Add version diff endpoint implementation

[Robinsonchiziterem]

📝 Summary

This pull request verifies the robust implementation of Unified Contract Search Filters (supporting mixed combinations of network, category, and verification-only filters alongside full-text search) inside the /api/contracts endpoint, ensuring that combining filters does not break pagination or search logic.
The endpoint /api/contracts maps to handlers::list_contracts inside backend/api/src/handlers.rs, which naturally implements all requested filters:

1. Combined Filters & AND Logic: Integrates networks, categories, verified_only, and query using top-level AND clauses in SQL queries.
2. Preserved Pagination: Computes pagination sizes and offsets correctly for filtered sets, matching count queries dynamically.
3. Response Metadata: Automatically parses active filters into SearchFilterMetadata and populates the "filters" property inside PaginatedResponse using .with_filters(filters).
   This pull request completes and verifies the implementation of the Version History Compare & Changelog Diff functionality (Issue Add changelog and version history diff endpoints #955) inside the Soroban Registry. It enables consumers to track semantic version history, explicitly analyze version-to-version metadata differences (such as WASM hashes, source URLs, commit hashes, release notes, and change notes), and ensures reliable backend builds with updated lockfile constraints.

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🚀 Changes Made

Area	Files Added/Modified	Description
Integration Tests	backend/api/tests/search_filter_tests.rs	[NEW] Adds robust integration tests to cover mixed filter scenarios, empty result sets, response active-filter metadata, and pagination stability.
Component	Files Added/Modified	Description
-----------	----------------------	-------------
API Routes	backend/api/src/routes.rs	Exposes the version comparison route: GET /api/contracts/:id/versions/compare mapping to the compare handler.
API Handlers	backend/api/src/handlers.rs	Refines and exports compare_contract_versions to parse version parameters, query database version records, perform semantic field comparisons, and return a structured difference.
Cargo Build	backend/Cargo.lock	Restores and updates dependency locking (redox_syscall, telemetry, etc.) to ensure build stability and resolve local/remote mismatch conflicts.

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🧪 Integration Test Coverage

🔍 Endpoint Details

We have introduced search_filter_tests.rs to cover:

• Mixed Filter Combinations: Calls GET /api/contracts?networks=testnet&categories=DeFi&verified_only=true&query=token and asserts that the response schema, pagination boundaries, and "filters" active-filters metadata matches the query.
• Empty Result Sets: Queries a nonexistent contract string combined with network filters, ensuring a 200 OK empty list with total count 0 is returned instead of errors.

GET /api/contracts/:id/versions/compare?from={version_a}&to={version_b}

Allows clients to retrieve a comprehensive diff between two version tags of a specific contract.
Sample Request:

curl "https://registry.soroban.org/api/contracts/550e8400-e29b-41d4-a716-446655440000/versions/compare?from=1.0.0&to=1.1.0"

Sample Response Schema:

{
  "contract_id": "550e8400-e29b-41d4-a716-446655440000",
  "from_version": {
    "version": "1.0.0",
    "wasm_hash": "a1b2c3d4...",
    "source_url": "https://github.com/example/contract",
    "commit_hash": "f623ad...",
    "release_notes": "Initial release",
    "change_notes": null
  },
  "to_version": {
    "version": "1.1.0",
    "wasm_hash": "e5f6g7h8...",
    "source_url": "https://github.com/example/contract",
    "commit_hash": "c71a30...",
    "release_notes": "Added performance improvements",
    "change_notes": "Optimized execution cost"
  },
  "differences": [
    {
      "field": "wasm_hash",
      "from_value": "a1b2c3d4...",
      "to_value": "e5f6g7h8..."
    },
    {
      "field": "commit_hash",
      "from_value": "f623ad...",
      "to_value": "c71a30..."
    },
    {
      "field": "release_notes",
      "from_value": "Initial release",
      "to_value": "Added performance improvements"
    },
    {
      "field": "change_notes",
      "from_value": null,
      "to_value": "Optimized execution cost"
    }
  ],
  "wasm_changed": true
}

---

✅ Checklist

• Code complies with the existing backend pagination patterns.
• Tested with multiple combinations of query variables.
• Added automated test coverage for empty result sets and combined query filters.
• Pushed feature branch to remote origin.
• Version comparison endpoint GET /api/contracts/:id/versions/compare registered and verified.
• Pull request synchronized with the latest commits from the upstream main branch.
• Resolved lockfile integration conflicts (backend/Cargo.lock) cleanly with the latest telemetry and observability updates.
• Verified that the workspace compiles successfully.
• Pushed and updated the remote branch feature/version-pagination-diff.

Closes #955

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Project	Deployment	Actions	Updated (UTC)
soroban-registry	Ready	Preview, Comment	Jun 2, 2026 11:38am