feat(anthropic): search result blocks and custom content documents

[lithdew]

Background

Anthropic's API supports search result blocks and custom content documents that enable Claude to cite specific passages in responses. This functionality was not exposed through the AI SDK, limiting users who want to build RAG applications with proper source attribution.

https://platform.claude.com/docs/en/build-with-claude/search-results
https://platform.claude.com/docs/en/build-with-claude/citations#custom-content-documents

Summary

Adds support for Anthropic's search result blocks and custom content documents, enabling Claude to cite specific passages from user-provided content.

Search results can be passed as file parts with provider options specifying type: 'search_result' along with a source URL. Custom content documents use source: { type: 'content', content: [...] } for pre-chunked text that Claude can cite directly.

Two new citation location types are now parsed in responses: search_result_location and content_block_location. These return as source parts with provider metadata containing the cited text, source URL, search result index, and block ranges.

Includes streaming support with full test coverage for both generateText and streamText flows. Documentation updated with usage examples and configuration options.

Manual Verification

Ran the example files to verify end-to-end functionality:

• pnpm tsx src/generate-text/anthropic-search-results.ts
• pnpm tsx src/stream-text/anthropic-search-results.ts
• pnpm tsx src/generate-text/anthropic-custom-content-documents.ts
• pnpm tsx src/stream-text/anthropic-custom-content-documents.ts

Confirmed that:

• Search results are sent correctly to the Anthropic API
• Citations are returned and parsed with correct metadata
• Streaming works with citations appearing in real-time

% pnpm tsx src/generate-text/anthropic-custom-content-documents.ts
Response: The document contains a first custom chunk and a second custom chunk.

[1] "First custom chunk." (blocks 0-1)
Title: Custom Content Doc

[2] "Second custom chunk." (blocks 1-2)
Title: Custom Content Doc

% pnpm tsx src/stream-text/anthropic-custom-content-documents.ts
The document contains two simple custom chunks. 

[1] "First custom chunk." (blocks 0-1)
Title: Custom Content Doc
The first is labeled as "First custom chunk." 

[2] "Second custom chunk." (blocks 1-2)
Title: Custom Content Doc
The second is labeled as "Second custom chunk."

Total citations: 2

% pnpm tsx src/generate-text/anthropic-search-results.ts
Response: Based on the search results provided, I can see there is information about quarterly revenue growth and additional context from the same search result. However, the search results only contain brief snippets without specific details, so I cannot provide a more comprehensive summary of the actual content or findings.

[1] "Search result snippet about quarterly revenue growth." (search_result 0, blocks 0-1)
Source: https://example.com/search/result1
Title: Quarterly Results

[2] "Additional context from the same search result." (search_result 1, blocks 0-1)
Source: https://example.com/search/result2
Title: Additional Context

% pnpm tsx src/stream-text/anthropic-search-results.ts
Based on the search results provided, I can see there is 

[1] "Search result snippet about quarterly revenue growth." (search_result 0, blocks 0-1)
Source: https://example.com/search/result1
Title: Quarterly Results
information about quarterly revenue growth and 

[2] "Additional context from the same search result." (search_result 1, blocks 0-1)
Source: https://example.com/search/result2
Title: Additional Context
additional context from the same search result. 

However, the search results only contain brief snippet descriptions without the actual detailed content, so I cannot provide a comprehensive summary of the specific findings, data, or conclusions. To give you a meaningful summary, I would need access to the full content of these search results.

Total citations: 2

Checklist

• Tests have been added / updated (for bug fixes / features)
• Documentation has been added / updated (for bug fixes / features)
• A patch changeset for relevant packages has been added (for bug fixes / features - run pnpm changeset in the project root)
• I have reviewed this pull request (self-review)

Future Work

Add support for returning search_result blocks from tool calls. Need to double-check if custom content documents can be returned from tool calls. Will be done in a subsequent PR.

[lithdew]

cc @aayush-kapoor @lgrammel

[lithdew]

Any chance for review? 👀

[gr2m]

Superseded by #16740.