deepseek-harness/packages/tool-bash/src/index.ts

/**
 * The model-facing bash tools: `bash`, `bash_output`, `bash_kill`. Pure
 * schema + text shaping — every process concern lives behind the `ctx.bash`
 * executor seam (`@deepseek-ai/dsh-bash`), so sandbox/permission/remote
 * executor implementations swap in without touching what the model sees.
 *
 * Background notifications: when a background task completes, a short notice
 * is injected into the owning agent's session (`agent.inject()` — the
 * documented context seam). Injection is durable context for the NEXT model
 * request, not a wake-up: an idle agent stays idle until something sends a
 * message, which is why the tool descriptions tell the model to poll with
 * `bash_output`.
 *
 * Task ownership: the owning agent is recorded per task id at spawn and kept
 * for the lifetime of THIS plugin instance (it is NOT cleared on task
 * completion — a finished task must stay un-readable / un-killable by a
 * different agent). `bash_output`/`bash_kill` reject a task owned by a DIFFERENT
 * agent (a task with no recorded owner is open to anyone). Task ids are global
 * and predictable (`bash-1`, …); under multi-session ACP (RFC 011) this
 * ownership check is the fence that stops one session's agent from reading or
 * killing another session's background task.
 *
 * TODO(tool-bash-owner-hmr): the ownership map is per-plugin-instance, so an
 * independent HMR reload of `tool-bash` (without reloading `dsh-bash`) starts a
 * fresh map and a task spawned before the reload becomes un-owned (open to any
 * caller). This is acceptable today — HMR is dev-only, the ACP session boundary
 * is one user's cooperative editor (not an adversarial trust boundary), and the
 * executor's own disposal kills its tasks — but a durable fix would attach
 * ownership to the executor/task lifetime via a `dsh-bash` seam.
 *
 * TODO(permissions): commands run with the executor's full authority. The
 * permission/sandbox seam is the `tools/execute` waterfall (veto/ask) plus
 * sandboxing `BashExecutor` implementations — see docs/architecture.md
 * § plugin checklist.
 *
 * @module @deepseek-ai/dsh-tool-bash
 */

import type { Context } from 'cordis'
import { isAbsolute, resolve as resolvePath } from 'node:path'
import { defineTool } from '@deepseek-ai/dsh-tools'
import type { ToolCallPresentation, ToolResult, ToolResultPresentation } from '@deepseek-ai/dsh-tools'
import type { Agent } from '@deepseek-ai/dsh-agent'
import type { BashRunResult, BashTask, CollectedOutput } from '@deepseek-ai/dsh-bash'

export const name = 'tool-bash'
export const inject = ['tools', 'bash']

/**
 * Validate the constraints the SchemaSpec can't express. `defineTool` now
 * validates parsed args against the SchemaSpec before `execute` runs (the
 * arg-validation RFC), so type/required/enum checks are already done and `args`
 * is the validated `InferArgs` shape here. What remains are value constraints
 * the DSL has no vocabulary for: non-empty strings and a positive, finite
 * timeout.
 */
function validateBashArgs(args: {
  command: string
  description: string
  timeoutMs?: number
  workdir?: string
  run_in_background?: boolean
}): void {
  if (args.command.trim().length === 0) {
    throw new Error('invalid command: expected a non-empty string')
  }
  if (args.description.trim().length === 0) {
    throw new Error('invalid description: expected a non-empty string')
  }
  if (args.timeoutMs !== undefined && (!Number.isFinite(args.timeoutMs) || args.timeoutMs <= 0)) {
    throw new Error(`invalid timeoutMs: expected a positive number, got ${JSON.stringify(args.timeoutMs)}`)
  }
}

/**
 * Reject an empty `task_id`. Type and presence are guaranteed by the
 * SchemaSpec validation (the arg-validation RFC); only the non-empty constraint, which the
 * DSL can't express, is left to check here.
 */
function validateTaskId(value: string): string {
  if (value.length === 0) {
    throw new Error(`invalid task_id: expected a string, got ${JSON.stringify(value)}`)
  }
  return value
}

