dsh-session-rescue

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

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npx 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

# 1. See which sessions are broken (safe, read-only)
npx dsh-session-rescue

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

# 3. Preview the repair — nothing is written yet
npx dsh-session-rescue repair 37374e34

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

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

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

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

What it can fix

Damage	Cause	Repair
Replayed duplicate rows	crash / force-kill / write-behind replay	drop duplicates — zero loss
Synthetic closer block colliding with the real continuation	interrupt recovery + second writer	drop the synthetic block, keep your real content — zero loss
Torn final zstd frame	power loss mid-write	none needed (dsh self-heals; we tell you so)
Unreadable/garbled header	manual edits, partial writes	header reconstruction
Real seq holes (events actually missing)	forced compaction, lost writes	explicit --truncate keeps the loadable prefix; export salvages the rest

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

	dsh-session-rescue	doctor-family tools	export-family tools
Detect corruption	✅	✅	—
Repair the session so it loads & continues	✅	❌	❌
Salvage transcript when unrepairable	✅	❌	✅
Refuses unsafe writes	✅	n/a	n/a

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