Bash Executor

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The bash execution seam is split across a Service Definition (dsh-shell, ctx.shell), Service Providers (dsh-bash-local and dsh-bash-sandbox), and Consumer (dsh-tool-bash, the bash schema). Generic background-job ids, ownership, and controls live in jobs.md; this seam returns a task-free process handle. Managed-range mechanics live behind the subprocess seam.

Source: packages/shell/shell/src/types.ts

Managed shell environment namespace

DSH_* variables are Harness-owned child-process facts. The model-facing bash tool collects them through ctx.shellEnv and passes them through ShellExecRequest.dshEnv; the subprocess service removes inherited DSH_* names before merging the current snapshot. The DshEnvironmentKey/DshEnvironment vocabulary is owned by the subprocess seam and re-exported by dsh-shell.

Request vs. spec: the resolve() split

The seam separates the model-/plugin-facing request (optional workdir/timeoutMs/stdoutMaxBytes, filled from config or request policy) from the fully-resolved spec the executor acts on (those fields required). The tool layer calls ctx.shell.resolve(request) between them (the repo's "explicit > implicit at package boundaries" rule); a ShellExecSpec carries resolved values.

/**
 * A caller's execution REQUEST: `workdir` and `timeoutMs` are optional and
 * filled by {@link ShellExecutor.resolve} from the implementation's config.
 * This is the model-/plugin-facing shape; pass it to `resolve()` to obtain a
 * fully-resolved {@link ShellExecSpec}.
 */
interface ShellExecRequest {
  command: string
  /** Working directory override (default: implementation-configured). */
  workdir?: string | undefined
  /** Timeout override in milliseconds (implementations cap it). */
  timeoutMs?: number | undefined
  /**
   * Foreground stdout capture budget in bytes. Absent uses the executor's
   * default output cap. Trusted in-process consumers use this when they must
   * parse complete stdout up to their own bounded limit; the model-facing bash
   * tool does not expose it as a parameter.
   */
  stdoutMaxBytes?: number | undefined
  /** Abort signal — implementations kill the command when it fires. */
  signal?: AbortSignal | undefined
  /**
   * Bytes to write to the command's stdin, then close it. Absent leaves stdin
   * closed/empty (the default for model-driven tool calls). Set by in-process
   * plugins (e.g. the hooks bridges, which write a hook command's JSON payload
   * to its stdin); the model-facing bash tool does not expose it as a parameter
   * (a model that needs stdin uses shell syntax like a heredoc or a pipe).
   */
  stdin?: string | undefined
  /**
   * Ordinary environment entries for the command, merged after the credential
   * scrub. Managed facts belong in {@link dshEnv}, which merges after this
   * map, so an entry here can never displace one. Set by in-process plugins
   * (the hooks bridges set `CLAUDE_PROJECT_DIR`, `CLAUDE_PLUGIN_ROOT`, …); the
   * model-facing bash tool does not expose it as a parameter.
   */
  env?: Record<string, string> | undefined
  /**
   * Harness-owned `DSH_*` variables for this execution (typed to managed
   * keys). Executors discard ambient `DSH_*` entries before merging this
   * snapshot last, so an unavailable current fact cannot inherit a stale
   * value from the harness process and a caller {@link env} entry cannot
   * displace a managed one.
   */
  dshEnv?: DshEnvironment | undefined
  /** Fully resolved per-call sandbox policy; sandboxing executors default it. */
  sandboxPolicy?: SandboxExecutionPolicy | undefined
}

/**
 * A resolved execution spec. {@link ShellExecutor.resolve} fills and caps the
 * required fields; {@link ShellExecutor.start} ignores `timeoutMs` because
 * background processes have no executor timeout.
 */
interface ShellExecSpec {
  command: string
  workdir: string
  timeoutMs: number
  /**
   * Resolved foreground stdout capture budget in bytes. `run()` uses it for
   * stdout; background jobs and stderr keep the executor's own output cap.
   */
  stdoutMaxBytes: number
  /** Abort signal — implementations kill the command when it fires. */
  signal?: AbortSignal | undefined
  /** Bytes to write to stdin before closing it; absent means no stdin. */
  stdin?: string | undefined
  /**
   * Ordinary environment entries carried through from
   * {@link ShellExecRequest.env}; {@link dshEnv} still merges after them.
   * OPTIONAL on the spec for the same reason as `stdin`: absent means no
   * ordinary extra environment.
   */
  env?: Record<string, string> | undefined
  /** Managed `DSH_*` snapshot (typed to managed keys); merges after {@link env}. */
  dshEnv?: DshEnvironment | undefined
  /** Resolved sandbox policy; ignored by executors that do not confine. */
  sandboxPolicy: SandboxExecutionPolicy | undefined
}

stdin and env are trusted in-process plugin inputs and are not exposed by dsh-tool-bash. The local executor scrubs ambient credentials before merging explicit caller-supplied env.

stdoutMaxBytes is also trusted-plugin-only. It lets a foreground consumer request complete stdout up to a bounded parser budget without changing stderr, background jobs, or the model-facing bash tool's ordinary output cap.

