dsh-fish-shell

A DeepSeek Harness (DSH) profile plugin that runs commands submitted through the model-facing bash tool with Fish instead:

bash tool call → fish -c <command>

The public tool remains named bash so its existing schema, presentation, sandbox approval, output, timeout, and background-job contracts remain intact. The plugin adds a system-prompt note instructing the agent to use Fish-compatible syntax.

It updates both foreground and background commands. When DSH mounts its sandboxing shell executor, it also changes the inner confined command from bash -c to fish -c. Persistent PTY terminal sessions are not changed.

When configured with Babelfish, it preprocesses commands containing standalone Bash assignments before Fish runs them. For example, NAME=value, export NAME=value, and NAME=$(command) become Fish set commands. Fish-native commands are left unchanged. Babelfish failures stop the tool call instead of executing untranslated Bash.

Dependency

Bash-assignment translation depends on Babelfish. It is optional: omit babelfishPath to run Fish directly without Bash translation.

Configuration

By default, the plugin uses $SHELL when it ends in /fish; otherwise it runs fish from PATH. On this system $SHELL is /opt/homebrew/bin/fish, so the default resolves to that absolute path.

Set explicit executable paths in the profile patch if needed:

- id: fish-shell
  config:
    fishPath: /opt/homebrew/bin/fish
    babelfishPath: /opt/homebrew/bin/babelfish

babelfishPath is optional. Without it, the plugin runs Fish directly and does not rewrite Bash syntax. Install Babelfish with brew install babelfish.

This is deliberately not a general Bash compatibility layer. Complex Bash syntax, inline environment assignments such as NAME=value command, and semantics Babelfish cannot translate should be written directly in Fish.

Install

From this repository:

dsh plugin --profile web add "$PWD"

Restart the DSH host after installation. A restart is required because this is a server-side shell-executor plugin; client-plugin HMR does not reload it.

To remove it:

dsh plugin --profile web remove dsh-fish-shell

Test

npm test

Compatibility

Tested against DSH 0.1.0-rc.6. The plugin requires DSH's local bash-compatible shell executor (runArgv and startArgv).

License

MIT