dsh-replay — time-travel debugger for DeepSeek Harness agents

Replay, visualize, and diff a DeepSeek Harness session's full trajectory straight from session.jsonl.zstd — the ground-truth event log. No @deepseek-ai/dsh dependency; just Node ≥ 22.19 (its bundled zstd).

Why

Debugging an agent by scrolling the terminal only shows the last N lines. dsh's session log already contains everything — every reasoning delta, every tool call, every result, with seq + timestamps — but it's a concatenated-zstd, packed-row format nobody can read by hand. dsh-replay decodes that format and renders it as a readable timeline.

What it does

• Decode the concatenated-Zstandard container and the packed text-chunks/reasoning-chunks/tool-call-chunks rows (the exact @deepseek-ai/dsh-session wire format, re-implemented with zero deps).
• Reconstruct turns → steps → user messages → reasoning → assistant text → tool calls with results (success/error).
• Render a self-contained dark-mode HTML timeline.
• Diff two sessions turn-by-turn (where did the two runs diverge?).
• Summarize per-tool call counts, error count, and latency as JSON (--stats).

Install / run

node bin/replay.mjs <session-id> --out replay.html
# or point at a file directly
node bin/replay.mjs --file ~/.dsh/sessions/.../session.jsonl.zstd
# print a turn/tool/error summary as JSON
node bin/replay.mjs <session-id> --stats
# compare two runs
node bin/replay.mjs diff <id-a> <id-b>
# compare two runs and render a side-by-side HTML diff
node bin/replay.mjs diff <id-a> <id-b> --diff-html

Open replay.html in any browser.

Example

node bin/replay.mjs session-94b0ee6a-dbbe-4497-bf31-3d5e90a01d6a
# -> session-94b0ee6a...replay.html

Correctness

The decoder mirrors the upstream scanZstdFrames + decodeStorageRecord format. Tests cover the packed-row expansion, tool-call/result reconstruction, and the diff summarizer.

npm test

Related

• dsh-shelf — session lifecycle CLI (list/stats/export/trash/rescue).
• dsh-plugin-doctor — plugin + profile preflight.

dsh-replay — DeepSeek Harness agent 的"时间旅行调试器"

从 session.jsonl.zstd 直接回放、可视化、对比一个会话的完整轨迹。这是 dsh 的 ground-truth 事件日志，包含每次推理分片、每次工具调用、每次结果。零依赖，只需 Node ≥ 22.19。

node bin/replay.mjs <session-id> --out replay.html
node bin/replay.mjs diff <id-a> <id-b>

打开 replay.html 即可看到按 turn → step 组织的轨迹：用户消息、推理（可折叠）、回复文本、工具调用（参数 + 成功/失败结果）。