deepseek-harness/packages/bash/tool-bash

@deepseek-ai/dsh-tool-bash

The model-facing bash tools — bash, bash_output, bash_kill — registered over the ctx.bash executor seam (@deepseek-ai/dsh-bash). Pure schema + text shaping; every process concern lives behind the seam, so sandboxed or remote executor implementations swap in without changing what the model sees.

Requires a loaded executor implementation (e.g. @deepseek-ai/dsh-bash-local); the plugin stays pending until ctx.bash exists (inject: ['tools', 'bash']).

Tools

bash

Arg	Type	Notes
command	string (required)	Run via bash -c. No state persists between calls — use workdir, not cd.
description	string (required)	One-line, active-voice summary of the command (5-10 words), for UI/log display only — no effect on execution.
timeoutMs	number	Timeout override in milliseconds. The executor applies its configured default and cap.
workdir	string	Working directory for this call. Defaults to the calling agent's session cwd (session.header.cwd) so each session runs in its own workspace; a relative workdir is resolved against that session cwd.
run_in_background	boolean	Return a task id immediately; no timeout applies.

command, workdir, and timeoutMs are resolved against the executor's config defaults via ctx.bash.resolve() before execution, so the executor seam (BashExecSpec) receives explicit workdir/timeoutMs values. The workdir default is applied in the tool layer (from the calling agent's session.header.cwd) BEFORE resolve() — the per-session cwd must come from exec.agent, since N sessions share one executor; only when no session cwd is available does the executor fall back to its own config / process.cwd().

Result text: stdout, then a [stderr] section, then status markers — [timed out after Nms] whenever the executor's timer fired (reported independently of how the process ended, so a command that traps SIGTERM and exits 0 still shows it), [killed by signal: …] for a signal death, [exit code: N] for a non-zero exit (reported, not isError: the model decides how to react), and [output truncated; full output: <path>] when the tail was kept and a safe spill file is available. If the executor knows output was dropped but cannot safely advertise a complete spill file, the path is reported as (unavailable). Only infrastructure failures (spawn errors, aborts) surface as isError results.

bash_output

task_id → output produced since the previous bash_output call plus a status line (running / completed, exit code: N / killed). Reads that lost data to buffer bounds say so and point at the full-output spill file when one is safely available, otherwise (unavailable).

bash_kill

task_id → ask the executor to kill the background task. The concrete executor decides how to signal or stop the process; killing an already-finished task is a reported no-op, and unknown ids are errors.

Task ownership (cross-session isolation)

The owning agent's session token (session.header.id) is stamped onto the task at spawn — passed to the executor via resolve({ …, owner }) and stored ON THE TASK inside the executor (the dsh-bash ownerOf(id) seam), not in a plugin-local map. bash_output/bash_kill compare ctx.bash.ownerOf(id) to the caller's token (session.header.id) with !== undefined semantics and reject a task owned by a different session with task <id> belongs to another session (a task started with no agent — a non-loop caller — has no owner token and is open to anyone; a call with no exec.agent cannot access an owned task). Task ids are global and predictable, so under multi-session ACP this token check is the fence that stops one session's agent from reading or killing another session's background task. Because ownership lives on the task in the executor (disposed with the dsh-bash fiber), it survives an independent tool-bash HMR reload — closing the old plugin-local-map gap where a reload orphaned pre-reload tasks. (The onTaskDone listener is still effect-scoped to this plugin's apply, so a completion landing during the reload gap still drops its one notice — the pre-existing reload-gap drop — but the ownership fence itself is HMR-proof.)

UI presentation

These tools own how their calls render in a UI (an editor's tool-call card) via the dsh-tools presentCall/presentResult seam — a UI never special-cases tool names. For bash: the title is the exact command ("ls -la src") and kind is execute (terminal/run treatment), matching the reference ACP adapters (claude-agent-acp, codex-acp), which both use the bare command as an execute tool's title. The command is ALSO the rawInput for non-terminal UIs that render it (an execute-kind card hides rawInput — Zed shows it only for non-terminal tools — so the command must BE the title to be seen). The model-written description rides as a content text block shown ABOVE the card. (claude-agent-acp DROPS the description in terminal mode and shows only the card; surfacing it as a content block is a deliberate divergence — we keep the human summary visible alongside the card.) The completed output is wrapped in a fenced ```console block as the no-terminal-capability fallback — a UI-only affordance, so the model-facing result text stays unfenced. A FOREGROUND bash run also flags itself as a terminal (the neutral terminal field: presentCall sets a cwd from the model workdir when given — absolute as-is, relative for the UI bridge to resolve against the session cwd — else leaves it for the bridge to fill from the session cwd; presentResult carries the raw output plus the parsed exitCode/signal) so a capable client (Zed) renders a terminal card with an exit-status pill instead of the text block — see packages/ui/acp ("Terminal card"). A run_in_background call is NOT a terminal (it returns a task id immediately and never streams a terminal — poll with bash_output), and an isError result (spawn failure / abort) carries no exit pill (there is no real process exit); both render as the ordinary execute card / fenced text. bash_output/bash_kill present a task-scoped title ("Read output from background task bash-3" / "Kill background task bash-3") with the task id as rawInput. These methods are pure/display-only (they also run on session/load replay), and a malformed/older logged arg shape falls back to a generic presentation rather than throwing. See packages/core/tools ("Tool-owned UI presentation") and packages/ui/acp ("Terminal card" / "Tool-call presentation").

Background completion notices

When a background task finishes, a short notice is injected into the owning agent's session (agent.inject(), source {kind: 'plugin', plugin: 'tool-bash'}). The owning agent is found by its session token: the listener reads ctx.bash.ownerOf(task.id) and scans ctx.get('agents')?.list() for an agent whose session.header.id matches (read via ctx.get — onTaskDone runs on the bash fiber, a foreign fiber, so the ctx.agents proxy would throw). If no live agent carries that token — e.g. the owning session disconnected and its agent was disposed while the task ran on — the notice is dropped cleanly. Injection is durable context for the next model request, not a wake-up — an idle agent stays idle until something sends a message. That's why the tool descriptions tell the model to poll with bash_output.

Permissions

TODO(permissions): commands run with the executor's full authority. The permission/sandbox seam is the tools/execute waterfall (veto or ask) plus sandboxing BashExecutor implementations — see docs/architecture.md. @cordisjs/plugin-capability (a named-permission service with a session test()) is a candidate building block for that work.