Summary

E2B PTY output collection only woke when stdout/stderr/PTY output arrived. If a process exited after its final output chunk, or exited without output, pty_exec_start and pty_write_stdin could wait until the full yield_time_s window before observing completion. This added avoidable latency to E2B-backed tool calls, which compounded across multi-turn episodes.

To fix this, I've added a small waiter task for each E2B AsyncCommandHandle to treat process exit as a new output-collection wakeup signal, matching the Daytona extension's existing _run_pty_waiter pattern (Modal achieves the same by polling exit inline during collection).

No documentation changes; this is an internal bugfix with no public API change.

Test plan

• make format
• make lint
• make typecheck
• uv run pytest -q tests/extensions/sandbox/test_e2b.py

Added regression coverage for:

• output followed by process exit before the yield window expires
• quiet process exit with no output
• nonzero process exit via E2B CommandExitException
• outer tty=True PTY session exit
• still-running command cleanup cancelling the waiter and killing the handle

Issue number

Closes #3609

Checks

• I've added new tests (if relevant)
• I've added/updated the relevant documentation
• I've run make lint and make format
• I've made sure tests pass