fix(claude_agent_sdk): preserve tool span output across back-to-back tool_use messages by AbhiPrasad · Pull Request #322 · braintrustdata/braintrust-sdk-python

Abhijeet Prasad (AbhiPrasad) · 2026-04-17T16:35:23Z

resolves#318

AI Summary

In claude-agent-sdk 0.1.61 a delegated subagent can emit multiple tool_use AssistantMessages (e.g. Bash then Read) inside one LLM turn before any tool_result arrives. ContextTracker._handle_assistant was unconditionally calling cleanup_context whenever the context already had an llm_span, which closed the in-flight Bash tool span with no output. When the matching tool_result finally arrived two events later, the span was already gone and its output was dropped (issue #318).

Only run cleanup_context when ctx.next_llm_start is set, which is the real LLM-turn boundary (set in _handle_user when a tool_result arrives). Back-to- back tool_use messages now merge into the existing LLM span without closing sibling tool spans.

Red/green regression: new ContextTracker unit test simulating the 0.1.61 event stream (Bash tool_use -> Read tool_use -> Read tool_result -> Bash tool_result, all under one subagent parent).
Re-records cassettes under claude-agent-sdk 0.1.61 and bumps the matrix latest pin to 0.1.61. test_interleaved_subagent_tool_spans_preserve_output and test_interleaved_subagent_tool_spans_parent_to_correct_llm now pass.
Full test_claude_agent_sdk(latest) and test_claude_agent_sdk(0.1.10) sessions green.

…tool_use messages In claude-agent-sdk 0.1.61 a delegated subagent can emit multiple tool_use AssistantMessages (e.g. Bash then Read) inside one LLM turn before any tool_result arrives. ContextTracker._handle_assistant was unconditionally calling cleanup_context whenever the context already had an llm_span, which closed the in-flight Bash tool span with no output. When the matching tool_result finally arrived two events later, the span was already gone and its output was dropped (issue #318). Only run cleanup_context when ctx.next_llm_start is set, which is the real LLM-turn boundary (set in _handle_user when a tool_result arrives). Back-to- back tool_use messages now merge into the existing LLM span without closing sibling tool spans. - Red/green regression: new ContextTracker unit test simulating the 0.1.61 event stream (Bash tool_use -> Read tool_use -> Read tool_result -> Bash tool_result, all under one subagent parent). - Re-records cassettes under claude-agent-sdk 0.1.61 and bumps the matrix latest pin to 0.1.61. test_interleaved_subagent_tool_spans_preserve_output and test_interleaved_subagent_tool_spans_parent_to_correct_llm now pass. - Full test_claude_agent_sdk(latest) and test_claude_agent_sdk(0.1.10) sessions green.

Includes - #324 - #323 - #322 - #321 - #333 - #345 - #341 - #346

Abhijeet Prasad (AbhiPrasad) · 2026-04-17T16:35:23Z

resolves#318

AI Summary

In claude-agent-sdk 0.1.61 a delegated subagent can emit multiple tool_use AssistantMessages (e.g. Bash then Read) inside one LLM turn before any tool_result arrives. ContextTracker._handle_assistant was unconditionally calling cleanup_context whenever the context already had an llm_span, which closed the in-flight Bash tool span with no output. When the matching tool_result finally arrived two events later, the span was already gone and its output was dropped (issue #318).

Only run cleanup_context when ctx.next_llm_start is set, which is the real LLM-turn boundary (set in _handle_user when a tool_result arrives). Back-to- back tool_use messages now merge into the existing LLM span without closing sibling tool spans.

Red/green regression: new ContextTracker unit test simulating the 0.1.61 event stream (Bash tool_use -> Read tool_use -> Read tool_result -> Bash tool_result, all under one subagent parent).
Re-records cassettes under claude-agent-sdk 0.1.61 and bumps the matrix latest pin to 0.1.61. test_interleaved_subagent_tool_spans_preserve_output and test_interleaved_subagent_tool_spans_parent_to_correct_llm now pass.
Full test_claude_agent_sdk(latest) and test_claude_agent_sdk(0.1.10) sessions green.

