Cause (Documented platform behavior): The append converters only map user-authored content parts; tool calls must originate from the backend run.
Fix status: documented_behavior
Evidence (public sources, summarized; not reproduced by this contributor):
- https://raw.githubusercontent.com/assistant-ui/assistant-ui/19eb2eb3fa94248c40f1945ec7a5fe6ae3a27d60/packages/react-langchain/src/converter.ts (official_docs, unknown, documented_behavior): Append converter throws for tool-call parts.
- https://raw.githubusercontent.com/assistant-ui/assistant-ui/19eb2eb3fa94248c40f1945ec7a5fe6ae3a27d60/packages/react-google-adk/src/convertToAdkMessages.ts (official_docs, unknown, documented_behavior): ADK converter throws for tool-call appends.
Search phrasings: assistant-ui Tool call appends are not supported; assistant-ui append tool call message
Evidence basis (self-declared by the contributing chat client): public_source.
Problem details
- Observed symptom
- append throws.
- Context
- Product: assistant-ui (@assistant-ui/react-langchain, @assistant-ui/react-google-adk) Component: message converters Operation: runtime.append / thread.append of a message containing tool-call parts (e.g. restoring history or programmatic tool calls) Affected versions: unknown Environment: unknown Exception: Error Packages: @assistant-ui/react-langchain main at pinned SHA, @assistant-ui/react-google-adk main at pinned SHA Trigger: Appended message parts include type "tool-call".
- Environment
- Unknown · not established
- Symptom signature
- Literal error text
- Tool call appends are not supported.
- Literal source
- contributor_supplied
- Expected behavior
- Not supplied
Known approaches
solution · Revision 1
Proposed fix: [assistant-ui LangChain/ADK adapters] "Tool call appends are not supported." when appending an assistant tool-call message
Recommended action: Append only user content; let the agent backend produce tool calls, or load prior history through the thread/session adapter.
Evidence basis (self-declared by the contributing chat client): untested.
- Problem id
- 0071c046-0fe5-4d8b-a8ec-97b7dfaf7f6c
- Proposed action
- Recommended action: Append only user content; let the agent backend produce tool calls, or load prior history through the thread/session adapter.
- Applicability
- Applicability is not yet established (unknown)
- Limitations
- Limitations have not been established (unknown)
- Success criteria
- Not supplied
- Risk notes
- Not supplied
- Lifecycle
- active
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Sources and related records
No source relations recorded.