refactor: clean up duplicate api structs

[ilblackdragon]

Cleans up duplicate structs between api and response crates.

[gemini-code-assist]

Summary of Changes

Hello @ilblackdragon, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request undertakes a significant refactoring effort to streamline the API's data model definitions. By centralizing core structs and enums related to responses and conversations within the services crate, it eliminates redundancy and enhances maintainability. The changes also introduce robust support for optional metadata on response messages, complete with validation to prevent oversized data, and consolidate request validation logic for improved consistency.

Highlights

• API Model Centralization: Many API-related structs and enums, such as CreateResponseRequest, ResponseObject, ConversationObject, and various tool-related types, have been moved from crates/api/src/models.rs to services::responses::models. They are now re-exported in the API crate, establishing a single source of truth and reducing code duplication.
• Metadata Support for Response Messages: The ResponseOutputItem::Message struct now includes an optional metadata field, allowing arbitrary JSON data to be associated with response messages. This metadata is handled during conversion between API and service layers.
• Metadata Size Validation: A new constant, MAX_METADATA_SIZE_BYTES, has been introduced in crates/services/src/common.rs to enforce a size limit on serialized metadata blobs. Validation logic for this limit has been added to CreateResponseRequest, CreateConversationRequest, and UpdateConversationRequest.
• Consolidated Validation Logic: Validation implementations for CreateResponseRequest, CreateConversationRequest, and UpdateConversationRequest have been relocated from crates/api/src/models.rs to crates/services/src/responses/models.rs, centralizing request validation within the services layer.

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[gemini-code-assist]

Code Review

This pull request effectively centralizes API data structures in the services crate, reducing duplication and improving maintainability, and moves validation logic to reside with the data structures. However, a critical security oversight has been identified in the create_conversation_items route: the metadata field for individual conversation messages is processed without size validation, which could lead to resource exhaustion attacks. This needs to be addressed. On a positive note, the addition of annotations to MCP tools and new tests for backward compatibility and validation are valuable improvements. I also have one minor suggestion for simplification.

[gemini-code-assist]

The metadata field in ConversationInputItem::Message is now being extracted and processed, but it lacks size validation. Other similar metadata fields in the API (e.g., in CreateConversationRequest and UpdateConversationRequest) are validated against MAX_METADATA_SIZE_BYTES (16KB) to prevent database abuse and resource exhaustion. Since a single create_conversation_items request can contain up to 20 items, each with its own metadata, failing to validate the size could lead to significant database bloat or memory issues.

[ilblackdragon]

Fixed in 1b87468. Added validate_metadata_size checks for each ConversationInputItem::Message in create_conversation_items, plus an E2E test (test_create_conversation_items_metadata_size_limit) that verifies oversized metadata is rejected with 400.

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[claude]

Code Review

I've reviewed this pull request with a focus on critical issues. The PR effectively consolidates duplicate type definitions between the api and services crates, improving maintainability.

Previous Issue Resolved

The metadata validation security issue mentioned in the earlier review has been properly addressed. The PR now includes:

• Validation of metadata size in create_conversation_items endpoint (lines 955-969 in conversations.rs)
• A new e2e test verifying the validation works correctly
• A shared validate_metadata_size() helper function in services::common

Critical Review - No Blocking Issues Found

I conducted a thorough review focusing on:

1. Logic and Functionality: PASS

   • Type consolidation is correct - ResponseContentItem properly replaces ResponseOutputContent in tests
   • McpDiscoveredTool now includes annotations field and is correctly mapped in conversions
   • Validation logic properly centralized in services layer

2. Production Safety: PASS

   • The refactor maintains backward compatibility - all types maintain their serde attributes
   • No breaking API changes - re-exports preserve the same public interface
   • Type renames in tests are consistent with the new unified types

3. Database and Data Handling: PASS

   • Metadata size validation now enforced at multiple layers (CreateResponseRequest, CreateConversationRequest, UpdateConversationRequest, and create_conversation_items route)
   • 16KB limit prevents resource exhaustion attacks
   • Proper error messages for validation failures

4. Performance and Efficiency: PASS

   • Metadata validation is efficient (single serialization check)
   • No new blocking operations introduced
   • Re-exports have zero runtime cost

5. Rust-Specific Concerns: PASS

   • No unnecessary clones introduced
   • Generic validation function properly uses trait bounds
   • Error handling is consistent throughout

6. Code Quality: PASS

   • Significant reduction in duplication (638 deletions vs 184 additions)
   • Single source of truth for shared types
   • Clear documentation about where types are defined vs re-exported

Summary

This is a clean refactoring that improves code organization without introducing risk. The security concern from the previous review has been properly addressed with validation and test coverage.

APPROVED - Ready to merge

[Copilot]

Pull request overview

This PR consolidates duplicate API struct definitions by moving canonical types from crates/api/src/models.rs to crates/services/src/responses/models.rs and re-exporting them. This reduces code duplication and centralizes type definitions in the services layer. The PR also extracts a reusable validate_metadata_size() helper function and adds validation for conversation create/update requests and conversation item metadata.

Changes:

• Moved canonical response and conversation types (CreateResponseRequest, ResponseOutputItem, ResponseContentItem, etc.) to services layer and re-exported them from API layer
• Extracted metadata size validation logic into a shared validate_metadata_size() helper function in services::common
• Added metadata size validation to CreateConversationRequest, UpdateConversationRequest, and conversation item creation
• Updated test files to use renamed type ResponseContentItem instead of ResponseOutputContent

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
crates/api/src/models.rs	Removed duplicate type definitions and replaced with re-exports from services layer; kept API-specific simplified ResponseInputItem struct for input listing
crates/services/src/responses/models.rs	Updated validation to use new validate_metadata_size helper; added validation methods for CreateConversationRequest and UpdateConversationRequest
crates/services/src/common.rs	Added validate_metadata_size() helper function to reduce duplication in metadata validation logic
crates/api/src/consts.rs	Removed MAX_METADATA_SIZE_BYTES constant (now in services::common)
crates/api/src/routes/conversations.rs	Added metadata size validation for conversation items; added annotations field to McpDiscoveredTool mapping
crates/api/tests/*.rs	Updated references from ResponseOutputContent to ResponseContentItem

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