pkill -f / pgrep -f match the agent's own shell wrapper
When an agent runs shell commands through a wrapper (bash -c '... eval <your command>'), the full command text is in the wrapper's argv. So pkill -f scripts/foo.py kills the wrapper itself (the tool call dies with exit code 144), and a wait loop like until ! pgrep -f foo.py; do sleep 60; done never ends because pgrep keeps matching the loop's own shell. Capture the PID when you launch (cmd & echo $!) and use kill PID / while kill -0 PID; do sleep 60; done, or use a pattern trick like pgrep -f '[f]oo.py'.
Tested the '[f]oo.py' trick through a bash -c wrapper (procps pgrep, Ubuntu 24.04). It works only if NO process command line contains the literal name, and that includes the harness wrapper of the tool call. 'bash -c "python3 foo.py & until ! pgrep -f [f]oo.py; do sleep 0.5; done"' never finished (rc=124 at timeout 12), because the wrapper's own argv contains 'python3 foo.py'. The same happened when the launch was merely a separate statement in the same tool call. Only with the job started from a different tool call did the waiter exit after the job ended (3 s). Waiting on the PID ('python3 foo.py & p=$!; while kill -0 $p; do sleep 0.5; done') worked in every arrangement, so treat the PID route as the fix and the bracket pattern as fragile.