/** Append the truncation notice (with the full-output spill path) to a stream's text. */
function streamText(output: CollectedOutput): string {
  if (!output.truncated) return output.text
  return `${output.text}\n[output truncated; full output: ${output.spillPath ?? '(unavailable)'}]`
}

/**
 * Shape one finished run into the text the model sees: stdout, then a marked
 * stderr section, then exit-status markers. Non-zero exits are REPORTED, not
 * errored — the model decides how to react; only infrastructure failures
 * (spawn errors, aborts) surface as isError results.
 */
export function renderResult(result: BashRunResult): string {
  const out = streamText(result.stdout)
  const err = streamText(result.stderr)

  let body = out
  if (err.length > 0) {
    // Single newline between sections (stdout usually ends with one already).
    if (body.length > 0 && !body.endsWith('\n')) body += '\n'
    body += `[stderr]\n${err}`
  }
  if (body.length === 0) body = '(no output)'

  const markers: string[] = []
  // Timeout is reported independently of how the process actually ended: a
  // command can trap SIGTERM and exit 0 after our timer fired (e.g.
  // `trap "exit 0" TERM; sleep 60`), giving timedOut:true / exitCode:0 /
  // signal:null — the model must still see that the command was cut short.
  if (result.timedOut) markers.push(`[timed out after ${result.timeoutMs}ms]`)
  if (result.signal !== null) {
    markers.push(`[killed by signal: ${result.signal}]`)
  } else if (result.exitCode !== 0) {
    markers.push(`[exit code: ${result.exitCode}]`)
  }
  if (markers.length === 0) return body

  if (!body.endsWith('\n')) body += '\n'
  return body + markers.join('\n')
}

// ---------------------------------------------------------------------------
// UI presentation (tool-owned). These shape how a UI (e.g. the ACP bridge)
// renders a bash call's pending and completed states. They are display-only and
// pure — a UI may call them during live streaming AND a session-log replay.
// ---------------------------------------------------------------------------

/**
 * Pending-state presentation for a `bash` call. The TITLE is the exact `command`
 * — a `kind: 'execute'` card is rendered as a terminal whose header label IS the
 * title, and an execute-kind card HIDES `rawInput` (Zed: `should_show_raw_input
 * = !is_terminal_tool`), so the command must BE the title to be seen. This
 * mirrors the reference ACP adapters (claude-agent-acp, codex-acp), which both
 * use the bare command as an execute tool's title. The model-written
 * `description` (a readable summary) rides as a `content` text block shown ABOVE
 * the card. (Note: claude-agent-acp DROPS the description in terminal mode and
 * shows only the card; surfacing it as a content block is a deliberate
 * divergence here — we keep the human summary visible alongside the card.)
 * `rawInput` still carries the bare command for non-execute UIs that DO render it.
 *
 * `terminal` marks the call so a capable UI renders a TERMINAL card — but ONLY a
 * FOREGROUND run is a terminal: a `run_in_background` call returns a task id
 * immediately (it never streams a terminal; its output is polled via
 * `bash_output`), so it is NOT marked terminal and renders as an ordinary
 * execute card. For a foreground run the `terminal.cwd` (header) is the model
 * `workdir` when given — ABSOLUTE as-is, RELATIVE for the UI bridge to resolve
 * against the session cwd; when omitted the bridge fills the session workspace
 * cwd (this PURE presenter, args only, can't see it).
 */
type BashCallArgs = { command: string; description: string; workdir?: string; run_in_background?: boolean }

function presentBashCall(args: BashCallArgs): ToolCallPresentation {
  const base = {
    title: args.command,
    kind: 'execute' as const,
    rawInput: args.command,
    content: [{ type: 'text' as const, text: args.description }],
  }
  // A background start is not an interactive terminal — no terminal card.
  if (args.run_in_background === true) return base
  return { ...base, terminal: args.workdir !== undefined ? { cwd: args.workdir } : {} }
}

