V2: starting a foreground server blocks the agent indefinitely #50278

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1. taka6745

   changed the title [-]V2: foreground shell commands block the agent until they exit[/-] [+]V2: starting a foreground server blocks the agent indefinitely[/+] on Sep 21, 2026
2. opencodejr commented on Oct 28, 2026

   

   opencodejrBot

   on Oct 28, 2026

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   Thanks for the detailed report and for putting together #50276!

   As far as I can tell from the v2 code, a foreground shell command blocking the agent is intended behaviour, not a bug. Foreground commands have a 2-minute default timeout, after which the process is killed and the model is told it timed out. The shell tool's description also tells the model to use background: true for dev servers, and a running command can be moved to the background by hand. So what you're describing is a request for the tool to move long-running foreground commands to the background automatically, so the agent doesn't depend on the model remembering to ask for it. Maintainers will consider it.

   If you saw a foreground uvicorn run for well over 2 minutes without being stopped (and the model hadn't passed timeout: 0), that would be a separate bug. Please add the session's tool call input and logs here if so.

   Related:

   • fix(core): background long-running shell commands #50276: your PR that auto-backgrounds commands after 5 seconds (closed by automated cleanup)
   • V2: define shell backgrounding semantics #34366: the original v2 shell backgrounding design (opt-in background option)
   • Shell tool never returns when a command leaves a background process holding its stdio #47350: an older v1 hang caused by processes holding the shell's stdio, a different cause