fix(process): child timeouts can hang when grandchildren retain pipes

[PierrunoYT]

Version / branch / commit

Audited on main at 903e3d13 (2026-08-23).

Problem

Five process-launching packages use exec.CommandContext without Cmd.WaitDelay or process-tree termination. Cancellation kills only the root PID. A surviving grandchild can retain stdout or stderr, leaving the os/exec copy goroutines waiting for EOF and Wait blocked indefinitely after the intended timeout.

Affected paths

• internal/verify/verify.go:301-307
• internal/agenteval/agent_command.go:63-70
• internal/agenteval/run.go:141-147
• internal/agenteval/materialize.go:190-201
• internal/perfbench/turn_bench.go:639-648
• internal/perfbench/taskbench.go:330-393
• internal/perfbench/perfbench.go:287-321
• internal/hooks/dispatch.go:299-323
• internal/dictation/runner.go:105-128

Expected behavior

A context deadline terminates the complete spawned process tree and returns within a bounded cleanup interval.

Actual behavior

Only the direct child is killed. Descendants can survive while holding inherited pipes, making the caller wait forever.

Existing pattern

internal/config, internal/execution, internal/specialist, internal/tools/bash*, and internal/worktrees already use WaitDelay and/or the shared process-group/tree-kill helpers.

Suggested fix

Set a bounded WaitDelay on every affected command and reuse execution.ConfigureProcessGroup plus execution.KillProcessTree where process trees are possible. Add a focused regression test that starts a child which leaves a grandchild holding stdout, cancels the context, and asserts bounded return. Run affected concurrent tests under -race.

[PierrunoYT]

I'm working on this.