dsh-codex-shell

dsh-codex-shell

dsh-codex-shell is a DeepSeek Harness npm bundle that provides the Codex-compatible exec_command and write_stdin tools.

The plugin starts a fresh shell process for every exec_command call and keeps that process available for later write_stdin calls while it is running. PTY transport is the default. If PTY allocation fails, the configured ptyFallback policy can use an explicit-argv pipe backend or fail the call.

Install and load

Install it into a DSH profile:

dsh plugin --profile web add dsh-codex-shell

The package contains a DSH bundle patch that disables the legacy tool-bash, tool-pwsh, and tool-jobs rows, then registers this plugin as codex-shell and selects codex-whale as the agent-preset default. Restart the profile after installation.

For a local checkout:

- insert:
    - id: codex-shell
      name: '/absolute/path/to/dsh-plugins/codex-shell/lib/index.js'

The npm bundle follows the same dsh.bundle.patch pattern used by the dsh-web-ui plugin: the package ships a cordis.patch.yml and declares it in package.json.

Codex Whale preset

The DSH checkout in this repository includes the Codex Whale preset with ID codex-whale. It is the recommended preset for this plugin and exposes the Codex shell exclusively. The preset must be shipped by the DSH application under apps/cli/config/agent-presets/codex-whale; the current stock CLI does not discover preset directories from an npm bundle.

The preset is intentionally separate from the legacy standard, code, and minimal presets so installing this bundle does not silently break existing profiles. Selecting one of those legacy presets can still expose its original shell tools.

macOS and Linux

On POSIX hosts, commands run through the resolved POSIX shell ($SHELL, then /bin/sh). On Windows, the adapter uses PowerShell. exec_command starts a fresh shell process; a running process returns an opaque session ID for write_stdin.

The model-visible schemas intentionally contain only cmd, workdir, yield_time_ms, max_output_tokens, session_id, and chars. Shell choice, PTY selection, execution policy, and process cleanup are deployment-level configuration.

When exec_command leaves a process running, its rendered text includes a [session_id: N] marker so the model can pass that ID to write_stdin.

PTY output is also normalized for model visibility: ANSI/VT control sequences such as Windows ConPTY startup and terminal-title codes are removed while printable text, line endings, Unicode, and interactive input remain intact.

On Windows, windowsPtyStartupGraceMs controls the startup grace before the first PTY input; it defaults to 2000 and may be set to 0 when the host does not need the PowerShell/ConPTY startup guard. This is deployment configuration, not part of either model-visible tool schema.

The default configuration is trusted execution with a pipe fallback. executionMode: host-policy is intentionally fail-closed and currently unsupported until this plugin is given an explicit DHS policy adapter; it does not silently grant host access or claim to provide confinement.