Client tool continuation stays pending for 60 seconds after completion #2055

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1. ben-reitz

   self-assigned this

   on Aug 10, 2026
2. ben-reitz commented on Aug 10, 2026

   

   ben-reitz

   on Aug 10, 2026

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   Hey @urjitc! Thanks for the report. I've done a quick investigation and confirmed that this reported frame sequence would cause useAgentChat to remain submitted until the 60-second pending timeout:

   cf_agent_stream_pending
   done: true
   # no cf_agent_stream_resuming
   

   The client currently does not retain the request ID from cf_agent_stream_pending, so it cannot use a matching terminal response to settle the continuation unless cf_agent_stream_resuming arrives first.

   ---

   However, I've not been able to reproduce the missing cf_agent_stream_resuming with stock @cloudflare/think. The relevant code in the reported versions is intended to emit:

   cf_agent_stream_pending → cf_agent_stream_resuming → done
   

   and our integration tests produce that sequence with matching request IDs.

   Could you share either a minimal reproduction or a complete WebSocket trace from immediately before addToolOutput through completion? The frame type, id, probeId, done, and timestamps are sufficient; message bodies can be redacted. It would also help to include:

   • Exact imports used for useAgentChat
   • Output from pnpm why agents @cloudflare/think (or equivalent)
   • Any custom lifecycle hooks or chat transport behavior

   There is a defensive client fix we could look at doing, but I'd also like to identify why the server notification was missing in your case.
3. urjitc commented on Aug 10, 2026

   

   urjitc

   on Aug 10, 2026

   Last edited by urjitc

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   @ben-reitz Thanks Ben, I isolated this to the sub agents and made a repro:

   https://github.com/urjitc/cloudflare-agents-2055-repro

   https://cloudflare-agents-2055-repro.chakrabortyurjit.workers.dev/?mode=sub-agent

   The reproduction uses the same Think implementation in two configurations:

   1. Direct Think: pending → resuming → done
   2. The same Think reached through a parent Agent as a sub-agent: pending → done

   The direct path returns useAgentChat to ready. The sub-agent path displays the completed assistant response but remains submitted until the pending timeout.

   The browser reproduction uses the real useAgentChat and addToolOutput flow. The only model customization is an overridden getModel() that returns a deterministic AI SDK model. It always requests the client tool and then returns Continuation completed.
   Exact imports:

   import { useAgentChat } from "@cloudflare/think/react";
   import { useAgent } from "agents/react";

   There are no custom lifecycle hooks, chat transports, or package patches. The parent agent is:

   export class ParentAgent extends Agent<Env> {}

   Dependency output:

   @cloudflare/think@0.15.0
   └── cloudflare-agents-2055-repro@0.0.0 (dependencies)
   
   agents@0.19.0
   ├─┬ @cloudflare/think@0.15.0
   │ └── cloudflare-agents-2055-repro@0.0.0 (dependencies)
   └── cloudflare-agents-2055-repro@0.0.0 (dependencies)
   
   Found 1 version of @cloudflare/think
   Found 1 version of agents
   

   To run the protocol reproduction:

   pnpm install
   pnpm reproduce

   It prints the relevant type, id, probeId, done, and continuation fields for both paths. The pending and terminal response IDs match in the failing sub-agent case, but cf_agent_stream_resuming is missing.
4. urjitc commented on Aug 10, 2026

   

   urjitc

   on Aug 10, 2026

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   For context I ran into this issue when trying to add a AskUserQuestion tool in https://github.com/ThinkEx-OSS/thinkex where an agent can ask questions and the user gets nice ui to do so and sends the results back
5. ben-reitz

   closed this as completedin #2090on Aug 26, 2026
6. ben-reitz commented on Aug 26, 2026

   

   ben-reitz

   on Aug 26, 2026

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   This fix will go out in the next release
7. O4epegb commented on Sep 1, 2026

   

   O4epegb

   on Sep 1, 2026

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   Hi, we upgraded to agents@0.22.0 and @cloudflare/think@0.17.0, but this issue still reproduces for client-side tool continuations through a sub-agent.
   After the user completes or dismisses a client-side tool interaction, we observe:

   cf_agent_stream_pending { id: "<request-id>" }
   cf_agent_use_chat_response {
     id: "<same-request-id>",
     done: true,
     continuation: true
   }
   # cf_agent_stream_resuming is missing
   

   The assistant’s response appears within a few seconds, but useAgentChat remains in the submitted state for approximately 60 seconds.
   This reproduces with autoContinueAfterToolResult: true for both completed and dismissed interactions. Setting it to false avoids the problem.

   It appears that PR #2090 does not cover every sub-agent continuation path maybe?
8. O4epegb commented on Sep 14, 2026

   

   O4epegb

   on Sep 14, 2026

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   Update: we can no longer reproduce the 60-second pending state with autoContinueAfterToolResult: true. We retested both submitted and skipped client-side questionnaires through our sub-agent setup. Both now return to ready normally.

   Current versions: agents@0.22.0, @cloudflare/think@0.17.0, ai@7.0.98, and @ai-sdk/react@4.0.101.

   Our app has since migrated from AI SDK 6 to 7, while the Cloudflare package versions stayed unchanged. That may explain the improvement, but we haven’t isolated the SDK upgrade as the cause.