[Zakaria Khchiche (Zakariakhchiche)]

Motivation & Context

In streaming mode Anthropic sends citations (web search results, search results, document citations) as content_block_delta events with delta.type == "citations_delta". AnthropicClient had no case for them, so streamed responses lost every citation, while non-streaming responses kept them as text annotations.

Description & Review Guide

• What are the major changes?
  • _parse_contents_from_anthropic handles citations_delta by emitting an empty text Content that carries the parsed annotation. This is the same pattern the Responses client uses for response.output_text.annotation.added, and text coalescing merges it into the block's text.
  • _parse_citations_from_anthropic also accepts the delta's single citation field, so all citation types keep the existing mapping.
  • Regression test that streams real anthropic SDK events (BetaCitationsDelta + BetaTextDelta) through get_response(stream=True) and checks the final response annotations.
• What is the impact of these changes? Streaming and non-streaming now return the same citation annotations. No change for responses without citations.
• What do you want reviewers to focus on? Using an empty text content as the annotation carrier, consistent with the OpenAI Responses client.

Related Issue

Fixes #8977

Contribution Checklist

• The code builds clean without any errors or warnings
• All unit tests pass, and I have added new tests where possible
• The PR follows the Contribution Guidelines
• This PR is linked to an issue and there is no other open PR for this issue (see Related Issue above).
• This is not a breaking change. If it is a breaking change, add the breaking change label (or add "[BREAKING]" to the title prefix, before or after any language prefix) — a workflow keeps the label and title prefix in sync automatically.

[Copilot]

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Copilot review overview

Review effort: Lite
Findings: 1 · 1

Open (2)

• Using Any here weakens type safety, and directly accessing content_block.citation relies on an… · New
• The test materializes the entire stream into a list but never uses it. This is unnecessary work and… · New

What changed in this PR

Adds support for Anthropic streaming citations_delta events so citation annotations are preserved in streaming mode, aligning behavior with non-streaming responses (fixing #8977).

Changes:

• Handle citations_delta in _parse_contents_from_anthropic by emitting an empty text Content carrying parsed citation annotations.
• Extend _parse_citations_from_anthropic to also accept the delta’s single citation field.
• Add a regression test that streams real Anthropic SDK delta events and asserts final response annotations.

File	Description
python/​packages/​anthropic/​agent_framework_anthropic/​_chat_client.py	Parses citations_delta during streaming and maps it into standard text annotations.
python/​packages/​anthropic/​tests/​test_anthropic_client.py	Adds a regression test validating streamed citations become response annotations.

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[Zakaria Khchiche (Zakariakhchiche)]

Notes on the automated review:

• The test now iterates the stream directly (pushed).
• Any for content_blocks: narrowing with isinstance(content_block, BetaCitationsDelta) makes pyright and mypy reject the location-specific attribute access further down in _parse_citations_from_anthropic, which handles several citation location types. So I kept the existing duck-typed handling and dispatch on content_block.type; uv run poe pyright and uv run poe mypy report no new errors for the package.

[Eduard van Valkenburg (eavanvalkenburg)]

Zakaria Khchiche (@Zakariakhchiche), streaming a citation from a plain-text document now aborts here. BetaCitationCharLocation exposes document_title, not title, but _parse_citations_from_anthropic() reads citation.title in its char_location branch. This new dispatch therefore turns a valid document citation delta into an AttributeError, terminating get_response(..., stream=True) as a ChatClientException instead of returning the response. Please map document_title and add a streaming regression using a real BetaCitationCharLocation; the new test covers only web-search citations, and the existing character-citation test supplies an invented title attribute through MagicMock.