…tool_use messages In claude-agent-sdk 0.1.61 a delegated subagent can emit multiple tool_use AssistantMessages (e.g. Bash then Read) inside one LLM turn before any tool_result arrives. ContextTracker._handle_assistant was unconditionally calling cleanup_context whenever the context already had an llm_span, which closed the in-flight Bash tool span with no output. When the matching tool_result finally arrived two events later, the span was already gone and its output was dropped (issue #318). Only run cleanup_context when ctx.next_llm_start is set, which is the real LLM-turn boundary (set in _handle_user when a tool_result arrives). Back-to- back tool_use messages now merge into the existing LLM span without closing sibling tool spans. - Red/green regression: new ContextTracker unit test simulating the 0.1.61 event stream (Bash tool_use -> Read tool_use -> Read tool_result -> Bash tool_result, all under one subagent parent). - Re-records cassettes under claude-agent-sdk 0.1.61 and bumps the matrix latest pin to 0.1.61. test_interleaved_subagent_tool_spans_preserve_output and test_interleaved_subagent_tool_spans_parent_to_correct_llm now pass. - Full test_claude_agent_sdk(latest) and test_claude_agent_sdk(0.1.10) sessions green.

Includes - #324 - #323 - #322 - #321 - #333 - #345 - #341 - #346

Abhijeet Prasad (AbhiPrasad) · 2026-04-17T16:35:23Z

resolves#318

AI Summary

In claude-agent-sdk 0.1.61 a delegated subagent can emit multiple tool_use AssistantMessages (e.g. Bash then Read) inside one LLM turn before any tool_result arrives. ContextTracker._handle_assistant was unconditionally calling cleanup_context whenever the context already had an llm_span, which closed the in-flight Bash tool span with no output. When the matching tool_result finally arrived two events later, the span was already gone and its output was dropped (issue #318).

Only run cleanup_context when ctx.next_llm_start is set, which is the real LLM-turn boundary (set in _handle_user when a tool_result arrives). Back-to- back tool_use messages now merge into the existing LLM span without closing sibling tool spans.

Red/green regression: new ContextTracker unit test simulating the 0.1.61 event stream (Bash tool_use -> Read tool_use -> Read tool_result -> Bash tool_result, all under one subagent parent).
Re-records cassettes under claude-agent-sdk 0.1.61 and bumps the matrix latest pin to 0.1.61. test_interleaved_subagent_tool_spans_preserve_output and test_interleaved_subagent_tool_spans_parent_to_correct_llm now pass.
Full test_claude_agent_sdk(latest) and test_claude_agent_sdk(0.1.10) sessions green.

…tool_use messages In claude-agent-sdk 0.1.61 a delegated subagent can emit multiple tool_use AssistantMessages (e.g. Bash then Read) inside one LLM turn before any tool_result arrives. ContextTracker._handle_assistant was unconditionally calling cleanup_context whenever the context already had an llm_span, which closed the in-flight Bash tool span with no output. When the matching tool_result finally arrived two events later, the span was already gone and its output was dropped (issue #318). Only run cleanup_context when ctx.next_llm_start is set, which is the real LLM-turn boundary (set in _handle_user when a tool_result arrives). Back-to- back tool_use messages now merge into the existing LLM span without closing sibling tool spans. - Red/green regression: new ContextTracker unit test simulating the 0.1.61 event stream (Bash tool_use -> Read tool_use -> Read tool_result -> Bash tool_result, all under one subagent parent). - Re-records cassettes under claude-agent-sdk 0.1.61 and bumps the matrix latest pin to 0.1.61. test_interleaved_subagent_tool_spans_preserve_output and test_interleaved_subagent_tool_spans_parent_to_correct_llm now pass. - Full test_claude_agent_sdk(latest) and test_claude_agent_sdk(0.1.10) sessions green.

Includes - #324 - #323 - #322 - #321 - #333 - #345 - #341 - #346

Abhijeet Prasad (AbhiPrasad) · 2026-04-17T16:35:23Z

resolves#318

AI Summary

In claude-agent-sdk 0.1.61 a delegated subagent can emit multiple tool_use AssistantMessages (e.g. Bash then Read) inside one LLM turn before any tool_result arrives. ContextTracker._handle_assistant was unconditionally calling cleanup_context whenever the context already had an llm_span, which closed the in-flight Bash tool span with no output. When the matching tool_result finally arrived two events later, the span was already gone and its output was dropped (issue #318).