Foreground runs: ShellRunResult

The outcome of one completed (or killed) foreground run. Orthogonal outcomes are reported independently — a process can both time out AND exit 0 because it trapped the signal — so timedOut, aborted, signal, and exitCode are each their own field; a caller never reads a cut-short run as a clean success.

/** The outcome of one completed (or killed) foreground run. */
interface ShellRunResult {
  /** Exit code; null when the process died from a signal. */
  exitCode: number | null
  /** Terminating signal (e.g. 'SIGTERM'); null on normal exit. */
  signal: NodeJS.Signals | null
  /**
   * True when the executor's own timeout was the FIRST cause to cut the command
   * short. Mutually exclusive with {@link aborted}: one fused deadline drives
   * both the timeout and the caller's cancellation, so a timeout and an abort
   * racing before process close report the single first-abort cause, not both
   * (see the [timeout-library Agent Note](../../../../.agents/notes/implemented/architecture/2026-07-06-timeout-deadline-library.md)).
   */
  timedOut: boolean
  /**
   * True when the caller's `AbortSignal` was the FIRST cause to kill the command
   * (and it was not the executor's own timeout). Mutually exclusive with
   * {@link timedOut} — see there for the first-cause classification.
   */
  aborted: boolean
  /** The effective timeout applied to this run (after defaulting/capping). */
  timeoutMs: number
  stdout: CollectedOutput
  stderr: CollectedOutput
  /** Sandbox execution facts, absent for an unsandboxed executor. */
  sandbox?: ShellSandboxInfo
}

Each stream is a CollectedOutput — the (possibly truncated) text plus recovery info; when truncated, text is the tail and the complete stream spills to a private file. The fields are owned by the subprocess seam and re-exported by dsh-shell.

File sandbox: ShellSandboxInfo

A sandbox-consuming executor exposes its configured mode fallback through ShellExecutor.sandboxMode. The tool layer asks @deepseek-ai/dsh-sandbox-policy to resolve each calling session's durable sandbox/mode override and immutable cwd into ShellExecRequest.sandboxPolicy; a user-approved strictly wider call replaces only the mode. The mode/root/enforcement vocabulary is owned by the @deepseek-ai/dsh-sandbox seam; modes govern file effects only.

A sandboxed run reports its mode, conservative denial classification, and enforcement completeness. runnerFailed marks a sandbox runner failure before the command ran; foreground execution throws SANDBOX_UNAVAILABLE, while a settled background process has only its facts channel.

/**
 * Sandbox facts for one run, present iff a sandboxing executor handled it.
 * Facts are reported independently of process exit status so callers can
 * distinguish command failures from policy denials and runner failures.
 */
interface ShellSandboxInfo {
  /** The mode the command actually ran under. */
  mode: SandboxMode
  /** Whether the sandbox denied a file operation. */
  denied: boolean
  /** How completely the selected runner enforced the requested mode. */
  enforcement?: SandboxEnforcement
  /** Whether the sandbox runner failed before the command could run. */
  runnerFailed?: boolean
}

The SANDBOX_UNAVAILABLE error code (owned by the sandbox seam) is what the ctx.sandbox provider throws — and the executor propagates — when a confined mode has no usable backend. A selected runner refusing its profile reaches the same fail-closed foreground error; a settled background job records runnerFailed. The model receives denial/runner facts in results, learns the effective mode only when a denial marker names it, and can request a one-shot strictly wider retry through sandbox_permissions plus justification; ctx.approval must grant that exact call before anything executes. The complete policy and switching design is the sandbox Agent Note.

Background processes: ShellProcess

start() returns a handle with no id or owner. dsh-tool-bash adapts it into ctx.jobs.start() hooks; the generic runtime then owns job identity and lifecycle. done resolves when the underlying process settles and never rejects; a subprocess provider rejection becomes a killed process with a stage-neutral error on stderr. Reads remain valid after settlement, and sandbox facts are stamped before done resolves.

/**
 * A background process handle returned by {@link ShellExecutor.start}. It is the
 * only access path; buffered output remains readable after exit. Composition
 * teardown (the subprocess service's disposal) kills running processes and
 * awaits {@link done}; an executor-only reload leaves them running.
 */
interface ShellProcess {
  /** Process lifecycle state (settled exactly once). */
  status: ShellProcessStatus
  /** Exit code once finished (null = killed by signal / still running). */
  exitCode: number | null
  /** Terminating signal name, when signal-killed. */
  signal: NodeJS.Signals | null
  /**
   * Resolves when the underlying process settles (never rejects — provider
   * rejection settles as `killed` with a stage-neutral error on stderr).
   */
  readonly done: Promise<void>
  /** Sandbox facts, stamped once a confined process settles. */
  sandbox?: ShellSandboxInfo
  /**
   * Read output produced since the previous read (consuming — consecutive
   * reads never re-deliver). Reads that lost data flag `lossy` and point at
   * full-stream spill files when available.
   */
  readOutput(): ShellProcessRead
  /**
   * Terminate the provider-managed range. Returns false when it had already finished
   * (no-op); idempotent.
   */
  kill(): boolean
}

readOutput() returns the incremental delta and spill recovery facts:

