deepseek-harness/examples/coding-agent/README.md

# coding-agent

Coding-agent demo wiring: DeepSeek V4 + the `read`/`write`/`edit` filesystem tools + the bash tool suite + subagent delegation + workflows + `todo_write` + JSONL persistence. `cordis.yml` runs the terminal readline REPL; `cli.cordis.yml` keeps the same coding capabilities behind a headless one-shot CLI.

## Run it

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

Type a coding task. The agent works through the `read`/`write`/`edit` filesystem tools for ordinary file operations and `bash` (+ `bash_output` / `bash_kill` for background tasks) for shell commands, searches, and test runs, each in a fresh `bash -c` (the system prompt tells the model to pass `workdir` instead of `cd`). Both the fs tools and bash resolve relative paths against the session workspace. It can also delegate with `subagent`/`subagent_fork` and track multi-step work with `todo_write` (a whole-list task tracker rendered as a checklist). 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]
  …
```

### One-shot CLI

Run one task through all model and tool steps, flush its fresh session, print the final result, and exit:

```sh
pnpm run demo:headless -- "fix the failing test in this workspace"
pnpm run demo:headless --output-format json -- "summarize the current implementation"
pnpm run demo:headless --output-format stream-json -- "run the focused tests"
```

The root command supplies `cli.cordis.yml`, which disables HMR and the REPL app and inserts [`@deepseek-ai/dsh-cli-demo`](../../packages/examples/cli-demo). Exactly one quoted positional task is required; there is no `-p` flag. `text` prints the last text-bearing assistant message, `json` prints one DSH-native result record, and `stream-json` emits the parent `main` session's canonical task-turn events before that record. Non-completed turns retain partial output but exit nonzero; argument and boot failures leave stdout empty.

This is non-interactive automation with the same local bash, filesystem, skill, subagent, workflow, and todo capabilities as the REPL. It can mutate the launch workspace and spend provider tokens. No prompt, approval, resume, further turn, or stdin context is available in v1; see the [CLI package contract](../../packages/examples/cli-demo/README.md).

### Resuming a prior session

Each run starts a fresh session by default (its event log lands under `./.sessions/`). To **continue** a previous conversation, set `RESUME_SESSION_ID` to that session's id — the `main` agent then rehydrates the persisted log instead of starting fresh, so the model sees the earlier turns as history:

```sh
RESUME_SESSION_ID=<prior-session-id> pnpm run demo:repl
```

The id is wired through `cordis.yml` (`resumeSessionId: !!js process.env.RESUME_SESSION_ID`); unset, the agent starts a new session. A missing/unreadable id is non-fatal — it logs a warning and starts no `main` agent.

## Code Mode

[`code-mode.cordis.yml`](code-mode.cordis.yml) overlays the same tree with the worker-thread runtime and `tools: { mode: code }`. The model receives one `run_code` transport plus a generated TypeScript SDK for the visible tools; only program output returns to model context. Use `mode: both` to expose native calls alongside `run_code`. See the [Code Mode RFC](../../docs/rfc/implemented/feature/2026-06-15-code-mode.md) for the execution contract.

```sh
pnpm run demo:code-mode        # this overlay under the REPL (default UI)
pnpm run demo:code-mode acp    # the acp-agent example's same-shaped overlay
```

Try a task that spans several tool calls, e.g.:

> Count the lines of every `*.md` file under docs/ and write the three largest to summary.txt.

and watch the transcript: one `run_code` call, a program looping over tools, and a result the model curated instead of five round-trips of raw tool output.

## What each leaf entry demonstrates

This example is a thin leaf `cordis.yml`: it picks the swappable backends, loads one app package, and adds product tools that are intentionally outside the shared spine. The spine (sessions, system-prompt, tools, agents, invariants, `agent-loop`) and the front-door cluster (console logger, JSONL persistence, readline UI, the pre-created `main` agent) live inside the [`@deepseek-ai/dsh-stdio-demo`](../../packages/examples/stdio-demo) app and the [`@deepseek-ai/dsh-agent-spine-demo`](../../packages/examples/agent-spine-demo) bundle it loads; the leaf wires the backends and model-facing optional tools:

| Entry | Demonstrates |
|---|---|
| `hmr` (`@cordisjs/plugin-hmr`) | the dev/demo edit-reload loop — a **leaf** entry (not baked into the app) because it is Loader-only and needs `node --expose-internals`, which `demo:repl` passes |
| `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`) | the executor implementation — the swappable half of the bash seam. The model-facing `bash`/`bash_output`/`bash_kill` tool schemas (`tool-bash`) come from `agent-core`, so only the executor is a leaf choice |
| `stdio-agent` (`@deepseek-ai/dsh-stdio-demo`) | the REPL app bundle: the agent-core spine + console logger + JSONL persistence + readline UI + a pre-created `main` agent. Its config carries the model, system prompt, `persistenceRoot` (`./.sessions`), and `resumeSessionId` — so persistence and the agent are configured here, not wired as separate leaf plugins |
| `subagent`, `subagent-spawn`, `subagent-fork` | the subagent provider registry plus the two in-process backends: a fresh child and a child seeded with the parent's completed-turn prefix |
| `tool-subagent`, `tool-subagent-fork` | two model-facing `dsh-tool-subagent` loads, each bound to a different provider and exposed under a distinct tool name (`subagent`, `subagent_fork`) |
| `tool-todo` | the model-facing `todo_write` tool; writes the whole task list to the session log and renders as a checklist in stdio |
| `fs-local`, `fs-policy`, `tool-fs` | the filesystem stack: the local `ctx.fs` provider, the read-before-write/edit policy gate (on the `fs/*` event gate), and the model-facing `read`/`write`/`edit` tools. Relative paths resolve against the session workspace |

## 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.
- `tests/resume.e2e.ts` — durable continuity across processes: run 1 tells the real model a secret code and persists the turn to a temp JSONL root, then the whole context is disposed; run 2 is a fresh context over the same root that RESUMES the session id and asks the model to recall the code. The recall can only come from the rehydrated log.
- `tests/compaction.e2e.ts` — the compaction smoke: a real multi-step bash task runs with a deliberately tiny context window so the auto-compaction listener fires MID-SESSION. Verifies the WORLD — a `compact/start…end` pair landed in the real log, the surface shrank (a replace node shadowed older nodes), and the agent still produced a correct final answer after compaction.
- `tests/todo-write.e2e.ts` — a real model drives the real `todo_write` tool and the test verifies the resulting `todo/write` session event.

These self-skip without `DEEPSEEK_API_KEY`. `tests/code-mode.e2e.ts` is the with-key Code Mode proof — a real model, a two-tool task, asserting the wire tool list was exactly `[run_code]`, the `tool/code-dispatch` events landed under the parent call, and the curated answer came back. `tests/cli.e2e.ts` runs the one-shot bin with a real model and verifies its temporary file externally. The keyless Loader smokes run in the default e2e gate: `tests/keyless-smoke.e2e.ts`, `tests/code-mode-keyless-smoke.e2e.ts`, and `tests/cli-keyless-smoke.e2e.ts`; the CLI smoke mocks only the LLM boundary and asserts a real bash round trip plus persisted stream output.