[Bug]: Raw internal tool-call metadata leaks into visible assistant message content #1147

Describe the bug

In a long tool-heavy chat, the assistant started rendering raw internal tool-call metadata directly into the visible assistant response.

Instead of only natural-language output, the message included serialized fragments that look like internal tool invocation payloads.

Expected behavior

Internal tool-call data should never appear in the visible assistant message.

Only the assistant’s final text should be rendered.

Actual behavior

The rendered assistant message included snippets like:

to=functions.exec_command ... {"cmd":"date +%s","workdir":"/Volumes/dev/edgeOps","yield_time_ms":1000,"max_output_tokens":200}

assistant to=functions.exec_command մեկնաբանություն 付款json {"cmd":"date +%s","workdir":"/Volumes/dev/edgeOps","yield_time_ms":1000,"max_output_tokens":200}

still to=functions.exec_command մեկնաբանություն leakingjson {"cmd":"date +%s","workdir":"/Volumes/dev/edgeOps","yield_time_ms":1000,"max_output_tokens":200}

There were also repeated garbled fragments around these payloads, e.g.:

to=functions.exec_command մեկնաբանություն ...

This content was appended to otherwise normal assistant replies.

Reproduction

I don’t have a minimal repro yet, but this happened consistently in a long conversation with many assistant/tool turns.

Observed pattern:

1. Long thread
2. Repeated tool usage
3. Assistant response starts normally
4. End of response includes raw tool-call payload text
5. Same issue repeats in later messages

Environment

• Repo/app: pingdotgg/t3code
• Browser: unknown
• OS: macOS
• App version / build: 0.0.11 (876bbd715ae6)

Impact

High. This leaks internal implementation details into user-visible content and breaks trust in the response stream.

Possibly related

• Chat timeline content overlaps (assistant text + tool call cards stack on top of each other) #1035
• Assistant message projections collide across threads when message IDs are reused #871
• [Bug]: Main timeline keeps counting "Working for X" while thread is awaiting user input #1069
• Responses duplicate when Stream assistant messages is on #349