/** One incremental {@link ShellProcess.readOutput} read. */
interface ShellProcessRead {
  /** Output produced since the previous read (stderr in a marked section). */
  delta: string
  /** True when truncation dropped unread bytes the delta cannot include. */
  lossy: boolean
  /** Full stdout spill file, when stdout truncation occurred and a safe path is available. */
  stdoutSpillPath?: string
  /** Full stderr spill file, when stderr truncation occurred and a safe path is available. */
  stderrSpillPath?: string
}

The service

ShellExecutor owns resolve, foreground run, background-process start, and the sandboxMode capability fact. dsh-bash-local owns command defaulting, timeout/abort classification, the terminal environment, and the background read merge; managed-range termination, bounded collectors, spill files, credential scrubbing, and disposal quiescence are the subprocess service's. dsh-tool-bash owns model-facing rendering and adapts background handles into the generic job runtime. dsh-shell owns the shell tools' shared exit-status contract: the exported parseExitStatus/ParsedExitStatus inverts the [exit code: N] / [killed by signal: X] markers dsh-tool-bash's renderResult and dsh-tool-pwsh's renderPwshResult append, and both tools' presentResult use it to split the rendered text into the terminal card's output body and its exit-status pill.

Cordis API

Generated from source by scripts/gen-cordis-catalog.ts (verified fresh by pnpm run verify-cordis-catalog in doc-sync; regenerate with pnpm run gen-cordis-catalog) — the language sides differ only in locale-specific paired document paths. Signature blocks use a ts cordis-catalog fence and keep the original source JSDoc; dispatch modes are defined in the primer, and the framework-inherited ctx API lives in cordis-api/inherited.md.

ctx.shell — ShellExecutor (abstract seam)

Abstract bash execution service. Subclass, implement the abstract methods, and load the subclass as a plugin — it registers as ctx.shell (one implementation per context; loading a second throws, which is cordis' standard duplicate-service behavior).

Implementations must honor these semantics:

• run rejects only for infrastructure failures. Nonzero exits, timeout kills, and abort kills resolve with a ShellRunResult.
• start returns immediately; no timeout applies to background processes. done settles at process close and never rejects; spawn failures settle as killed with the error on stderr.
• ShellProcess.readOutput is incremental: consecutive reads never repeat output. Lossy reads report truncation and available spill files.
• A still-running background process is stopped and awaited when its owning composition tears down. With the subprocess seam that boundary is ctx.subprocess disposal, so a background process survives an executor-only reload.

/**
 * Apply implementation-owned defaults and caps to a request before execution.
 * @param request - the caller's request; omitted fields get this
 *   implementation's defaults, capped fields are clamped.
 * @returns the fully-specified spec to hand to {@link run}/{@link start}.
 */
abstract resolve(request: ShellExecRequest): ShellExecSpec

/**
 * Run a command in the foreground; resolves when it finishes.
 * @param spec - a resolved spec from {@link resolve}, never a raw request.
 * @returns the outcome; nonzero exits, timeout kills, and abort kills
 *   resolve with a descriptive result rather than reject.
 */
abstract run(spec: ShellExecSpec): Promise<ShellRunResult>

/**
 * Start a background process and return its handle immediately.
 * @param spec - a resolved spec from {@link resolve}, never a raw request.
 * @returns the live process handle (reads, kill, quiescence promise).
 */
abstract start(spec: ShellExecSpec): ShellProcess

Source: packages/shell/shell/src/index.ts

ctx.shellEnv — ShellEnvRegistry

Registry (ctx.shellEnv) for trusted, per-execution DSH_* variables. The namespace is rebuilt for every model shell call: ambient DSH_* values are discarded by the executor, then the registry's current snapshot is injected. Built-in shell facts remain owned by the registry itself while plugins can register additional, enumerable facts with effect-scoped disposal.

/**
 * Register one environment contributor. Names and keys are unique; built-in
 * keys are reserved. Registration is disposed with the calling plugin fiber.
 * @param contributor - declared key ownership and per-execution resolver.
 * @returns the disposer that unregisters the contribution.
 */
register(contributor: BashEnvContributor): () => void

/**
 * Build the trusted `DSH_*` snapshot for one shell tool execution.
 * @param execution - the current tool execution.
 * @returns an immutable environment overlay containing built-ins and current contributions.
 */
collect(execution: ToolExecution): DshEnvironment

/**
 * Enumerate plugin-contributed variables without executing their resolvers.
 * @returns declarations sorted by environment variable name.
 */
list(): BashEnvVariableInfo[]

Types: DshEnvironment · ToolExecution

Source: packages/shell/shell-env/src/index.ts