/**
 * Completed-state presentation for a `bash` call. Two parallel renderings of the
 * same output: `terminal.output` for a UI that shows a terminal card (the run's
 * stdout/stderr + status markers, exactly as the model sees them — the RAW text,
 * newlines preserved, since a terminal renderer relies on exact bytes), and a
 * fenced ```console `content` block as the fallback for a UI without terminal
 * support (the fences are a UI-only affordance, so they live here, not in the
 * model-facing result; the fenced body is trimmed of trailing blank lines for a
 * tidy block). A capable UI also gets an exit-status pill from `terminal.exitCode`
 * / `terminal.signal`, parsed from the status markers `renderResult` appended.
 *
 * Terminal output/exit is suppressed for results that are NOT a finished
 * foreground run: a `run_in_background` start (`isBackground` — the text is a
 * task-id ack, not a streamed run) and an `isError` result (a spawn failure or
 * abort — there is no real process exit to pill, and the body is an error
 * message, not `renderResult` output, so parsing it would be meaningless). Those
 * fall back to the fenced `content` block with no terminal metadata. The bridge's
 * orphan guard also drops a result terminal when the call wasn't terminal, so a
 * background call (not marked terminal in `presentBashCall`) is doubly safe.
 * A non-text result (unexpected for bash) falls through to `undefined`.
 */
function presentBashResult(args: unknown, result: ToolResult): ToolResultPresentation | undefined {
  const block = result.content.length === 1 ? result.content[0] : undefined
  if (block === undefined || block.type !== 'text') return undefined
  const raw = block.text
  const fenced = raw.replace(/\n+$/, '')
  const content = [{ type: 'text' as const, text: `\`\`\`console\n${fenced}\n\`\`\`` }]
  const isBackground = typeof args === 'object' && args !== null && (args as { run_in_background?: unknown }).run_in_background === true
  // No exit pill / terminal output for a background ack or an errored run.
  if (isBackground || result.isError) return { content }
  return { content, terminal: { output: raw, ...parseExitStatus(raw) } }
}

/**
 * Recover the structured exit status from a rendered `renderResult` string — the
 * inverse of the status markers it appends. A `[killed by signal: SIG]` marker
 * yields `{signal}`; otherwise an `[exit code: N]` marker yields `{exitCode:N}`;
 * absent both we report `{exitCode:0}` (a clean run appends no marker — and a
 * trapped-timeout run that exits 0 also has none and is accurately exit 0).
 *
 * Why parse rendered text at all: `presentResult` is replay-safe and on a
 * `session/load` the ONLY thing persisted is this content text — the structured
 * `BashRunResult` is long gone — so unless the exit were added to the persisted
 * event schema (deliberately NOT done; see the terminal-rendering RFC), parsing
 * is the only channel. The match is anchored to a LEADING newline + end-of-string
 * because `renderResult` always inserts a `\n` before the marker (line ~124) onto
 * a non-empty body: a real marker is therefore always its own final line. That
 * defeats the common spoof (program output that simply ENDS in `[exit code: 5]`
 * with no trailing newline — a clean exit 0 — no longer reads as a failure).
 *
 * KNOWN RESIDUAL (inherent to the replay-only-sees-text design): a clean exit 0
 * whose body's FINAL line is itself exactly `\n[exit code: N]` (the program
 * printed that line and nothing after) is still indistinguishable from a real
 * marker and would show a wrong pill. This is display-only (execution and the
 * model-facing text are unaffected) and narrow; the complete fix is to persist a
 * structured exit on the result event, which the RFC names as the escape hatch.
 */
function parseExitStatus(text: string): { exitCode: number } | { signal: string } {
  const signal = /\n\[killed by signal: ([^\]\n]+)\]$/.exec(text)
  if (signal?.[1] !== undefined) return { signal: signal[1] }
  const exit = /\n\[exit code: (\d+)\]$/.exec(text)
  if (exit?.[1] !== undefined) return { exitCode: Number(exit[1]) }
  return { exitCode: 0 }
}

