[CT-22] Implement Membership Token ID and Ownership Validator in Rust

[devwums]

Problem

Membership token validation is scattered and untested. There is no utility to independently verify a token ID format or confirm ownership without parsing the full token contract state.

Proposed Solution

Create contracts/cntr/token_validator.rs implementing: pub fn is_valid_token_id(token_id: &str) -> bool (validates UUID v4 format using the regex ^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$) and pub fn is_token_owner(token_id: &str, claimed_owner: &str, registry: &[(String, String)]) -> bool where the registry is a list of (token_id, owner_address) pairs. All implementation must live inside contracts/cntr/.

Acceptance Criteria

• File at contracts/cntr/token_validator.rs
• is_valid_token_id validates UUID v4 format exactly
• Rejects UUID v1, v3, v5, and malformed strings
• is_token_owner returns false for unregistered token IDs
• is_token_owner returns false when owner does not match
• At least 6 unit tests for is_valid_token_id and at least 4 for is_token_owner
• Compiles with cargo test

[jethrojohn739-max]

@jethrojohn739-max has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

Hi maintainer, i would to work on this issue

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[jaynomyaro]

@jaynomyaro has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

Hi! I would love to work on this issue, Could you please assign this to me?

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[PetJs]

@PetJs has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

HI Maintainer
I would like to work on this issue

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[Mkalbani]

@Mkalbani has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

Hi Maintainers, can I work on this?

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[drips-wave]

Congratulations, @Mkalbani! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 2, 2026.

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