[Generation]: Anthropic support in TypeScript

[Copilot]

Description

Implements Anthropic provider for TypeScript per blueprint/providers/anthropic.md. Converts OpenAI-compatible API to Anthropic's message format with full support for tool calling and streaming.

Changes

• ts/src/providers/anthropic.ts: New provider implementing all blueprint conversions:

  • System messages extracted to system parameter
  • Tool messages → tool_result blocks in user messages
  • Tool calls → tool_use blocks
  • Image URLs (base64 and regular)
  • Tool choice/spec conversion ("required" → "any", etc.)
  • parallel_tool_calls inverted to disable_parallel_tool_use
  • Stop reason mapping (end_turn → stop, tool_use → tool_calls)
  • Default max_tokens: 8192
  • response_format rejection with guidance
  • Error mapping to AnyLLM error types

• ts/src/any_llm.ts: Register "anthropic" in factory

• ts/src/index.ts: Export AnthropicProvider

• ts/tests/integration.test.ts: Parallel tool calls agent loop test

Usage

const llm = await AnyLLM.create("anthropic", ANTHROPIC_API_KEY);
const result = await llm.completion("claude-haiku-4-5-20251001", messages, { tools });

PR Type

• 🆕 New Feature

Relevant issues

Fixes #6

Checklist

• I understand the code I am submitting.
• I have added unit tests that prove my fix/feature works
• I have run this code locally and verified it fixes the issue.
• New and existing tests pass locally
• Documentation was updated where necessary
• I have read and followed the contribution guidelines
• AI Usage:
  • No AI was used.
  • AI was used for drafting/refactoring.
  • This is fully AI-generated.

AI Usage Information

• AI Model used: Claude Sonnet 4
• AI Developer Tool used: GitHub Copilot Coding Agent
• Any other info you'd like to share: Implementation follows Python provider as reference

When answering questions by the reviewer, please respond yourself, do not copy/paste the reviewer comments into an AI system and paste back its answer. We want to discuss with you, not your AI :)

Original prompt

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This section details on the original issue you should resolve

<issue_title>[Generation]: Anthropic support in TypeScript</issue_title>
<issue_description>Implement the feature described in blueprint/providers/anthropic.md for TypeScript.

Put the output in ts/providers/anthropic.ts.

Update integration tests to run against Anthropic API and make sure they pass.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes [Generation]: Anthropic support in TypeScript #770

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