Only run cleanup_context when ctx.next_llm_start is set, which is the real LLM-turn boundary (set in _handle_user when a tool_result arrives). Back-to- back tool_use messages now merge into the existing LLM span without closing sibling tool spans.

Red/green regression: new ContextTracker unit test simulating the 0.1.61 event stream (Bash tool_use -> Read tool_use -> Read tool_result -> Bash tool_result, all under one subagent parent).
Re-records cassettes under claude-agent-sdk 0.1.61 and bumps the matrix latest pin to 0.1.61. test_interleaved_subagent_tool_spans_preserve_output and test_interleaved_subagent_tool_spans_parent_to_correct_llm now pass.
Full test_claude_agent_sdk(latest) and test_claude_agent_sdk(0.1.10) sessions green.

…tool_use messages In claude-agent-sdk 0.1.61 a delegated subagent can emit multiple tool_use AssistantMessages (e.g. Bash then Read) inside one LLM turn before any tool_result arrives. ContextTracker._handle_assistant was unconditionally calling cleanup_context whenever the context already had an llm_span, which closed the in-flight Bash tool span with no output. When the matching tool_result finally arrived two events later, the span was already gone and its output was dropped (issue #318). Only run cleanup_context when ctx.next_llm_start is set, which is the real LLM-turn boundary (set in _handle_user when a tool_result arrives). Back-to- back tool_use messages now merge into the existing LLM span without closing sibling tool spans. - Red/green regression: new ContextTracker unit test simulating the 0.1.61 event stream (Bash tool_use -> Read tool_use -> Read tool_result -> Bash tool_result, all under one subagent parent). - Re-records cassettes under claude-agent-sdk 0.1.61 and bumps the matrix latest pin to 0.1.61. test_interleaved_subagent_tool_spans_preserve_output and test_interleaved_subagent_tool_spans_parent_to_correct_llm now pass. - Full test_claude_agent_sdk(latest) and test_claude_agent_sdk(0.1.10) sessions green.

Includes - #324 - #323 - #322 - #321 - #333 - #345 - #341 - #346

Abhijeet Prasad (AbhiPrasad) · 2026-04-17T16:35:23Z

resolves#318

AI Summary

In claude-agent-sdk 0.1.61 a delegated subagent can emit multiple tool_use AssistantMessages (e.g. Bash then Read) inside one LLM turn before any tool_result arrives. ContextTracker._handle_assistant was unconditionally calling cleanup_context whenever the context already had an llm_span, which closed the in-flight Bash tool span with no output. When the matching tool_result finally arrived two events later, the span was already gone and its output was dropped (issue #318).

Only run cleanup_context when ctx.next_llm_start is set, which is the real LLM-turn boundary (set in _handle_user when a tool_result arrives). Back-to- back tool_use messages now merge into the existing LLM span without closing sibling tool spans.

Red/green regression: new ContextTracker unit test simulating the 0.1.61 event stream (Bash tool_use -> Read tool_use -> Read tool_result -> Bash tool_result, all under one subagent parent).
Re-records cassettes under claude-agent-sdk 0.1.61 and bumps the matrix latest pin to 0.1.61. test_interleaved_subagent_tool_spans_preserve_output and test_interleaved_subagent_tool_spans_parent_to_correct_llm now pass.
Full test_claude_agent_sdk(latest) and test_claude_agent_sdk(0.1.10) sessions green.

…tool_use messages In claude-agent-sdk 0.1.61 a delegated subagent can emit multiple tool_use AssistantMessages (e.g. Bash then Read) inside one LLM turn before any tool_result arrives. ContextTracker._handle_assistant was unconditionally calling cleanup_context whenever the context already had an llm_span, which closed the in-flight Bash tool span with no output. When the matching tool_result finally arrived two events later, the span was already gone and its output was dropped (issue #318). Only run cleanup_context when ctx.next_llm_start is set, which is the real LLM-turn boundary (set in _handle_user when a tool_result arrives). Back-to- back tool_use messages now merge into the existing LLM span without closing sibling tool spans. - Red/green regression: new ContextTracker unit test simulating the 0.1.61 event stream (Bash tool_use -> Read tool_use -> Read tool_result -> Bash tool_result, all under one subagent parent). - Re-records cassettes under claude-agent-sdk 0.1.61 and bumps the matrix latest pin to 0.1.61. test_interleaved_subagent_tool_spans_preserve_output and test_interleaved_subagent_tool_spans_parent_to_correct_llm now pass. - Full test_claude_agent_sdk(latest) and test_claude_agent_sdk(0.1.10) sessions green.

