deepseek-harness/packages/bash/bash-local

@deepseek-ai/dsh-bash-local

Local implementation of the @deepseek-ai/dsh-bash executor seam over the @deepseek-ai/dsh-subprocess service: LocalBashExecutor spawns bash -c <command> per call as a managed process group through ctx.subprocess, and owns everything bash-shaped — command defaulting and caps, timeout/cancel classification, the model-friendly terminal environment, and the model-facing stdout/stderr merge for background reads. Group mechanics (bounded spill-backed output, credential scrub, kill escalation, disposal) are the subprocess service's.

The package root exports the default and named LocalBashExecutor plugin plus its Config.

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
    maxSpillBytes: 67108864    # per-stream full-output spill cap
    graceMs: 3000              # kill escalation and post-exit pipe-drain grace

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/index.ts records the two proven stateful designs (Claude Code's cwd-only persistence; Codex's PTY exec sessions) for when real workflows demand them.
• Configured budgets over managed groups — resolve() fills workdir/timeoutMs/stdoutMaxBytes from config, and every spawn hands the service explicit byte caps, spill cap, and graceMs (default 3s — OpenCode's escalation). Process-group kills, the post-exit pipe-drain grace, tail-keep truncation, and bounded spill files are dsh-subprocess-local mechanics. A foreground BashExecRequest.stdoutMaxBytes can raise stdout's capture budget for one trusted caller; stderr and background runs still use maxOutputBytes.
• Timeout and cancel classification — run() fuses its config-clamped timeout with the caller's signal through one deadline; only the executor's own timeout reports timedOut, an upstream cancel reports aborted, and a self-signaled command reports neither (timeout-library Agent Note).
• Model-friendly terminal env — NO_COLOR=1 TERM=dumb PAGER=cat GIT_PAGER=cat (Codex's hardcoded set) so pagers and ANSI color don't garble results, merged as ordinary env under the service's credential scrub and DSH_* channel rules; an explicit caller entry still wins. See the stdin/env Agent Note and managed environment Agent Note.
• Background processes — start() returns a live BashProcess handle immediately, no timeout applies (Claude Code detaches timeouts when backgrounding), and the handle's readOutput() merges the service's offset-based stdout/stderr reads into one marked-section delta with a consuming cursor. A still-running process belongs to the subprocess service, so it survives executor reloads and dies (killed and joined) with the service's disposal. 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.

Model Experience

Indirectly, through dsh-tool-bash, which renders this executor's bounded stdout/stderr tails, background-process deltas, spill-file paths, and infrastructure failures.

KV Cache effect

No direct invalidation; the named consumer owns any request-prefix changes.

Known Limitations and Deferred Work

• Unconfined by itself — this executor always runs commands with the harness process's authority; deployments needing confinement compose dsh-bash-sandbox, while per-call allow/deny/ask policy belongs on tools/pre-execute.
• No persistent shell or PTY — every call starts a fresh non-login bash -c; cwd-only persistence and interactive terminal sessions remain deferred until a real workflow requires them.
• POSIX-only — the bash binary is hardcoded, and the underlying service's group semantics are POSIX; Windows is unsupported.
• A background spawn-failure note is single-delivery — the subprocess service buffers no output for a process that never ran, so the executor injects spawn failed: … into exactly one readOutput() delta; a reader that discards that delta cannot recover it.

Scrub-heuristic and spill-retention caveats live with dsh-subprocess-local, which owns those mechanics.