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The four DeepSeek Harness modes: a complete guide

August 14, 2026 · dshbase

DeepSeek Harness ships four built-in presets. Don't overthink them — they're template presets that bundle a set of plugins so you can start out of the box. Switching modes changes which tools the agent holds and what rules it runs by, not model capability. Here's each one, plus the practical details we learned running them on dsh 0.1.0-rc.6.

1. Standard mode

If it's your first time, or you don't care about the internals, just use standard mode. It's a full coding agent with everything pre-configured:

  • File reading and editing
  • Shell access
  • File search and web search
  • Skills, planning, and goals
  • Background tasks, sub-agents, and workflows

The tradeoff: that's a large tool surface, which is fine for capability but rough on DeepSeek's prefix cache. Each tool is a block at the front of every request, and a large surface is harder to keep stable. If you're cost-sensitive, this matters — more on that in minimal mode below.

2. PTC mode (Programmatic Tool Calling)

PTC has all of standard mode's capabilities — the difference is how tools are presented. In standard mode, the model makes one tool call, gets the result, then decides the next step. In PTC mode, the model gets a Code Mode SDK: it writes a TypeScript program that chains many tool operations inside a single run_code.

What used to take five model round-trips — read, search, filter, parallel calls, combine results — can collapse into one program execution. Fewer round-trips between the model and tools means it's ideal for structured, multi-step, parallelizable work, and it saves tokens — partly because fewer round-trips means less re-sent context, and partly because intermediate data never re-enters the context.

The catch: it needs the model to have stable code-planning ability, and debugging is harder. Beginners: skip PTC and use standard mode. Turn it on when you hit a lot of repetitive tool round-trips, or you want to test DeepSeek's programmatic tool-calling ability.

3. Minimal mode

Minimal mode gives the model just two tools: a persistent bash shell and a file editor. It also freezes the system prompt to a simple "you are a helpful software engineering assistant" and strips conversation compression and most other capabilities.

This mode is for model benchmarking in a minimal environment — comparing the bare agent ability of two models without harness interference. Don't use it daily; you'll find it hard to get anything done. But it's also the cache-optimal config: two tools and a frozen prompt is the smallest possible stable prefix, which is exactly the recipe behind the 99.93% cache hit rate playbook. If you ever want to measure a model's raw cost floor, minimal mode is the place to do it.

4. Create mode — the "make your own wrench" mode

Create mode is where DeepSeek Harness gets special. It has all of standard mode, plus the ability to inspect the running Cordis environment and experiment with plugins in memory — letting the agent modify itself.

Examples:

"Build a read-only, security-audit-only mode that can read code but never modify files."
"Build a research agent with company search, a fixed model, and three custom skills."

You can even have the agent inspect its own loaded plugins, notice one is missing, create it, and hot-attach it to the running flow. The metaphor: the agent realizes it has no wrench, forges one on the spot, attaches it to its hand, and keeps working.

Two pitfalls to watch when the agent builds plugins for you, both reproduced in our testing:

  • Missing dsh.bundle manifest — a self-created plugin without the manifest installs silently as a plain dependency and never activates. Verify the manifest before trusting the result.
  • allowBuilds confirmation — a GitHub-sourced plugin with a prepare build script is blocked by pnpm until you confirm. That prompt is a permission boundary, not a bug.

Full fixes are in the troubleshooting guide.

How to think about modes

A preset is the set of plugins an agent runs with — its tools, prompts, and capabilities. Copy an existing one and tweak it, or use Create mode to have the agent build one for you. Different presets expose different slash commands (minimal mode has only a goal command, while standard/code/create include compression, goals, and planning).

Presets are also DSH's answer to plugin fatigue. Our audit of 101 community plugins found only 11 that install cleanly from npm — the rest are GitHub-source or need extra runtimes. The presets exist so you don't start from that long tail; you start from a bundled, tested set and reach into the plugin directory only when you need to.

Related: DeepSeek Harness sessions are append-only event logs — see our piece on session observability.

FAQ

Which mode should a beginner use? Standard mode. It's the full agent with everything pre-configured. PTC and Create add power but also add failure modes; minimal is for benchmarking, not daily work.

Which mode is cheapest to run? Minimal mode, by design — two tools and a frozen prompt is the smallest stable prefix, so it maximizes cache hits. PTC is second, because it collapses tool round-trips and keeps intermediate data out of context.

Can I switch modes mid-session? Modes are presets that change the plugin set, so switching means a different active surface rather than an in-place tweak. Copy the preset you're closest to and modify it.

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