feat: pos client

[ganchoradkov]

Description

This PR introduces a new POS (Point-of-Sale) client package to the WalletConnect ecosystem, enabling merchants to create payment intents for cryptocurrency transactions through WalletConnect.

• Implements a new @walletconnect/pos-client package with core POS functionality
• Provides APIs for token configuration and payment intent creation
• Includes comprehensive validation for tokens, payment amounts, and chain compatibility

Type of change

• Chore (non-breaking change that addresses non-functional tasks, maintenance, or code quality improvements)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Draft PR (breaking/non-breaking change which needs more work for having a proper functionality [Mark this PR as ready to review only when completely ready])
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

How has this been tested?

tests

Checklist

• I have performed a self-review of my own code
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules

Additional Information (Optional)

Please include any additional information that may be useful for the reviewer.

[Copilot]

Pull Request Overview

This PR introduces a new POS (Point-of-Sale) client package to the WalletConnect ecosystem, enabling merchants to create payment intents for cryptocurrency transactions through WalletConnect.

• Implements a new @walletconnect/pos-client package with core POS functionality
• Provides APIs for token configuration and payment intent creation
• Includes comprehensive validation for tokens, payment amounts, and chain compatibility

Reviewed Changes

Copilot reviewed 24 out of 25 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
packages/pos-client/src/client.ts	Main POS client implementation with initialization and method delegation
packages/pos-client/src/controllers/engine.ts	Core engine handling payment flows, wallet communication, and transaction processing
packages/pos-client/src/types/	Type definitions for client options, payment intents, and engine interfaces
packages/pos-client/src/utils/validator.ts	Validation logic for tokens and payment intents
packages/pos-client/src/constants/	Configuration constants for supported chains and client settings
packages/pos-client/test/pos.spec.ts	Comprehensive test suite covering client initialization and payment flows
packages/pos-client/package.json	Package configuration with dependencies and build scripts
package.json	Workspace configuration update to include the new package

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[Copilot]

Console.log statements should be removed from production code. Consider using the logger from the signClient instead: this.signClient.logger.debug().

Suggested change

	console.log("emit", event, args);
	this.signClient.logger.debug("emit", event, args);

[jakubuid]

In Kotlin I decided to not have setTokens as it's kinda verbose
Instead I pass chains in the init functions to build the namespaces based on the chains
Token are passed only in the createPaymentIntent method

I find it cleaner but up to you

[riveign]

I think its good that we agree on one approach that we can maintain across all sdks!

[jakubuid]

LGTM

[lukaisailovic]

Should this be hardcoded? If yes we need a new release for a new namespace

[cursor]

Bug: Duplicate Export Causes Module Issues

The export * from "./client"; statement is duplicated in packages/pos-client/src/constants/index.ts. This creates a redundant export that may cause module resolution or bundling issues.