c182543dd5
Per a design revision, the per-scenario snapshot fixture becomes EXACTLY the persisted session JSONL (<scenario>/session.jsonl) rather than a hand-authored llm.json. The log already holds all LLM behavior (assistant/chunk carries every StreamChunk) AND all harness behavior (tool/call, tool/result, turn/*, usage), so one artifact drives replay and doubles as a behavioral golden. llm-replay becomes replay-only (the record-tee is removed; recording is now "run the real agent once and harvest the .jsonl", done by the harness in a later commit). deriveReplayScript(events) groups assistant/chunk by (turn,step) in log order — exact because the loop makes one ctx.llm.stream() call per step and tags each chunk with the current (turn,step). The two failure modes the log can't express (a thrown stream — no terminal finish; cancel/hang — timing) use an optional replay.override.json sidecar. Hardens against a Codex review finding: a derived group is only valid if it ends in a `finish` chunk. A group without one is the fingerprint of a thrown stream() and is NOT silently replayed as a clean stop — deriveReplayScript throws, naming the (turn,step), so a missing sidecar override fails loud. Updates the unit tests (parse/derive/load helpers, sidecar override, finish- terminated grouping, HMR), the example README, and the RFC prose to the JSONL format. Two goldens (stdout transcript + re-persisted JSONL) and the harness wiring land in the next commit.
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acp-agent example
The DeepSeek Harness coding agent exposed as an Agent Client Protocol (ACP) server over JSON-RPC stdio — drive it from Zed or any other ACP client.
pnpm run demo:acp # needs DEEPSEEK_API_KEY (repo-root .env or env)
This boots @deepseek-ai/dsh-acp over the shared provider/tool core (../base.yml), with agent-loop configured with no pre-created agents (ACP session/new creates them on demand) and JSONL session persistence (so session/load works).
stdout is the protocol
This example loads no stdout logger — stdout carries the JSON-RPC frames, and any other write corrupts them. Do not add @cordisjs/plugin-logger-console or a stdio UI here. Use a stderr exporter if you need logs.
Zed configuration
Add to your Zed settings.json under agent_servers:
{
"agent_servers": {
"DeepSeek Harness": {
"command": "pnpm",
"args": ["run", "demo:acp"],
"env": { "DEEPSEEK_API_KEY": "sk-…" }
}
}
}
The editor sets each session's cwd to the project it opens; the agent's bash tools run there (see the per-session cwd note in packages/acp), so the server does not need to be launched in the workspace.
Snapshot tests (record-once / replay-deterministic)
This example is the home of the harness's snapshot tests — they boot this server as a real subprocess, drive it with a deterministic input script, and diff its normalized output against committed golden files. The model is made deterministic by src/llm-replay.ts, a function/namespace plugin that installs an llm/stream waterfall listener and short-circuits it, serving model streams reconstructed from a recorded session JSONL fixture (<scenario>/session.jsonl) — so replay needs no API key. The fixture IS the persisted session log: its assistant/chunk events carry every StreamChunk, so grouping them by (turn, step) reconstructs each stream() call (one model call per loop step). Recording is therefore "run the real agent once and harvest the .jsonl". The two failure modes not expressible as logged chunks — a pure throw before any chunk, and cancel/hang — use an optional <scenario>/replay.override.json sidecar (a ReplayEntry[] that replaces the derived script). See docs/rfc/implemented/2026-06-19-acp-snapshot-tests.md for the full design.
MVP limitations
The bridge supports N concurrent sessions per connection, each in its own workspace cwd (RFC 011). Remaining limits: text-only prompts, additionalDirectories rejected (a session operates in its single cwd), and the tool-permission gate is deferred (TODO(rfc010-permission-gate) — tools run with the executor's full authority). See packages/acp/README.md for the full contract.