/** Pending-state presentation for `bash_output`/`bash_kill` (background-task tools). */
function presentTaskCall(verb: string, args: { task_id: string }): ToolCallPresentation {
  return { title: `${verb} background task ${args.task_id}`, kind: 'execute', rawInput: args.task_id }
}

/**
 * Resolve the working directory for a bash call. Precedence: an explicit model
 * `workdir` wins; otherwise default to the calling agent's session cwd
 * (`session.header.cwd`) so each ACP session's commands run in ITS workspace,
 * not the server's launch dir. A RELATIVE model `workdir` is resolved against
 * the session cwd (the tool tells the model to pass `workdir` instead of `cd`,
 * so a relative one should be relative to the session's root, not `process.cwd()`).
 * Returns `undefined` when neither is available (no agent / headerless session /
 * no session cwd) — the executor then applies its own config/`process.cwd()`
 * default, preserving today's non-ACP behavior.
 */
function resolveWorkdir(modelWorkdir: string | undefined, exec: { agent?: Agent }): string | undefined {
  const sessionCwd = exec.agent?.session.header.cwd
  if (modelWorkdir === undefined) return sessionCwd
  if (sessionCwd !== undefined && !isAbsolute(modelWorkdir)) {
    return resolvePath(sessionCwd, modelWorkdir)
  }
  return modelWorkdir
}

/** Status line for background task reads. */
function statusLine(task: BashTask): string {
  switch (task.status) {
    case 'running': return '[status: running]'
    case 'killed': return `[status: killed${task.signal !== null ? ` by ${task.signal}` : ''}]`
    case 'completed': return `[status: completed, exit code: ${task.exitCode ?? 0}]`
  }
}

export function apply(ctx: Context): void {
  // Owning agent per background task id, recorded at spawn. Kept for the
  // lifetime of THIS plugin instance (NOT cleared on completion): a completed
  // task must stay un-readable / un-killable by a DIFFERENT agent, so the
  // ownership record outlives the task. Under multi-session ACP (RFC 011) this
  // is the isolation fence — one session's agent must never read or kill
  // another session's background task. A task with no recorded owner (started by
  // a non-loop caller, `exec.agent` absent) is unowned and accessible to anyone.
  // An independent `tool-bash` HMR reload resets this map — see the
  // TODO(tool-bash-owner-hmr) note in the module doc.
  const taskOwner = new Map<string, Agent>()

  /**
   * Authorize a `bash_output`/`bash_kill` call against a task's owner. Rejects
   * when the task has a recorded owner and the caller is not that exact agent —
   * including the conservative no-agent case (`exec.agent` absent cannot prove
   * ownership of an owned task). An unowned task (no record) is allowed.
   */
  const assertTaskAccess = (taskId: string, exec: { agent?: Agent }): void => {
    const owner = taskOwner.get(taskId)
    if (owner !== undefined && owner !== exec.agent) {
      throw new Error(`task ${taskId} belongs to another session`)
    }
  }

  // Background completion → inject a notice into the owning agent's session.
  ctx.bash.onTaskDone((task) => {
    const agent = taskOwner.get(task.id)
    if (!agent) return
    try {
      agent.inject(
        [{ type: 'text', text: `background bash task ${task.id} finished ${statusLine(task)}. Read its output with bash_output.` }],
        { source: { kind: 'plugin', plugin: 'tool-bash' } },
      )
    } catch (error: unknown) {
      // The ONE expected failure: the agent was disposed between task
      // completion and this injection (LoopAgent.inject throws
      // `agent "<id>" is disposed`). That race is benign — drop the notice.
      // Anything else is a real bug and must surface, not be swallowed.
      if (error instanceof Error && error.message.includes('is disposed')) return
      throw error
    }
  })

