deepseek-harness/packages/bash/bash-local/README.md

@deepseek-ai/dsh-bash-local

Local-subprocess implementation of the @deepseek-ai/dsh-bash executor seam: LocalBashExecutor spawns bash -c <command> per call in its own process group, collects bounded output with full-stream spill files, and escalates kills SIGTERM→SIGKILL across the whole group.

Config

- id: bash
  name: '@deepseek-ai/dsh-bash-local'
  config:
    cwd: /path/to/workspace   # default: process.cwd()
    timeoutMs: 120000          # default foreground timeout
    maxTimeoutMs: 600000       # cap for per-call overrides
    maxOutputBytes: 64000      # per-stream in-memory cap; overflow spills to disk
    graceMs: 3000              # SIGTERM→SIGKILL escalation grace on kills

Behavior (and where it came from)

Design surveyed against the bash tools of Claude Code, OpenCode, Codex, and pi; the notable choices:

• Spawn per call, no shell state — every call is a fresh non-login bash -c (deterministic; no rc files). All four surveyed tools spawn per call. XXX(stateful-shell) in src/run.ts records the two proven stateful designs (Claude Code's cwd-only persistence; Codex's PTY exec sessions) for when real workflows demand them.
• Process-group kills with escalation — children are spawned detached (own process group); kills send SIGTERM to the group, then SIGKILL after the graceMs grace (default 3s — OpenCode's escalation; pipelines and subshells die with the parent). ESRCH is tolerated; daemons that re-parent away from the group can still survive — same caveat as the surveyed tools.
• Tail-keep truncation + spill files — output beyond maxOutputBytes keeps the in-memory TAIL (errors/results cluster at the end — pi/OpenCode rationale) while the FULL stream is appended to a temp file whose path is reported when available. If the final spill close reports a delayed writeback failure, the executor still returns the tail but withholds the path rather than advertising a possibly incomplete file.
• Model-friendly env + credential scrub — process.env minus credential-shaped vars (*KEY*/*SECRET*/*TOKEN*), then NO_COLOR=1 TERM=dumb PAGER=cat GIT_PAGER=cat (Codex's hardcoded set) so pagers and ANSI color don't garble results. This scrub is the security control that keeps the harness's ambient credentials out of a spawned command. A spec's env is merged LAST (after the scrub), so a caller's explicit entry — a value it already holds — wins even on a credential-shaped name. The spec's stdin, when supplied, is written to the child and closed; with none supplied, fd 0 is /dev/null — the exact pre-seam default, so a command that probes stdin's file type is unaffected. Both env/stdin are set by in-process plugins (the hooks bridges); the model-facing tool doesn't expose them. See the bash-stdin-env RFC.
• Background processes — start() returns a live BashProcess handle immediately, no timeout applies (Claude Code detaches timeouts when backgrounding), the handle's readOutput() is incremental with whole-stream byte offsets, and disposal kills every running process and awaits its exit. Everything task-shaped (ids, ownership, polling, notices) lives in the generic ctx.tasks runtime, which the tool layer registers the handle with — this executor never sees a session or a registry.

Sandboxing

TODO(permissions/sandbox): execution policy does NOT belong in this package. Use the tools/pre-execute deny/ask gate or implement a sandboxing BashExecutor — see docs/architecture.md § Extending The Harness. Reference points: Claude Code wraps commands in sandbox-exec/bubblewrap; Codex applies seatbelt/landlock plus an execpolicy prefix-rule engine.