refactor: migrate deepinfra provider to AI SDK

[daniel-lxs]

Migrates the DeepInfra provider from legacy RouterProvider (direct openai SDK) to AI SDK using the official @ai-sdk/deepinfra package.

Changes

src/api/providers/deepinfra.ts

• Extends BaseProvider directly instead of RouterProvider (follows the deepseek/groq pattern)
• Uses createDeepInfra from @ai-sdk/deepinfra with streamText/generateText from ai
• Uses AI SDK transform utilities (convertToAiSdkMessages, convertToolsForAiSdk, processAiSdkStreamPart, mapToolChoice, handleAiSdkError)

Preserved Features

• Dynamic model fetching: getModels/getModelsFromCache integration with fetchModel() override
• reasoning_effort: Passed via providerOptions.deepinfra
• prompt_cache_key: Passed via providerOptions.deepinfra when model supports prompt caching
• Custom cost calculation: calculateApiCostOpenAI with cache token details in processUsageMetrics()
• Temperature control: Handled via getModelParams (o3-mini models get undefined temperature)
• max_completion_tokens: Only included when includeMaxTokens is true
• Custom headers: X-Deepinfra-Source: roo-code and X-Deepinfra-Version: 2025-08-25
• isAiSdkProvider(): Returns true

Dependencies

• Added @ai-sdk/deepinfra (^2.0.31) to src/package.json

Tests

• Rewrote src/api/providers/__tests__/deepinfra.spec.ts (21 tests, all passing)
• Tests cover: constructor, createProvider, getModel, createMessage (streaming, reasoning, usage/cost, tools, tool calls, errors), completePrompt, processUsageMetrics, isAiSdkProvider

---

Important

Refactors DeepInfra provider to use AI SDK, updating deepinfra.ts and tests, and adds @ai-sdk/deepinfra dependency.

• Behavior:
  • Migrates DeepInfraHandler in deepinfra.ts to use AI SDK, replacing RouterProvider with BaseProvider.
  • Utilizes createDeepInfra, streamText, and generateText from AI SDK.
  • Implements AI SDK utilities for message conversion and error handling.
• Preserved Features:
  • Dynamic model fetching with getModels and getModelsFromCache.
  • Supports reasoning_effort, prompt_cache_key, and custom cost calculation.
  • Maintains temperature control and max_completion_tokens logic.
  • Custom headers X-Deepinfra-Source and X-Deepinfra-Version.
  • isAiSdkProvider() returns true.
• Dependencies:
  • Adds @ai-sdk/deepinfra to package.json.
• Tests:
  • Rewrites deepinfra.spec.ts to cover new AI SDK-based implementation.

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[roomote]

Rooviewer   See task

Both issues from the previous review have been addressed. No new issues found.

• Missing DEFAULT_HEADERS: Standard Roo Code identification headers (HTTP-Referer, X-Title, User-Agent) are dropped in the migration. All other AI SDK providers include them.
• Provider re-created per request: createProvider() runs on every API call instead of being cached in the constructor like DeepSeek and Groq.

Previous reviews

• 462eda5: Review #1

_{Mention @roomote in a comment to request specific changes to this pull request or fix all unresolved issues.}

[roomote]

The old RouterProvider-based implementation merged DEFAULT_HEADERS (HTTP-Referer, X-Title, User-Agent) with the DeepInfra-specific headers. This migration drops those standard headers. Every other AI SDK provider in the codebase (DeepSeek, Groq, Fireworks, Mistral, xAI, etc.) includes DEFAULT_HEADERS in their provider creation. Without them, DeepInfra requests no longer carry the Roo Code identification headers that other providers send.

Suggested change

	headers: DEEPINFRA_HEADERS,
	headers: { ...DEFAULT_HEADERS, ...DEEPINFRA_HEADERS },

You'll also need to add import { DEFAULT_HEADERS } from "./constants" to the imports.

_{Fix it with Roo Code or mention @roomote and request a fix.}

[roomote]

createProvider() is called inside getLanguageModel(), which runs on every createMessage() and completePrompt() invocation. This creates a new @ai-sdk/deepinfra provider instance per API call. The DeepSeek and Groq handlers both create the provider once in the constructor and store it as this.provider. Consider caching it the same way for consistency and to avoid the repeated setup cost.

_{Fix it with Roo Code or mention @roomote and request a fix.}