  ctx.tools.register(defineTool({
    name: 'bash',
    description: 'Execute a bash command (`bash -c`) and return its stdout/stderr. '
      + 'Each call runs in a fresh shell: no state (cwd, variables, functions) persists between calls — '
      + 'pass `workdir` instead of using `cd`. Non-zero exits are reported as `[exit code: N]`. '
      + 'Long output is truncated to its tail; the full output is saved to a file whose path is reported. '
      + 'Set `run_in_background: true` for long-running commands: the call returns a task id immediately; '
      + 'poll it with `bash_output` and stop it with `bash_kill`.',
    parameters: {
      command: { type: 'string', required: true, description: 'The bash command to execute.' },
      description: {
        type: 'string',
        required: true,
        description: 'Clear, concise description of what this command does in active voice, '
          + '5-10 words (shown in the UI). Examples: "ls" → "List files in current directory"; '
          + '"git status" → "Show working tree status"; "npm install" → "Install package dependencies".',
      },
      timeoutMs: { type: 'number', description: 'Timeout in milliseconds (default 120000, max 600000). The command is killed on expiry.' },
      workdir: { type: 'string', description: 'Working directory for this command. Defaults to the session workspace; a relative path is resolved against it.' },
      run_in_background: { type: 'boolean', description: 'Run in the background and return a task id immediately. No timeout applies.' },
    },
    async execute(args, exec) {
      validateBashArgs(args)
      // `description` is display/logging metadata only (surfaced to UIs via
      // the tool/call session event); it is intentionally NOT forwarded to
      // ctx.bash and has no effect on execution.
      // Default the workdir to the calling agent's session cwd so each ACP
      // session runs in its own workspace (see resolveWorkdir); an explicit
      // model workdir still wins.
      const workdir = resolveWorkdir(args.workdir, exec)
      const request = {
        command: args.command,
        ...workdir !== undefined ? { workdir } : {},
        ...args.timeoutMs !== undefined ? { timeoutMs: args.timeoutMs } : {},
        ...exec.signal ? { signal: exec.signal } : {},
      }
      if (args.run_in_background === true) {
        const task = ctx.bash.start(ctx.bash.resolve(request))
        if (exec.agent) taskOwner.set(task.id, exec.agent)
        return [{ type: 'text', text: `started background task ${task.id}` }]
      }
      const result = await ctx.bash.run(ctx.bash.resolve(request))
      if (result.aborted) throw new Error('command aborted')
      return [{ type: 'text', text: renderResult(result) }]
    },
    presentCall: presentBashCall,
    presentResult: presentBashResult,
  }))

  ctx.tools.register(defineTool({
    name: 'bash_output',
    description: 'Read new output from a background bash task started with `bash` + `run_in_background`. '
      + 'Returns only output produced since the previous bash_output call, plus the task status. '
      + 'Tasks keep running while you do other work; poll again later for more output.',
    parameters: {
      task_id: { type: 'string', required: true, description: 'Task id returned by the bash tool.' },
    },
    // execute is synchronous (registry reads + string shaping) but the
    // ToolDefinition contract wants a Promise — hence resolve(), not async.
    execute(args, exec) {
      const id = validateTaskId(args.task_id)
      assertTaskAccess(id, exec)
      const read = ctx.bash.readOutput(id)
      let text = read.delta.length > 0 ? read.delta : '(no new output)'
      if (read.lossy) {
        const paths = [read.stdoutSpillPath, read.stderrSpillPath].filter((p): p is string => p !== undefined)
        text += `\n[some output was dropped from memory; full output: ${paths.join(', ')}]`
      }
      text += `\n${statusLine(read.task)}`
      return Promise.resolve([{ type: 'text', text }])
    },
    presentCall: args => presentTaskCall('Read output from', args),
  }))

  ctx.tools.register(defineTool({
    name: 'bash_kill',
    description: 'Kill a running background bash task (SIGTERM, then SIGKILL) by task id.',
    parameters: {
      task_id: { type: 'string', required: true, description: 'Task id returned by the bash tool.' },
    },
    execute(args, exec) {
      const id = validateTaskId(args.task_id)
      assertTaskAccess(id, exec)
      const killed = ctx.bash.kill(id)
      return Promise.resolve([{
        type: 'text',
        text: killed ? `killed background task ${id}` : `task ${id} had already finished`,
      }])
    },
    presentCall: args => presentTaskCall('Kill', args),
  }))
}