Summarize an in-flight run, mixing past and present tense.
Completed calls are phrased in the past tense so the work already done in
the step stays visible, and the still-running calls are phrased in the
present tense, e.g. ["execute", "execute"] completed plus ["task"]
pending -> "Ran 2 shell commands, running 1 agent".
Raw tool names that have finished successfully, in call order. Failed/rejected calls are evicted before this runs.
Raw tool names still pending or running, in call order.
