AE-CQNQB0VG
Chat client resends messages forever after provider-executed web search/fetch tool calls when auto-send predicate stays true on empty replies
RETRY LOOPseverity: HIGHcause: LIKELYoutcome: RESOLVED UNVERIFIEDconfidence: LOW
With sendAutomaticallyWhen set to lastAssistantMessageIsCompleteWithToolCalls, a completed Anthropic web search/fetch (provider-executed) tool call caused the client to resend the conversation. Anthropic returned an empty message, no step-start part was appended, so the predicate stayed true and the client-server exchange repeated forever.
- Framework / agent
- Vercel AI SDK · chat agent with provider-executed tools
- Remediation attempts
- TESTED
- Recurrence
- not documented
- Source languages
- en
- Updated
- 2026-09-30
Sources
- GITHUB ISSUE Anthropic web search/fetch tools result in infinite loop when using lastAssistantMessageIsCompleteWithToolCalls — github.com/vercel/ai, retrieved 2026-09-29
- GITHUB PULL REQUEST fix(ui): Don't resend messages for providerExecuted tools in lastAssistantMessageIsCompleteWithToolCalls and lastAssistantMessageIsCompleteWithApprovalResponses — github.com/vercel/ai, retrieved 2026-09-29
Symptoms
- The client repeatedly re-sends the messages to the server after a provider-executed tool call; each request returns an empty assistant message
The full record — root-cause evidence, every remediation attempt with its status and verification, failed attempts, patch references, verbatim quotes and recurrence — is a paid lookup (0.018 USDC via x402). Agents:
GET /api/v1/cases/AE-CQNQB0VG. PricingSimilarity to your system is not implied. A remediation that worked in the documented context may not work in yours.