sPTC Brings Speculative Execution to AI Tool Calls

The clever idea is treating programmatic tool calls like futures: overlap model generation and tool latency instead of waiting for the entire code block to finish.

• –A shadow REPL parses partial code, safely speculates eligible calls, and routes matching real calls to cached outputs.
• –The largest gains should come from slow sub-agents, independent calls, long reasoning traces, and locally served models.
• –Side effects and time-sensitive tools remain dangerous; purity annotations, allowlists, and isolated state are essential.
• –Initial RLM tests show roughly 1–1.2x speedups, so the concept is promising but highly dependent on workload, serving congestion, and speculation accuracy.