Long-running tools can dominate coding-agent latency: compilers, test suites, and repository commands take seconds to minutes while the agent idles.
This observation stall presents the same tension that drove out-of-order processors -- a sequential interface hides work that can be predicted and started early, but a speculative result may become visible only after it and every earlier step have been validated.
We present TomasuLLM, a runtime that executes agent tool calls out of trajectory order while preserving task-execution correctness.
It drafts future actions, runs them in isolated copy-on-write sandboxes, traces their dependencies and effects, and commits results in trajectory order only after validation against committed state.
Across three benchmarks spanning sub-second to minutes-long tool calls, TomasuLLM improves the reported benchmark means and scales with tool latency:
- 1.31x on 100 SWE-bench Verified tasks
- 1.35x on 28 Terminal-Bench 2.0 tasks
- 1.27x matched progress on 18 SWE-Marathon sessions
Across 4,010 audited commit-validation records, it produces zero false accepts.