fix(anthropic): instrument beta stream managers (fixes #4388)

[Anai-Guo]

Summary

Fixes #4388.

client.beta.messages.stream(...) (both sync and async, on the regular and Bedrock SDKs) returns a BetaMessageStreamManager / BetaAsyncMessageStreamManager from anthropic.lib.streaming._beta_messages. The beta stream methods are already listed in WRAPPED_METHODS, but is_stream_manager only recognized the non-beta MessageStreamManager / AsyncMessageStreamManager, so the wrapped beta calls fell through the is_stream_manager(response) branch and were left uninstrumented.

In addition, the async routing compared response.__class__.__name__ == "AsyncMessageStreamManager", so even if a beta async manager reached that branch it would be misrouted to the sync WrappedMessageStreamManager.

Changes

• is_stream_manager now also imports and isinstance-checks BetaMessageStreamManager / BetaAsyncMessageStreamManager (with the same class-name fallback extended for older SDKs that lack the beta module).
• Added is_async_stream_manager() which matches both AsyncMessageStreamManager and BetaAsyncMessageStreamManager, and used it at both stream-manager routing sites so beta async streams route to WrappedAsyncMessageStreamManager.
• Added tests/test_stream_manager_detection.py: a cassette-free unit test asserting all four manager classes are detected and that only the async variants (including beta) are treated as async.

Verification

Ran the detection logic against anthropic==0.120.2: all four manager classes are now recognized by is_stream_manager, and is_async_stream_manager returns True only for the two async variants. ruff check (E/F/W, line-length 120) passes.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes
  • Improved Anthropic streaming detection across standard and beta synchronous and asynchronous variants.
  • Ensured asynchronous streams are handled correctly, including environments where beta types are unavailable.
• Tests
  • Added coverage for standard and beta stream managers.
  • Added validation that unsupported objects are rejected.

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No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 368a9313-f33b-4e53-b1eb-475bde055a50

📥 Commits

Reviewing files that changed from the base of the PR and between 93429cf and 62af8a7.

📒 Files selected for processing (2)

• packages/opentelemetry-instrumentation-anthropic/opentelemetry/instrumentation/anthropic/__init__.py
• packages/opentelemetry-instrumentation-anthropic/tests/test_stream_manager_detection.py

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📝 Walkthrough

Walkthrough

The Anthropic instrumentation adds reusable detection for standard and beta stream managers. Sync and async response wrappers use the detection helper. Tests cover synchronous and asynchronous manager variants, including beta managers.

Changes

Anthropic stream-manager detection

Layer / File(s)	Summary
Stream-manager type detection packages/opentelemetry-instrumentation-anthropic/opentelemetry/instrumentation/anthropic/__init__.py	Detection now includes beta message and asynchronous stream managers, with class-name fallback checks.
Response wrapping and validation packages/opentelemetry-instrumentation-anthropic/opentelemetry/instrumentation/anthropic/__init__.py, packages/opentelemetry-instrumentation-anthropic/tests/test_stream_manager_detection.py	Sync and async wrappers use is_async_stream_manager. Tests cover supported managers, plain objects, and beta asynchronous classification.

Estimated code review effort: 2 (Simple) | ~10 minutes

Suggested reviewers: dvirski

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly identifies the Anthropic beta stream manager instrumentation fix.
Linked Issues check	✅ Passed	The changes satisfy [#4388] by detecting and instrumenting beta synchronous and asynchronous stream managers.
Out of Scope Changes check	✅ Passed	The detection logic and tests directly support the linked issue and stated instrumentation objectives.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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