deepseek-harness/examples/coding-agent

coding-agent

The first REAL agent wiring: DeepSeek V4 + the bash tool suite + stdio chat

• JSONL persistence, loaded from cordis.yml. Where echo-agent proves the skeleton with mocks, this example is a usable coding assistant.

Run it

# repo root .env (gitignored) or exported env:
#   DEEPSEEK_API_KEY=sk-…
#   DEEPSEEK_BASE_URL=https://…   # optional; defaults to the public API
pnpm run demo:coding

Type a coding task. The agent's only tools are bash (+ bash_output / bash_kill for background tasks): file reads, writes, searches, and test runs all happen through shell commands, each in a fresh bash -c (the system prompt tells the model to pass workdir instead of cd). Reasoning streams dimmed; tool calls/results render inline.

> fix the failing test in /path/to/project
[main turn 1] (reasoning…)
  [tool call] bash({"command": "node --test", "workdir": "/path/to/project"})
  [tool result] … [exit code: 1]
  …

What each plugin demonstrates

Entry	Demonstrates
llm-deepseek	real LlmAdapter via config (!!js process.env.… secrets); swap one line to @deepseek-ai/dsh-llm-pi-ai for the library-backed twin
bash (dsh-bash-local) + tool-bash	the executor seam + tool schemas as separate plugins
agent-loop	agent created from config with a coding system prompt
src/session-jsonl.ts	write-behind persistence on session/event + session/flush (copied from echo-agent)
src/stdio-chat.ts	UI as a plugin; copied from echo-agent with reasoning-dimming and an exit-on-idle close handler for piped stdin. Example-local on purpose — extract a shared UI package when a third example needs it

End-to-end tests (pnpm run test:e2e, key-gated)

• tests/full-loop.e2e.ts — the canary: real model runs echo e2e-ok through the real bash tool; asserts tool/call/tool/result session events and the final answer.
• tests/coding-task.e2e.ts — the swebench-style smoke: a temp dir holds add.js (with a - b where a + b belongs) and a failing add.test.js; the agent must fix the bug and verify. The test re-runs node add.test.js ITSELF and inspects the files — agent claims are not trusted.

Both self-skip without DEEPSEEK_API_KEY.