feat: refactor nft-kindfi with SEP-0050 compatibility

[aguilar1x]

Summary

• Refactor NFT metadata attributes from Vec<String> to Vec<NFTAttribute> to comply with the SEP-0050 Non-Fungible Metadata JSON Schema
• Add NFTAttribute struct with trait_type, value, display_type, and max_value fields matching the SEP-0050 specification
• Update the reputation contract's mirrored types and level attribute helpers to use the new structured format

Motivation

The previous attribute format used plain strings (ej, "level:gold", "badge:early_supporter"), which is not compatible with the SEP-0050 standard. Marketplaces and external tools that follow SEP-0050 expect attributes as structured objects:

{
  "trait_type": "level",
  "value": "gold",
  "display_type": "string"
}

Changes

apps/contract/contracts/nft-kindfi/src/types.rs

• Added NFTAttribute struct with fields: trait_type, value, display_type (optional), max_value (optional)
• Updated NFTMetadata.attributes from Vec<String> to Vec<NFTAttribute>

apps/contract/contracts/nft-kindfi/src/test.rs

• Updated create_metadata helper and test_update_metadata to construct NFTAttribute instances

apps/contract/contracts/reputation/src/nft_client.rs

• Added mirrored NFTAttribute struct for cross-contract call compatibility
• Refactored build_level_attribute() to return NFTAttribute instead of String
• Simplified is_level_attribute() to check trait_type field instead of comparing full strings
• Updated update_attributes_with_level() to operate on Vec<NFTAttribute>
• Updated all related tests to use the new format

Test plan

• cargo test --package nft-kindfi — 18 tests passed
• cargo test --package reputation — 33 tests passed

Summary by CodeRabbit

• New Features

  • Implemented SEP-0050 standard for NFT attributes with enriched metadata structure. Attributes now support detailed trait information including display formatting and maximum value constraints, enabling more expressive NFT metadata representation.

• Tests

  • Updated test cases across contracts to validate new attribute structure and ensure SEP-0050 compliance.

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Project	Deployment	Review	Updated (UTC)
kindfi	Ready	Preview, Comment	Jan 28, 2026 5:22pm

[coderabbitai]

Walkthrough

This change implements SEP-0050 compliant NFT attributes by replacing string-based representation with a structured NFTAttribute type. The refactoring updates metadata handling across NFT contract types, metadata definitions, and attribute management functions while maintaining existing test coverage.

Changes

Cohort / File(s)	Summary
Type Definitions apps/contract/contracts/nft-kindfi/src/types.rs, apps/contract/contracts/reputation/src/nft_client.rs	Added new public NFTAttribute struct with fields for trait_type, value, display_type, and max_value. Updated NFTMetadata.attributes from Vec<String> to Vec<NFTAttribute> to align with SEP-0050 schema.
Attribute Helpers apps/contract/contracts/reputation/src/nft_client.rs	Introduced build_level_attribute() to construct SEP-0050 compliant level attributes. Added internal helpers level_to_value() and is_level_attribute(). Refactored update_attributes_with_level() to operate on Vec<NFTAttribute> with updated signature.
Test Updates apps/contract/contracts/nft-kindfi/src/test.rs	Updated test metadata construction to use NFTAttribute structs instead of plain strings. Modified TestEnv::create_metadata() and test_update_metadata() to reflect new attribute structure with optional display_type and max_value fields.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Suggested labels

enhancement, contract

Suggested reviewers

• Bran18

Poem

✨ Attributes now structured bright,
SEP-0050 shining in the light,
From strings to types, we've made the change,
Metadata now with proper range,
The NFT world feels more aligned! 🎨

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main change: refactoring NFT metadata to use SEP-0050 compatible structures across the nft-kindfi and reputation contracts.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing touches

• 📝 Generate docstrings

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[coderabbitai]

Actionable comments posted: 2

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (2)

apps/contract/contracts/nft-kindfi/src/test.rs (1)

211-243: Consider enhancing attribute verification in the test.