Includes - #324 - #323 - #322 - #321 - #333 - #345 - #341 - #346

Abhijeet Prasad (AbhiPrasad) · 2026-04-17T16:35:23Z

resolves#318

AI Summary

In claude-agent-sdk 0.1.61 a delegated subagent can emit multiple tool_use AssistantMessages (e.g. Bash then Read) inside one LLM turn before any tool_result arrives. ContextTracker._handle_assistant was unconditionally calling cleanup_context whenever the context already had an llm_span, which closed the in-flight Bash tool span with no output. When the matching tool_result finally arrived two events later, the span was already gone and its output was dropped (issue #318).

Only run cleanup_context when ctx.next_llm_start is set, which is the real LLM-turn boundary (set in _handle_user when a tool_result arrives). Back-to- back tool_use messages now merge into the existing LLM span without closing sibling tool spans.

Red/green regression: new ContextTracker unit test simulating the 0.1.61 event stream (Bash tool_use -> Read tool_use -> Read tool_result -> Bash tool_result, all under one subagent parent).
Re-records cassettes under claude-agent-sdk 0.1.61 and bumps the matrix latest pin to 0.1.61. test_interleaved_subagent_tool_spans_preserve_output and test_interleaved_subagent_tool_spans_parent_to_correct_llm now pass.
Full test_claude_agent_sdk(latest) and test_claude_agent_sdk(0.1.10) sessions green.

…tool_use messages In claude-agent-sdk 0.1.61 a delegated subagent can emit multiple tool_use AssistantMessages (e.g. Bash then Read) inside one LLM turn before any tool_result arrives. ContextTracker._handle_assistant was unconditionally calling cleanup_context whenever the context already had an llm_span, which closed the in-flight Bash tool span with no output. When the matching tool_result finally arrived two events later, the span was already gone and its output was dropped (issue #318). Only run cleanup_context when ctx.next_llm_start is set, which is the real LLM-turn boundary (set in _handle_user when a tool_result arrives). Back-to- back tool_use messages now merge into the existing LLM span without closing sibling tool spans. - Red/green regression: new ContextTracker unit test simulating the 0.1.61 event stream (Bash tool_use -> Read tool_use -> Read tool_result -> Bash tool_result, all under one subagent parent). - Re-records cassettes under claude-agent-sdk 0.1.61 and bumps the matrix latest pin to 0.1.61. test_interleaved_subagent_tool_spans_preserve_output and test_interleaved_subagent_tool_spans_parent_to_correct_llm now pass. - Full test_claude_agent_sdk(latest) and test_claude_agent_sdk(0.1.10) sessions green.

Includes - #324 - #323 - #322 - #321 - #333 - #345 - #341 - #346

Abhijeet Prasad (AbhiPrasad) · 2026-04-17T16:35:23Z

resolves#318

AI Summary

In claude-agent-sdk 0.1.61 a delegated subagent can emit multiple tool_use AssistantMessages (e.g. Bash then Read) inside one LLM turn before any tool_result arrives. ContextTracker._handle_assistant was unconditionally calling cleanup_context whenever the context already had an llm_span, which closed the in-flight Bash tool span with no output. When the matching tool_result finally arrived two events later, the span was already gone and its output was dropped (issue #318).

Only run cleanup_context when ctx.next_llm_start is set, which is the real LLM-turn boundary (set in _handle_user when a tool_result arrives). Back-to- back tool_use messages now merge into the existing LLM span without closing sibling tool spans.

Red/green regression: new ContextTracker unit test simulating the 0.1.61 event stream (Bash tool_use -> Read tool_use -> Read tool_result -> Bash tool_result, all under one subagent parent).
Re-records cassettes under claude-agent-sdk 0.1.61 and bumps the matrix latest pin to 0.1.61. test_interleaved_subagent_tool_spans_preserve_output and test_interleaved_subagent_tool_spans_parent_to_correct_llm now pass.
Full test_claude_agent_sdk(latest) and test_claude_agent_sdk(0.1.10) sessions green.

