dsh-session-rescue

Fix "history unavailable for session … corrupt session log" in DeepSeek Harness — safely, with zero data loss in the common cases.

中文文档

npx github:po-et/dsh-session-rescue

If dsh greets you with any of these, this tool is for you:

• corrupt session log: seq gap in committed region at line N (expected X, got Y)
• corrupt session log: unparsable committed event at line N
• first line is not a session header
• SessionPersistenceCorruptionError after a crash, force-kill, or running two dsh instances on one session

dsh session logs are append-only and strictly validated: one duplicated write after a crash or a second process, and the whole conversation becomes permanently unloadable — even though your content is usually still all there. dsh-session-rescue diagnoses exactly what dsh's loader rejects, removes the redundant side (replayed rows, stale synthetic interrupt-closers), and rebuilds a loadable log.

Quick start

npx github:… builds from source on first run (about half a minute); later runs are cached. Once the package is on npm the shorter npx dsh-session-rescue will work too.

# 1. See which sessions are broken (safe, read-only)
npx github:po-et/dsh-session-rescue

# 2. Deep-diagnose one session (path or any unique id fragment)
npx github:po-et/dsh-session-rescue doctor 37374e34

# 3. Preview the repair — nothing is written yet
npx github:po-et/dsh-session-rescue repair 37374e34

# 4. Apply it (a timestamped backup is always kept; close dsh first)
npx github:po-et/dsh-session-rescue repair 37374e34 --apply

Can't be repaired? Get your conversation back anyway:

npx github:po-et/dsh-session-rescue export 37374e34        # salvages the transcript to Markdown
npx github:po-et/dsh-session-rescue quarantine 37374e34    # move a broken session out of dsh's sight

Using an AI agent? Just tell it: "Run npx github:po-et/dsh-session-rescue and fix my broken dsh sessions."

What it can fix

Both repair paths are pinned by regression tests modeled on the two corruption shapes reported in deepseek-harness#1497 (interrupt closers colliding with a resumed real tool result; a full tail rewritten from a recycled seq) — the tool's output matches the fixes those users validated by hand.

Why it's safe

Community experience shows naive repairs can kill a session permanently (dangling sourceEventSeqs poisoning). This tool:

1. Never touches the original without a timestamped backup sitting right next to it.
2. Validates before writing: the rebuilt log must pass seq-contiguity and sourceEventSeqs reference checks — the same invariants dsh enforces. An unsafe plan is refused, not "fixed harder".
3. Verifies after writing: the repaired file is re-scanned; if it wouldn't load, the tool tells you and the backup is untouched.
4. Preserves original bytes: kept lines are copied verbatim, never re-serialized.
5. Rebuilds the exact physical layout dsh expects (zstd frame 0 = header only).

vs. other tools

Scope & honesty

• Supports session format version 0 (current dsh developer preview), .jsonl and .jsonl.zstd, JSONL backend only. dsh is pre-1.0 with no format-compatibility promise; on an unknown version this tool refuses loudly instead of guessing.
• Repair requires dsh to be closed (or at least that session idle) — a live writer would race the swap.
• Zero dependencies. Node ≥ 22.15 (built-in zstd).

License

MIT