The credential store is 0600 under a 0700 directory, which stops other OS users but not the model: tool processes run as the same user, so under the shipped danger-full-access default they read it like any other file. SandboxExecutionPolicy grows readDenyPaths, and sandbox-policy defaults it to $DSH_HOME/.env — the exact file rather than the harness home, so the model keeps its documented access to its own session log. Seatbelt appends a trailing deny (last matching rule wins) and bwrap maps /dev/null over each path after any workspace bind; Landlock grants are a pure allow-list that cannot subtract from its own / read grant, so confine() reports partial enforcement there instead of claiming a boundary the process does not have. A real-kernel Seatbelt e2e proves the shape: the same read succeeds unconfined and fails under the denial, while a sibling file in the same directory stays readable. Both READMEs state the residual boundary plainly — no confining mode means no boundary — and record the OS keychain provider as the real answer.
DeepSeek Harness
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DeepSeek Harness (dsh) is an open-source coding agent built on the DeepSeek Harness SDK.
It uses an architecture where everything is a plugin.
Install
Install dsh with one command:
curl -fsSL https://raw.githubusercontent.com/deepseek-harness/deepseek-harness/master/scripts/install.sh | sh
The installer requires git and Node ^22.19 || >=24, offers to install pnpm when it is missing, and prompts for a DeepSeek API key.
The installer keeps every checkout under ~/.dsh/source: the master clone at ~/.dsh/source/master and each install's staging checkout as a git worktree ~/.dsh/source/staging-<timestamp>. The stable symlink ~/.dsh/source/current points at the active staging worktree, and dsh in ~/.local/bin links to current/bin/dsh, so an upgrade repoints one symlink and the dsh on PATH never moves. Re-running the command adds a fresh staging worktree from an updated master and repoints current at it. See scripts/install.sh for alternate install locations and other options.
Use DeepSeek Harness
Web UI
For the recommended local interface, build the frontend after installation and after each update, then start the Web UI. Resolve the running checkout from the dsh launcher so the command holds regardless of which staging worktree is current (the launcher resolves through the stable current symlink):
dsh_bin=$(cd "$(dirname "$(command -v dsh)")" && pwd -P)/$(basename "$(command -v dsh)")
while [ -L "$dsh_bin" ]; do
link=$(readlink "$dsh_bin")
case $link in /*) dsh_bin=$link ;; *) dsh_bin=$(cd "$(dirname "$dsh_bin")" && cd "$(dirname "$link")" && pwd -P)/$(basename "$link") ;; esac
done
dsh_dir=$(cd "$(dirname "$dsh_bin")/.." && pwd -P)
pnpm --dir "$dsh_dir" run build && pnpm --dir "$dsh_dir" run build:web
dsh web
The Web UI is served at http://127.0.0.1:3080 by default.
TUI
Start the full-screen terminal interface:
dsh
Headless
Run one task, print the final answer, and exit:
dsh -p "summarize this workspace"
Why DeepSeek Harness
Built-in capabilities cover file reading, editing, and search; shell execution; reusable skills; task tracking; subagents and workflows; persistent sessions; and context compaction. The TUI also includes Plan Mode.
- Everything is a plugin. Models, tools, policies, storage, context management, and interfaces are composable Cordis plugins, so deployments can extend or replace behavior without forking the agent loop. See the architecture for the underlying design.
- Code Mode (opt-in). It exposes a
run_codetool and a generated TypeScript SDK; only program output re-enters model context. See Code Mode. - Self-referential Cordis tools are opt-in. They let the agent inspect its live runtime and mount or unmount plugins while it runs. See the Cordis tools.
Community
Follow DeepSeek Harness on Twitter for project updates.
Development
pnpm install
pnpm run test:coverage
Start with the development guide and read the architecture before changing packages.
For agents, follow AGENTS.md.
DeepSeek Harness is currently pre-release.