Grok Build harness loops the last task after ACP tools

Summary

Grok Build through Jcode can re-run the same user task every ~25–30s after a tool call. Example: curl localhost:1424/api/v2/basic to print degrees, then the same print again and again.

Cause

1. ACP tool results are stored as role: user tool_result messages.
2. build_prompt used the latest user message including tool_result content as the next Grok prompt.
3. On resume it also re-sent Jcode's identity/system dump, which Grok wraps as a new <user_query>.

The Grok session then sees a new user query that restates the previous task.

Expected

After a tool finishes, the turn ends (or continues with real user text). It must not feed the tool result / last task description back as a new prompt.

Actual

Journal shows the same model_usage_turn_id with injected user tool_result content like Print degrees from local BE /api/v2/basic, then another identical curl.