…tool_use messages In claude-agent-sdk 0.1.61 a delegated subagent can emit multiple tool_use AssistantMessages (e.g. Bash then Read) inside one LLM turn before any tool_result arrives. ContextTracker._handle_assistant was unconditionally calling cleanup_context whenever the context already had an llm_span, which closed the in-flight Bash tool span with no output. When the matching tool_result finally arrived two events later, the span was already gone and its output was dropped (issue #318). Only run cleanup_context when ctx.next_llm_start is set, which is the real LLM-turn boundary (set in _handle_user when a tool_result arrives). Back-to- back tool_use messages now merge into the existing LLM span without closing sibling tool spans. - Red/green regression: new ContextTracker unit test simulating the 0.1.61 event stream (Bash tool_use -> Read tool_use -> Read tool_result -> Bash tool_result, all under one subagent parent). - Re-records cassettes under claude-agent-sdk 0.1.61 and bumps the matrix latest pin to 0.1.61. test_interleaved_subagent_tool_spans_preserve_output and test_interleaved_subagent_tool_spans_parent_to_correct_llm now pass. - Full test_claude_agent_sdk(latest) and test_claude_agent_sdk(0.1.10) sessions green.

Includes - #324 - #323 - #322 - #321 - #333 - #345 - #341 - #346

Abhijeet Prasad (AbhiPrasad) · 2026-04-17T16:35:23Z

resolves#318

AI Summary

In claude-agent-sdk 0.1.61 a delegated subagent can emit multiple tool_use AssistantMessages (e.g. Bash then Read) inside one LLM turn before any tool_result arrives. ContextTracker._handle_assistant was unconditionally calling cleanup_context whenever the context already had an llm_span, which closed the in-flight Bash tool span with no output. When the matching tool_result finally arrived two events later, the span was already gone and its output was dropped (issue #318).

Only run cleanup_context when ctx.next_llm_start is set, which is the real LLM-turn boundary (set in _handle_user when a tool_result arrives). Back-to- back tool_use messages now merge into the existing LLM span without closing sibling tool spans.

Red/green regression: new ContextTracker unit test simulating the 0.1.61 event stream (Bash tool_use -> Read tool_use -> Read tool_result -> Bash tool_result, all under one subagent parent).
Re-records cassettes under claude-agent-sdk 0.1.61 and bumps the matrix latest pin to 0.1.61. test_interleaved_subagent_tool_spans_preserve_output and test_interleaved_subagent_tool_spans_parent_to_correct_llm now pass.
Full test_claude_agent_sdk(latest) and test_claude_agent_sdk(0.1.10) sessions green.

…tool_use messages In claude-agent-sdk 0.1.61 a delegated subagent can emit multiple tool_use AssistantMessages (e.g. Bash then Read) inside one LLM turn before any tool_result arrives. ContextTracker._handle_assistant was unconditionally calling cleanup_context whenever the context already had an llm_span, which closed the in-flight Bash tool span with no output. When the matching tool_result finally arrived two events later, the span was already gone and its output was dropped (issue #318). Only run cleanup_context when ctx.next_llm_start is set, which is the real LLM-turn boundary (set in _handle_user when a tool_result arrives). Back-to- back tool_use messages now merge into the existing LLM span without closing sibling tool spans. - Red/green regression: new ContextTracker unit test simulating the 0.1.61 event stream (Bash tool_use -> Read tool_use -> Read tool_result -> Bash tool_result, all under one subagent parent). - Re-records cassettes under claude-agent-sdk 0.1.61 and bumps the matrix latest pin to 0.1.61. test_interleaved_subagent_tool_spans_preserve_output and test_interleaved_subagent_tool_spans_parent_to_correct_llm now pass. - Full test_claude_agent_sdk(latest) and test_claude_agent_sdk(0.1.10) sessions green.

Includes - #324 - #323 - #322 - #321 - #333 - #345 - #341 - #346

Abhijeet Prasad (AbhiPrasad) self-assigned this Apr 17, 2026

Andrew Kent (realark) approved these changes Apr 20, 2026
View reviewed changes

Abhijeet Prasad (AbhiPrasad) merged commit db796a2 into mainApr 20, 2026
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