DSH Coding Agent Preset

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DSH Coding Agent Preset is a Windows-adapted “coding mode” agent preset for DeepSeek Harness (DSH) — an exact Windows port of the official minimal preset. It keeps the official minimal composition (fixed persona, no context compaction, only pwsh + str_replace_editor), but replaces the official persistent bash with a persistent PowerShell 7 (pwsh) shell.

• PTY backend (packages/dsh-terminal-pwsh/): a node-pty/ConPTY persistent pwsh backend, mirroring @deepseek-ai/dsh-terminal-bash.
• Model-facing tool (packages/dsh-tool-pwsh-persistent/): a persistent pwsh tool, mirroring @deepseek-ai/dsh-tool-bash-persistent.
• Preset files (agent.cordis.yml / preset.yml): mount the two local packages into a DSH coding agent preset.

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Installation

The preset is published as a single npm package (@gamegeek-saikel/dsh-coding-agent-preset). Installing it into a DSH web profile automatically deploys the preset files and the two internal packages via the package postinstall script.

Prerequisite: This preset requires PowerShell 7 (pwsh), not the built-in Windows PowerShell 5.1 (powershell.exe). Please install PowerShell 7 manually from https://github.com/PowerShell/PowerShell/releases or run winget install Microsoft.PowerShell.

Install into the web profile:

npx @deepseek-ai/dsh plugin --profile web add @gamegeek-saikel/dsh-coding-agent-preset

Start DSH:

npx @deepseek-ai/dsh web

If you already have the DSH CLI installed globally, you can use dsh instead of npx @deepseek-ai/dsh:

dsh plugin --profile web add @gamegeek-saikel/dsh-coding-agent-preset
dsh web

The package also keeps the original manual deployment path: copy agent.cordis.yml / preset.yml into ~/.dsh/.agent-presets/coding/, then run install.ps1 to copy the two internal packages into ~/.dsh/profiles/node_modules and the harness node_modules.

Demo / Evaluation

Validated with DeepSeek V4 Pro (reasoningEffort=max) on two one-sentence web-app generation tasks. Both sessions used only pwsh + str_replace_editor and produced complete single-file HTML demos.

Artifact	Reasoning blocks	we	let's	let me	Visible replies	Tool calls	Duration
blackhole.html	98	411	383	6	1	102	~29 min
mc.html	162	525	539	4	1	167	~54 min

Demo files and session logs: demo/
Full analysis: docs/pro-test-evaluation.md

Overview

The official persistent bash backend cannot run on Windows (its subprocess terminal inspection is Linux/macOS-only), and the official dsh-tool-pwsh is not persistent (every command starts a fresh pwsh -Command). This project therefore provides a Windows-native persistent pwsh stack with the same three-layer architecture as the official persistent bash:

1. PTY registry — reuse the official @deepseek-ai/dsh-terminal service, scoped to an agent-owned terminals realm.
2. Backend — dsh-terminal-pwsh spawns pwsh directly through node-pty/ConPTY, detects readiness with a controlled prompt, and cleans up the process tree with taskkill.
3. Tool — dsh-tool-pwsh-persistent implements the same start/end marker protocol and PowerShell command wrapping, so state (cwd, variables, functions, aliases, activated environments) persists across calls.

Key Properties

Property	Value
Scope	Windows-adapted copy of the official minimal coding preset
Shell	Persistent PowerShell 7 (pwsh) via node-pty/ConPTY
Tools	pwsh + str_replace_editor only
Persona	Official minimal persona verbatim: You are a helpful software engineer assistant.
Command wrapping	Invoke-Expression + backtick-escaped double-quoted string; $ErrorActionPreference = 'Stop'
Readiness detection	Controlled prompt __DSH_PERSISTENT_PWSH_PROMPT__ + silence/timeout fallbacks
Sandbox modes	danger-full-access → persistent PTY shell; confined modes → one-shot pwsh execution
Escalation	Single-call sandbox_permissions + justification via ctx.approval; fail-closed
Mode switching	Any effective sandbox-mode change closes persistent terminals; next call respawns under the new mode
Install	dsh plugin --profile web add @gamegeek-saikel/dsh-coding-agent-preset
Tests	Prompt parity, sandbox escalation, sandbox mode switch
Locale	English + Simplified Chinese
License	MIT

Usage

Once installed and restarted, a coding-mode session exposes exactly two tools: pwsh and str_replace_editor.

• Persistent path (danger-full-access): commands run in a shared persistent pwsh PTY. Variables, functions, aliases, and the current directory survive across calls.
• Confined path (read-only / workspace-write): commands run as one-shot pwsh -Command executions, matching the official non-persistent dsh-tool-pwsh behavior. State does not persist.
• Sandbox escalation: if a confined command is denied, the output includes [sandbox: file access denied ...] and escalation available — retry this exact command once with sandbox_permissions. Retry with sandbox_permissions and justification to request a one-time approval; the granted mode applies only to that single call and never changes the session mode.

