feat: migrate DeepSeek to @ai-sdk/deepseek + fix AI SDK tool streaming

[daniel-lxs]

Summary

Migrates DeepSeek provider from OpenAI SDK to the dedicated @ai-sdk/deepseek package, achieving full feature parity with significant improvements. Also fixes tool streaming for all AI SDK providers.

Changes

DeepSeek Provider Migration

• Before: 150 lines using OpenAI SDK directly
• After: 181 lines using @ai-sdk/deepseek
• Native reasoning support for deepseek-reasoner model
• Cache metrics from providerMetadata.deepseek
• Automatic consecutive message handling (no manual R1 format conversion)
• Azure AI Inference support via custom baseURL
• All 29 tests passing ✅

Tool Streaming Fixes (affects DeepSeek + Moonshot)

• Added handleToolCallEvent() helper in Task.ts (DRY)
• Added top-level handlers for tool_call_start/delta/end events
• Fixed duplicate tool rendering by ignoring redundant tool-call events
• Tools now display with real-time argument streaming (character-by-character)

Files Modified

• src/api/providers/deepseek.ts - New AI SDK implementation
• src/api/providers/__tests__/deepseek.spec.ts - Updated tests
• src/core/task/Task.ts - Tool streaming event handlers
• src/api/transform/ai-sdk.ts - Fixed duplication
• src/package.json - Added @ai-sdk/deepseek dependency

Testing

• ✅ 29/29 DeepSeek tests passing
• ✅ All provider tests passing (5284 total)
• ✅ Tool streaming verified working without duplicates
• ✅ Reasoning content streaming working

Related Issues

Closes EXT-644

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Important

Migrates DeepSeek to @ai-sdk/deepseek and fixes tool streaming for AI SDK providers, enhancing functionality and compatibility.

• DeepSeek Provider Migration:
  • Migrated from OpenAI SDK to @ai-sdk/deepseek in deepseek.ts.
  • Added native reasoning support for deepseek-reasoner model.
  • Implemented cache metrics from providerMetadata.deepseek.
  • Enabled Azure AI Inference via custom baseURL.
  • All 29 tests in deepseek.spec.ts passing.
• Tool Streaming Fixes:
  • Added handleToolCallEvent() in Task.ts for tool streaming events.
  • Implemented handlers for tool_call_start/delta/end events.
  • Ignored tool-call events to prevent duplicate tool rendering.
• Miscellaneous:
  • Updated package.json to include @ai-sdk/deepseek dependency.
  • Modified ai-sdk.ts to process tool streaming events correctly.

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[roomote]

🤖 Roo Code Review

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Summary

Status: ✅ Approved

This PR successfully migrates the DeepSeek provider from the OpenAI SDK to the dedicated @ai-sdk/deepseek package and fixes a duplicate tool rendering issue in AI SDK providers.

Key Changes Reviewed:

1. DeepSeek Provider Migration (src/api/providers/deepseek.ts)

   • Clean implementation using @ai-sdk/deepseek package (v2.0.14)
   • Native reasoning support for deepseek-reasoner model
   • Cache metrics extraction from providerMetadata.deepseek (promptCacheHitTokens, promptCacheMissTokens)
   • Proper tool choice mapping with AI SDK format

2. AI SDK Tool Streaming Fix (src/api/transform/ai-sdk.ts)

   • Fixed duplicate tool rendering by ignoring tool-call events
   • Uses tool-input-start/delta/end events for streaming tool calls
   • Well-documented with comments explaining the rationale

3. DRY Refactoring (src/core/task/Task.ts)

   • Added handleToolCallEvent() helper method for reusable tool call handling
   • Direct case handlers for tool_call_start/delta/end events for AI SDK providers
   • Maintains backward compatibility with legacy tool_call_partial processing

4. Test Coverage

   • Comprehensive tests for DeepSeek handler (39 tests)
   • AI SDK transform tests including tool-call ignore verification (13 tests)
   • Updated Moonshot tests to verify consistent behavior (19 tests)
   • All 71 tests pass

No Issues Found

The implementation is clean, well-tested, and follows established patterns in the codebase.

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TODO

• Initial review - no issues found (commit fd1fc0f)
• Re-review after new commits - no issues found (commit 908677b)

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Review run complete. View Job

[roomote]

LGTM! This PR cleanly migrates DeepSeek to the dedicated @ai-sdk/deepseek package with native reasoning support and fixes the duplicate tool rendering issue in AI SDK providers. All 71 tests pass.