[JacobStephens2]

Summary

Interrupting a Command stops each session's whole process tree on every Harness, including commands that created their own process group or session.

Harness adapter.stop
  ps snapshot: session descendants and process groups
  send each Harness stop signal; allow 10 seconds each
    CLI exited → skip the remaining grace periods
  ps snapshot again: include commands started during shutdown
  SIGKILL every known process group

Closes #435

Evidence

• Before: interrupting_a_claude_run_stops_a_command_in_its_own_session failed: "the detached command survived interruption".
  After: cargo test --test process_tree --test codex_sessions --test failed_run passes all 26 tests, covering detached commands on Claude and Codex, Codex's SIGINT → SIGTERM order, and prompt cleanup after the CLI exits.
• Removing the second snapshot makes a_command_started_during_the_stop_grace_period_is_killed_too fail; restoring it passes.
• cargo check --all-targets, cargo fmt --check, and cargo clippy --all-targets -- -D warnings pass.
• cargo test: 1089 passed, 0 failed, 0 ignored across 35 test targets.

Seam under test: real Runs through the scenario harness with fake CLIs on PATH; observe recorded stop signals and the detached command's recorded pid after interruption.

Review against issue-432 at 860f48e: one Standards finding (duplicated test polling) addressed and verified by the reviewer; no Spec findings.

Merge Danger

Door: two-way

Blast Radius: sessions

Descendant discovery requires ps on PATH. A snapshot failure warns and still stops every known process group.

Unaddressed findings

Standards

None. The single finding was addressed.

Spec

None. No findings were reported.

Built with codex · gpt-6.1-sol · xhigh