Python: [Bug]: HandoffBuilder drops agent-level compaction_strategy when cloning participants #8320

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1. Melissa Zulle (melzeta)

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   issue type on Sep 11, 2026
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4. Melissa Zulle (melzeta)

   changed the title [-]Python: [Bug]: HandoffBuilder drops agent-level compaction_strategy and tokenizer when cloning participants[/-] [+]Python: [Bug]: HandoffBuilder drops agent-level compaction_strategy when cloning participants[/+] on Sep 11, 2026
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   🤖 Automated triage reproduction notes (agent-authored — trust but verify)

   Agent analysis

   The bug occurs in python/packages/orchestrations/agent_framework_orchestrations/_handoff.py::HandoffAgentExecutor._clone_chat_agent at lines 294-304, where participant reconstruction omits compaction_strategy and tokenizer. It is triggered whenever a HandoffBuilder participant has either agent-level setting configured. Minimal repro: construct such an Agent, build a handoff workflow, retrieve its executor agent, and observe both cloned attributes are None.

   • Failing test: python/packages/orchestrations/tests/test_handoff.py::test_handoff_clone_preserves_compaction_strategy_and_tokenizer
   • Files examined: python/packages/orchestrations/agent_framework_orchestrations/_handoff.py, python/packages/orchestrations/tests/test_handoff.py, python/packages/core/agent_framework/_agents.py, python/packages/core/agent_framework/_compaction.py, python/packages/orchestrations/pyproject.toml
   • Tests run: test_handoff_clone_preserves_compaction_strategy_and_tokenizer, test_handoff_clone_preserves_per_service_call_history_persistence, test_handoff_clone_preserves_all_middleware_types, test_handoff_clone_preserves_additional_properties
   • Reported version: agent-framework-orchestrations 1.1.1 (agent-framework-core 1.18.0)
   • Current version: agent-framework-orchestrations 1.1.1
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   Eduard van Valkenburg (eavanvalkenburg)

   on Sep 11, 2026
9. manjunathshiva commented on Sep 12, 2026

   

   Manjunath Janardhan (manjunathshiva)

   on Sep 12, 2026

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   Opened #8329 for this.

   One thing worth confirming, Melissa Zulle (@melzeta): the report says the clone "gets None for both" and asks to
   "forward both fields", but only names compaction_strategy. The second one is tokenizer —
   it also lives outside default_options and is dropped the same way:

   compaction_strategy   original=ToolResultCompactionStrategy   clone=None   *** DROPPED ***
   tokenizer             original=CharacterEstimatorTokenizer    clone=None   *** DROPPED ***
   instructions          KEPT          name  KEPT
   

   The PR forwards both, by reference rather than deep-copied — matching context_providers and
   middleware on the neighbouring lines, since both hold immutable configuration the clone never
   mutates and a tokenizer can carry a vocabulary that is costly to copy.

   It also adds a guard test, because this is at least the fourth field to go missing here: the three
   test_handoff_clone_preserves_* tests already in the suite were each written after a drop was found.
   The guard reads the keyword names off the Agent(...) call and fails if any Agent.__init__
   parameter is neither forwarded nor explicitly excused, so the next one fails in CI rather than in
   someone's workflow.

   Happy to drop the guard if maintainers would rather not carry it — the two-line fix stands on its own.
10. Evan Mattson (moonbox3)

    closed this as completedin #8329on Sep 17, 2026
11. github-project-automation

    moved this to Done in Agent Frameworkon Sep 17, 2026