Quick verification:

Write-Output "hello"

then run a second command that reads a variable set by the first command to confirm persistence in a danger-full-access session.

Architecture

Layer	Official (bash, Linux/macOS)	This project (pwsh, Windows)
PTY registry	@deepseek-ai/dsh-terminal (terminals service)	Same official service, isolate: terminals private realm
Backend	dsh-terminal-bash (subprocess + Linux process inspector)	dsh-terminal-pwsh: node-pty/ConPTY, controlled-prompt readiness, taskkill tree cleanup
Tool	dsh-tool-bash-persistent (start/end marker protocol)	dsh-tool-pwsh-persistent: same protocol + PowerShell dialect wrapper

Key implementation points:

• Command wrapping — Invoke-Expression + backtick-escaped double-quoted string; multi-line commands, $ interpolation, and quotes survive safely.
• Exit-code semantics — $ErrorActionPreference = 'Stop' makes failing cmdlets report nonzero like bash; try/catch and explicit -ErrorAction still work normally.
• Ready detection — PowerShell/PSReadLine strip OSC 133 prompt markers, so readiness matches the controlled prompt text tail with silence/timeout fallbacks.
• Lifecycle — timeout closes and resets the shell; exit detection resets it; owner-level cache and serialized command queue match the official design.
• Dual-path execution — danger-full-access uses the persistent PTY shell; confined modes use one-shot execution.
• Single-call escalation — sandbox_permissions + justification resolve through ctx.approval; rejection, non-widening requests, missing justification, or missing approval service all fail closed.
• Sandbox-mode switches — any effective mode change closes persistent terminals in the background; the next call transparently rebuilds the shell under the new mode.
• Prompt parity — the persona and tool description stay aligned with official minimal; no escalation paragraph is appended at runtime.

Project Structure

dsh-coding-agent-preset/
├── agent.cordis.yml              # Root preset composition (manual install)
├── preset.yml                    # Root preset metadata (manual install)
├── cordis.patch.yml              # Web-profile bundle patch (defaults to coding preset)
├── presets/coding/               # Auto-installed preset directory shipped in npm package
│   ├── agent.cordis.yml
│   └── preset.yml
├── install.ps1                   # One-shot deployment into the current DSH
├── package.json                  # Single npm package metadata for publishing
├── pnpm-lock.yaml                # Lockfile for npm/GitHub Actions
├── LICENSE                       # MIT License
├── README.md                     # English documentation
├── README.zh-CN.md               # 简体中文文档
├── docs/
│   ├── pro-test-evaluation.md    # Pro-mode black-hole / MC evaluation evidence
│   └── pro-test-data.json        # Machine-readable evaluation data
├── demo/
│   ├── blackhole/                # Black-hole demo artifact + session log
│   └── mc/                       # Minecraft-style demo artifact
├── .github/workflows/publish.yml # npm auto-publish on v* tags
├── scripts/
│   ├── analyze-session.mjs       # Session JSONL trajectory fingerprint analyzer
│   ├── check.mjs                 # Syntax check used by pnpm build
│   └── install-preset.mjs        # postinstall: copies preset + internal packages to DSH home
├── packages/
│   ├── dsh-terminal-pwsh/        # PTY backend package (node-pty/ConPTY)
│   │   └── lib/index.js
│   └── dsh-tool-pwsh-persistent/ # Model-facing persistent pwsh tool
│       └── lib/index.js
└── tests/
    ├── prompt-parity.mjs         # Prompt-surface parity (no PTY needed)
    ├── sandbox-escalation.mjs    # Escalation / dual-path behavior
    └── sandbox-mode-switch.mjs   # Sandbox-mode switch behavior

Development & Testing

The repository root has a package.json for npm packaging; there is no runtime build step. pnpm build runs syntax checks over the package and test JS files. The tests themselves are plain Node scripts that import from the installed DSH harness node_modules.

node tests/prompt-parity.mjs

prompt-parity.mjs does not need a PTY and can run in confined mode. The other two suites spawn real ConPTY pwsh sessions and therefore require danger-full-access:

node tests/sandbox-escalation.mjs
node tests/sandbox-mode-switch.mjs

Run install.ps1 first so the two packages are present in the harness node_modules path used by the tests.

Documentation

• packages/dsh-terminal-pwsh/README.md — backend design and configuration
• packages/dsh-tool-pwsh-persistent/README.md — tool contract and known Windows limitations
• README.zh-CN.md — 简体中文版本

License

This repository (source, tests, README, and the DSH preset shape) is licensed under the MIT License — see LICENSE.

Copyright (c) 2026 Saikel-Orado-Liu aka GameGeek-Saikel