it across body-bearing HTTP methods.
• Add unit tests validating raw-body capture behavior (whitespace/order preservation).

Reviewed changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated 4 comments.

File	Description
modules/express/src/expressApp.ts	Adds bodyParser.json verify hook to capture raw request bytes into req.rawBodyBuffer.
modules/express/src/clientRoutes.ts	Introduces sendRequestBody and updates redirectRequest to forward raw bytes when present.
modules/express/types/express/index.d.ts	Extends Express Request typing with optional rawBodyBuffer.
modules/express/test/unit/clientRoutes/rawBodyBuffer.ts	Adds tests validating raw-body buffer capture and preservation characteristics.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 4 changed files in this pull request and generated 2 comments.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[lokesh-bitgo]

@claude review this PR with a primary focus on the bug, and confirm whether these changes impact any other flows.

[Copilot]

Copilot encountered an error and was unable to review this pull request. You can try again by re-requesting a review.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 4 changed files in this pull request and generated 1 comment.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 5 out of 6 changed files in this pull request and generated 1 comment.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 5 out of 6 changed files in this pull request and generated 1 comment.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 5 out of 6 changed files in this pull request and generated 1 comment.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 5 out of 6 changed files in this pull request and generated 3 comments.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 5 out of 6 changed files in this pull request and generated no new comments.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 5 out of 6 changed files in this pull request and generated 1 comment.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Copilot encountered an error and was unable to review this pull request. You can try again by re-requesting a review.