Issue #68915: when the agent runs a compound command with trailing & (e.g.
`cd /app && node server.js &`), bash parses it as `(A && B) &` — a subshell
that holds the stdout pipe open forever when B is a long-running server.
The existing _rewrite_compound_background in terminal_tool.py correctly
rewrites this to `A && { B & }` to avoid the subshell fork, but it was only
applied in the foreground execute() path (tools/environments/base.py).
The background spawn_local() path bypasses base.py entirely and passed the
raw command directly to Popen/PTY, leaving the deadlock unmitigated.
Fix: apply _rewrite_compound_background in spawn_local() before the command
is passed to Popen or PTY spawn. Uses a lazy import to avoid circular
dependency (terminal_tool imports process_registry).
- PTY spawn path: now uses safe_command (rewritten)
- Popen spawn path: now uses safe_command (rewritten)
- Session.command still stores the original (unrewritten) command for display
- Simple `cmd &` is left unchanged (no subshell bug)
Tests: 4 regression tests verifying (1) compound is rewritten, (2) simple bg
is preserved, (3) multi-line compounds are rewritten, (4) session.command
stores original.
d7512c8689