The test correctly updates metadata with NFTAttribute instances, including the max_value field which is great for coverage. We could enhance the test by also verifying that the attributes were persisted correctly:

💡 Optional enhancement

     // Verify metadata was updated
     let stored = test.client.get_metadata(&token_id).unwrap();
     assert_eq!(stored.name, String::from_str(&test.env, "Updated Name"));
     assert_eq!(
         stored.description,
         String::from_str(&test.env, "Updated description")
     );
+    // Verify attributes were updated
+    assert_eq!(stored.attributes.len(), 2);

apps/contract/contracts/reputation/src/nft_client.rs (1)

20-41: Intentional type mirroring for cross-contract compatibility.

The duplication of NFTAttribute and NFTMetadata is a necessary pattern for Soroban cross-contract calls. Consider adding a note in the module documentation or a comment linking to the source of truth to help future maintainers keep these types synchronized:

📝 Optional documentation enhancement

 /// NFT attribute following SEP-0050 JSON schema.
-/// Must match the nft-kindfi NFTAttribute structure exactly.
+/// Must match the nft-kindfi NFTAttribute structure exactly.
+/// Source of truth: apps/contract/contracts/nft-kindfi/src/types.rs
 #[contracttype]
 #[derive(Clone, Debug, Eq, PartialEq)]
 pub struct NFTAttribute {

🤖 Fix all issues with AI agents

In `@apps/contract/contracts/nft-kindfi/src/types.rs`:
- Around line 3-26: Fix the minor typos in the NFTAttribute doc comments:
replace "e.j." with "e.g." in the trait_type comment (inside struct
NFTAttribute), and replace both occurrences of "ej." with "e.g." in the value
and display_type comments so all examples use the correct "e.g." convention.

In `@apps/contract/contracts/reputation/src/nft_client.rs`:
- Around line 78-81: The is_level_attribute function currently allocates a new
String on every call via String::from_str(e, LEVEL_TRAIT_TYPE); change the
design to avoid per-iteration allocation by hoisting the comparison string:
either (1) change is_level_attribute signature to accept a &str or &Symbol-like
type (e.g., fn is_level_attribute(attr: &NFTAttribute, target: &str) -> bool)
and compare attr.trait_type == target, or (2) keep the signature but add an
overload/variant that takes a precomputed String (or cached value created once
in update_attributes_with_level) and pass that into is_level_attribute; update
update_attributes_with_level to create the comparison value once and reuse it in
the loop so the allocation isn’t repeated.

[coderabbitai]

🧹 Nitpick | 🔵 Trivial

Well-structured SEP-0050 compliant attribute type!

The NFTAttribute struct nicely captures the SEP-0050 schema with appropriate use of Option<String> for optional fields. Consider fixing the minor typos in the documentation comments:

• Line 18: "e.j." → "e.g."
• Line 20: "ej." → "e.g."
• Line 22: "ej." → "e.g."

📝 Suggested documentation fixes

 /// NFT attribute following SEP-0050 JSON schema.
 /// Represents a single trait/property of the NFT.
 ///
 /// Compatible with the "Non-Fungible Metadata JSON Schema" defined in SEP-0050:
 /// ```json
 /// {
 ///   "display_type": "string",
 ///   "trait_type": "string",
 ///   "value": "string | number",
 ///   "max_value": "number (optional)"
 /// }
 /// ```
 #[contracttype]
 #[derive(Clone, Debug, Eq, PartialEq)]
 pub struct NFTAttribute {
-    /// The type of trait this attribute represents (e.j., "level", "badge", "rarity")
+    /// The type of trait this attribute represents (e.g., "level", "badge", "rarity")
     pub trait_type: String,
-    /// The value of the attribute (ej., "gold", "100", "rare")
+    /// The value of the attribute (e.g., "gold", "100", "rare")
     pub value: String,
-    /// Optional display type hint for UIs (ej., "string", "number", "date", "boost_percentage")
+    /// Optional display type hint for UIs (e.g., "string", "number", "date", "boost_percentage")
     pub display_type: Option<String>,
     /// Optional maximum value for numeric traits (stored as string for flexibility)
     pub max_value: Option<String>,
 }

🤖 Prompt for AI Agents

In `@apps/contract/contracts/nft-kindfi/src/types.rs` around lines 3 - 26, Fix the
minor typos in the NFTAttribute doc comments: replace "e.j." with "e.g." in the
trait_type comment (inside struct NFTAttribute), and replace both occurrences of
"ej." with "e.g." in the value and display_type comments so all examples use the
correct "e.g." convention.

[Bran18]

LGTM! Perfect, this will be super handy once we are on mainnet