useUIMessages / streaming freezes when message count approaches initialNumItems limit

[christiannwamba]

When using useUIMessages (or useThreadMessages) with an initialNumItems limit, streaming consistently freezes once the thread's message count approaches that limit. The stream completes successfully on the backend, but the frontend remains stuck in a streaming state.

Reproduction Steps

1. Set initialNumItems: 20 in the messages hook (or any value)
2. Have a conversation that accumulates messages approaching that limit
3. Send a new message when message count is near/at the limit
4. Result: Frontend freezes in streaming state indefinitely

Expected Behavior

Streaming should complete normally regardless of how many messages exist in the thread relative to initialNumItems.

Actual Behavior

• Backend: Stream completes successfully (onFinish, consumeStream all fire correctly)
• Frontend: UI remains stuck in streaming state

Environment

• @convex-dev/agent: PR strip out old streams when they are no longer present #186 build (https://pkg.pr.new/get-convex/agent/@convex-dev/agent@186)
• ai: ^5.0.44
• Framework: React Native / Expo

[ianmacartney]

When the pagination can't fetch a full UIMessage, what do you think the behavior should be? Maybe the client should automatically fetch more pages until it has a full UIMessage?

…

On Tue, Dec 2, 2025 at 2:38 AM Christian Nwamba ***@***.***> wrote: *christiannwamba* created an issue (get-convex/agent#193) <#193> Description When using useUIMessages (or useThreadMessages) with an initialNumItems limit, streaming consistently freezes once the thread's message count approaches that limit. The stream completes successfully on the backend, but the frontend remains stuck in a streaming state. Reproduction Steps 1. Set initialNumItems: 50 in the messages hook (or any value) 2. Have a conversation that accumulates messages approaching that limit 3. Send a new message when message count is near/at the limit 4. *Result:* Frontend freezes in streaming state indefinitely *Key observation:* Setting initialNumItems: 2 causes the freeze to occur after just 2 messages, confirming the issue is tied to the pagination limit, not message content. Expected Behavior Streaming should complete normally regardless of how many messages exist in the thread relative to initialNumItems. Actual Behavior - *Backend:* Stream completes successfully (onFinish, consumeStream all fire correctly) - *Frontend:* UI remains stuck in streaming state - *Console warning:* "Tool result without preceding tool call.. adding anyways" appears (even for properly paired tool calls), suggesting message grouping/ordering breaks when pagination is involved Environment - @convex-dev/agent: PR #186 <#186> build ( ***@***.******@***.***) - ai: ^5.0.44 - Framework: React Native / Expo Additional Context The "Tool result without preceding tool call" warning in UIMessages.js (line 346) suggests the issue is in how messages are grouped when they span across the pagination boundary. Tool calls and their results may be getting separated during the toUIMessages conversion when not all messages are loaded. Logs Backend shows successful completion: [STREAM_DEBUG] onFinish triggered { threadId: '...', finishReason: 'stop', ... } [STREAM_DEBUG] consumeStream completed successfully { ... } [STREAM_DEBUG] Stream lifecycle complete - starting post-stream tasks { ... } But pre-stream analysis shows orphaned tool results in the context: [STREAM_DEBUG] ⚠️ ORPHANED TOOL RESULTS DETECTED - This may cause stream to freeze! { orphanedToolResults: [ 'removeSchedule:call_xxx', 'searchSchedule:call_yyy', ... ] } — Reply to this email directly, view it on GitHub <#193>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AACZQW3M3SPQGVNT776MUXT37VTZXAVCNFSM6AAAAACNY5RAHCVHI2DSMVQWIX3LMV43ASLTON2WKOZTGY4DKMRRGA3TMOA> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>