# @deepseek-ai/dsh-bash

The **bash executor seam**: an abstract `BashExecutor` service (`ctx.bash`) defining WHAT a bash backend does — run commands, manage background tasks — without saying HOW.

This package is one third of the bash capability, split so each concern can evolve (and be swapped) independently:

| Package | Role |
|---|---|
| `@deepseek-ai/dsh-bash` (this) | the interface: abstract service + vocabulary types |
| `@deepseek-ai/dsh-bash-local` | an implementation: local subprocesses |
| `@deepseek-ai/dsh-tool-bash` | the model-facing tool schemas over `ctx.bash` |

The split mirrors the LLM seam (`LlmService`/`LlmAdapter`) and the agent-tool survey: pi hides execution behind a `BashOperations` interface (local shell / SSH / VM backends), Codex behind an exec-server protocol. A future sandboxed, containerized, or remote executor implements this interface and the tool schemas don't change.

## Service API (`ctx.bash`)

| Member | Semantics |
|---|---|
| `run(spec)` | Foreground execution. Resolves when the command finishes. **Rejects only for infrastructure failures** (unusable workdir, missing shell, pre-aborted signal); nonzero exits, timeout kills, and abort kills resolve with a descriptive `BashRunResult`. |
| `start(spec)` | Background execution. Returns a `BashTask` handle immediately; **no timeout applies** (stop tasks via `kill`). |
| `get(id)` / `list()` | Task lookup. |
| `readOutput(id)` | **Incremental** output read — consecutive reads never re-deliver. Reads that lost data to buffer bounds flag `lossy` and point at full-stream spill files. Throws for unknown ids. |
| `kill(id)` | Kill a running task. Returns `false` when it already finished; throws for unknown ids. |
| `onTaskDone(listener)` | Completion listener (effect-based, disposer returned). Fires exactly once per task; never after the service is disposed. |

Implementations subclass `BashExecutor`, implement the abstract methods, and call `notifyTaskDone(task)` on background completion. Disposal must kill every running task (no orphan processes) — see the HMR-safety tests.

## Vocabulary

`BashExecSpec` (command, workdir?, timeoutMs?, signal?) → `BashRunResult` (exitCode, signal, timedOut, aborted, timeoutMs, stdout/stderr as `CollectedOutput`) and `BashTask`/`BashTaskRead` for the background side. See `src/types.ts` for the full contracts.